@import url('https://fonts.googleapis.com/css2?family=Manrope:wght@400;500;600;700;800&family=Space+Grotesk:wght@500;600;700&family=JetBrains+Mono:wght@400;600&display=swap');

:root{
  --ink:#18191b;--paper:#faf8f3;--card:#fff;--green:#2e9b68;--green-dark:#237b52;
  --orange:#d4521e;--blue:#365d91;--muted:#666a66;--line:#dfddd5;--soft:#f2f0ea;
  --good:#edf7f1;--warn:#fff4e9;--danger:#fdeeee;--focus:#0b6fc2;
  --shadow:0 3px 16px rgba(24,25,27,.08);--max:1040px;
}
*{box-sizing:border-box}
html{scroll-behavior:smooth}
body{margin:0;background:var(--paper);color:var(--ink);font-family:'Manrope',system-ui,sans-serif;line-height:1.62}
button,input,select,textarea{font:inherit}
a{color:var(--green-dark);text-decoration-thickness:2px;text-underline-offset:2px}
a:hover{color:var(--orange)}
:focus-visible{outline:3px solid var(--focus);outline-offset:3px}
.skip{position:absolute;left:-9999px;top:8px;background:var(--ink);color:#fff;padding:10px 14px;z-index:100}
.skip:focus{left:8px}
.shell{min-height:100vh;display:grid;grid-template-columns:300px minmax(0,1fr)}
.side{background:var(--ink);color:#eee;position:sticky;top:0;height:100vh;overflow:auto;padding-bottom:30px}
.brand{padding:24px;border-bottom:1px solid rgba(255,255,255,.12)}
.brandline{display:flex;align-items:center;gap:12px}
.mark{display:grid;place-items:center;width:44px;height:44px;border:2px solid var(--green);border-radius:12px;font-family:'Space Grotesk';font-weight:700;color:#fff}
.brand strong{font-family:'Space Grotesk';font-size:18px}.brand small{display:block;color:#aaa;font-family:'JetBrains Mono';letter-spacing:.08em;text-transform:uppercase}
.code{margin-top:16px;color:#6fd19f;font-family:'JetBrains Mono';font-weight:600}.side-title{font-size:13px;color:#d0d0ca}
.toc-title{padding:18px 22px 6px;color:#8d8f8b;font-size:11px;text-transform:uppercase;letter-spacing:.12em}
.toc button{display:block;width:100%;border:0;border-left:4px solid transparent;background:transparent;color:#d7d7d2;padding:10px 22px;text-align:left;cursor:pointer}
.toc button:hover{background:rgba(255,255,255,.06);color:#fff}.toc button[aria-current='true']{border-left-color:var(--green);background:rgba(46,155,104,.15);color:#fff;font-weight:700}.toc button.locked{opacity:.45}
.content{min-width:0}.topbar{position:sticky;top:0;z-index:20;background:rgba(250,248,243,.96);backdrop-filter:blur(8px);border-bottom:1px solid var(--line);padding:12px 28px}
.resource-links{max-width:var(--max);margin:auto;display:flex;gap:8px;flex-wrap:wrap}.resource-links a{background:#fff;border:1px solid var(--line);border-radius:999px;padding:7px 12px;text-decoration:none;font-size:13px;font-weight:700}
.stage{max-width:var(--max);margin:auto;padding:44px 44px 120px}.lesson{display:none}.lesson.active{display:block;animation:enter .2s ease-out}@keyframes enter{from{opacity:.25;transform:translateY(5px)}to{opacity:1;transform:none}}
.eyebrow{font-family:'JetBrains Mono';font-size:12px;text-transform:uppercase;letter-spacing:.12em;color:var(--orange);font-weight:600}
h1,h2,h3,h4{font-family:'Space Grotesk',system-ui,sans-serif;line-height:1.2}h1{font-size:clamp(30px,5vw,48px);margin:.25em 0 .35em}h2{font-size:28px;margin:1.5em 0 .5em}h3{font-size:20px;margin:1.35em 0 .4em;color:var(--green-dark)}h4{font-size:16px;margin:1.1em 0 .35em}
p,li{font-size:16px}.lead{font-size:19px;color:#33363a;max-width:820px}.muted{color:var(--muted)}
.card,.callout,.artifact,.critical,.example,.quiz-card,.lab-card,.figure-card{background:var(--card);border:1px solid var(--line);border-radius:14px;padding:20px 22px;margin:18px 0;box-shadow:var(--shadow)}
.callout{background:var(--good);border-left:6px solid var(--green)}.callout.warn{background:var(--warn);border-left-color:var(--orange)}.critical{background:var(--danger);border-left:6px solid #a92727}.artifact{background:#eef5fa;border-left:6px solid var(--blue)}.example{background:var(--soft)}
.grid{display:grid;grid-template-columns:repeat(2,minmax(0,1fr));gap:16px;margin:18px 0}.grid.three{grid-template-columns:repeat(3,minmax(0,1fr))}.grid>.card{margin:0}
.steps{counter-reset:step;list-style:none;margin:20px 0;padding:0}.steps li{counter-increment:step;display:grid;grid-template-columns:38px 1fr;gap:12px;align-items:start;margin:12px 0}.steps li:before{content:counter(step);display:grid;place-items:center;width:34px;height:34px;border-radius:50%;background:var(--ink);color:#fff;font-family:'JetBrains Mono';font-weight:600}
.trace{display:flex;align-items:stretch;gap:8px;overflow:auto;margin:20px 0;padding:4px}.trace .node{min-width:130px;flex:1;border:1px solid var(--line);border-radius:12px;background:#fff;padding:12px;text-align:center}.trace .arrow{align-self:center;color:var(--orange);font-size:24px;font-weight:700}.trace b,.trace span{display:block}.trace span{font-size:13px;color:var(--muted)}
.table-wrap{overflow-x:auto;margin:18px 0}table{border-collapse:collapse;width:100%;background:#fff;border:1px solid var(--line)}th,td{padding:12px 14px;text-align:left;vertical-align:top;border-bottom:1px solid var(--line)}th{background:var(--ink);color:#fff;font-size:13px}tr:nth-child(even) td{background:#fbfaf7}
.formula{font-family:'JetBrains Mono';background:#efeee9;border:1px solid var(--line);border-radius:10px;padding:15px 18px;white-space:pre-wrap;margin:16px 0}
.source-tag{display:inline-block;font-family:'JetBrains Mono';font-size:11px;border:1px solid var(--line);background:#fff;border-radius:5px;padding:2px 7px;margin:2px}
.footer-nav{position:fixed;bottom:0;left:300px;right:0;background:#fff;border-top:1px solid var(--line);padding:12px 24px;display:grid;grid-template-columns:auto 1fr auto auto;gap:14px;align-items:center;z-index:30}.progress{height:8px;background:#e9e6de;border-radius:10px;overflow:hidden}.progress span{height:100%;display:block;background:var(--green);width:0;transition:width .2s}.counter{font-size:13px;color:var(--muted);font-family:'JetBrains Mono'}
.btn{border:0;border-radius:9px;padding:10px 17px;background:var(--ink);color:#fff;font-weight:700;cursor:pointer}.btn.primary{background:var(--green-dark)}.btn.secondary{background:#6b6d6a}.btn:disabled{opacity:.38;cursor:not-allowed}.btn:hover:not(:disabled){filter:brightness(.9)}
.quiz-card fieldset{border:0;padding:0;margin:0 0 18px}.quiz-card legend{font-weight:700;margin-bottom:8px}.option{display:block;border:1px solid var(--line);border-radius:9px;padding:10px 12px;margin:7px 0;cursor:pointer}.option:hover{border-color:var(--green)}.option input{margin-right:9px}.feedback{display:none;border-radius:10px;padding:14px 16px;margin-top:14px}.feedback.show{display:block}.feedback.pass{background:var(--good);border:1px solid #b9dec9}.feedback.fail{background:var(--danger);border:1px solid #edbcbc}.item-rationale{font-size:14px;margin:8px 0 0 27px;color:var(--muted)}
.mastery{display:flex;gap:12px;align-items:center;flex-wrap:wrap}.mastery .score{font-family:'JetBrains Mono';font-weight:600}
.figure{border:1px solid var(--line);background:#fff;border-radius:12px;padding:18px;margin:18px 0}.figure figcaption{font-size:14px;color:var(--muted);margin-top:12px}.visual-flow{display:flex;gap:10px;align-items:center;flex-wrap:wrap}.visual-box{flex:1;min-width:130px;padding:16px;border:2px solid var(--ink);border-radius:10px;text-align:center;background:#fff}.visual-box.active{border-color:var(--green);background:var(--good)}.visual-box.stop{border-color:var(--orange);background:var(--warn)}
.wire{display:grid;grid-template-columns:140px 1fr 140px;gap:16px;align-items:center}.wire-line{height:9px;background:linear-gradient(90deg,var(--green),var(--blue));position:relative}.wire-line:before,.wire-line:after{content:'';position:absolute;top:-6px;width:20px;height:20px;border-radius:50%;background:var(--ink)}.wire-line:before{left:-2px}.wire-line:after{right:-2px}
.meter{height:16px;background:#e7e5de;border-radius:20px;overflow:hidden}.meter span{height:100%;display:block;background:var(--green)}
.lab-controls{display:grid;grid-template-columns:repeat(2,minmax(0,1fr));gap:14px}.lab-controls label{font-weight:700}.lab-controls input,.lab-controls select,.workbook input,.workbook textarea{display:block;width:100%;padding:10px 11px;border:1px solid #aaa;border-radius:8px;margin-top:5px;background:#fff;color:var(--ink)}.workbook textarea{min-height:110px;resize:vertical}.result{padding:15px;border-left:6px solid var(--blue);background:#eef5fa;margin-top:16px}.result.good{border-left-color:var(--green);background:var(--good)}.result.bad{border-left-color:#a92727;background:var(--danger)}
.dochead{background:var(--ink);color:#fff;padding:34px 28px}.dochead .inner,.document{max-width:var(--max);margin:auto}.dochead h1{margin:6px 0;color:#fff}.docnav{background:#fff;border-bottom:1px solid var(--line);padding:12px 20px;position:sticky;top:0;z-index:20}.docnav .inner{max-width:var(--max);margin:auto;display:flex;gap:10px;flex-wrap:wrap}.document{padding:38px 30px 90px}.anchor{scroll-margin-top:90px}.print-only{display:none}
@media(max-width:860px){.shell{display:block}.side{position:relative;height:auto}.toc{display:grid;grid-template-columns:1fr 1fr}.toc-title{grid-column:1/-1}.stage{padding:30px 20px 110px}.topbar{position:relative;padding:10px 16px}.footer-nav{left:0;padding:10px 12px;grid-template-columns:auto 1fr auto}.counter{display:none}.grid,.grid.three,.lab-controls{grid-template-columns:1fr}.trace{flex-direction:column}.trace .arrow{transform:rotate(90deg)}.wire{grid-template-columns:1fr}.wire-line{height:70px;width:9px;margin:auto}.wire-line:before{top:-2px;left:-6px}.wire-line:after{top:auto;bottom:-2px;right:-6px}.document{padding:28px 18px 80px}}
@media print{body{background:#fff}.side,.topbar,.footer-nav,.docnav,.no-print{display:none!important}.shell{display:block}.stage,.document{max-width:none;padding:0}.lesson{display:block!important;page-break-after:always}.card,.figure,.quiz-card{box-shadow:none;break-inside:avoid}.print-only{display:block}}


/* TTS course production extensions */
.document{max-width:1180px;margin:0 auto;padding:2rem clamp(1rem,4vw,4rem) 5rem}.document>h1{max-width:24ch}.document-footer{display:flex;justify-content:space-between;gap:1rem;flex-wrap:wrap;padding:1rem 2rem;border-top:1px solid var(--line);background:var(--paper)}
.visual-orbit{display:grid;grid-template-columns:repeat(6,minmax(120px,1fr));gap:.5rem;margin:1rem 0}.visual-orbit>div{min-height:118px;padding:1rem;border:1px solid var(--line);border-top:5px solid var(--teal);background:var(--paper);display:flex;flex-direction:column;justify-content:space-between}.visual-orbit b{font-family:'Space Grotesk',sans-serif}.visual-orbit span{font-size:.86rem;color:var(--muted)}
.hero-review{display:grid;grid-template-columns:2fr 1fr;gap:2rem;align-items:center;padding:2rem;background:linear-gradient(135deg,var(--ink),#163a42);color:#fff;border-radius:18px;margin-bottom:1.5rem}.metrics{display:grid;grid-template-columns:1fr 1fr;gap:.75rem}.metrics div{padding:1rem;border:1px solid rgba(255,255,255,.25);border-radius:12px}.metrics strong{display:block;font-size:2rem}.metrics span{font-size:.8rem;text-transform:uppercase;letter-spacing:.08em}.course-card{display:flex;flex-direction:column}.course-card .resource-links{margin-top:auto}.question-review{margin:1rem 0}.choice-review{list-style:none;padding:0}.choice-review li{padding:.65rem;border-bottom:1px solid var(--line)}.correct-choice{background:#e8f7f0;border-left:5px solid var(--green)!important}.choice-letter{font-family:'JetBrains Mono',monospace;font-weight:700}.source-list li{margin-bottom:1rem}.workbook-section td[contenteditable]{min-width:480px;min-height:70px;background:#fff}.lab-card textarea{width:100%;min-height:130px}.bridge-topic details{margin-top:1rem}.topbar{padding-bottom:1rem}
@media(max-width:900px){.visual-orbit{grid-template-columns:repeat(2,1fr)}.hero-review{grid-template-columns:1fr}.workbook-section td[contenteditable]{min-width:280px}}
@media(max-width:560px){.visual-orbit{grid-template-columns:1fr}.document{padding:1rem}.dochead{align-items:flex-start;gap:1rem}.workbook-section td[contenteditable]{min-width:200px}}

/* --- TTS mobile nav + video (2026-07-20 patch) --- */
.toc-toggle{display:none}
.video-embed{position:relative;width:100%;aspect-ratio:16/9;margin:14px 0 20px;border-radius:12px;overflow:hidden;background:#0d0e0f;box-shadow:var(--shadow)}
.video-embed iframe,.video-embed video{position:absolute;inset:0;width:100%;height:100%;border:0}
@media(max-width:860px){
  .toc-toggle{display:block;width:calc(100% - 32px);margin:10px 16px 4px;padding:11px 14px;background:#242628;color:#eee;border:1px solid #3a3d40;border-radius:10px;font:inherit;font-weight:600;text-align:left;cursor:pointer}
  .toc-toggle::after{content:' \25BE';color:var(--green)}
  body.toc-open .toc-toggle::after{content:' \25B4'}
  body:not(.toc-open) .toc,body:not(.toc-open) .toc-title{display:none}
}