:root {
  --ink: #0a1524;
  --navy: #0c192a;
  --navy-2: #13243a;
  --paper: #f4f1e9;
  --paper-2: #e9e5da;
  --white: #fffdf7;
  --amber: #ffb000;
  --amber-2: #ffd166;
  --lime: #b8f34a;
  --cyan: #65d9ff;
  --red: #ff6b57;
  --muted: #6f7782;
  --line: rgba(10, 21, 36, .16);
  --shadow: 0 18px 50px rgba(10, 21, 36, .12);
  --radius: 22px;
  --mono: "Cascadia Mono", "SFMono-Regular", Consolas, monospace;
  --sans: Inter, ui-sans-serif, system-ui, -apple-system, BlinkMacSystemFont, "Segoe UI", sans-serif;
}

* { box-sizing: border-box; }
html { scroll-behavior: smooth; scroll-padding-top: 90px; }
body {
  margin: 0;
  color: var(--ink);
  background:
    linear-gradient(rgba(10,21,36,.035) 1px, transparent 1px),
    linear-gradient(90deg, rgba(10,21,36,.035) 1px, transparent 1px),
    var(--paper);
  background-size: 28px 28px;
  font-family: var(--sans);
  line-height: 1.55;
  overflow-x: hidden;
}

button, input { font: inherit; }
button, a { -webkit-tap-highlight-color: transparent; }
a { color: inherit; }
.skip-link { position: fixed; top: -100px; left: 16px; z-index: 1000; background: var(--amber); padding: 10px 16px; font-weight: 800; }
.skip-link:focus { top: 12px; }

.topbar {
  position: fixed;
  inset: 0 0 auto 0;
  height: 72px;
  z-index: 100;
  display: grid;
  grid-template-columns: 1fr auto 1fr;
  align-items: center;
  gap: 24px;
  padding: 0 30px;
  color: var(--white);
  background: rgba(9, 18, 31, .94);
  border-bottom: 1px solid rgba(255,255,255,.12);
  backdrop-filter: blur(18px);
}
.brand { display: inline-flex; align-items: center; gap: 11px; text-decoration: none; width: max-content; }
.brand-mark { display: grid; place-items: center; width: 34px; height: 34px; color: var(--ink); background: var(--amber); border-radius: 50%; font-weight: 950; }
.brand b { display: block; font-size: 14px; line-height: 1.15; letter-spacing: .08em; }
.brand small { display: block; color: #aab4c1; font: 10px/1.4 var(--mono); letter-spacing: .08em; }
.timer-wrap { display: flex; align-items: center; gap: 10px; border: 1px solid rgba(255,255,255,.16); border-radius: 999px; padding: 7px 9px 7px 16px; background: rgba(255,255,255,.05); }
.timer-label { color: #8d99a8; font: 10px var(--mono); letter-spacing: .14em; text-transform: uppercase; }
.timer { min-width: 90px; font: 700 19px var(--mono); letter-spacing: .05em; }
.timer.warning { color: var(--amber-2); }
.timer.danger { color: var(--red); animation: pulse 1s infinite; }
.timer-button, .timer-reset { border: 0; cursor: pointer; }
.timer-button { padding: 6px 13px; color: var(--ink); background: var(--amber); border-radius: 999px; font-size: 12px; font-weight: 850; }
.timer-reset { color: #9ba6b4; background: transparent; font-size: 18px; }
.top-progress { justify-self: end; min-width: 160px; }
.top-progress > span { display: block; margin-bottom: 5px; color: #aab4c1; text-align: right; font: 10px var(--mono); text-transform: uppercase; letter-spacing: .1em; }
.progress-track { height: 4px; overflow: hidden; background: rgba(255,255,255,.12); border-radius: 20px; }
.progress-track span { display: block; width: 0; height: 100%; background: var(--lime); transition: width .3s ease; }

.rail {
  position: fixed;
  z-index: 50;
  left: 0;
  top: 72px;
  bottom: 0;
  width: 190px;
  display: flex;
  flex-direction: column;
  padding: 36px 16px;
  color: #aab4c1;
  background: var(--navy);
  border-right: 1px solid rgba(255,255,255,.08);
}
.rail a { display: grid; grid-template-columns: 30px 1fr auto; align-items: center; gap: 8px; padding: 12px 10px; text-decoration: none; border-radius: 10px; font-size: 12px; transition: .2s ease; }
.rail a:hover, .rail a.active { color: var(--white); background: rgba(255,255,255,.07); transform: translateX(3px); }
.rail a.active span { color: var(--amber); }
.rail span { color: #6e7b8c; font: 10px var(--mono); }
.rail em { color: #657285; font: 9px var(--mono); font-style: normal; }
.rail-home { margin-bottom: 24px; border-bottom: 1px solid rgba(255,255,255,.08); border-radius: 0 !important; }

main, footer { margin-left: 190px; }
main { overflow: hidden; }
.hero {
  min-height: 720px;
  display: grid;
  grid-template-columns: 1.05fr .95fr;
  align-items: center;
  gap: 30px;
  padding: 148px clamp(40px, 7vw, 110px) 80px;
  color: var(--white);
  background:
    radial-gradient(circle at 74% 44%, rgba(255,176,0,.17), transparent 32%),
    linear-gradient(135deg, #09121f, #10243a 65%, #09121f);
  position: relative;
}
.hero::after { content: ""; position: absolute; inset: auto 0 0; height: 1px; background: linear-gradient(90deg, transparent, var(--amber), transparent); }
.eyebrow, .section-tag, .card-index { font: 700 11px var(--mono); letter-spacing: .17em; text-transform: uppercase; }
.eyebrow { color: var(--amber); }
.hero h1 { max-width: 760px; margin: 18px 0 24px; font-size: clamp(47px, 6vw, 86px); line-height: .98; letter-spacing: -.06em; }
.hero h1 span { color: var(--amber); }
.hero-lede { max-width: 660px; color: #c2cad4; font-size: 18px; line-height: 1.65; }
.hero-actions { display: flex; flex-wrap: wrap; gap: 12px; margin: 34px 0 20px; }
.button { display: inline-flex; align-items: center; justify-content: center; gap: 24px; min-height: 48px; padding: 0 20px; border: 1px solid var(--line); border-radius: 10px; text-decoration: none; cursor: pointer; font-weight: 800; transition: transform .2s ease, background .2s ease; }
.button:hover { transform: translateY(-2px); }
.button.primary { border-color: var(--amber); color: var(--ink); background: var(--amber); }
.button.ghost { color: inherit; background: transparent; border-color: currentColor; }
.microcopy { color: #758398; font: 11px var(--mono); }
.hero-visual { position: relative; min-height: 510px; display: grid; place-items: center; }
.hero-dial { position: relative; z-index: 3; width: 235px; height: 235px; display: flex; flex-direction: column; align-items: center; justify-content: center; border: 1px solid rgba(255,255,255,.26); border-radius: 50%; background: radial-gradient(circle, rgba(255,176,0,.2), rgba(9,18,31,.9) 65%); box-shadow: 0 0 70px rgba(255,176,0,.1); }
.hero-dial::before, .hero-dial::after { content: ""; position: absolute; background: rgba(255,255,255,.18); }
.hero-dial::before { width: 1px; height: 280px; }
.hero-dial::after { width: 280px; height: 1px; }
.hero-dial > * { position: relative; z-index: 1; }
.hero-dial strong { color: var(--amber); font: 900 76px/1 var(--mono); letter-spacing: -.08em; }
.hero-dial span { color: #aab4c1; font: 11px var(--mono); letter-spacing: .2em; }
.hero-dial .dial-kicker { color: var(--white); }
.orbit { position: absolute; z-index: 1; border: 1px solid rgba(255,255,255,.1); border-radius: 50%; }
.orbit-a { width: 390px; height: 390px; border-style: dashed; animation: spin 50s linear infinite; }
.orbit-b { width: 490px; height: 490px; border-color: rgba(255,176,0,.15); }
.dial-tag { position: absolute; z-index: 4; padding: 7px 10px; color: #9daaba; border: 1px solid rgba(255,255,255,.12); border-radius: 6px; background: #102136; font: 10px var(--mono); text-transform: uppercase; }
.dial-tag b { color: var(--white); }
.tag-1 { top: 58px; right: 18%; }
.tag-2 { top: 30%; left: 4%; }
.tag-3 { bottom: 23%; right: 2%; }
.tag-4 { bottom: 42px; left: 19%; }
.tag-5 { top: 17%; right: -1%; }

.runbook, .module, .cheatsheet, .source-note { max-width: 1320px; margin: 0 auto; padding: 94px clamp(28px, 6vw, 88px); }
.runbook { display: grid; grid-template-columns: .65fr 1.35fr; gap: 55px 70px; }
.section-tag { color: #a36d00; margin: 0 0 10px; }
h2 { margin: 0; font-size: clamp(34px, 4vw, 56px); line-height: 1.04; letter-spacing: -.045em; }
.timeline { grid-column: 2; grid-row: 1 / span 2; margin: 0; padding: 0; list-style: none; border-top: 1px solid var(--line); }
.timeline li { display: grid; grid-template-columns: 90px 1fr auto; gap: 18px; align-items: center; padding: 18px 0; border-bottom: 1px solid var(--line); }
.timeline span { color: #a36d00; font: 700 12px var(--mono); }
.timeline b { font-size: 16px; }
.timeline small { color: var(--muted); font: 11px var(--mono); }
.runbook-rule { align-self: end; color: #485362; font-size: 14px; }

.module { border-top: 1px solid var(--line); }
.module-head { display: grid; grid-template-columns: 70px 1fr auto; gap: 26px; align-items: start; margin-bottom: 50px; }
.module-number { width: 62px; height: 62px; display: grid; place-items: center; color: var(--amber); background: var(--ink); border-radius: 50%; font: 800 17px var(--mono); }
.module-head h2 { margin-bottom: 12px; }
.module-head p:last-child { max-width: 680px; margin: 0; color: var(--muted); font-size: 17px; }
.complete-button { display: inline-flex; gap: 9px; align-items: center; margin-top: 8px; padding: 10px 14px; color: #4b5664; border: 1px solid var(--line); background: rgba(255,255,255,.35); border-radius: 999px; cursor: pointer; font-size: 12px; font-weight: 750; }
.complete-button span { font-size: 18px; line-height: 1; }
.complete-button.is-complete { color: #193000; background: var(--lime); border-color: #91c72f; }

.grid { display: grid; gap: 18px; margin: 18px 0; }
.grid.two-one { grid-template-columns: 2fr 1fr; }
.grid.equal { grid-template-columns: 1fr 1fr; }
.card, .decision-card, .process-card, .theory-card { border: 1px solid var(--line); border-radius: var(--radius); background: rgba(255,253,247,.8); box-shadow: 0 1px 0 rgba(255,255,255,.7) inset; }
.card { padding: 30px; }
.card h3, .decision-card h3, .theory-card h3 { margin: 9px 0 13px; font-size: 23px; letter-spacing: -.025em; }
.card-index { color: #8b6420; }
.dark-card { color: var(--white); background: var(--ink); border-color: var(--ink); }
.dark-card .card-index { color: var(--amber); }
.dark-card p { color: #afbac8; }
.tensor-row { display: flex; align-items: center; gap: 24px; margin: 24px 0; }
.matrix { position: relative; display: grid; grid-template-columns: repeat(3, 1fr); gap: 5px 16px; padding: 8px 16px; font: 17px var(--mono); }
.matrix::before, .matrix::after { content: ""; position: absolute; inset-block: 0; width: 7px; border-top: 1px solid; border-bottom: 1px solid; }
.matrix::before { left: 0; border-left: 1px solid; }
.matrix::after { right: 0; border-right: 1px solid; }
.equals { color: var(--amber); font-size: 30px; }
.symmetry-list { display: grid; gap: 6px; font: 13px var(--mono); color: #a9b5c3; }
.exam-move { border-top: 5px solid var(--amber); }
.exam-move ol { margin: 18px 0 0; padding-left: 22px; }
.exam-move li { margin: 10px 0; }

.mohr-lab { display: grid; grid-template-columns: .9fr 1.1fr; gap: 35px; align-items: center; padding: 40px; background: var(--white); }
.mohr-lab h3 { font-size: 30px; }
.slider-group { display: grid; gap: 13px; margin-top: 25px; }
.slider-group label { display: grid; grid-template-columns: 1fr 50px 28px; align-items: center; gap: 4px; font: 12px var(--mono); }
.slider-group output { color: #8b6000; text-align: right; font-weight: 800; }
.slider-group input { grid-column: 1 / -1; width: 100%; accent-color: var(--amber); }
.lab-results { display: grid; grid-template-columns: 1fr 1fr; gap: 8px; margin-top: 22px; }
.lab-results span { padding: 10px 12px; background: var(--paper); border-radius: 8px; }
.lab-results small { display: block; color: var(--muted); font: 9px var(--mono); text-transform: uppercase; }
.lab-results b { display: block; font: 800 18px var(--mono); }
.canvas-wrap { min-width: 0; }
.canvas-wrap canvas { width: 100%; height: auto; border: 1px solid var(--line); border-radius: 14px; background: #0d1b2b; }
.canvas-wrap p { margin-bottom: 0; text-align: center; color: var(--muted); font: 11px var(--mono); }
.formula-strip { display: grid; grid-template-columns: repeat(4, 1fr); margin-top: 18px; color: var(--white); background: var(--ink); border-radius: 15px; overflow: hidden; }
.formula-strip > div { padding: 17px 20px; border-right: 1px solid rgba(255,255,255,.1); }
.formula-strip > div:last-child { border-right: 0; }
.formula-strip small { display: block; color: var(--amber); margin-bottom: 5px; font: 9px var(--mono); letter-spacing: .12em; }
.formula-strip b { font: 650 14px var(--mono); }
.analysis-pipeline { margin-top: 18px; border-top: 5px solid var(--cyan); }
.pipeline-intro { max-width: 760px; color: var(--muted); }
.pipeline-steps { display: grid; grid-template-columns: 1fr auto 1fr auto 1fr auto 1fr auto 1fr; align-items: stretch; gap: 10px; margin: 24px 0; }
.pipeline-steps > div { display: grid; grid-template-columns: auto 1fr; gap: 4px 9px; align-content: start; padding: 14px; background: var(--paper); border-radius: 10px; }
.pipeline-steps span { grid-row: 1 / 3; display: grid; place-items: center; width: 27px; height: 27px; color: var(--ink); background: var(--amber); border-radius: 50%; font: 800 10px var(--mono); }
.pipeline-steps b { font-size: 13px; }
.pipeline-steps small { color: var(--muted); font-size: 10px; line-height: 1.5; }
.pipeline-steps > i { align-self: center; color: #a1a8b0; font-style: normal; }
.stress-formula-grid { display: grid; grid-template-columns: repeat(4, 1fr); gap: 8px; }
.stress-formula-grid > div { padding: 12px 14px; color: var(--white); background: var(--ink); border-radius: 8px; }
.stress-formula-grid small { display: block; margin-bottom: 5px; color: var(--amber); font: 8px var(--mono); letter-spacing: .1em; }
.stress-formula-grid b { font: 700 12px var(--mono); }
.true-stress-row { align-items: stretch; }
.true-stress-card, .true-strain-card { height: 100%; }
.stress-compare { display: grid; grid-template-columns: 1fr 1fr; gap: 10px; margin: 18px 0; }
.stress-compare > div { padding: 14px; background: var(--paper); border-radius: 9px; }
.stress-compare small, .true-example-flow small { display: block; margin-bottom: 6px; color: #8b5e00; font: 8px var(--mono); letter-spacing: .1em; }
.stress-compare b { font: 700 14px var(--mono); }
.stress-compare p, .true-strain-card p { color: var(--muted); font-size: 12px; }
.caution { padding: 12px 14px; border-left: 3px solid var(--red); background: #fff0ed; border-radius: 0 8px 8px 0; color: #5e4a48 !important; font-size: 12px; }
.true-stress-example { margin-top: 18px; }
.true-example-flow { display: grid; grid-template-columns: 1fr auto 1fr auto 1fr; gap: 14px; align-items: stretch; margin: 20px 0; }
.true-example-flow > div { padding: 15px; background: var(--paper); border-radius: 9px; }
.true-example-flow > i { align-self: center; color: #a1a8b0; font-style: normal; }
.true-example-flow b { display: block; margin: 3px 0; font: 700 14px var(--mono); }
.true-example-flow p { margin-bottom: 0; color: var(--muted); font-size: 11px; }

.decision-card { overflow: hidden; margin-bottom: 18px; }
.decision-head { padding: 28px 30px 15px; }
.decision-controls { display: flex; flex-wrap: wrap; gap: 8px; padding: 0 30px 22px; }
.decision-chip { padding: 9px 13px; color: #4f5965; border: 1px solid var(--line); background: transparent; border-radius: 999px; cursor: pointer; font-size: 12px; font-weight: 750; }
.decision-chip.active { color: var(--ink); border-color: var(--amber); background: var(--amber); }
.decision-result { display: grid; grid-template-columns: auto 1fr auto; gap: 22px; align-items: center; padding: 26px 30px; color: var(--white); background: var(--ink); }
.decision-result > span { display: grid; place-items: center; width: 66px; height: 66px; color: var(--ink); background: var(--amber); border-radius: 50%; font: 900 19px var(--mono); }
.decision-result small { color: var(--amber-2); font: 10px var(--mono); letter-spacing: .1em; }
.decision-result h4 { margin: 5px 0; font-size: 20px; }
.decision-result p { max-width: 650px; margin: 0; color: #aab5c2; font-size: 13px; }
.decision-formula { padding: 12px 16px; border: 1px solid rgba(255,255,255,.14); border-radius: 9px; font: 700 14px var(--mono); }
.theory-grid { display: grid; grid-template-columns: repeat(2, 1fr); gap: 18px; }
.theory-card { position: relative; padding: 27px 28px 24px 95px; overflow: hidden; }
.theory-card.accent { border-color: #d89a10; background: #fff8e5; }
.theory-code { position: absolute; top: 28px; left: 22px; display: grid; place-items: center; width: 54px; height: 54px; color: var(--amber); background: var(--ink); border-radius: 50%; font: 800 15px var(--mono); }
.theory-card > small { color: #8b6420; font: 9px var(--mono); letter-spacing: .1em; }
.theory-card h3 { font-size: 20px; }
.big-formula { padding: 12px 14px; background: var(--paper-2); border-radius: 8px; font: 700 13px/1.6 var(--mono); }
.theory-card p { color: var(--muted); font-size: 13px; }
.theory-card .note { color: #4d5865; font: 11px var(--mono); }
.failure-procedure { margin-top: 18px; border-left: 6px solid var(--amber); }
.failure-steps { display: grid; grid-template-columns: repeat(5, 1fr); gap: 10px; margin-top: 20px; }
.failure-steps > div { padding: 13px; background: var(--paper); border-radius: 9px; }
.failure-steps span { display: grid; place-items: center; width: 26px; height: 26px; margin-bottom: 8px; color: var(--white); background: var(--ink); border-radius: 50%; font: 700 10px var(--mono); }
.failure-steps p { margin: 0; color: var(--muted); font-size: 11px; line-height: 1.55; }
.brittle-deep-dive { margin-top: 18px; padding: 0; overflow: hidden; }
.brittle-head { display: flex; justify-content: space-between; gap: 30px; padding: 28px 30px 20px; }
.brittle-head p { max-width: 440px; color: var(--muted); font-size: 12px; }
.branch-columns { display: grid; grid-template-columns: 1fr 1fr; gap: 1px; background: var(--line); border-top: 1px solid var(--line); border-bottom: 1px solid var(--line); }
.branch-block { padding: 25px; background: #fffdf7; }
.branch-block h4 { margin: 0 0 14px; font-size: 19px; }
.branch-row { display: grid; gap: 4px; min-height: 96px; margin-bottom: 8px; padding: 12px; background: var(--paper); border-radius: 8px; }
.branch-row.featured { border: 1px solid #ddb252; background: #fff6dc; }
.branch-row > span { color: #8b5e00; font: 700 9px var(--mono); text-transform: uppercase; letter-spacing: .08em; }
.branch-row code { color: var(--muted); font: 10px/1.45 var(--mono); }
.branch-row b { font: 650 11px/1.5 var(--mono); }
.branch-note { margin-bottom: 0; color: var(--muted); font-size: 11px; }
.mm-construction { padding: 27px 30px 30px; background: #101d2e; color: var(--white); }
.mm-construction h4 { margin: 0 0 15px; color: var(--amber); font-size: 19px; }
.mm-construction ol { display: grid; grid-template-columns: repeat(4, 1fr); gap: 12px; padding: 0; list-style-position: inside; }
.mm-construction li { padding: 13px; color: #adb8c6; background: rgba(255,255,255,.045); border-radius: 8px; font-size: 11px; line-height: 1.55; }
.mm-construction li b { color: var(--white); }
.mm-graph { max-width: 900px; margin: 22px auto 0; background: #fffdf7; border: 1px solid rgba(255,255,255,.12); border-radius: 13px; overflow: hidden; }
.mm-graph svg { display: block; width: 100%; height: auto; }
.mm-grid line { stroke: #e7e0d3; stroke-width: 1; stroke-dasharray: 4 6; }
.mm-safe-region { fill: rgba(184,243,74,.2); }
.mm-envelope { fill: none; stroke: #e95743; stroke-width: 5; stroke-linejoin: round; }
.cm-envelope { fill: none; stroke: #6f7b89; stroke-width: 2.5; stroke-dasharray: 9 7; stroke-linejoin: round; }
.mm-axes line { stroke: #172436; stroke-width: 2; }
.mm-axis-arrow { fill: #172436; }
.mm-ray-arrow { fill: #178bad; }
.axis-label { fill: #172436; font: 800 20px var(--mono); }
.origin-label { fill: #516070; font: 700 12px var(--mono); }
.mm-ticks line { stroke: #172436; stroke-width: 2; }
.mm-ticks text { fill: #516070; font: 700 13px var(--mono); }
.mm-ticks tspan, .axis-label tspan, .divider-label tspan, .mm-annotations tspan, .graph-note tspan { font-size: 9px; }
.branch-divider { stroke: #29a8c9; stroke-width: 2; stroke-dasharray: 6 6; }
.divider-label { fill: #16819e; font: 700 10px var(--mono); }
.loading-ray { stroke: #178bad; stroke-width: 3; stroke-dasharray: 7 5; }
.stress-point { fill: #ffb000; stroke: #172436; stroke-width: 2; }
.failure-point { fill: #e95743; stroke: #172436; stroke-width: 2; }
.point-label { fill: #8b5e00; font: 700 11px var(--mono); }
.point-label.failure { fill: #b33b2c; }
.ray-label { fill: #177d98; font: 800 12px var(--mono); }
.mm-annotations path { fill: none; stroke: #85909c; stroke-width: 1.5; }
.mm-annotations text { fill: #455362; font: 700 10px var(--mono); }
.safe-label { fill: #4f7700; font: 900 14px var(--mono); letter-spacing: .08em; }
.graph-note { fill: #7b8692; font: 10px var(--mono); }
.mm-graph figcaption { display: flex; flex-wrap: wrap; gap: 12px 24px; padding: 13px 18px; color: #53606e; background: #f2eee5; font-size: 10px; }
.mm-graph figcaption span { display: inline-flex; align-items: center; gap: 7px; }
.legend-line { display: inline-block; width: 28px; height: 0; border-top: 3px solid; }
.legend-line.mm { border-color: #e95743; }
.legend-line.cm { border-color: #6f7b89; border-top-style: dashed; }
.legend-line.ray { border-color: #178bad; border-top-style: dashed; }
.mm-derivation { display: grid; grid-template-columns: 1fr 1fr; gap: 12px; margin-top: 16px; }
.mm-derivation > div { padding: 15px; border: 1px solid rgba(255,255,255,.12); border-radius: 9px; }
.mm-derivation small { display: block; margin-bottom: 7px; color: var(--cyan); font: 8px var(--mono); letter-spacing: .1em; }
.mm-derivation b { font: 700 11px/1.5 var(--mono); }
.mm-derivation p { margin-bottom: 0; color: #aeb8c5; font-size: 11px; }
.brittle-calculator { display: grid; grid-template-columns: 1.35fr .65fr; gap: 28px; margin-top: 18px; border-top: 5px solid var(--red); }
.brittle-inputs { display: grid; grid-template-columns: repeat(4, 1fr); gap: 8px; margin-top: 20px; }
.brittle-inputs label { padding: 10px; background: var(--paper); border-radius: 8px; font: 11px var(--mono); }
.brittle-inputs input { width: 100%; margin: 8px 0 2px; padding: 8px; border: 1px solid var(--line); border-radius: 6px; background: var(--white); font: 700 14px var(--mono); }
.brittle-results { display: grid; gap: 8px; }
.brittle-results > div { padding: 11px 13px; color: var(--white); background: var(--ink); border-radius: 8px; }
.brittle-results small { display: block; margin-bottom: 4px; color: var(--amber); font: 8px var(--mono); letter-spacing: .1em; }
.brittle-results b { font: 700 14px var(--mono); }
.brittle-results p { margin: 3px 0 0; color: var(--muted); font-size: 10px; }
.worked-row { margin-top: 34px; }
.worked-example { border-left: 6px solid var(--cyan); }
.worked-example .problem-line { color: var(--muted); font: 11px/1.6 var(--mono); }
.solution-steps { display: grid; grid-template-columns: 1fr 1fr; gap: 12px; margin-top: 22px; }
.solution-steps div { display: grid; grid-template-columns: 32px 1fr; gap: 8px; align-items: start; padding: 12px; background: var(--paper); border-radius: 9px; }
.solution-steps span { display: grid; place-items: center; width: 26px; height: 26px; color: var(--white); background: var(--ink); border-radius: 50%; font: 700 11px var(--mono); }
.solution-steps p { margin: 0; font-size: 12px; }
.solution-steps strong { color: #8b5b00; }
.trap-card { color: var(--white); background: #16243a; border-color: #16243a; }
.trap-card .card-index { color: var(--red); }
.trap-list { padding-left: 18px; }
.trap-list li { margin: 15px 0; color: #b5bec9; font-size: 13px; }
.trap-list b { color: var(--white); }
.checkpoint { margin-top: 18px; border: 1px solid var(--line); border-radius: 13px; background: rgba(255,255,255,.52); }
.checkpoint summary { display: flex; align-items: center; gap: 12px; padding: 17px 20px; cursor: pointer; font-weight: 750; }
.checkpoint summary span { color: #8b5e00; font: 700 10px var(--mono); letter-spacing: .1em; }
.checkpoint summary b { margin-left: auto; color: #8b5e00; font-size: 12px; }
.checkpoint > div { padding: 0 20px 18px; color: #4f5a67; font-size: 14px; }

.manufacturing-map { display: grid; grid-template-columns: repeat(3, 1fr); gap: 18px; }
.process-card { position: relative; min-height: 240px; padding: 70px 26px 25px; }
.process-num { position: absolute; top: 18px; right: 20px; color: #c9c3b7; font: 900 36px var(--mono); }
.process-card h3 { margin: 0 0 10px; font-size: 23px; }
.process-card p { color: var(--muted); font-size: 14px; }
.mini-formula { padding: 11px; background: var(--paper); border-radius: 8px; font: 11px/1.8 var(--mono); }
.cooling-ladder { display: grid; grid-template-columns: auto 1fr auto 1fr auto auto; align-items: center; gap: 6px; margin-top: 25px; font: 10px var(--mono); }
.cooling-ladder i { height: 2px; background: var(--amber); }
.cooling-ladder span { color: var(--muted); }
.comparison { display: grid; grid-template-columns: 1fr auto 1fr; align-items: center; gap: 18px; }
.comparison small { display: block; color: #946100; font: 10px var(--mono); }
.comparison b { display: block; margin: 7px 0; }
.comparison ul { margin: 8px 0 0; padding-left: 17px; color: var(--muted); font-size: 13px; }
.versus { display: grid; place-items: center; width: 42px; height: 42px; color: var(--amber); background: var(--ink); border-radius: 50%; font: 700 10px var(--mono); }
.steel-number { display: flex; gap: 4px; margin: 18px 0 3px; font: 900 40px var(--mono); }
.steel-number span, .steel-number strong { padding: 2px 8px; color: var(--white); background: var(--ink); border-radius: 4px; }
.steel-number strong { color: var(--ink); background: var(--amber); }
.steel-labels { display: grid; grid-template-columns: 52px 52px 1fr; gap: 4px; color: var(--muted); font: 8px var(--mono); text-align: center; }
.steel-card p { margin-bottom: 0; color: var(--muted); font-size: 13px; }
.steel-examples { display: grid; gap: 5px; margin-top: 12px; }
.steel-examples span { padding: 8px 10px; background: var(--paper); border-radius: 7px; color: var(--muted); font-size: 11px; }
.alloy-reference { margin-top: 18px; padding: 0; overflow: hidden; }
.alloy-reference-head { display: flex; justify-content: space-between; align-items: end; gap: 20px; padding: 28px 30px 20px; }
.alloy-tabs { display: flex; gap: 6px; padding: 5px; background: var(--paper); border-radius: 10px; }
.alloy-tab { padding: 9px 16px; border: 0; border-radius: 7px; background: transparent; cursor: pointer; font-weight: 750; }
.alloy-tab.active { color: var(--ink); background: var(--amber); }
.alloy-panel { padding: 28px 30px 30px; border-top: 1px solid var(--line); }
.designation-breakdown { display: grid; grid-template-columns: auto 95px 95px; gap: 6px; max-width: 470px; margin-bottom: 22px; }
.designation-breakdown > b { grid-row: 1 / 3; align-self: stretch; display: grid; place-items: center; padding: 8px 12px; color: var(--amber); background: var(--ink); border-radius: 7px; font: 700 10px var(--mono); }
.designation-breakdown > span { display: grid; place-items: center; padding: 7px; color: var(--white); background: #2a3a50; border-radius: 6px; font: 900 28px var(--mono); }
.designation-breakdown > .digit-grade { color: var(--ink); background: var(--amber); }
.designation-breakdown > i { color: var(--muted); font: 8px var(--mono); text-align: center; font-style: normal; }
.designation-breakdown.aluminum-code { grid-template-columns: auto 70px 70px 90px; max-width: 520px; }
.designation-breakdown .digit-variant { background: #596a80; }
.alloy-series-grid { display: grid; grid-template-columns: repeat(3, 1fr); gap: 8px; }
.aluminum-series { grid-template-columns: repeat(4, 1fr); }
.alloy-series-grid > div { display: grid; gap: 3px; padding: 13px; background: var(--paper); border-radius: 8px; }
.alloy-series-grid b { color: #8b5e00; font: 800 15px var(--mono); }
.alloy-series-grid span { font-size: 12px; font-weight: 750; }
.alloy-series-grid small { color: var(--muted); font-size: 9px; line-height: 1.5; }
.designation-caveat { margin: 17px 0 0; padding: 12px 14px; border-left: 3px solid var(--amber); background: #fff7e3; color: var(--muted); font-size: 11px; }
.temper-guide { display: grid; grid-template-columns: 1fr 1fr; gap: 9px; margin-top: 13px; }
.temper-guide > div { padding: 14px; color: var(--white); background: var(--ink); border-radius: 8px; }
.temper-guide small { display: block; margin-bottom: 6px; color: var(--amber); font: 8px var(--mono); letter-spacing: .1em; }
.temper-guide b { color: var(--white); }
.temper-guide p { margin: 0; color: #b8c1cd; font-size: 11px; }

.derivative-ladder { display: grid; grid-template-columns: 1fr auto 1fr auto 1fr auto 1fr auto 1fr; align-items: center; gap: 10px; padding: 28px; color: var(--white); background: var(--ink); border-radius: 18px; }
.derivative-ladder div { padding: 14px; text-align: center; border: 1px solid rgba(255,255,255,.12); border-radius: 10px; }
.derivative-ladder span, .derivative-ladder small { display: block; color: #8e9aaa; font: 9px var(--mono); text-transform: uppercase; }
.derivative-ladder b { display: block; color: var(--amber); margin: 5px 0; font: 800 24px var(--mono); }
.derivative-ladder i { color: #7d8998; font: 9px var(--mono); font-style: normal; }
.ladder-note { margin: 10px 0 32px; color: var(--muted); font: 11px/1.7 var(--mono); }
.method-card.featured { border-top: 5px solid var(--amber); }
.method-card > p { min-height: 65px; color: var(--muted); }
.singularity-table { display: grid; gap: 6px; }
.singularity-table div { display: grid; grid-template-columns: 120px 1fr; gap: 12px; padding: 9px 11px; background: var(--paper); border-radius: 7px; }
.singularity-table b { font: 700 13px var(--mono); }
.singularity-table span { color: var(--muted); font-size: 12px; }
.method-card ol { margin: 15px 0; padding-left: 20px; color: var(--muted); }
.method-card li { margin: 7px 0; }
.method-rule { margin-top: 16px; padding: 12px; border-left: 3px solid var(--amber); background: #fff7e3; font-size: 12px; }
.workflow-card { margin: 30px 0 18px; }
.workflow { display: grid; grid-template-columns: 1fr auto 1fr auto 1fr auto 1fr auto 1fr; align-items: center; gap: 10px; margin-top: 20px; }
.workflow > div { display: grid; grid-template-columns: auto 1fr; gap: 2px 8px; align-items: center; }
.workflow span { grid-row: 1 / 3; display: grid; place-items: center; width: 28px; height: 28px; color: var(--ink); background: var(--amber); border-radius: 50%; font: 800 10px var(--mono); }
.workflow b { font-size: 13px; }
.workflow small { color: var(--muted); font: 8px var(--mono); }
.workflow > i { color: #a1a8b0; font-style: normal; }
.singularity-foundation { margin-top: 18px; }
.bracket-card, .integration-card { height: 100%; }
.piecewise-formula { display: flex; gap: 22px; align-items: center; margin: 18px 0; padding: 16px; color: var(--white); background: var(--ink); border-radius: 10px; }
.piecewise-formula > b { color: var(--amber); font: 700 16px var(--mono); }
.piecewise-formula span { padding-left: 18px; border-left: 2px solid rgba(255,255,255,.18); font: 12px/2 var(--mono); }
.piecewise-formula i { color: var(--white); font-style: normal; font-weight: 800; }
.bracket-card > p, .integration-card > p { color: var(--muted); font-size: 12px; }
.bracket-demo { display: grid; grid-template-columns: 1fr 1fr; gap: 8px; }
.bracket-demo > div { padding: 12px; background: var(--paper); border-radius: 8px; }
.bracket-demo small, .udl-rule small { display: block; color: #8b5e00; font: 8px var(--mono); }
.bracket-demo b { display: block; margin: 6px 0; font: 700 12px var(--mono); }
.bracket-demo span { color: var(--muted); font-size: 10px; }
.integration-rules { display: grid; gap: 7px; margin: 18px 0; }
.integration-rules b { padding: 10px 12px; background: var(--paper); border-radius: 7px; font: 650 11px var(--mono); }
.udl-rule { padding: 13px; border: 1px solid #e4c16e; background: #fff7df; border-radius: 9px; }
.udl-rule b { display: block; margin: 7px 0; font: 700 12px var(--mono); }
.udl-rule p { margin: 0; color: var(--muted); font-size: 10px; }
.singularity-walkthrough { margin: 18px 0; padding: 0; overflow: hidden; }
.walkthrough-head { display: flex; justify-content: space-between; gap: 30px; padding: 28px 30px 20px; }
.walkthrough-head p { max-width: 470px; color: var(--muted); font: 10px/1.6 var(--mono); }
.reaction-strip { display: grid; grid-template-columns: 1fr 1fr; color: var(--white); background: var(--ink); }
.reaction-strip > span { padding: 16px 30px; border-right: 1px solid rgba(255,255,255,.12); }
.reaction-strip > span:last-child { border-right: 0; }
.reaction-strip small { display: block; margin-bottom: 5px; color: var(--amber); font: 8px var(--mono); letter-spacing: .1em; }
.reaction-strip b { font: 700 12px var(--mono); }
.equation-ladder { display: grid; gap: 1px; background: var(--line); }
.equation-ladder > div { display: grid; grid-template-columns: 90px minmax(0, 1fr); gap: 5px 18px; padding: 15px 30px; background: #fffdf7; }
.equation-ladder span { grid-row: 1 / 3; align-self: start; padding: 6px 8px; color: var(--ink); background: var(--amber); border-radius: 5px; font: 800 8px var(--mono); text-align: center; }
.equation-ladder b { font: 650 11px/1.55 var(--mono); overflow-wrap: anywhere; }
.equation-ladder small { color: var(--muted); font-size: 9px; }
.sign-note { margin: 0; padding: 16px 30px; color: #aeb8c5; background: #101d2e; font-size: 11px; }
.sign-note b { color: var(--white); }
.bc-grid { align-items: stretch; }
.boundary-card, .singularity-traps { height: 100%; }
.bc-table { display: grid; gap: 6px; }
.bc-table > div { display: grid; grid-template-columns: 125px 1fr; gap: 10px; padding: 10px 12px; background: var(--paper); border-radius: 7px; }
.bc-table b { font-size: 11px; }
.bc-table span { color: var(--muted); font: 10px var(--mono); }
.singularity-traps { color: var(--white); background: #16243a; border-color: #16243a; }
.singularity-traps .card-index { color: var(--red); }
.singularity-traps ol { margin: 16px 0 0; padding-left: 20px; color: #bdc5d0; }
.singularity-traps li { margin: 10px 0; font-size: 12px; }
.equation-stack { display: grid; gap: 7px; margin: 20px 0; }
.equation-stack span { padding: 10px 12px; background: var(--paper); border-radius: 7px; font: 11px/1.6 var(--mono); overflow-wrap: anywhere; }
.answer-pair { display: grid; grid-template-columns: 1fr 1fr; gap: 10px; }
.answer-pair span { padding: 14px; color: var(--white); background: var(--ink); border-radius: 9px; }
.answer-pair small { display: block; color: var(--amber); font: 9px var(--mono); text-transform: uppercase; }
.answer-pair b { font: 700 13px var(--mono); }
.dependency-card table { width: 100%; border-collapse: collapse; margin: 16px 0; font-size: 12px; }
.dependency-card th, .dependency-card td { padding: 9px 6px; border-bottom: 1px solid var(--line); text-align: center; }
.dependency-card th:first-child, .dependency-card td:first-child { text-align: left; }
.dependency-card th { color: var(--muted); font: 9px var(--mono); text-transform: uppercase; }
.dependency-card td:not(:first-child) { color: #446d00; font-weight: 800; }
.dependency-card p { color: var(--muted); font-size: 12px; }

.drill { background: rgba(255,255,255,.24); }
.quiz-status { display: grid; grid-template-columns: repeat(3, 1fr); max-width: 520px; margin-bottom: 30px; border: 1px solid var(--line); border-radius: 12px; overflow: hidden; }
.quiz-status div { padding: 12px 18px; border-right: 1px solid var(--line); }
.quiz-status div:last-child { border-right: 0; }
.quiz-status span { display: block; font: 800 22px var(--mono); }
.quiz-status small { color: var(--muted); font: 9px var(--mono); text-transform: uppercase; }
.quiz-question { display: grid; grid-template-columns: 45px 1fr; gap: 15px; padding: 24px 0; border-top: 1px solid var(--line); }
.q-number { display: grid; place-items: center; width: 38px; height: 38px; color: var(--white); background: var(--ink); border-radius: 50%; font: 700 11px var(--mono); }
.q-body fieldset { margin: 0; padding: 0; border: 0; }
.q-body legend { margin-bottom: 14px; font-weight: 700; }
.quiz-options { display: flex; flex-wrap: wrap; gap: 8px; }
.quiz-options label { display: inline-flex; align-items: center; gap: 7px; min-width: 120px; padding: 9px 13px; border: 1px solid var(--line); border-radius: 8px; background: rgba(255,255,255,.55); cursor: pointer; font-size: 12px; }
.quiz-options label:has(input:checked) { border-color: var(--amber); background: #fff1c6; }
.q-explanation { display: none; margin-top: 12px; padding: 12px; border-left: 4px solid var(--amber); background: rgba(255,255,255,.65); font-size: 13px; }
.quiz-question.graded .q-explanation { display: block; }
.quiz-question.correct .q-number { color: #173300; background: var(--lime); }
.quiz-question.incorrect .q-number { background: var(--red); }
.quiz-actions { display: flex; gap: 12px; margin-top: 28px; }
.quiz-actions .ghost { color: var(--ink); }
.quiz-result { margin-top: 24px; padding: 26px; color: var(--white); background: var(--ink); border-radius: 14px; }
.quiz-result strong { color: var(--amber); font: 800 32px var(--mono); }

.cheatsheet { max-width: none; color: var(--white); background: var(--ink); }
.cheat-head { max-width: 1144px; margin: 0 auto 34px; display: flex; align-items: end; justify-content: space-between; gap: 20px; }
.cheat-head .section-tag { color: var(--amber); }
.cheat-head button { padding: 10px 14px; color: var(--white); border: 1px solid rgba(255,255,255,.2); border-radius: 8px; background: transparent; cursor: pointer; }
.cheat-grid { max-width: 1144px; margin: 0 auto; display: grid; grid-template-columns: repeat(3, 1fr); border: 1px solid rgba(255,255,255,.15); border-radius: 15px; overflow: hidden; }
.cheat-grid article { display: grid; gap: 10px; min-height: 170px; padding: 22px; border-right: 1px solid rgba(255,255,255,.12); border-bottom: 1px solid rgba(255,255,255,.12); }
.cheat-grid article:nth-child(3n) { border-right: 0; }
.cheat-grid article:nth-last-child(-n+3) { border-bottom: 0; }
.cheat-grid small { color: var(--amber); font: 700 10px var(--mono); letter-spacing: .12em; }
.cheat-grid b { color: #c3ccd8; font: 600 12px/1.55 var(--mono); }
.source-note { display: grid; grid-template-columns: .7fr 1.3fr; gap: 70px; align-items: end; }
.source-note p:last-child { color: var(--muted); }
footer { display: flex; justify-content: space-between; align-items: center; gap: 20px; padding: 24px 50px; color: #9da8b6; background: #07101c; font: 10px var(--mono); }
footer p { margin: 0; }
footer a { color: var(--amber); }

@keyframes spin { to { transform: rotate(360deg); } }
@keyframes pulse { 50% { opacity: .5; } }

@media (max-width: 1100px) {
  .rail { display: none; }
  main, footer { margin-left: 0; }
  .hero { grid-template-columns: 1fr; padding-top: 130px; }
  .hero-visual { min-height: 460px; }
  .runbook, .module, .source-note { padding-inline: 42px; }
  .two-one, .mohr-lab { grid-template-columns: 1fr !important; }
  .formula-strip { grid-template-columns: 1fr 1fr; }
  .decision-result { grid-template-columns: auto 1fr; }
  .decision-formula { grid-column: 1 / -1; }
  .derivative-ladder { overflow-x: auto; }
  .derivative-ladder > div { min-width: 115px; }
  .pipeline-steps, .failure-steps { grid-template-columns: 1fr 1fr; }
  .pipeline-steps > i { display: none; }
  .stress-formula-grid { grid-template-columns: 1fr 1fr; }
  .brittle-calculator { grid-template-columns: 1fr; }
  .aluminum-series { grid-template-columns: repeat(2, 1fr); }
}

@media (max-width: 760px) {
  .topbar { grid-template-columns: 1fr auto; height: 66px; padding: 0 14px; }
  .brand small, .timer-label, .top-progress { display: none; }
  .timer-wrap { gap: 6px; padding-left: 11px; }
  .timer { min-width: 74px; font-size: 15px; }
  .hero { min-height: auto; padding: 115px 22px 62px; }
  .hero h1 { font-size: 48px; }
  .hero-lede { font-size: 16px; }
  .hero-visual { min-height: 380px; transform: scale(.82); margin: -35px -50px; }
  .runbook, .module, .source-note { padding: 68px 20px; }
  .runbook { grid-template-columns: 1fr; gap: 34px; }
  .timeline { grid-column: 1; grid-row: auto; }
  .timeline li { grid-template-columns: 72px 1fr; }
  .timeline small { grid-column: 2; }
  .module-head { grid-template-columns: 48px 1fr; gap: 15px; }
  .module-number { width: 46px; height: 46px; }
  .complete-button { grid-column: 2; width: max-content; }
  .grid.equal, .theory-grid, .manufacturing-map { grid-template-columns: 1fr; }
  .card, .mohr-lab { padding: 23px; }
  .tensor-row { align-items: flex-start; flex-wrap: wrap; }
  .matrix { font-size: 13px; }
  .formula-strip { grid-template-columns: 1fr; }
  .formula-strip > div { border-right: 0; border-bottom: 1px solid rgba(255,255,255,.1); }
  .decision-result { grid-template-columns: 1fr; }
  .decision-result > span { width: 55px; height: 55px; }
  .theory-card { padding: 88px 22px 24px; }
  .solution-steps, .answer-pair { grid-template-columns: 1fr; }
  .comparison { grid-template-columns: 1fr; }
  .versus { margin: 0 auto; }
  .workflow { grid-template-columns: 1fr; gap: 14px; }
  .workflow > i { transform: rotate(90deg); text-align: center; }
  .workflow-card { overflow: hidden; }
  .pipeline-steps, .failure-steps, .stress-formula-grid, .true-example-flow { grid-template-columns: 1fr; }
  .true-example-flow > i { transform: rotate(90deg); text-align: center; }
  .stress-compare, .branch-columns, .mm-derivation, .temper-guide { grid-template-columns: 1fr; }
  .brittle-head, .alloy-reference-head, .walkthrough-head { align-items: flex-start; flex-direction: column; }
  .mm-construction ol { grid-template-columns: 1fr; }
  .mm-graph { max-width: 100%; overflow-x: auto; }
  .mm-graph svg, .mm-graph figcaption { min-width: 640px; }
  .brittle-inputs, .alloy-series-grid, .aluminum-series { grid-template-columns: 1fr 1fr; }
  .designation-breakdown, .designation-breakdown.aluminum-code { grid-template-columns: auto 1fr; max-width: none; }
  .designation-breakdown > b { grid-row: auto; grid-column: 1 / -1; }
  .designation-breakdown > i { display: none; }
  .reaction-strip { grid-template-columns: 1fr; }
  .reaction-strip > span { border-right: 0; border-bottom: 1px solid rgba(255,255,255,.12); }
  .equation-ladder > div { grid-template-columns: 1fr; padding: 14px 18px; }
  .equation-ladder span { grid-row: auto; width: max-content; }
  .quiz-question { grid-template-columns: 1fr; }
  .quiz-options { display: grid; }
  .cheat-head { align-items: flex-start; flex-direction: column; }
  .cheat-grid { grid-template-columns: 1fr; }
  .cheat-grid article { border-right: 0; border-bottom: 1px solid rgba(255,255,255,.12) !important; }
  .cheat-grid article:last-child { border-bottom: 0 !important; }
  .source-note { grid-template-columns: 1fr; gap: 20px; }
  footer { flex-direction: column; text-align: center; }
}

@media (max-width: 480px) {
  .brittle-inputs, .alloy-series-grid, .aluminum-series, .bracket-demo { grid-template-columns: 1fr; }
  .alloy-tabs { width: 100%; }
  .alloy-tab { flex: 1; }
  .bc-table > div { grid-template-columns: 1fr; }
}

@media print {
  body { background: white; }
  .topbar, .rail, .hero, .runbook, .module, .source-note, footer { display: none !important; }
  main { margin: 0; }
  .cheatsheet { display: block !important; padding: 24px; color: #000; background: white; }
  .cheat-head button { display: none; }
  .cheat-grid { grid-template-columns: repeat(2, 1fr); border-color: #555; }
  .cheat-grid article { min-height: auto; border-color: #999 !important; break-inside: avoid; }
  .cheat-grid small, .cheat-grid b { color: #000; }
}

@media (prefers-reduced-motion: reduce) {
  *, *::before, *::after { scroll-behavior: auto !important; animation-duration: .01ms !important; animation-iteration-count: 1 !important; }
}