@font-face {
  font-family: 'EB Garamond';
  src: url('./fonts/ebg.ttf') format('truetype');
  font-style: normal;
  font-weight: 400 800;
  font-display: swap;
}

@font-face {
  font-family: 'Manrope';
  src: url('./fonts/manrope.ttf') format('truetype');
  font-style: normal;
  font-weight: 400 800;
  font-display: swap;
}

:root {
  --paper: #FCFAF5;
  --surface: #F4F1E9;
  --card: #FFFDF9;
  --ink: #26282E;
  --muted: #6E7178;
  --label: #6F6B5E;
  --q-bg: #F0EEF2;
  --q-border: #C8C4DB;
  --q-accent: #5B4BC4;
  --q-accent-dark: #483D96;
  --q-opt-bg: #FAFAFD;
  --q-correct: #1E9E6E;
  --q-correct-bg: rgba(30, 158, 110, .13);
  --gold: #B8923E;
  --font-display: 'EB Garamond', Georgia, serif;
  --font-ui: 'Manrope', system-ui, sans-serif;
  --r-sm: 8px;
  --r-md: 12px;
  --r-lg: 16px;
  --r-pill: 999px;
  --hairline: 1px solid rgba(30, 37, 71, .07);
  --hairline-str: 1px solid rgba(30, 37, 71, .12);
  --shadow: 0 1px 2px rgba(30, 37, 71, .04), 0 8px 22px rgba(30, 37, 71, .05);
}

* { box-sizing: border-box; }
html { scroll-behavior: smooth; }
body {
  margin: 0;
  overflow-x: clip;
  background: var(--paper);
  color: var(--ink);
  font-family: var(--font-ui);
  font-weight: 600;
  -webkit-font-smoothing: antialiased;
  text-rendering: optimizeLegibility;
}
button, input, textarea { font: inherit; }
button, a, summary { -webkit-tap-highlight-color: transparent; }
button:focus-visible, a:focus-visible, summary:focus-visible, [tabindex]:focus-visible {
  outline: 3px solid var(--q-accent-dark);
  outline-offset: 3px;
}
[hidden] { display: none !important; }
.no-js [data-js-only] { display: none !important; }
.no-js.js-loading [data-no-js-only] { display: none !important; }
.js [data-no-js-only] { display: none !important; }
.no-js .a1-shell { grid-template-columns: minmax(0, 1fr); grid-template-areas: 'stage'; }
.no-js .a1-rail, .no-js .a1-reason, .no-js .a1-diagnostic, .no-js .a1-practice, .no-js .a1-mobile-bar { display: none !important; }
.a1-no-js-work { max-width: 980px; margin: 0 auto 28px; }
.a1-no-js-work h2 { margin: 0 0 13px; font: 600 clamp(23px, 2.1vw, 25px)/1.1 var(--font-display); }
.a1-no-js-work ol { margin: 0; padding-left: 22px; color: var(--ink); }
.a1-no-js-work li { margin: 8px 0; font-size: 13px; line-height: 1.65; }
.js [data-a1-gated]:not(.a1-gate-open) { display: none !important; }
.a1-skip {
  position: fixed;
  z-index: 50;
  top: -80px;
  left: 16px;
  padding: 12px 16px;
  border-radius: var(--r-sm);
  background: var(--ink);
  color: var(--card);
  text-decoration: none;
}
.a1-skip:focus { top: 12px; }

.a1-topbar {
  min-height: 78px;
  max-width: 1520px;
  margin: 0 auto;
  padding: 14px 34px;
  display: grid;
  grid-template-columns: 1fr auto 1fr;
  align-items: center;
  border-bottom: var(--hairline);
}
.a1-brand {
  width: max-content;
  min-height: 44px;
  display: inline-flex;
  align-items: center;
  gap: 10px;
  color: var(--ink);
  text-decoration: none;
}
.a1-brand-mark {
  width: 40px;
  height: 40px;
  display: grid;
  place-items: center;
  border: 1.5px solid var(--q-accent);
  border-radius: 50%;
  color: var(--q-accent);
  font: 700 20px var(--font-display);
}
.a1-brand > span:last-child { display: grid; gap: 1px; }
.a1-brand strong { font-size: 14px; font-weight: 800; }
.a1-brand small { color: var(--muted); font-size: 11px; }
.a1-mode {
  min-height: 44px;
  padding: 5px 15px 5px 6px;
  display: inline-flex;
  align-items: center;
  gap: 9px;
  border-radius: var(--r-pill);
  background: var(--q-bg);
}
.a1-mode span {
  width: 32px;
  height: 32px;
  display: grid;
  place-items: center;
  border-radius: 50%;
  background: var(--q-accent);
  color: var(--card);
  font-size: 10px;
  font-weight: 800;
}
.a1-mode strong { color: var(--q-accent-dark); font-size: 12px; }
.a1-draft {
  justify-self: end;
  padding: 7px 12px;
  border: 1px solid rgba(184, 146, 62, .26);
  border-radius: var(--r-pill);
  background: #FFF9EC;
  color: #725517;
  font-size: 10px;
  font-weight: 800;
  letter-spacing: .08em;
  text-transform: uppercase;
}

.a1-main { max-width: 1520px; margin: 0 auto; padding: 0 34px 72px; }
.a1-lesson-head { padding: 48px 0 31px; }
.a1-kicker {
  display: flex;
  align-items: center;
  gap: 10px;
  color: var(--muted);
  font-size: 11px;
  font-weight: 800;
  letter-spacing: .13em;
  text-transform: uppercase;
}
.a1-kicker i { width: 28px; height: 1px; background: var(--q-border); }
.a1-heading-row { margin-top: 16px; display: flex; justify-content: space-between; align-items: end; gap: 48px; }
.a1-eyebrow {
  margin: 0 0 10px;
  color: var(--q-accent-dark);
  font-size: 11.5px;
  font-weight: 800;
  letter-spacing: .14em;
  text-transform: uppercase;
}
h1, h2, h3, p { text-wrap: pretty; }
code {
  color: inherit;
  background: transparent;
  font: 650 1em var(--font-ui);
  font-variant-numeric: tabular-nums;
}
h1 {
  max-width: 920px;
  margin: 0;
  font: 600 clamp(40px, 4.5vw, 68px)/.98 var(--font-display);
  letter-spacing: -.035em;
}
h1 em { color: var(--q-accent); font-weight: 500; }
.a1-lead { max-width: 780px; margin: 18px 0 0; color: var(--muted); font-size: 15px; line-height: 1.65; }
.a1-progress {
  min-width: 272px;
  padding-bottom: 7px;
  display: grid;
  grid-template-columns: auto auto auto;
  align-items: center;
  gap: 13px;
}
.a1-progress > span { color: var(--q-accent); font: 600 32px var(--font-display); }
.a1-progress > .a1-progress-muted { color: var(--muted); }
.a1-progress div { display: grid; gap: 3px; }
.a1-progress strong { font-size: 12px; }
.a1-progress small { color: var(--muted); font-size: 10px; }

.a1-shell {
  display: grid;
  grid-template-columns: minmax(184px, 220px) minmax(520px, 1fr) minmax(276px, 326px);
  grid-template-areas: 'rail stage reason';
  align-items: stretch;
  gap: 14px;
}
.a1-rail, .a1-stage, .a1-reason {
  border: var(--hairline);
  border-radius: var(--r-lg);
  background: var(--card);
}
.a1-rail { grid-area: rail; padding: 23px 14px 16px; display: flex; flex-direction: column; }
.a1-rail-label { margin: 0 10px 13px; color: var(--muted); font-size: 10px; font-weight: 800; letter-spacing: .14em; text-transform: uppercase; }
.a1-rail ol { list-style: none; margin: 0; padding: 0; display: grid; gap: 3px; }
.a1-rail li > div {
  width: 100%;
  min-height: 59px;
  padding: 8px 10px;
  display: grid;
  grid-template-columns: 30px 1fr;
  grid-template-rows: auto auto;
  align-items: center;
  column-gap: 9px;
  border-radius: var(--r-md);
  color: var(--muted);
}
.a1-rail li > div > span {
  grid-row: 1 / 3;
  width: 28px;
  height: 28px;
  display: grid;
  place-items: center;
  border: var(--hairline-str);
  border-radius: 50%;
  font-size: 10px;
  font-weight: 800;
}
.a1-rail li strong { align-self: end; font-size: 13px; }
.a1-rail li small { align-self: start; opacity: .82; font-size: 11px; }
.a1-rail li.a1-active > div { background: var(--q-bg); color: var(--q-accent-dark); }
.a1-rail li.a1-active > div > span { border-color: var(--q-accent); background: var(--q-accent); color: var(--card); }
.a1-rail li.a1-done > div > span { border-color: var(--ink); background: var(--ink); color: var(--card); font-size: 15px; }
.a1-step-check svg { width: 16px; height: 16px; fill: none; stroke: currentColor; stroke-width: 2; stroke-linecap: round; stroke-linejoin: round; }
.no-js .a1-step-check svg { display: none; }
.no-js .a1-step-check::after { content: '01'; }
.a1-rail-note { margin-top: auto; padding: 17px 12px 6px; border-top: var(--hairline); }
.a1-rail-note > span { color: var(--muted); font-size: 9.5px; font-weight: 800; letter-spacing: .12em; text-transform: uppercase; }
.a1-rail-note strong { display: block; margin-top: 5px; font: 600 20px var(--font-display); }
.a1-rail-note p { margin: 6px 0 0; color: var(--muted); font-size: 13px; line-height: 1.55; }

.a1-stage { grid-area: stage; min-width: 0; padding: 27px 28px 24px; overflow: hidden; box-shadow: var(--shadow); }
.a1-stage-head { display: flex; justify-content: space-between; align-items: start; gap: 20px; }
.a1-stage h2, .a1-reason h2, .a1-section-head h2, .a1-status h2 {
  margin: 0;
  font: 600 clamp(24px, 1.9vw, 29px)/1.08 var(--font-display);
  letter-spacing: -.018em;
}
.a1-equation-chip { min-width: 154px; padding: 9px 13px; display: grid; gap: 2px; border-radius: var(--r-md); background: var(--q-bg); }
.a1-equation-chip span { font-size: 10px; letter-spacing: .12em; text-transform: uppercase; }
.a1-equation-chip strong { color: var(--q-accent-dark); font: 600 18px var(--font-display); white-space: nowrap; }
.a1-figure-wrap { margin: 14px 0 7px; }
#a1-fraction-svg { width: 100%; height: auto; max-height: 310px; display: block; }
.a1-svg-kicker { fill: var(--muted); font: 800 13px var(--font-ui); letter-spacing: .12em; }
.a1-svg-fraction { fill: var(--q-accent-dark); font: 600 26px var(--font-display); }
.a1-whole { fill: var(--q-opt-bg); }
.a1-pattern-bg { fill: rgba(91, 75, 196, .12); }
.a1-pattern-line { stroke: var(--q-accent); stroke-width: 4; opacity: .42; }
.a1-filled { stroke: none; }
.a1-whole-outline { fill: none; stroke: var(--q-accent-dark); stroke-width: 1.7; }
#a1-cut-lines line { stroke: rgba(38, 40, 46, .47); stroke-width: 1.4; }
.a1-svg-caption line, .a1-svg-caption path { fill: none; stroke: var(--muted); stroke-width: 1.2; }
.a1-svg-caption text { fill: var(--muted); font: 700 13px var(--font-ui); }
.a1-taken-label path { fill: none; stroke: var(--q-accent-dark); stroke-width: 1.5; }
.a1-taken-label text { fill: var(--q-accent-dark); font: 800 13px var(--font-ui); }
.a1-model-legend { display: flex; justify-content: center; gap: 20px; color: var(--muted); font-size: 12px; }
.a1-model-legend span { display: inline-flex; align-items: center; gap: 7px; }
.a1-model-legend i { width: 20px; height: 10px; display: inline-block; border: var(--hairline-str); }
.a1-legend-pattern { background: repeating-linear-gradient(45deg, rgba(91,75,196,.2), rgba(91,75,196,.2) 3px, transparent 3px, transparent 6px); }
.a1-legend-empty { background: var(--q-opt-bg); }

.a1-piece-control {
  margin-top: 15px;
  padding: 15px 17px;
  display: grid;
  grid-template-columns: minmax(170px, .8fr) minmax(270px, 1.2fr);
  gap: 13px 18px;
  border-radius: var(--r-md);
  background: var(--q-bg);
}
.a1-piece-control .a1-eyebrow { margin-bottom: 4px; }
.a1-piece-control > div:first-child > strong { font: 600 17px/1.35 var(--font-display); }
.a1-piece-buttons { display: grid; grid-template-columns: repeat(3, 1fr); gap: 7px; }
.a1-piece-buttons button {
  min-height: 52px;
  padding: 6px 8px;
  display: grid;
  place-items: center;
  gap: 1px;
  border: var(--hairline-str);
  border-radius: var(--r-md);
  background: var(--card);
  color: var(--ink);
  cursor: pointer;
}
.a1-piece-buttons button span { font-size: 9px; color: var(--muted); }
.a1-piece-buttons button strong { font: 600 18px var(--font-display); }
.a1-piece-buttons button[aria-checked="true"] { border-color: var(--q-accent); background: var(--card); color: var(--q-accent-dark); box-shadow: 0 1px 8px rgba(72, 61, 150, .09); }
.a1-seen { grid-column: 1 / -1; margin: 0; color: var(--label); font-size: 11px; text-align: right; }

.a1-prediction {
  margin-top: 14px;
  padding: 15px 17px;
  display: grid;
  grid-template-columns: minmax(190px, 1fr) auto;
  gap: 12px 18px;
  border: var(--hairline-str);
  border-radius: var(--r-md);
}
.a1-prediction .a1-eyebrow { margin-bottom: 5px; }
.a1-prediction p:not(.a1-eyebrow):not(.a1-feedback) { margin: 0; font: 600 17px/1.42 var(--font-display); }
.a1-answer-actions { display: flex; align-items: center; gap: 7px; }
.a1-answer-actions button, .a1-diagnostic-grid button {
  min-height: 44px;
  padding: 0 12px;
  border: var(--hairline-str);
  border-radius: var(--r-pill);
  background: var(--card);
  color: var(--ink);
  font-size: 11.5px;
  font-weight: 800;
  cursor: pointer;
}
.a1-answer-actions button[data-state="correct"], .a1-diagnostic-grid button[data-state="correct"] { border-color: var(--q-correct); background: var(--q-correct-bg); }
.a1-answer-actions button[data-state="wrong"], .a1-diagnostic-grid button[data-state="route"] { border-color: var(--gold); background: #FFF9EC; }
.a1-answer-actions button:disabled { cursor: default; }
.a1-feedback { grid-column: 1 / -1; min-height: 0; margin: 0; color: var(--muted); font-size: 13px; line-height: 1.55; }
.a1-feedback:not(:empty) { padding-top: 9px; border-top: var(--hairline); }

.a1-proof { margin-top: 14px; padding: 17px; border: 1px solid rgba(30, 158, 110, .28); border-radius: var(--r-md); background: rgba(30, 158, 110, .055); }
.a1-proof-formulas { display: grid; grid-template-columns: 1fr auto 1fr auto 1fr; align-items: center; gap: 10px; }
.a1-proof-formulas div { min-height: 62px; padding: 8px 10px; display: grid; place-items: center; border: var(--hairline); border-radius: var(--r-sm); background: var(--card); }
.a1-proof-formulas div span { color: var(--muted); font-size: 9.5px; }
.a1-proof-formulas div strong { color: var(--q-accent-dark); font: 600 22px var(--font-display); }
.a1-proof-formulas > i { color: var(--q-accent-dark); font: 600 22px var(--font-display); }
.a1-proof > p { margin: 13px 0 0; color: var(--ink); font-size: 13px; line-height: 1.62; }
.a1-number-line { width: 100%; height: auto; display: block; margin-top: 7px; }
.a1-number-axis, .a1-number-ticks { fill: none; stroke: var(--ink); stroke-width: 2; stroke-linecap: round; }
.a1-number-point { fill: var(--q-accent); stroke: var(--card); stroke-width: 4; }
.a1-number-line text { fill: var(--muted); font: 700 14px var(--font-ui); }
.a1-number-line .a1-number-label { fill: var(--q-accent-dark); font: 600 20px var(--font-display); }

.a1-ratio-view { margin-top: 14px; padding: 17px; border: var(--hairline-str); border-radius: var(--r-md); background: var(--q-opt-bg); }
.a1-ratio-view > svg { width: 100%; height: auto; display: block; }
.a1-ratio-purple { fill: rgba(91,75,196,.16); stroke: var(--q-accent-dark); stroke-width: 1.8; }
.a1-ratio-white { fill: var(--card); stroke: var(--ink); stroke-width: 1.4; }
.a1-ratio-tiles text { fill: var(--ink); font: 800 22px var(--font-ui); }
.a1-ratio-brace { fill: none; stroke: var(--muted); stroke-width: 1.3; }
.a1-ratio-count { fill: var(--muted); font: 800 13px var(--font-ui); }
.a1-ratio-statements { display: grid; grid-template-columns: 1fr 1fr; gap: 10px; }
.a1-ratio-statements div { padding: 13px; border: var(--hairline); border-radius: var(--r-sm); background: var(--card); }
.a1-ratio-statements span { color: var(--muted); font-size: 9.5px; font-weight: 800; letter-spacing: .1em; text-transform: uppercase; }
.a1-ratio-statements strong { display: block; margin-top: 5px; color: var(--q-accent-dark); font: 600 22px var(--font-display); }
.a1-ratio-statements p { margin: 4px 0 0; color: var(--muted); font-size: 12px; line-height: 1.5; }
.a1-ratio-warning { margin: 11px 0 0; padding: 12px 13px; border-left: 4px solid #E3B341; background: #FFF9EC; color: #725517; font-size: 12.5px; line-height: 1.55; }
.a1-secondary {
  width: 100%;
  min-height: 48px;
  margin-top: 11px;
  padding: 0 19px;
  border: var(--hairline-str);
  border-radius: var(--r-pill);
  background: transparent;
  color: var(--ink);
  font-size: 12px;
  font-weight: 800;
  cursor: pointer;
}
.a1-static { margin-top: 14px; padding: 16px 17px; border: var(--hairline-str); border-radius: var(--r-md); background: var(--q-bg); }
.a1-static h3 { margin: 0 0 10px; font: 600 clamp(19px, 1.8vw, 21px) var(--font-display); }
.a1-static table { width: 100%; border-collapse: collapse; font-size: 12px; }
.a1-static th, .a1-static td { padding: 8px; border: var(--hairline-str); text-align: left; }
.a1-static p { font-size: 13px; line-height: 1.6; }
.a1-proof > h3, .a1-ratio-view > h3 { margin: 0 0 14px; font: 600 clamp(20px, 1.9vw, 22px)/1.1 var(--font-display); }

.a1-reason { grid-area: reason; padding: 27px 25px 22px; display: flex; flex-direction: column; }
.a1-reason-top { display: flex; justify-content: space-between; align-items: center; }
.a1-reason-top > span { display: inline-flex; align-items: center; gap: 7px; color: var(--muted); font-size: 10.5px; }
.a1-reason-top > span i { width: 6px; height: 6px; border-radius: 50%; background: var(--q-accent); box-shadow: 0 0 0 4px rgba(91,75,196,.1); }
.a1-reason h2 { margin-top: 5px; font-size: clamp(27px, 2vw, 29px); }
.a1-reason-intro { margin: 12px 0 18px; color: var(--muted); font-size: 13px; line-height: 1.6; }
.a1-reason-steps { list-style: none; margin: 0; padding: 0; display: grid; gap: 7px; }
.a1-reason-steps li { min-height: 86px; padding: 13px 12px; display: grid; grid-template-columns: 28px 1fr; gap: 9px; border: var(--hairline); border-radius: var(--r-md); }
.a1-reason-steps li > span { width: 27px; height: 27px; display: grid; place-items: center; border-radius: 50%; background: var(--q-bg); color: var(--q-accent-dark); font-size: 11px; font-weight: 800; }
.a1-reason-steps strong { font-size: 13px; }
.a1-reason-steps p { margin: 4px 0 2px; color: var(--q-accent-dark); font: 600 18px var(--font-display); }
.a1-reason-steps small { color: var(--muted); font-size: 12px; line-height: 1.48; }
.a1-reason-steps .a1-locked { border-style: dashed; background: var(--q-opt-bg); }
.a1-reason-steps .a1-unlocked { border-color: var(--q-accent); background: rgba(91,75,196,.055); }
.a1-primary {
  width: 100%;
  min-height: 48px;
  margin-top: 11px;
  padding: 0 19px;
  border: 0;
  border-radius: var(--r-pill);
  background: var(--q-accent);
  color: var(--card);
  font-size: 12px;
  font-weight: 800;
  cursor: pointer;
}
.a1-primary:disabled { background: var(--q-border); color: var(--muted); cursor: not-allowed; }
.a1-clinic { margin-top: auto; padding-top: 18px; display: grid; grid-template-columns: 66px 1fr; align-items: center; gap: 12px; border-top: var(--hairline); }
.a1-clinic-mark { height: 66px; display: grid; grid-template-columns: 1fr auto 1fr; place-items: center; gap: 4px; border-radius: var(--r-sm); background: #FFF9EC; color: #725517; }
.a1-clinic-mark span { width: 22px; height: 28px; display: grid; place-items: center; border: 1px solid rgba(184,146,62,.3); border-radius: 6px; background: var(--card); font: 600 18px var(--font-display); }
.a1-clinic-mark i { font-style: normal; font-size: 12px; }
.a1-clinic > div:last-child > span { color: #725517; font-size: 9.5px; font-weight: 800; letter-spacing: .1em; text-transform: uppercase; }
.a1-clinic strong { display: block; margin: 4px 0; font-size: 13px; }
.a1-clinic p { margin: 0; color: var(--muted); font-size: 12px; line-height: 1.52; }

.a1-takeaway { margin-top: 15px; padding: 25px 28px; display: grid; grid-template-columns: minmax(300px, 1fr) auto; align-items: center; gap: 28px; border: var(--hairline); border-radius: var(--r-lg); background: var(--card); }
.a1-takeaway h2 { margin: 0; font: 600 clamp(23px, 2.2vw, 34px)/1.08 var(--font-display); }
.a1-takeaway h2 em { color: var(--q-accent); }
.a1-formula-lockup { display: grid; grid-template-columns: auto auto; align-items: center; gap: 3px 12px; }
.a1-formula-lockup span { color: var(--muted); font-size: 10px; font-weight: 800; text-align: right; }
.a1-formula-lockup strong { color: var(--q-accent-dark); font: 600 21px var(--font-display); white-space: nowrap; }

.a1-diagnostic, .a1-practice { margin-top: 64px; padding-top: 30px; border-top: var(--hairline); }
.a1-diagnostic { margin-top: 12px; }
.a1-section-head { display: grid; grid-template-columns: minmax(300px, 1fr) minmax(280px, 520px); align-items: end; gap: 36px; margin-bottom: 22px; }
.a1-section-head h2 { font-size: clamp(28px, 2.5vw, 38px); }
.a1-section-head > p { margin: 0; color: var(--muted); font-size: 13px; line-height: 1.65; }
.a1-diagnostic-grid { display: grid; grid-template-columns: repeat(4, 1fr); gap: 12px; }
.a1-diagnostic-grid article, .a1-practice-grid article { min-width: 0; padding: 19px; border: var(--hairline); border-radius: var(--r-lg); background: var(--card); }
.a1-diagnostic-grid article.a1-diagnostic-locked { background: var(--q-opt-bg); opacity: .68; }
.a1-diagnostic-grid article > span, .a1-practice-grid article > span { color: var(--q-accent-dark); font-size: 9.5px; font-weight: 800; letter-spacing: .1em; text-transform: uppercase; }
.a1-diagnostic-grid h3, .a1-practice-grid h3 { margin: 9px 0 13px; font: 600 clamp(18px, 1.6vw, 19px)/1.2 var(--font-display); }
.a1-diagnostic-grid article > div { display: flex; flex-wrap: wrap; gap: 7px; }
.a1-diagnostic-grid button { padding-inline: 14px; }
.a1-diag-feedback { min-height: 38px; margin: 12px 0 0; padding-top: 10px; border-top: var(--hairline); color: var(--muted); font-size: 11.5px; line-height: 1.5; }
.a1-mini { margin-top: 12px; padding: 13px; border-radius: var(--r-md); background: var(--q-bg); }
.a1-mini > strong { color: var(--q-accent-dark); font-size: 11px; font-weight: 800; letter-spacing: .08em; text-transform: uppercase; }
.a1-mini > p { margin: 7px 0 0; color: var(--label); font-size: 11.5px; line-height: 1.5; }
.a1-mini > .a1-mini-question { color: var(--ink); font-weight: 800; }
.a1-mini > div { display: flex; flex-wrap: wrap; gap: 7px; margin-top: 10px; }
.a1-diagnostic-footer {
  margin-top: 14px;
  padding: 15px 17px;
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 18px;
  border: var(--hairline-str);
  border-radius: var(--r-lg);
  background: var(--q-bg);
}
.a1-diagnostic-footer p { margin: 0; display: grid; gap: 3px; }
.a1-diagnostic-footer span { color: var(--q-accent-dark); font-size: 10px; font-weight: 800; letter-spacing: .1em; text-transform: uppercase; }
.a1-diagnostic-footer strong { font: 600 17px var(--font-display); }
.a1-diagnostic-footer button {
  min-height: 48px;
  padding: 0 22px;
  border: 0;
  border-radius: var(--r-pill);
  background: var(--q-accent);
  color: var(--card);
  font-size: 11.5px;
  font-weight: 800;
  cursor: pointer;
}
.a1-diagnostic-footer button:disabled { background: var(--q-border); color: var(--muted); cursor: not-allowed; }
.a1-static-compact { margin-top: 0; }

.a1-practice-progress {
  max-width: 920px;
  margin: 0 auto 12px;
  padding: 14px 17px;
  display: grid;
  grid-template-columns: minmax(230px, 1fr) minmax(180px, .8fr);
  align-items: center;
  gap: 18px;
  border-radius: var(--r-md);
  background: var(--q-bg);
}
.a1-practice-progress > div:first-child { display: grid; gap: 3px; }
.a1-practice-progress span { color: var(--q-accent-dark); font-size: 9.5px; font-weight: 800; letter-spacing: .1em; text-transform: uppercase; }
.a1-practice-progress strong { font: 600 16px var(--font-display); }
.a1-progress-track { height: 8px; overflow: hidden; border-radius: var(--r-pill); background: var(--q-border); }
.a1-progress-track i { width: 0; height: 100%; display: block; border-radius: inherit; background: var(--q-accent); transition: width .24s ease; }
.a1-practice-grid { display: grid; grid-template-columns: minmax(0, 920px); justify-content: center; gap: 12px; }
.a1-practice-grid article { min-height: 0; padding: 26px 28px; display: flex; flex-direction: column; }
.a1-practice-grid h3 { max-width: 790px; margin-bottom: 18px; font-size: clamp(22px, 2vw, 27px); line-height: 1.23; }
.a1-practice-model { margin: 0 0 18px; padding: 14px 15px; border: var(--hairline); border-radius: var(--r-md); background: var(--surface); }
.a1-practice-model figcaption { margin-top: 9px; color: var(--label); font-size: 10.5px; line-height: 1.5; }
.a1-strip-pair > div { display: grid; grid-template-columns: 96px minmax(0, 1fr); align-items: center; gap: 8px 12px; }
.a1-strip-pair b, .a1-measure-pair b { font: 700 12px var(--font-ui); }
.a1-segment-bar { height: 30px; display: grid; overflow: hidden; border: 1px solid var(--q-accent-dark); border-radius: var(--r-sm); background: var(--card); }
.a1-segment-bar > * { min-width: 0; border-right: 1px solid rgba(38, 40, 46, .35); }
.a1-segment-bar > *:last-child { border-right: 0; }
.a1-segment-bar i, .a1-measure-bar i { background: repeating-linear-gradient(45deg, rgba(91,75,196,.22), rgba(91,75,196,.22) 4px, rgba(91,75,196,.07) 4px, rgba(91,75,196,.07) 8px); }
.a1-parts-3 { grid-template-columns: repeat(3, 1fr); }
.a1-parts-6 { grid-template-columns: repeat(6, 1fr); }
.a1-measure-pair { display: grid; grid-template-columns: repeat(2, minmax(0, 1fr)); gap: 10px 16px; }
.a1-measure-pair > div { display: grid; grid-template-columns: auto 1fr auto; align-items: center; gap: 9px; }
.a1-measure-pair small { color: var(--label); font-size: 10px; white-space: nowrap; }
.a1-measure-pair figcaption { grid-column: 1 / -1; margin-top: 0; }
.a1-measure-bar { height: 26px; overflow: hidden; border: 1px solid var(--q-accent-dark); border-radius: var(--r-sm); background: var(--card); }
.a1-measure-bar i { width: var(--a1-fill); height: 100%; display: block; border-right: 1px solid var(--q-accent-dark); }
.a1-line-reveal svg { width: 100%; height: auto; display: block; }
.a1-practice-axis, .a1-practice-ticks { fill: none; stroke: var(--ink); stroke-width: 2; }
.a1-practice-point-one { fill: var(--q-bg); stroke: var(--q-accent); stroke-width: 3; }
.a1-practice-point-two { fill: var(--q-accent); stroke: var(--ink); stroke-width: 2; }
.a1-line-reveal text { fill: var(--label); font: 700 12px var(--font-ui); }
.a1-line-reveal .a1-practice-line-label { fill: var(--q-accent-dark); font: 600 17px var(--font-display); }
.a1-symbol-model > div { display: flex; flex-wrap: wrap; align-items: center; gap: 10px 14px; }
.a1-triangle { position: relative; width: 0; height: 0; display: inline-block; border-right: 14px solid transparent; border-bottom: 25px solid var(--q-accent-dark); border-left: 14px solid transparent; }
.a1-triangle::after { content: ''; position: absolute; top: 5px; left: -10px; width: 0; height: 0; border-right: 10px solid transparent; border-bottom: 18px solid var(--surface); border-left: 10px solid transparent; }
.a1-circle { width: 25px; height: 25px; display: inline-block; border: 2px solid var(--ink); border-radius: 50%; background: var(--card); }
.a1-book-model > div { display: grid; grid-template-columns: repeat(8, minmax(28px, 1fr)); gap: 7px; }
.a1-book-model i, .a1-book-model b { min-height: 38px; display: grid; place-items: center; border: 1px solid var(--q-accent-dark); border-radius: var(--r-sm); color: var(--q-accent-dark); font: 800 11px var(--font-ui); }
.a1-book-model i { background: repeating-linear-gradient(45deg, rgba(91,75,196,.2), rgba(91,75,196,.2) 4px, var(--card) 4px, var(--card) 8px); }
.a1-book-model b { border-color: var(--ink); background: var(--card); color: var(--ink); }
.a1-practice-options { display: grid; grid-template-columns: repeat(2, minmax(0, 1fr)); gap: 8px; }
.a1-practice-options button {
  min-height: 52px;
  padding: 10px 14px;
  border: var(--hairline-str);
  border-radius: var(--r-md);
  background: var(--q-opt-bg);
  color: var(--ink);
  font-size: 12px;
  font-weight: 750;
  line-height: 1.4;
  text-align: left;
  cursor: pointer;
}
.a1-practice-options button[data-state="selected"] { border-color: var(--q-accent); background: var(--q-bg); color: var(--q-accent-dark); }
.a1-practice-options button[data-state="correct"] { border-color: var(--q-correct); background: var(--q-correct-bg); }
.a1-practice-options button[data-state="wrong"] { border-color: var(--gold); background: #FFF9EC; }
.a1-practice-options button:disabled { cursor: default; }
.a1-check {
  align-self: flex-end;
  min-height: 48px;
  margin-top: 13px;
  padding: 0 22px;
  border: 0;
  border-radius: var(--r-pill);
  background: var(--q-accent);
  color: var(--card);
  font-size: 11.5px;
  font-weight: 800;
  cursor: pointer;
}
.a1-check:disabled { background: var(--q-border); color: var(--muted); cursor: not-allowed; }
.a1-practice-feedback, .a1-parallel-feedback { min-height: 0; margin: 12px 0 0; color: var(--label); font-size: 12.5px; line-height: 1.6; }
.a1-practice-feedback:not(:empty), .a1-parallel-feedback:not(:empty) { padding: 12px 13px; border-left: 4px solid var(--q-accent); background: var(--q-bg); }
.a1-practice-grid details { margin-top: 14px; border-top: var(--hairline); }
.a1-practice-grid summary { min-height: 44px; display: flex; align-items: center; color: var(--q-accent-dark); font-size: 11.5px; font-weight: 800; cursor: pointer; list-style: none; }
.a1-practice-grid summary::-webkit-details-marker { display: none; }
.a1-practice-grid summary::after { content: '+'; margin-left: auto; font: 600 19px var(--font-display); }
.a1-practice-grid details[open] summary::after { content: '−'; }
.a1-practice-grid details p { margin: 0 0 10px; padding: 12px 13px; border-radius: var(--r-sm); background: var(--q-bg); color: var(--label); font-size: 12px; line-height: 1.55; }
.a1-parallel { margin-top: 15px; padding: 18px; border: 1px dashed var(--q-accent); border-radius: var(--r-md); background: var(--q-opt-bg); }
.a1-parallel > span { color: var(--q-accent-dark); font-size: 9.5px; font-weight: 800; letter-spacing: .1em; text-transform: uppercase; }
.a1-parallel h4 { margin: 8px 0 14px; font: 600 clamp(18px, 1.7vw, 20px)/1.3 var(--font-display); }
.a1-mastery { max-width: 920px; margin: 12px auto 0; padding: 25px 28px; border: 1px solid rgba(30, 158, 110, .28); border-radius: var(--r-lg); background: var(--q-correct-bg); }
.a1-mastery > span { color: var(--q-accent-dark); font-size: 10px; font-weight: 800; letter-spacing: .1em; text-transform: uppercase; }
.a1-mastery h3 { margin: 8px 0 6px; font: 600 clamp(23px, 2.2vw, 26px)/1.15 var(--font-display); }
.a1-mastery p { margin: 0; color: var(--label); font-size: 13px; line-height: 1.65; }
.a1-passport-link { margin: 16px 0 0; color: var(--muted); font-size: 12px; }
.a1-passport-link a { min-height: 44px; display: inline-flex; align-items: center; color: var(--q-accent-dark); font-weight: 800; }
.a1-status { margin-top: 64px; padding: 24px 28px; display: grid; grid-template-columns: minmax(220px, .5fr) 1fr; gap: 28px; align-items: center; border: 1px solid #F0DCA8; border-left: 4px solid #E3B341; border-radius: var(--r-lg); background: #FFF9EC; }
.a1-status h2 { color: #725517; }
.a1-status > p { margin: 0; color: #725517; font-size: 12.5px; line-height: 1.62; }
.a1-mobile-bar { display: none; }

@media (max-width: 1200px) {
  .a1-shell { grid-template-columns: 190px minmax(470px, 1fr) 270px; }
  .a1-main, .a1-topbar { padding-left: 24px; padding-right: 24px; }
  .a1-stage { padding-inline: 22px; }
  .a1-reason { padding-inline: 20px; }
  .a1-diagnostic-grid { grid-template-columns: repeat(2, 1fr); }
}

@media (max-width: 900px) {
  .a1-heading-row { display: block; }
  .a1-progress { min-width: 0; margin-top: 18px; padding: 0; }
  .a1-shell { grid-template-columns: minmax(0, 1fr); grid-template-areas: 'stage' 'reason' 'rail'; }
  .a1-rail { min-height: 0; }
  .a1-rail ol { grid-template-columns: repeat(3, 1fr); }
  .a1-rail-note { display: none; }
  .a1-reason { display: grid; grid-template-columns: minmax(220px, .6fr) minmax(360px, 1fr); column-gap: 22px; }
  .a1-reason-top, .a1-reason h2, .a1-reason-intro { grid-column: 1; }
  .a1-reason-steps { grid-column: 2; grid-row: 1 / span 5; }
  .a1-primary, .a1-clinic { grid-column: 1; }
  .a1-clinic { margin-top: 18px; }
  .a1-practice-grid { grid-template-columns: minmax(0, 920px); }
}

@media (max-width: 640px) {
  html { scroll-padding-bottom: calc(92px + env(safe-area-inset-bottom)); }
  body { padding-bottom: calc(82px + env(safe-area-inset-bottom)); }
  html.no-js body { padding-bottom: 0; }
  button, summary, [tabindex] { scroll-margin-block: 92px; }
  .a1-topbar { min-height: 64px; padding: 10px 16px; grid-template-columns: 1fr auto; }
  .a1-brand small, .a1-mode { display: none; }
  .a1-brand-mark { width: 36px; height: 36px; }
  .a1-draft { max-width: 142px; padding: 6px 9px; font-size: 8px; text-align: center; }
  .a1-main { padding: 0 14px 40px; }
  .a1-lesson-head { padding: 34px 2px 16px; }
  .a1-kicker, .a1-lead { display: none; }
  .a1-heading-row { margin-top: 12px; }
  h1 { font-size: clamp(33px, 10vw, 40px); line-height: 1.01; }
  h1 br { display: none; }
  .a1-progress { display: none; }
  .a1-shell { display: flex; flex-direction: column; gap: 10px; }
  .a1-stage { order: 1; padding: 20px 16px 17px; }
  .a1-reason { order: 2; padding: 22px 18px; display: flex; }
  .a1-rail { order: 3; padding: 12px; }
  .a1-stage-head { display: block; }
  .a1-stage h2 { font-size: clamp(24px, 6.5vw, 27px); }
  .a1-equation-chip { width: max-content; max-width: 100%; margin-top: 13px; }
  .a1-figure-wrap { margin: 8px -8px 3px; }
  #a1-fraction-svg { min-height: 205px; }
  .a1-svg-kicker { font-size: 18px; }
  .a1-svg-fraction { font-size: 38px; }
  .a1-svg-caption text, .a1-taken-label text { font-size: 20px; }
  .a1-model-legend { gap: 13px; font-size: 10px; }
  .a1-piece-control { grid-template-columns: 1fr; padding: 14px 13px; }
  .a1-piece-buttons button { min-height: 54px; }
  .a1-seen { grid-column: 1; text-align: left; }
  .a1-prediction { grid-template-columns: 1fr; padding: 15px 13px; }
  .a1-answer-actions { display: grid; grid-template-columns: repeat(3, 1fr); }
  .a1-answer-actions button { min-height: 48px; padding: 4px 6px; line-height: 1.25; }
  .a1-proof { padding: 14px 12px; }
  .a1-proof-formulas { grid-template-columns: 1fr auto 1fr; }
  .a1-proof-formulas div:last-child { grid-column: 2 / 4; width: calc(50% + 10px); justify-self: end; }
  .a1-proof-formulas > i:last-of-type { grid-column: 1; grid-row: 2; justify-self: end; }
  .a1-number-line { margin-top: 10px; }
  .a1-ratio-view { padding: 14px 11px; }
  .a1-ratio-statements { grid-template-columns: 1fr; }
  .a1-reason h2 { font-size: clamp(26px, 7.5vw, 29px); }
  .a1-reason-steps li { min-height: 88px; }
  .a1-reason-steps small, .a1-reason-intro, .a1-clinic p { font-size: 13px; }
  .a1-primary { display: none; }
  .a1-clinic { margin-top: 18px; }
  .a1-rail ol { display: flex; overflow-x: auto; scroll-snap-type: x mandatory; scrollbar-width: none; }
  .a1-rail ol::-webkit-scrollbar { display: none; }
  .a1-rail li { min-width: 178px; scroll-snap-align: start; }
  .a1-takeaway { margin-top: 10px; padding: 22px 18px; grid-template-columns: 1fr; gap: 17px; }
  .a1-formula-lockup { grid-template-columns: auto 1fr; }
  .a1-formula-lockup strong { font-size: 19px; white-space: normal; }
  .a1-diagnostic, .a1-practice { margin-top: 42px; padding-top: 24px; }
  .a1-section-head { grid-template-columns: 1fr; align-items: start; gap: 10px; }
  .a1-diagnostic-grid, .a1-practice-grid { grid-template-columns: 1fr; }
  .a1-diagnostic-grid article, .a1-practice-grid article { padding: 18px 16px; }
  .a1-practice-grid article { min-height: 0; padding: 20px 16px; }
  .a1-practice-progress { grid-template-columns: 1fr; gap: 10px; }
  .a1-practice-options { grid-template-columns: 1fr; }
  .a1-strip-pair > div { grid-template-columns: 82px minmax(0, 1fr); }
  .a1-measure-pair { grid-template-columns: 1fr; }
  .a1-measure-pair figcaption { grid-column: auto; }
  .a1-book-model > div { grid-template-columns: repeat(8, minmax(22px, 1fr)); gap: 5px; }
  .a1-check { width: 100%; align-self: stretch; }
  .a1-parallel { padding: 15px 12px; }
  .a1-diagnostic-footer { align-items: stretch; flex-direction: column; }
  .a1-diagnostic-footer button { width: 100%; }
  .a1-status { margin-top: 42px; padding: 20px 17px; grid-template-columns: 1fr; gap: 10px; }
  .a1-mobile-bar {
    position: fixed;
    z-index: 20;
    right: 0;
    bottom: 0;
    left: 0;
    min-height: 70px;
    padding: 10px 14px calc(10px + env(safe-area-inset-bottom));
    display: flex;
    align-items: center;
    justify-content: space-between;
    gap: 12px;
    border-top: var(--hairline-str);
    background: rgba(252, 250, 245, .96);
    backdrop-filter: blur(14px);
  }
  .a1-mobile-bar div { display: grid; gap: 2px; }
  .a1-mobile-bar span { color: var(--muted); font-size: 9px; }
  .a1-mobile-bar strong { font-size: 12px; }
  .a1-mobile-bar button { min-height: 48px; padding: 0 22px; border: 0; border-radius: var(--r-pill); background: var(--q-accent); color: var(--card); font-size: 11.5px; font-weight: 800; }
  .a1-mobile-bar:has(button[hidden]) { justify-content: center; text-align: center; }
}

@media (prefers-reduced-motion: reduce) {
  *, *::before, *::after { scroll-behavior: auto !important; transition: none !important; animation: none !important; }
}