:root{--bg:#080909;--bg2:#0d0f10;--panel:#0b0d0d;--text:#f2f2ee;--muted:#8c9090;--dim:#6f7372;--line:rgba(255,255,255,.12);--line2:rgba(255,255,255,.07);--orange:#ff5a00;--max:1440px;--display:Saira,Inter,Arial,sans-serif;--mono:ui-monospace,SFMono-Regular,Consolas,"Liberation Mono",monospace;--header:76px;--gutter:clamp(20px,5vw,72px)}
*{box-sizing:border-box}
html{scroll-behavior:smooth;scroll-padding-top:calc(var(--header) + 16px)}
body{margin:0;background:var(--bg);color:var(--text);font-family:Inter,Arial,sans-serif;font-size:14px;line-height:1.55;-webkit-font-smoothing:antialiased;overflow-x:hidden}
a{color:inherit;text-decoration:none}
h1,h2,h3{font-family:var(--display);font-weight:700}
em{font-style:normal;color:var(--orange)}
code,kbd,pre{font-family:var(--mono)}
a:focus-visible,button:focus-visible,input:focus-visible,summary:focus-visible{outline:2px solid var(--orange);outline-offset:3px}
.sr-only{position:absolute;width:1px;height:1px;padding:0;margin:-1px;overflow:hidden;clip:rect(0,0,0,0);white-space:nowrap;border:0}
.skip-link{position:absolute;left:16px;top:-60px;z-index:60;background:var(--orange);color:#080909;padding:10px 14px;font-weight:600;font-size:12px}
.skip-link:focus{top:12px}
.no-webgl canvas{display:none}

/* ---------- header ---------- */
.site-header{height:var(--header);border-bottom:1px solid var(--line);display:flex;align-items:center;gap:36px;padding:0 var(--gutter);position:sticky;top:0;z-index:40;background:rgba(8,9,9,.92);backdrop-filter:blur(14px)}
.brand{display:flex;align-items:center;gap:10px;line-height:.82;letter-spacing:.18em;font-weight:800;flex:none}
.brand-text{display:flex;flex-direction:column}
.brand-logo{display:block;width:30px;height:auto;flex:none}
.brand-main{font-family:var(--display);font-size:22px;letter-spacing:.04em}
.brand-mark{color:var(--orange);font-size:12px;margin-left:3px}
.brand-sub{font-size:8px;letter-spacing:.55em;margin-top:7px}
.main-nav{display:flex;align-items:center;gap:26px;font-size:12.5px}
.main-nav a{color:#c5c7c6;transition:color .25s}
.main-nav a:hover,.main-nav a.active{color:#fff}
.main-nav a.active{position:relative}
.main-nav a.active:after{content:"";position:absolute;left:0;right:0;bottom:-10px;height:2px;background:var(--orange)}
.nav-soon{color:#6f7372;display:inline-flex;align-items:center;gap:6px;cursor:default}
.nav-soon em,.tag-soon{font-style:normal;font-size:9px;letter-spacing:.06em;color:#9a9e9d;background:#1a1d1d;border:1px solid #2a2e2d;padding:1px 6px;border-radius:3px}
.header-tools{margin-left:auto;display:flex;align-items:center;gap:14px}
.menu-toggle,.search-toggle{display:none;background:none;border:0;color:#fff;font:inherit;font-size:11px;letter-spacing:.1em;cursor:pointer;padding:8px}
.search-toggle svg{width:20px;height:20px;fill:none;stroke:currentColor;stroke-width:1.6}

/* ---------- buttons, chips, tags ---------- */
.button{display:inline-flex;align-items:center;gap:12px;border:1px solid #5e6261;padding:14px 20px;font-size:11px;letter-spacing:.1em;font-weight:500;transition:all .25s;background:none;color:inherit;font-family:inherit;cursor:pointer;text-transform:uppercase}
.button:hover{border-color:var(--orange);background:rgba(255,90,0,.06)}
.button span{color:var(--orange);font-size:15px}
.button-primary{border-color:rgba(255,90,0,.75)}
.button-sm{padding:10px 14px;font-size:10.5px}
.chip{display:inline-flex;align-items:center;gap:8px;border:1px solid #2f3433;border-radius:999px;padding:6px 13px;font-size:12px;color:#d0d2cf;background:transparent;font-family:inherit;cursor:pointer;transition:border-color .2s,color .2s,background .2s}
.chip:hover{border-color:var(--orange);color:#fff;background:rgba(255,90,0,.06)}
.chip.muted{color:#8c9090}
.chips{display:flex;flex-wrap:wrap;gap:10px}
.tag-level{font-size:9.5px;letter-spacing:.12em;text-transform:uppercase;color:#a8acab;border:1px solid #2f3433;padding:3px 8px;border-radius:3px;white-space:nowrap}
.level-intermediate{color:#ffb27f;border-color:rgba(255,90,0,.3)}
.level-advanced{color:#ff8a4a;border-color:rgba(255,90,0,.55)}
.eyebrow{font-size:10px;letter-spacing:.2em;color:#a8acab;display:flex;align-items:center;gap:12px}
.eyebrow>span{width:40px;height:1px;background:#6f7373}
.eyebrow-sm{font-size:10px;letter-spacing:.18em;color:#a8acab;text-transform:uppercase;display:flex;align-items:center;gap:10px;margin-bottom:12px}
.eyebrow-sm:before{content:"";width:3px;height:12px;background:var(--orange);box-shadow:5px 0 0 var(--orange)}
.index{display:block;color:var(--orange);font-size:10px;letter-spacing:.14em;margin-bottom:10px;font-family:var(--display);font-weight:600;text-transform:uppercase}
.link-arrow{color:var(--orange);font-size:12px;letter-spacing:.06em}

/* ---------- search ---------- */
.search{position:relative;display:flex;align-items:center}
.search-icon{position:absolute;left:14px;width:16px;height:16px;fill:none;stroke:#8c9090;stroke-width:1.8;pointer-events:none}
.search input{width:100%;background:#0d0f10;border:1px solid #2f3433;color:var(--text);font:inherit;outline:none;transition:border-color .2s}
.search input::placeholder{color:#7d8281}
.search input:focus{border-color:rgba(255,90,0,.7)}
.search input::-webkit-search-cancel-button{filter:invert(.6)}
.search-compact{width:230px}
.search-compact input{height:38px;padding:0 34px 0 38px;font-size:13px;border-radius:4px}
.search-compact kbd{position:absolute;right:10px;font-size:10px;color:#8c9090;border:1px solid #2f3433;border-radius:3px;padding:0 5px;pointer-events:none}
.search-compact input:focus~kbd{display:none}
.search-hero{max-width:620px;margin:0 0 20px}
.search-hero .search-icon{left:20px;width:20px;height:20px}
.search-hero input{height:62px;padding:0 64px 0 54px;font-size:16px;border-radius:8px;background:rgba(13,15,16,.92);border-color:#3a3f3e}
.search-go{position:absolute;right:10px;width:42px;height:42px;border:0;background:none;color:#c8ccca;font-size:20px;cursor:pointer;border-radius:6px}
.search-go:hover{color:var(--orange);background:rgba(255,90,0,.08)}
.search-results{position:absolute;top:calc(100% + 6px);left:0;right:0;z-index:50;list-style:none;margin:0;padding:6px;background:#0d0f10;border:1px solid #2f3433;border-radius:8px;box-shadow:0 18px 40px rgba(0,0,0,.6);max-height:min(420px,60vh);overflow:auto}
.search-compact .search-results{left:auto;width:360px}
.search-results a{display:flex;flex-direction:column;gap:2px;padding:10px 12px;border-radius:5px}
.search-results li.active a,.search-results a:hover{background:rgba(255,90,0,.08)}
.r-title{color:#fff;font-size:14px}
.r-meta{color:var(--muted);font-size:11.5px}
.search-results .empty{padding:12px;color:var(--muted);font-size:13px}
.search-results .empty a{display:inline;padding:0;color:var(--orange)}

/* ---------- layout helpers ---------- */
.section{max-width:var(--max);margin:auto;padding:88px var(--gutter);border-bottom:1px solid var(--line);position:relative}
.section:before,.section:after{content:"+";position:absolute;bottom:-.62em;font:300 18px/1 var(--display);color:#4a4f4e;pointer-events:none}
.section:before{left:10px}.section:after{right:10px}
.section-head{display:flex;justify-content:space-between;align-items:flex-end;gap:40px;margin-bottom:40px}
.section-head h2{font-size:clamp(30px,3.6vw,48px);line-height:1.02;letter-spacing:.01em;margin:0 0 10px}
.section-head p{color:var(--muted);max-width:560px;margin:0;font-size:15px}
.reveal{opacity:0;transform:translateY(16px);transition:opacity .7s ease,transform .7s ease}
.reveal.visible{opacity:1;transform:none}

/* ---------- hero ---------- */
.hero{position:relative;min-height:640px;border-bottom:1px solid var(--line);background-image:linear-gradient(rgba(255,255,255,.022) 1px,transparent 1px),linear-gradient(90deg,rgba(255,255,255,.022) 1px,transparent 1px);background-size:64px 64px;display:flex;align-items:center}
.hero-visual{position:absolute;inset:0;overflow:hidden}
.hero-visual:after{content:"";position:absolute;inset:0;pointer-events:none;background:linear-gradient(90deg,var(--bg) 0%,rgba(8,9,9,.92) 34%,rgba(8,9,9,.2) 58%,transparent 70%)}
.hero-visual canvas{width:100%;height:100%;display:block}
/* label box sits 60px above its 3D anchor; a leader line drops to an orange dot on the anchor */
.robot-label{position:absolute;left:0;top:0;z-index:2;pointer-events:none;will-change:transform;margin:-60px 0 0 -10px;height:24px;line-height:14px;padding:4px 9px;border:1px solid rgba(255,255,255,.35);background:rgba(8,9,9,.75);font-size:9.5px;letter-spacing:.16em;color:#e1e3df;white-space:nowrap}
.robot-label:after{content:"";position:absolute;left:9px;top:100%;height:36px;border-left:1px solid rgba(255,255,255,.35)}
.robot-label:before{content:"";position:absolute;left:6px;top:calc(100% + 33px);width:7px;height:7px;border-radius:50%;background:var(--orange)}
.hero-copy{position:relative;z-index:3;width:min(660px,100%);padding:84px 0 72px var(--gutter)}
.hero h1{font-size:clamp(40px,4.6vw,68px);line-height:1;letter-spacing:.005em;margin:22px 0 18px}
.hero-lead{max-width:520px;color:#b4b8b7;font-size:17px;line-height:1.6;margin:0 0 32px}
.topic-chips{list-style:none;margin:0;padding:0;display:flex;flex-wrap:wrap;gap:10px;max-width:640px}

/* ---------- category cards ---------- */
.cat-grid{display:grid;grid-template-columns:repeat(5,1fr);gap:14px}
.cat-card{position:relative;display:flex;flex-direction:column;padding:18px 18px 20px;border:1px solid var(--line);border-radius:4px;background:var(--panel);transition:border-color .3s,box-shadow .3s,background .3s;color:#9ea2a1;overflow:hidden}
.cat-card:hover{border-color:rgba(255,90,0,.55);box-shadow:0 0 26px rgba(255,90,0,.14);background:rgba(255,90,0,.03)}
.cat-art{width:100%;height:auto;aspect-ratio:160/100;color:#7d8281}
.cat-card .cat-art{width:calc(100% + 36px);margin:-18px -18px 16px;padding:10px 14px;background:#090a0a linear-gradient(rgba(255,255,255,.03) 1px,transparent 1px) 0 0/16px 16px,linear-gradient(90deg,rgba(255,255,255,.03) 1px,transparent 1px) 0 0/16px 16px;border-bottom:1px solid var(--line2)}
.cat-card h3{font-size:17px;color:#fff;margin:0 0 8px;letter-spacing:.02em}
.cat-card ul{list-style:none;margin:0 0 16px;padding:0;font-size:12.5px;line-height:1.7;color:#a8acab}
.cat-card .more{color:var(--dim)}
.cat-count{margin-top:auto;font-size:10.5px;letter-spacing:.12em;color:var(--dim);text-transform:uppercase}
.cat-card .arrow{position:absolute;right:18px;bottom:16px;color:var(--orange);transition:transform .25s}
.cat-card:hover .arrow{transform:translateX(4px)}
.start-strip{display:grid;grid-template-columns:auto auto 1fr auto;align-items:center;gap:24px;margin-top:14px;padding:20px 24px;border:1px solid var(--line);border-radius:4px;transition:border-color .3s}
.start-strip:hover{border-color:rgba(255,90,0,.55)}
.start-strip .eyebrow-sm{margin:0}
.start-strip strong{font:700 18px var(--display);letter-spacing:.02em}
.start-strip>span:nth-of-type(2){color:var(--muted)}

/* ---------- method / about ---------- */
.method-steps{list-style:none;margin:0;padding:0;display:grid;grid-template-columns:1fr 1.25fr 1fr 1fr;gap:0;border:1px solid var(--line);border-radius:4px}
.method-steps>li{padding:26px 24px;border-left:1px solid var(--line)}
.method-steps>li:first-child{border-left:0}
.method-steps h3{font-size:20px;margin:0 0 10px}
.method-steps p{color:var(--muted);margin:0}
.method-figure svg{width:100%;height:auto;display:block}
.dg-grid rect.unk{fill:#0d0f10;stroke:#1d2121;stroke-width:.5}
.dg-grid rect.free{fill:#262a2a;stroke:#1d2121;stroke-width:.5}
.dg-grid rect.occ{fill:#ff5a00;stroke:#0d0f10;stroke-width:.5}
.legend-list{list-style:none;margin:0;padding:0;display:grid;gap:14px}
.legend-list li{display:flex;gap:12px;align-items:flex-start;color:var(--muted)}
.legend-list strong{display:block;color:#fff;font-weight:600;margin-bottom:2px}
.sw{flex:none;width:14px;height:14px;margin-top:3px;border:1px solid #2f3433}
.sw-free{background:#262a2a}.sw-occ{background:var(--orange);border-color:var(--orange)}.sw-unk{background:#0d0f10}
.mini-code{margin:0 0 12px;padding:14px 16px;background:#0b0d0d;border:1px solid var(--line2);border-radius:4px;font-size:12.5px;line-height:1.7;color:#e1e3df;overflow-x:auto}

/* ---------- request a topic ---------- */
.request{display:flex;justify-content:space-between;align-items:center;gap:40px}
.request h2{font-size:clamp(28px,3vw,40px);margin:0 0 12px}
.request p{color:var(--muted);max-width:560px;margin:0;font-size:15px}
.request-action{display:flex;align-items:center;gap:22px;padding:24px 28px;border:1px solid var(--line);border-radius:4px;flex:none}
.request-action svg{width:44px;height:44px;fill:none;stroke:#cfd2d0;stroke-width:1.2;padding:9px;border:1px solid var(--line);border-radius:4px}
.request-action p{font-size:12px;margin-top:8px}
.request-inline{color:var(--muted);margin:28px 0 0}
.request-inline a{color:var(--orange)}

/* ---------- footer ---------- */
.footer{max-width:var(--max);margin:auto;padding:34px var(--gutter);display:grid;grid-template-columns:1fr 1fr auto;align-items:center;gap:40px}
.footer-brand{display:flex;align-items:center;gap:12px;line-height:.82}
.footer-brand .brand-logo{width:34px}
.footer p{color:var(--muted);margin:0}
.footer-links{display:flex;gap:22px;font-size:10px;letter-spacing:.1em;color:#aaaead}
.footer-links a:hover{color:var(--orange)}

/* ---------- learn layout ---------- */
.learn-layout{max-width:var(--max);margin:auto;display:grid;grid-template-columns:250px minmax(0,1fr);gap:44px;padding:28px var(--gutter) 80px;border-bottom:1px solid var(--line)}
.sidebar{position:sticky;top:calc(var(--header) + 20px);align-self:start;max-height:calc(100vh - var(--header) - 40px);overflow:auto;border:1px solid var(--line);border-radius:4px;padding:6px 0;scrollbar-width:thin}
.side-wrap>summary{display:none}
.side-title{margin:10px 16px 8px;font-size:10px;letter-spacing:.2em;color:#8c9090}
.side-cats,.side-cats ul{list-style:none;margin:0;padding:0}
.side-cats>li{border-top:1px solid var(--line2)}
.side-cats summary{list-style:none;cursor:pointer;padding:10px 16px;font-size:13px;color:#d0d2cf;display:flex;align-items:center;gap:10px}
.side-cats summary::-webkit-details-marker{display:none}
.side-cats summary:before{content:"";width:6px;height:6px;border:1px solid #6f7372;border-radius:50%;flex:none}
.side-cats summary:after{content:"";margin-left:auto;width:6px;height:6px;border-right:1px solid #8c9090;border-bottom:1px solid #8c9090;transform:rotate(45deg) translateY(-2px);transition:transform .2s}
.side-cats details[open]>summary:after{transform:rotate(-135deg) translateY(-2px)}
.side-cats summary.on{color:#fff}
.side-cats summary.on:before{background:var(--orange);border-color:var(--orange)}
.side-cats ul{padding:0 0 10px 30px;border-left:1px solid var(--line2);margin-left:19px}
.side-cats ul a{display:flex;align-items:center;gap:8px;padding:5px 10px;font-size:12.5px;color:#b4b8b7;border-radius:3px}
.side-cats ul a:hover{color:#fff;background:rgba(255,255,255,.03)}
.side-cats ul a.muted{color:#7d8281}
.side-cats ul a[aria-current]{color:#fff;background:rgba(255,90,0,.1);box-shadow:inset 2px 0 0 var(--orange)}
.side-cats .side-all{color:#8c9090;font-size:11px;letter-spacing:.08em;text-transform:uppercase}
.side-cats .tag-soon{margin-left:auto;font-size:8px;padding:0 5px}
.breadcrumb ol{list-style:none;margin:0 0 26px;padding:0;display:flex;flex-wrap:wrap;gap:8px;font-size:12px;color:#8c9090}
.breadcrumb li+li:before{content:"›";margin-right:8px;color:#4a4f4e}
.breadcrumb a:hover{color:var(--orange)}
.breadcrumb [aria-current]{color:#e1e3df}
.page-head h1,.c-head h1{font-size:clamp(34px,4.4vw,58px);line-height:1;letter-spacing:.01em;margin:4px 0 18px}
.c-intro{color:#b4b8b7;font-size:16.5px;line-height:1.7;max-width:760px;margin:0 0 20px}
.start-card{display:grid;grid-template-columns:1fr 320px;gap:30px;align-items:center;padding:28px 30px;border:1px solid var(--line);border-radius:4px;margin:30px 0 36px;transition:border-color .3s}
.start-card:hover{border-color:rgba(255,90,0,.55)}
.start-card h2{font-size:28px;margin:0 0 8px}
.start-card p{color:var(--muted);margin:0 0 14px}
.learn-main .cat-grid{grid-template-columns:repeat(auto-fill,minmax(210px,1fr))}
.cat-head{display:grid;grid-template-columns:1fr 240px;gap:30px;align-items:center}
.cat-head .cat-art{color:#8a8f8d}
.cat-stats{font-size:11px;letter-spacing:.12em;text-transform:uppercase;color:var(--dim);margin:0}
.concept-list{list-style:none;margin:26px 0 0;padding:0;border-top:1px solid var(--line)}
.concept-list li{display:grid;grid-template-columns:44px 1fr auto 130px;gap:20px;align-items:center;padding:18px 12px;border-bottom:1px solid var(--line);transition:background .4s}
.concept-list li.highlight{background:rgba(255,90,0,.07);box-shadow:inset 2px 0 0 var(--orange)}
.cl-num{font:600 12px var(--display);color:var(--orange)}
.concept-list h2{font-size:17px;margin:0 0 3px;letter-spacing:.02em}
.concept-list h2 a:hover{color:var(--orange)}
.concept-list p{margin:0;color:var(--muted)}
.cl-action{text-align:right;color:var(--orange);font-size:12px;letter-spacing:.06em}
.cl-action.muted{color:#7d8281}

/* ---------- concept page ---------- */
.c-head{display:grid;grid-template-columns:minmax(0,1fr) 340px;gap:32px;align-items:start;padding-bottom:28px;border-bottom:1px solid var(--line)}
.c-cat{display:inline-flex;align-items:center;gap:10px;font-size:11px;letter-spacing:.16em;color:var(--orange);text-transform:uppercase;margin-bottom:14px}
.c-cat:before{content:"";width:3px;height:12px;background:var(--orange);box-shadow:5px 0 0 var(--orange)}
.c-meta{display:flex;align-items:center;gap:14px;font-size:12px;color:var(--dim)}
.c-stack{border:1px solid var(--line);border-radius:4px;padding:18px 20px;background:var(--panel)}
.dg-stack{display:grid;grid-template-columns:140px 1fr;gap:20px;align-items:center}
.dg-stack svg{width:100%;height:auto}
.dg-stack ol{list-style:none;margin:0;padding:0;display:grid;gap:9px;font-size:12.5px;color:#8c9090}
.dg-stack li{display:flex;align-items:center;gap:10px}
.dg-stack li:before{content:"";width:6px;height:6px;border-radius:50%;border:1px solid #5a605e}
.dg-stack li.on{color:#fff;font-weight:600}
.dg-stack li.on:before{background:var(--orange);border-color:var(--orange)}
.c-body{display:grid;grid-template-columns:repeat(2,minmax(0,1fr));gap:20px;margin-top:28px}
.c-sec{grid-column:1/-1;border:1px solid var(--line);border-radius:4px;padding:28px;background:var(--panel);min-width:0}
.c-half{grid-column:auto}
.c-h{font-size:22px;letter-spacing:.02em;margin:0 0 10px}
.c-lead{color:#a9adad;margin:0 0 22px;max-width:720px;font-size:14.5px;line-height:1.7}
.c-why{display:grid;grid-template-columns:minmax(0,.9fr) minmax(0,2fr);gap:28px;align-items:start}
.c-why .c-lead{margin:0}
.c-points{list-style:none;margin:0;padding:0;display:grid;grid-template-columns:repeat(4,1fr);gap:12px}
.c-points li{border:1px solid var(--line2);border-radius:4px;padding:16px;display:flex;flex-direction:column;gap:6px;background:rgba(255,255,255,.012)}
.c-point-icon{width:26px;height:26px;color:var(--orange);margin-bottom:6px}
.c-points strong{font-size:13.5px}
.c-points span{color:var(--muted);font-size:12.5px;line-height:1.5}
.c-fig{margin:0}
.c-fig figcaption{color:var(--muted);font-size:13px;margin-top:18px;padding-top:14px;border-top:1px dashed var(--line);max-width:760px}
.icon,.dg-icon{width:22px;height:22px}

/* tiered diagram */
.dg-tiers{display:flex;flex-direction:column;align-items:stretch}
.dg-tier{display:grid;grid-template-columns:110px 1fr;gap:14px;align-items:center}
.dg-tier-label{font-size:9.5px;letter-spacing:.16em;color:#7d8281;text-transform:uppercase;text-align:right}
.dg-row{display:flex;flex-wrap:wrap;gap:8px;justify-content:center}
.dg-box{flex:1 1 0;min-width:0;max-width:240px;overflow-wrap:anywhere;border:1px solid #3a3f3e;border-radius:4px;padding:9px 10px;text-align:center;background:#0f1111}
.dg-box strong{display:block;font-size:12.5px;font-weight:600;font-family:var(--mono)}
.dg-tier:first-child .dg-box strong,.dg-tier .dg-box.accent strong,.dg-tier:nth-child(n+7) .dg-box strong{font-family:Inter,Arial,sans-serif}
.dg-box span{display:block;font-size:11px;color:var(--muted);margin-top:2px}
.dg-box.accent{border-color:var(--orange);background:rgba(255,90,0,.1);box-shadow:0 0 18px rgba(255,90,0,.15)}
.dg-link{height:26px;margin-left:124px;position:relative}
.dg-link:before{content:"";position:absolute;left:50%;top:2px;bottom:6px;border-left:1px dashed rgba(255,90,0,.7)}
.dg-link:after{content:"";position:absolute;left:calc(50% - 4px);bottom:2px;border:4px solid transparent;border-top:5px solid var(--orange);border-bottom:0}

/* pipeline diagram */
.dg-pipe{list-style:none;margin:0;padding:0;display:flex;align-items:stretch}
.dg-step{flex:1 1 0;min-width:0;border:1px solid #3a3f3e;border-radius:4px;padding:14px 10px;text-align:center;background:#0f1111;display:flex;flex-direction:column;align-items:center;gap:4px}
.dg-step .dg-icon{color:var(--orange);margin-bottom:4px}
.dg-step strong{font-size:12.5px}
.dg-step span{font-size:11px;color:var(--muted)}
.dg-edge{flex:0 0 74px;display:flex;flex-direction:column;justify-content:center;align-items:center;position:relative}
.dg-edge:before{content:"";position:absolute;left:4px;right:8px;top:50%;border-top:1px dashed rgba(255,90,0,.75)}
.dg-edge:after{content:"";position:absolute;right:3px;top:calc(50% - 4px);border:4px solid transparent;border-left:5px solid var(--orange);border-right:0}
.dg-edge code{position:relative;top:-14px;font-size:10px;color:#ffb27f;background:var(--panel);padding:0 3px;white-space:nowrap;max-width:100%;overflow:hidden;text-overflow:ellipsis}

/* code example */
.code{border:1px solid var(--line);border-radius:4px;overflow:hidden;background:#090b0b}
.code-bar{display:flex;align-items:center;gap:12px;padding:8px 10px 8px 14px;border-bottom:1px solid var(--line);font-size:12px;color:#c8ccca;font-family:var(--mono)}
.code-lang{font-size:10px;letter-spacing:.1em;text-transform:uppercase;color:#7d8281}
.code-copy{margin-left:auto;background:none;border:1px solid #2f3433;color:#c8ccca;font:inherit;font-size:11px;padding:4px 10px;border-radius:3px;cursor:pointer}
.code-copy:hover{border-color:var(--orange);color:#fff}
.code pre{margin:0;padding:16px 18px;overflow-x:auto;font-size:12px;line-height:1.65;color:#e1e3df}
.tk-kw{color:#ff8a4a}.tk-str{color:#a7d7a0}.tk-com{color:#6f7a78}.tk-num{color:#e8c48a}.tk-fn{color:#8fc3ff}.tk-self{color:#c9a5f7}
.code-notes{margin:18px 0 0;display:grid;gap:10px}
.code-notes div{display:grid;grid-template-columns:minmax(110px,38%) 1fr;gap:14px;font-size:13px}
.code-notes dt code{overflow-wrap:anywhere}
.code-notes dt code{color:#ffb27f;font-size:12px}
.code-notes dd{margin:0;color:var(--muted)}

/* core concepts, related, next */
.c-terms{margin:0;display:grid;grid-template-columns:repeat(4,1fr);gap:12px}
.c-terms div{border:1px solid var(--line2);border-radius:4px;padding:14px;background:rgba(255,255,255,.012)}
.c-terms dt{margin-bottom:10px}
.c-terms dd{margin:0;color:var(--muted);font-size:12.5px}
.c-foot{display:grid;grid-template-columns:minmax(0,1.4fr) minmax(0,1fr);gap:20px;margin-top:20px}
.c-related{grid-column:auto}
.c-next{display:flex;flex-direction:column;gap:6px;border:1px solid var(--line);border-radius:4px;padding:24px 26px;background:var(--panel);transition:border-color .3s}
.c-next:hover{border-color:rgba(255,90,0,.55)}
.c-next strong{font:700 20px var(--display)}
.c-next>span:nth-of-type(2){color:var(--muted)}

/* ---------- responsive ---------- */
@media(max-width:1280px){
  .main-nav{gap:18px}
  .search-compact{width:190px}
  .cat-grid{grid-template-columns:repeat(4,1fr)}
  .c-points,.c-terms{grid-template-columns:repeat(2,1fr)}
}
@media(max-width:1100px){
  .get-started{display:none}
  .cat-grid{grid-template-columns:repeat(3,1fr)}
  .method-steps{grid-template-columns:1fr 1fr}
  .method-steps>li:nth-child(3){border-left:0}
  .method-steps>li:nth-child(n+3){border-top:1px solid var(--line)}
  .c-why{grid-template-columns:1fr}
  .c-body{grid-template-columns:minmax(0,1fr)}
  .c-half{grid-column:1/-1}
}
@media(max-width:1000px){
  .learn-layout{grid-template-columns:minmax(0,1fr);gap:20px;padding-top:20px}
  .sidebar{position:static;max-height:none}
  .side-wrap>summary{display:flex;list-style:none;align-items:center;justify-content:space-between;padding:12px 16px;cursor:pointer;font-size:12px;letter-spacing:.08em;text-transform:uppercase;color:#d0d2cf}
  .side-wrap>summary::-webkit-details-marker{display:none}
  .side-wrap>summary:after{content:"+";color:var(--orange);font-size:16px}
  .side-wrap[open]>summary:after{content:"−"}
  .c-head{grid-template-columns:minmax(0,1fr)}
  .c-foot{grid-template-columns:minmax(0,1fr)}
  .dg-pipe{flex-direction:column;align-items:center}
  .dg-step{width:100%;max-width:340px;flex:none;flex-direction:row;text-align:left;gap:12px}
  .dg-step span{margin-left:auto;text-align:right}
  .dg-step .dg-icon{margin:0}
  .dg-edge{flex:none;height:44px;width:100%;max-width:340px}
  .dg-edge:before{left:50%;right:auto;top:4px;bottom:8px;border-top:0;border-left:1px dashed rgba(255,90,0,.75)}
  .dg-edge:after{right:auto;left:calc(50% - 4px);top:auto;bottom:3px;border:4px solid transparent;border-top:5px solid var(--orange);border-bottom:0}
  .dg-edge code{top:0;left:22px;align-self:center;transform:translateX(50%)}
}
@media(max-width:900px){
  :root{--header:64px}
  .site-header{gap:16px}
  .menu-toggle,.search-toggle{display:block}
  .main-nav{display:none;position:absolute;top:var(--header);left:0;right:0;background:#090a0a;border-bottom:1px solid var(--line);padding:22px var(--gutter);flex-direction:column;align-items:flex-start;gap:16px;font-size:14px}
  .main-nav.open{display:flex}
  .main-nav a.active:after{bottom:-4px}
  .header-tools .search-compact{display:none;position:absolute;top:var(--header);left:0;right:0;width:auto;padding:12px var(--gutter);background:#090a0a;border-bottom:1px solid var(--line)}
  .site-header.search-open .search-compact{display:flex}
  .search-compact .search-icon{left:calc(var(--gutter) + 14px)}
  .search-compact kbd{display:none}
  .search-compact .search-results{left:var(--gutter);right:var(--gutter);width:auto}
  .hero{flex-direction:column;align-items:stretch;min-height:0}
  .hero-copy{order:1;padding:56px var(--gutter) 24px}
  .hero-visual{position:relative;order:2;height:380px}
  .hero-visual:after{background:linear-gradient(180deg,var(--bg) 0%,transparent 22%,transparent 80%,var(--bg) 100%)}
  .section-head{display:block}
  .section-head .button{margin-top:18px}
  .cat-grid,.learn-main .cat-grid{grid-template-columns:repeat(2,1fr)}
  .start-strip{grid-template-columns:1fr;gap:8px}
  .request{flex-direction:column;align-items:flex-start}
  .footer{grid-template-columns:1fr 1fr}
  .footer-links{grid-column:1/-1}
  .start-card{grid-template-columns:1fr}
  .cat-head{grid-template-columns:1fr}
  .cat-head .cat-art{display:none}
  .concept-list li{grid-template-columns:34px 1fr;gap:6px 14px}
  .concept-list .tag-level{grid-column:2;justify-self:start}
  .concept-list .cl-action{grid-column:2;text-align:left}
}
@media(max-width:600px){
  .section{padding-top:64px;padding-bottom:64px}
  .hero h1{font-size:36px}
  .hero-lead{font-size:15px}
  .search-hero input{height:54px;font-size:15px}
  .hero-visual{height:320px}
  .robot-label{font-size:8.5px;padding:4px 7px}
  .cat-grid,.learn-main .cat-grid{grid-template-columns:1fr}
  .method-steps{grid-template-columns:1fr}
  .method-steps>li{border-left:0!important;border-top:1px solid var(--line)}
  .method-steps>li:first-child{border-top:0}
  .c-sec{padding:20px 16px}
  .c-points,.c-terms{grid-template-columns:1fr}
  .dg-tier{grid-template-columns:1fr;gap:6px}
  .dg-tier-label{text-align:center}
  .dg-link{margin-left:0}
  .dg-box{min-width:calc(50% - 4px)}
  .dg-stack{grid-template-columns:110px 1fr}
  .code-notes div{grid-template-columns:1fr;gap:2px}
  .request-action{flex-direction:column;align-items:flex-start;width:100%}
  .footer{grid-template-columns:1fr}
  .footer-links{grid-column:auto;flex-wrap:wrap}
}
@media(prefers-reduced-motion:reduce){
  html{scroll-behavior:auto}
  .reveal{opacity:1;transform:none;transition:none}
  *,*:before,*:after{transition-duration:0s!important;animation-duration:0s!important}
}

/* ---------- concept page: graph, sequence and timeline diagrams ---------- */
.dg-scroll{overflow-x:auto;scrollbar-width:thin;padding-bottom:4px}
.dg-graph,.dg-seq{width:100%;height:auto;display:block;margin:0 auto}
.dg-graph .flow{stroke:#ff5a00;stroke-width:1.4;stroke-dasharray:5 5;animation:flow 1.2s linear infinite}
@keyframes flow{to{stroke-dashoffset:-20}}
.gd-node rect{fill:#0f1111;stroke:#5a605e}
.gd-hw rect{fill:#0f1111;stroke:#3a3f3e;stroke-dasharray:3 3}
.gd-topic rect{fill:rgba(255,90,0,.08);stroke:rgba(255,90,0,.75)}
.gd-label{fill:#f2f2ee;font:600 13px var(--mono);text-anchor:middle}
.gd-topic .gd-label{fill:#ffb27f}
.gd-hw .gd-label{fill:#a8acab}
.gd-sub{fill:#8c9090;font:11px Inter,Arial,sans-serif;text-anchor:middle}
.sq-actor rect{fill:#0f1111;stroke:#5a605e}
.sq-life{stroke:#3a3f3e;stroke-dasharray:4 5}
.sq-msg line{stroke-width:1.4}
.sq-request line{stroke:#ff5a00}
.sq-response line{stroke:#c8ccca;stroke-dasharray:6 4}
.sq-feedback line{stroke:#ff5a00;stroke-dasharray:2 4;stroke-opacity:.8}
.sq-text{fill:#e1e3df;font:12px var(--mono);text-anchor:middle}
.sq-feedback .sq-text{fill:#ffb27f}
.sq-note rect{fill:#151818;stroke:#2f3433}
.dg-events{list-style:none;margin:0;padding:0;display:grid;grid-template-columns:repeat(2,minmax(0,1fr));gap:12px}
.dg-events li{display:grid;grid-template-columns:34px 1fr;gap:12px;border:1px solid var(--line2);border-radius:4px;padding:16px;background:rgba(255,255,255,.012)}
.ev-num{font:600 12px var(--display);color:var(--orange);padding-top:2px}
.dg-events strong{display:block;font-size:14px;margin-bottom:4px}
.dg-events p{margin:0 0 10px;color:var(--muted);font-size:13px}
.chips-sm{gap:6px}
.chips-sm .chip{font-size:11px;padding:3px 10px}

/* ---------- concept page: steps, real-world example, try it, mistakes ---------- */
.steplist{list-style:none;margin:0;padding:0;counter-reset:step;display:grid;gap:0}
.steplist li{counter-increment:step;display:grid;grid-template-columns:34px 1fr;column-gap:12px;padding:12px 0;border-top:1px solid var(--line2)}
.steplist li:first-child{border-top:0}
.steplist li:before{content:counter(step,decimal-leading-zero);grid-row:span 2;font:600 12px var(--display);color:var(--orange);padding-top:2px}
.steplist strong{font-size:14px}
.steplist span{color:var(--muted);font-size:13.5px}
.c-example{border-color:rgba(255,90,0,.35);background:linear-gradient(180deg,rgba(255,90,0,.045),transparent 60%),var(--panel)}
.ex-head{display:flex;gap:16px;align-items:flex-start}
.ex-icon{width:34px;height:34px;flex:none;color:var(--orange);padding:6px;border:1px solid rgba(255,90,0,.4);border-radius:4px}
.ex-scenario{margin:0 0 20px;padding:10px 14px;border-left:2px solid #3a3f3e;color:#a8acab;font-size:13px;background:rgba(255,255,255,.015)}
.ex-p{color:#c8ccca;font-size:14.5px;line-height:1.75;max-width:820px;margin:0 0 14px}
.ex-takeaway{margin:18px 0 0;padding-top:14px;border-top:1px dashed var(--line);color:#e1e3df;display:flex;gap:14px;align-items:baseline}
.ex-takeaway strong{flex:none;font-size:10px;letter-spacing:.16em;text-transform:uppercase;color:var(--orange)}
.c-example .c-fig{margin-bottom:18px}
.try-note{color:var(--muted);font-size:13px;margin:-8px 0 14px}
.term-lines{list-style:none;margin:0;padding:14px 18px;display:grid;gap:10px;overflow-x:auto}
.term-lines li{display:flex;flex-wrap:wrap;column-gap:16px;row-gap:2px;align-items:baseline}
.term-lines code{font-size:12.5px;color:#e1e3df;white-space:pre}
.term-prompt{color:var(--orange);margin-right:4px}
.term-note{font-family:var(--mono);font-size:12px;color:#6f7a78}
.mistakelist{list-style:none;margin:0;padding:0;display:grid;grid-template-columns:repeat(2,minmax(0,1fr));gap:12px}
.mistakelist li{display:flex;flex-direction:column;gap:4px;padding:14px 16px 14px 40px;border:1px solid var(--line2);border-radius:4px;position:relative}
.mistakelist li:before{content:"!";position:absolute;left:14px;top:14px;width:16px;height:16px;border-radius:50%;border:1px solid #ff8a4a;color:#ff8a4a;font:700 10px/15px Inter,sans-serif;text-align:center}
.mistakelist strong{font-size:14px}
.mistakelist span{color:var(--muted);font-size:13px}
@media(max-width:900px){
  .dg-events,.mistakelist{grid-template-columns:1fr}
}
@media(prefers-reduced-motion:reduce){.dg-graph .flow{animation:none}}
@media(max-width:700px){.dg-scroll:after{content:"← Scroll sideways to see the full diagram →";display:block;position:sticky;left:0;margin-top:8px;font-size:11px;color:var(--dim);text-align:center}}

/* interface definition files */
.dg-files{display:grid;grid-template-columns:repeat(auto-fit,minmax(220px,1fr));gap:12px}
.dg-file{border:1px solid #3a3f3e;border-radius:4px;background:#090b0b;display:flex;flex-direction:column;min-width:0}
.dg-file-head{display:flex;align-items:center;gap:10px;padding:9px 12px;border-bottom:1px solid var(--line)}
.dg-file-head code{font-size:12.5px;color:#fff;overflow-wrap:anywhere}
.dg-file-head span{margin-left:auto;font-size:9.5px;letter-spacing:.12em;text-transform:uppercase;color:#ffb27f;border:1px solid rgba(255,90,0,.4);border-radius:3px;padding:1px 6px}
.dg-part{padding:10px 12px;position:relative}
.dg-part-label{display:block;font-size:9.5px;letter-spacing:.14em;text-transform:uppercase;color:var(--orange);margin-bottom:4px}
.dg-part pre{margin:0;font-size:12px;line-height:1.7;color:#e1e3df;white-space:pre;overflow-x:auto}
.dg-sep{padding:0 12px;font-family:var(--mono);font-size:12px;color:#6f7372;border-top:1px dashed #2f3433;border-bottom:1px dashed #2f3433;line-height:22px}
.dg-file-note{margin:auto 0 0;padding:10px 12px;border-top:1px solid var(--line2);font-size:12px;color:var(--muted)}

/* thread timelines (executors) */
.dg-lanes{display:grid;grid-template-columns:minmax(0,1fr);gap:22px}
.dg-lane{margin:0;min-width:0}
.dg-lane figcaption{display:flex;align-items:center;gap:10px;font-size:13px;font-weight:600;margin-bottom:8px}
.ln-verdict{width:20px;height:20px;border-radius:50%;display:inline-flex;align-items:center;justify-content:center;font-size:11px}
.dg-lane.bad .ln-verdict{border:1px solid #ff8a4a;color:#ff8a4a}
.dg-lane.good .ln-verdict{background:var(--orange);color:#080909}
.dg-lane svg{width:100%;height:auto;display:block}
.dg-lane p{margin:6px 0 0;color:var(--muted);font-size:13px}
.ln-track{fill:#0b0d0d;stroke:#1d2121}
.ln-label{fill:#8c9090;font:11px var(--mono);text-anchor:end}
.ln-axis{fill:#6f7372;font:10px var(--mono);text-anchor:middle}
.ln-due{stroke:rgba(255,90,0,.35);stroke-dasharray:2 4}
.ln-mark{fill:var(--orange)}
.ln-slow rect{fill:#262a2a;stroke:#4a4f4e}
.ln-slow text{fill:#d0d2cf;font:11px Inter,sans-serif;text-anchor:middle}
.ln-timer rect{fill:var(--orange)}
.ln-late rect{fill:rgba(255,90,0,.12);stroke:#ff8a4a;stroke-dasharray:3 2}
.ln-timer text,.ln-late text{fill:#080909;font:600 10px Inter,sans-serif;text-anchor:middle}
.ln-late text{fill:#ff8a4a}

/* QoS compatibility grids */
.dg-matrices{display:grid;grid-template-columns:repeat(auto-fit,minmax(280px,1fr));gap:18px}
.dg-matrix{border-collapse:collapse;width:100%;font-size:13px}
.dg-matrix caption{text-align:left;font:600 15px var(--display);letter-spacing:.02em;padding-bottom:10px}
.dg-matrix th,.dg-matrix td{border:1px solid #2a2e2d;padding:10px 12px;text-align:center}
.dg-matrix thead th{font-family:var(--mono);font-size:12px;color:#e1e3df;font-weight:500;background:#0f1111}
.dg-matrix thead th:first-child{text-align:left;font-family:Inter,sans-serif;font-size:10px;color:var(--dim);line-height:1.5}
.dg-matrix thead th:first-child span{display:block}
.dg-matrix tbody th{font-family:var(--mono);font-size:12px;color:#e1e3df;font-weight:500;text-align:left;background:#0f1111}
.dg-matrix td.ok{color:#ffb27f;background:rgba(255,90,0,.08)}
.dg-matrix td.no{color:#6f7372}

/* static graph edges (trees) */
.dg-graph .edge{stroke:#8a8f8d;stroke-width:1.2}

/* interactive 3D frame tree */
.frames3d{position:relative;height:460px;border:1px solid var(--line);border-radius:4px;overflow:hidden;background:#090b0b linear-gradient(rgba(255,255,255,.02) 1px,transparent 1px) 0 0/32px 32px}
.frames3d canvas{width:100%;height:100%;display:block;cursor:grab}
.frames3d canvas:active{cursor:grabbing}
.frame-label{position:absolute;left:0;top:0;pointer-events:none;font:11px var(--mono);color:#e1e3df;background:rgba(8,9,9,.75);border:1px solid #3a3f3e;padding:1px 6px;border-radius:3px;margin:-26px 0 0 6px;white-space:nowrap;will-change:transform}
.frame-label.tote{color:#ffb27f;border-color:rgba(255,90,0,.5)}
.frames-readout{position:absolute;right:12px;top:12px;background:rgba(8,9,9,.85);border:1px solid var(--line);border-radius:4px;padding:10px 12px;font-size:12px;min-width:250px}
.frames-title{display:block;font-size:9.5px;letter-spacing:.14em;text-transform:uppercase;color:var(--muted);margin-bottom:6px}
.frames-readout dl{margin:0;display:grid;gap:4px}
.frames-readout dl div{display:grid;grid-template-columns:92px 1fr;gap:8px}
.frames-readout dt{font-family:var(--mono);color:#a8acab}
.frames-readout dd{margin:0;font-family:var(--mono);color:#fff;white-space:pre;font-variant-numeric:tabular-nums}
.frames-readout .fixed dt,.frames-readout .fixed dd{color:#ffb27f}
.frames-hint{position:absolute;left:12px;bottom:10px;margin:0;font-size:11px;color:var(--dim)}
.frames3d.no-webgl:after{content:"The interactive 3D view needs WebGL.";position:absolute;inset:0;display:flex;align-items:center;justify-content:center;color:var(--muted)}
@media(max-width:700px){
  .frames3d{height:auto;display:flex;flex-direction:column}
  .frames3d canvas{height:320px}
  .frames-readout{position:static;margin:0;border:0;border-top:1px solid var(--line);border-radius:0;min-width:0}
  .frames-hint{display:none}
}
.frame-label[data-frame="map"]{margin:-26px 0 0 -52px}
.frame-label[data-frame="laser"]{margin:-28px 0 0 -58px}
.frame-label[data-frame="base_link"]{margin:8px 0 0 8px}

/* comparison tables and formulas */
.table-wrap{overflow-x:auto;border:1px solid var(--line);border-radius:4px}
.cmp-table{width:100%;border-collapse:collapse;font-size:13px;min-width:560px}
.cmp-table th,.cmp-table td{padding:11px 14px;text-align:left;border-bottom:1px solid var(--line2);vertical-align:top}
.cmp-table thead th{font-size:10px;letter-spacing:.14em;text-transform:uppercase;color:var(--muted);font-weight:500;background:#0f1111}
.cmp-table tbody th{font-weight:600;color:#fff;white-space:nowrap}
.cmp-table td{color:#b4b8b7}
.cmp-table tbody tr:last-child>*{border-bottom:0}
.table-note{color:var(--muted);font-size:13px;margin:12px 0 0}
.c-formulas{margin:0;display:grid;gap:10px}
.c-formulas div{display:grid;grid-template-columns:minmax(0,1fr) minmax(0,1.3fr);gap:20px;align-items:center;padding:14px 16px;border:1px solid var(--line2);border-radius:4px;background:rgba(255,255,255,.012)}
.c-formulas dt code{font-size:15px;color:#ffb27f;overflow-wrap:anywhere}
.c-formulas dd{margin:0;color:#b4b8b7;font-size:13.5px}

/* plots */
.dg-plot{width:100%;height:auto;display:block;margin:0 auto}
.pl-line{fill:none;stroke:var(--orange);stroke-width:2.2}
.pl-axis{stroke:#5a605e}
.pl-grid{stroke:#1d2121}
.pl-tick{fill:#8c9090;font:11px var(--mono)}
.pl-label{fill:#a8acab;font:11px Inter,sans-serif}
.pl-mark{stroke:#c8ccca;stroke-dasharray:3 4;stroke-opacity:.5}
.pl-mark-label{fill:#c8ccca;font:10.5px var(--mono)}
.pl-band{fill:rgba(255,90,0,.08)}
.pl-band-label{fill:#ffb27f;font:10.5px Inter,sans-serif;text-anchor:middle}

/* interactive algorithm visualizers */
.viz{border:1px solid var(--line);border-radius:4px;background:#090b0b;padding:14px}
.viz-bar{display:flex;flex-wrap:wrap;gap:10px;justify-content:space-between;align-items:center;margin-bottom:12px}
.viz-seg{display:inline-flex;flex-wrap:wrap;border:1px solid #2f3433;border-radius:5px;overflow:hidden}
.viz-seg button{background:none;border:0;border-left:1px solid #2f3433;color:#b4b8b7;font:inherit;font-size:12.5px;padding:7px 12px;cursor:pointer}
.viz-seg button:first-child{border-left:0}
.viz-seg button[aria-pressed=true]{background:rgba(255,90,0,.14);color:#fff;box-shadow:inset 0 -2px 0 var(--orange)}
.viz-actions{display:flex;flex-wrap:wrap;gap:8px;align-items:center}
.viz-actions button{background:none;border:1px solid #2f3433;color:#e1e3df;font:inherit;font-size:12px;padding:7px 12px;border-radius:4px;cursor:pointer}
.viz-actions button:hover,.viz-seg button:hover{border-color:var(--orange);color:#fff}
.viz-check{display:inline-flex;gap:6px;align-items:center;font-size:12px;color:var(--muted)}
.viz-check input{accent-color:var(--orange)}
.viz-canvas{width:100%;display:flex;justify-content:center}
.viz-canvas canvas{display:block;touch-action:none;border-radius:3px}
.viz-stats{display:flex;flex-wrap:wrap;gap:8px 22px;margin-top:12px;font-size:12.5px;color:var(--muted)}
.viz-stats b{color:#fff;font-family:var(--mono);font-weight:500}
.viz-compare{margin-top:12px;border-collapse:collapse;font-size:12px;width:100%;max-width:520px}
.viz-compare caption{text-align:left;font-size:10px;letter-spacing:.14em;text-transform:uppercase;color:var(--dim);padding-bottom:6px}
.viz-compare th,.viz-compare td{padding:6px 10px;border-bottom:1px solid var(--line2);text-align:left}
.viz-compare th{color:var(--dim);font-weight:500}
.viz-compare td{font-family:var(--mono);color:#c8ccca}
.viz-compare tr.on td{color:#ffb27f}
.viz-compare:has(tbody:empty){display:none}
.viz-hint{margin:10px 0 0;font-size:12px;color:var(--dim)}
@media(max-width:600px){.c-formulas div{grid-template-columns:1fr;gap:6px}}

.learn-main{min-width:0}

/* copyright row */
.footer .footer-legal{grid-column:1/-1;margin:0;padding-top:20px;border-top:1px solid var(--line);font-size:12px;color:var(--dim)}

/* unavailable items: not clickable, and they say so on hover or keyboard focus */
[data-tip]{position:relative;cursor:not-allowed}
[data-tip]:hover::after,[data-tip]:focus-visible::after{content:attr(data-tip);position:absolute;left:50%;bottom:calc(100% + 8px);transform:translateX(-50%);z-index:70;pointer-events:none;white-space:pre;text-align:center;font:500 11px/1.5 Inter,Arial,sans-serif;letter-spacing:.02em;color:#f2f2ee;background:#1a1d1d;border:1px solid #3a3f3e;border-radius:4px;padding:6px 9px;box-shadow:0 6px 18px rgba(0,0,0,.5)}
.side-cats ul [data-tip]:hover::after,.side-cats ul [data-tip]:focus-visible::after{left:auto;right:6px;transform:none;bottom:auto;top:50%;transform:translateY(-50%);margin-top:0}
.search-results [data-tip]:hover::after{left:auto;right:10px;transform:none;bottom:auto;top:50%;transform:translateY(-50%);margin-top:0}
.nav-soon[data-tip]:hover::after,.nav-soon[data-tip]:focus-visible::after{bottom:auto;top:calc(100% + 10px)}
.side-cats ul span.muted{display:flex;align-items:center;gap:8px;padding:5px 10px;font-size:12.5px;color:#7d8281;border-radius:3px}
.search-results .r-row{display:flex;flex-direction:column;gap:2px;padding:10px 12px;border-radius:5px}
.search-results li.disabled .r-title{color:#8c9090}
.search-results li.disabled.active .r-row{background:rgba(255,255,255,.03)}
.c-next.soon{opacity:.75}
.c-next.soon .link-arrow{color:var(--muted)}

/* range slider in visualizers */
.viz-range{display:inline-flex;align-items:center;gap:10px;font-size:12.5px;color:var(--muted)}
.viz-range input{accent-color:var(--orange);width:160px}
.viz-range b{color:#fff;font-family:var(--mono);font-weight:500;min-width:4em}
/* trajectory drawings and hand-drawn figures */
.dg-traj,.dg-figure{width:100%;height:auto;display:block;margin:0 auto;max-width:760px}
.dg-figure text{font:12px Inter,Arial,sans-serif;fill:#c8ccca}
.dg-figure .fig-label{font:11px var(--mono);fill:#a8acab}

/* multi-series plots and visualizer legends */
.pl-muted{stroke:#8c9090;stroke-width:1.4}
.pl-dashed{stroke:#c8ccca;stroke-width:1.4;stroke-dasharray:5 4}
.pl-light{stroke:#f2f2ee;stroke-width:1.6}
.viz-legend{display:flex;flex-wrap:wrap;gap:6px 18px;font-size:11.5px;color:var(--muted)}
.viz-legend span{display:inline-flex;align-items:center;gap:7px}
.viz-legend i{display:inline-block;width:18px;height:0;border-top:2px solid}
.pl-legend{margin-top:10px;justify-content:center}
.pl-key.pl-main,.lg-fused{border-color:var(--orange)!important}
.pl-key.pl-muted{border-color:#8c9090!important}
.pl-key.pl-dashed,.lg-wheel{border-top-style:dashed!important;border-color:#a0a5a3!important}
.pl-key.pl-light,.lg-true{border-color:#f2f2ee!important}
.lg-meas{width:6px!important;height:6px!important;border:0!important;border-radius:50%;background:#a0a5a3}
.lg-particle{width:5px!important;height:5px!important;border:0!important;background:var(--orange)}
.lg-est{width:12px!important;height:12px!important;border:1.5px dashed #f2f2ee!important;border-radius:50%}
.viz-canvas.kf{display:block}
/* Markov localization histogram */
.hist{padding:8px 4px}
.hist-bars{display:grid;grid-template-columns:repeat(20,1fr);gap:4px;align-items:end;height:150px;border-bottom:1px solid var(--line)}
.hist-bars span{background:rgba(255,90,0,.45);border-radius:2px 2px 0 0;transition:height .35s ease}
.hist-bars span.best{background:var(--orange)}
.hist-corridor{display:grid;grid-template-columns:repeat(20,1fr);gap:4px;margin-top:8px}
.hist-corridor span{height:34px;background:#1d2121;border:1px solid #2f3433;border-radius:2px;position:relative;display:flex;align-items:center;justify-content:center}
.hist-corridor span.door{background:#0b0d0d;border-color:#8c9090;border-style:dashed}
.hist-robot{width:12px;height:12px;border-radius:50%;background:#f2f2ee;box-shadow:0 0 0 3px rgba(242,242,238,.2)}

/* step-by-step walkthroughs */
.stepper .viz-bar{margin-bottom:10px}
.step-count{font:12px var(--mono);color:var(--muted)}
.viz-actions button:disabled{opacity:.35;cursor:default}
.step-body{display:grid;grid-template-columns:minmax(0,1.6fr) minmax(0,1fr);gap:20px;align-items:start}
.step-graph svg{width:100%;height:auto;display:block}
.se line{stroke:#3a3f3e;stroke-width:2}
.se rect{fill:#0b0d0d;stroke:#3a3f3e}
.se text{fill:#a8acab;font:600 14px var(--mono);text-anchor:middle}
.se-tree line{stroke:#8c9090;stroke-width:2.5}
.se-better line{stroke:var(--orange);stroke-width:3.5}
.se-better rect{stroke:var(--orange)}.se-better text{fill:#ffb27f}
.se-worse line{stroke:#8c9090;stroke-width:2;stroke-dasharray:6 5}
.se-path line{stroke:var(--orange);stroke-width:5}
.se-path rect{stroke:var(--orange)}.se-path text{fill:#ffb27f}
.sn circle{fill:#0f1111;stroke:#5a605e;stroke-width:2}
.sn-id{fill:#f2f2ee;font:600 14px Inter,sans-serif;text-anchor:middle}
.sn-val{fill:#e1e3df;font:600 13.5px var(--mono);text-anchor:middle}
.sn-note{fill:#8c9090;font:12px Inter,sans-serif;text-anchor:middle;letter-spacing:.08em;text-transform:uppercase}
.sn-frontier circle{stroke:var(--orange);stroke-dasharray:4 3}
.sn-done circle{fill:#262a2a;stroke:#c8ccca}
.sn-current circle{fill:var(--orange);stroke:#ffb27f;stroke-width:3}
.sn-current .sn-id{fill:#080909}
.sn-path circle{fill:rgba(255,90,0,.25);stroke:var(--orange);stroke-width:3}
.step-title{font:700 16px var(--display);margin:0 0 10px;letter-spacing:.02em}
.step-lines{margin:0;padding-left:18px;display:grid;gap:7px;color:#c8ccca;font-size:13px;line-height:1.55}
.step-lines li::marker{color:var(--orange)}
.step-table{margin-top:14px;max-width:100%}
.stepper{min-width:0;max-width:100%}
.step-tbl tr.hl>*{background:rgba(255,90,0,.08)}
.step-tbl td,.step-tbl th{font-family:var(--mono);font-size:12px}
@media(max-width:900px){.step-body{grid-template-columns:minmax(0,1fr)}}

/* formula symbol breakdowns */
.c-formulas div.deep{align-items:start}
.f-where{margin:12px 0 0;display:grid;gap:5px;padding:10px 12px;border-left:2px solid rgba(255,90,0,.4);background:rgba(255,255,255,.015)}
.f-where-label{font-size:9.5px;letter-spacing:.16em;text-transform:uppercase;color:var(--dim)}
.f-where div{display:grid!important;grid-template-columns:minmax(70px,auto) 1fr!important;gap:12px!important;padding:0!important;border:0!important;background:none!important}
.f-where dt code{font-size:12.5px;color:#ffb27f}
.f-where dd{margin:0;font-size:12.5px;color:#b4b8b7}
.f-note{margin:10px 0 0;font-size:13px;color:#a9adad}

/* worked numeric examples */
.worked{list-style:none;margin:0;padding:0;counter-reset:w;display:grid;gap:0;border:1px solid var(--line2);border-radius:4px}
.worked li{counter-increment:w;display:grid;grid-template-columns:28px minmax(120px,.8fr) minmax(0,1.6fr) auto;gap:6px 14px;align-items:baseline;padding:10px 14px;border-top:1px solid var(--line2)}
.worked li:first-child{border-top:0}
.worked li:before{content:counter(w);font:600 11px var(--display);color:var(--orange)}
.w-label{color:#e1e3df;font-size:13px}
.w-expr{font-size:13px;color:#c8ccca;overflow-wrap:anywhere}
.w-result{font:600 13px var(--mono);color:#ffb27f;white-space:nowrap}
.w-note{grid-column:2/-1;color:var(--muted);font-size:12.5px}
@media(max-width:700px){.worked li{grid-template-columns:24px minmax(0,1fr)}.w-expr,.w-result,.w-note{grid-column:2}.w-result{white-space:normal;overflow-wrap:anywhere}}

/* 2D walkthrough drawings */
.w2d{width:100%;height:auto;display:block}
.w2d .w-bg{fill:#0b0d0d}
.w2d .w-grid{stroke:rgba(255,255,255,.05)}
.w2d .w-obst{fill:#1d2121;stroke:#5a605e}
.w2d .w-tree{stroke:#8c9090;stroke-width:1.6;fill:none}
.w2d .w-node{fill:#c8ccca}
.w2d .w-new{stroke:var(--orange);stroke-width:3;fill:none}
.w2d .w-newnode{fill:var(--orange)}
.w2d .w-reject{stroke:#8c9090;stroke-width:2;stroke-dasharray:5 4;fill:none}
.w2d .w-sample{stroke:#f2f2ee;stroke-width:2}
.w2d .w-near{fill:none;stroke:#f2f2ee;stroke-width:2}
.w2d .w-radius{fill:rgba(255,90,0,.06);stroke:rgba(255,90,0,.6);stroke-dasharray:5 4}
.w2d .w-path{stroke:var(--orange);stroke-width:4;fill:none;stroke-linejoin:round}
.w2d .w-dim{stroke:#5a605e;stroke-width:1.4;fill:none;stroke-dasharray:3 4}
.w2d .w-hint{stroke:#ffb27f;stroke-width:1.6;fill:none;stroke-dasharray:4 4}
.w2d .w-start{fill:#f2f2ee}
.w2d .w-goal{fill:none;stroke:var(--orange);stroke-width:2.5}
.w2d .w-label{fill:#e1e3df;font:600 13px var(--mono)}
.w2d .w-small{fill:#a8acab;font:12px var(--mono)}
.w2d .w-orange{fill:#ffb27f;font:600 13px var(--mono)}
.w2d .w-cell{stroke:#1d2121}
.w2d .w-arrow{stroke:#f2f2ee;stroke-width:2;fill:none}
.w2d .w-farrow{stroke:var(--orange);stroke-width:2.5;fill:none}
.w2d .w-cobst{fill:rgba(255,90,0,.1);stroke:rgba(255,90,0,.7);stroke-width:1.5;stroke-dasharray:5 4}
.w2d .w-robot{fill:rgba(242,242,238,.14);stroke:#f2f2ee;stroke-width:2}
.w2d .w-robotbad{fill:rgba(255,90,0,.22);stroke:var(--orange);stroke-width:2}
.w2d .w-robotghost{fill:rgba(242,242,238,.05);stroke:rgba(242,242,238,.45);stroke-width:1.2}
.w2d .w-window{fill:rgba(255,178,127,.04);stroke:#ffb27f;stroke-width:1.4;stroke-dasharray:6 4}
.w2d .w-person{fill:#c8ccca}
.w2d .w-ghost{fill:none;stroke:rgba(200,204,202,.3);stroke-width:1.5;stroke-dasharray:3 3}
.w2d .w-bt{fill:#121515;stroke:#3c4241;stroke-width:1.4}
.w2d .w-bt-run{fill:rgba(255,178,127,.12);stroke:#ffb27f;stroke-width:2}
.w2d .w-bt-ok{fill:rgba(255,90,0,.26);stroke:var(--orange);stroke-width:2.4}
.w2d .w-bt-fail{fill:#0b0d0d;stroke:#8c9090;stroke-width:2;stroke-dasharray:5 4}
.w2d .w-bar{fill:rgba(255,90,0,.75)}
.w2d .w-bar2{fill:rgba(200,204,202,.55)}
.w2d .w-door{fill:rgba(255,178,127,.07)}
.w2d .w-thin{stroke:rgba(200,204,202,.45);stroke-width:1;fill:none}
.w2d .w-stem{stroke:rgba(255,90,0,.55);stroke-width:2}
.w2d .w-truth{stroke:var(--orange);stroke-width:2;stroke-dasharray:6 4}
.w2d .w-est{stroke:#f2f2ee;stroke-width:2;stroke-dasharray:2 3}
.w2d .w-ellipse{fill:rgba(255,90,0,.12);stroke:var(--orange);stroke-width:2}
.w2d .w-ellipse-old{fill:none;stroke:#8c9090;stroke-width:1.4;stroke-dasharray:5 4}
.w2d .w-ghostdot{fill:rgba(242,242,238,.45)}
.w2d .w-cloud{fill:rgba(200,204,202,.35)}
.w2d .w-wall{fill:none;stroke:#5a605e;stroke-width:2}
.w2d .w-ghostobst{fill:rgba(29,33,33,.55);stroke:rgba(90,96,94,.55);stroke-dasharray:4 3}
.w2d .w-mapdot{fill:rgba(200,204,202,.7)}
.w2d .w-loop{stroke:var(--orange);stroke-width:3;stroke-dasharray:7 5;fill:none}
.w2d .w-loopcand{stroke:#ffb27f;stroke-width:1.6;stroke-dasharray:4 4;fill:none}
.w2d .w-edge{stroke:rgba(242,242,238,.45);stroke-width:1.6}
.w2d .w-pair{stroke:rgba(255,178,127,.45);stroke-width:1}
.w2d .w-ray{stroke:rgba(255,178,127,.3);stroke-width:1}
.w2d .w-ellipse2{fill:rgba(242,242,238,.08);stroke:#c8ccca;stroke-width:1.4}
.w2d .w-ghostrobot{fill:rgba(242,242,238,.25)}
.w2d .w-fov{stroke:rgba(255,178,127,.4);stroke-width:1.2;fill:none}
.w2d .w-quad{fill:none;stroke:rgba(200,204,202,.22);stroke-width:1}
.w2d .w-occ{fill:rgba(255,90,0,.75)}
.w2d .w-ndtcell{fill:none;stroke:rgba(255,255,255,.12);stroke-dasharray:3 3}

/* sliders used by the Foundations visualizers */
.viz-sliders{display:grid;grid-template-columns:repeat(auto-fit,minmax(min(100%,220px),1fr));gap:8px 18px;margin:10px 0 12px}
.viz-slider{display:grid;grid-template-columns:minmax(0,1fr) auto;align-items:center;gap:4px 10px;font:12px var(--mono);color:var(--muted)}
.viz-slider span{grid-column:1}
.viz-slider b{grid-column:2;grid-row:1;color:#f2f2ee;font-weight:600}
.viz-slider input[type=range]{grid-column:1/-1;width:100%;accent-color:var(--orange);margin:0}
.viz-canvas canvas{display:block}

/* Foundations drawings */
.w2d .w-axisx{stroke:var(--orange);stroke-width:2.4;fill:none}
.w2d .w-axisy{stroke:#f2f2ee;stroke-width:2.4;fill:none}
.w2d .w-axisz{stroke:#8c9090;stroke-width:2.4;fill:none}
.w2d .w-axisx2{stroke:rgba(255,90,0,.45);stroke-width:1.6;fill:none}
.w2d .w-axisy2{stroke:rgba(242,242,238,.4);stroke-width:1.6;fill:none}
.w2d .w-boxedge{stroke:rgba(242,242,238,.8);stroke-width:1.6;fill:none}
.w2d .w-farrow2{stroke:var(--orange);stroke-width:3.5;fill:none;stroke-linecap:round}
.w2d .w-grid2{stroke:rgba(255,255,255,.09);stroke-width:1}
.w2d .w-link{stroke:#c8ccca;stroke-width:7;stroke-linecap:round}
.w2d .w-link2{stroke:rgba(200,204,202,.3);stroke-width:5;stroke-linecap:round}
.w2d .w-shape{fill:rgba(255,90,0,.18);stroke:var(--orange);stroke-width:2}
.w2d .w-shape2{fill:rgba(255,90,0,.15);stroke:var(--orange);stroke-width:1.6}
.w2d .w-reject2{fill:none;stroke:#8c9090;stroke-width:2.5}
.w2d .w-axisz2{stroke:rgba(140,144,144,.55);stroke-width:1.6;fill:none}

/* Perception drawings */
.w2d .w-pix{stroke:rgba(0,0,0,.35);stroke-width:.5}
.w2d .w-pixnum{font:10px var(--mono)}
.w2d .w-pixmark{fill:none;stroke:var(--orange);stroke-width:3}
.w2d .w-pixmark2{fill:none;stroke:#f2f2ee;stroke-width:3}
.w2d .w-imgframe{fill:none;stroke:#3c4241;stroke-width:2}
.w2d .w-gtbox{fill:none;stroke:#f2f2ee;stroke-width:2;stroke-dasharray:7 5}
.w2d .w-detbox{fill:rgba(255,90,0,.08);stroke:var(--orange);stroke-width:2.5}
.w2d .w-detbox2{fill:rgba(255,178,127,.06);stroke:#ffb27f;stroke-width:2;stroke-dasharray:4 3}
.w2d .w-detboxoff{fill:none;stroke:#5a605e;stroke-width:1.5;stroke-dasharray:3 4}
.w2d .w-bbox{fill:none;stroke:#ffb27f;stroke-width:1.5;stroke-dasharray:4 3}
.w2d text{font:12px var(--mono)}
.w2d .w-orange{fill:#ffb27f}