:root {
  color-scheme: dark;
  --bg: #07101d;
  --bg-elevated: #0b1525;
  --surface: #101d30;
  --surface-2: #15243a;
  --surface-3: #1c2d46;
  --text: #edf5ff;
  --text-muted: #a9b9cc;
  --text-faint: #74869d;
  --border: #2a3d57;
  --border-strong: #3d5676;
  --primary: #3dd6c6;
  --primary-strong: #63eee0;
  --primary-ink: #041514;
  --accent: #ffc857;
  --accent-ink: #261900;
  --danger: #ff7a8a;
  --success: #65e09b;
  --warning: #ffd26f;
  --info: #78b7ff;
  --code-bg: #050a12;
  --shadow: 0 18px 48px rgba(0, 0, 0, .28);
  --shadow-soft: 0 8px 28px rgba(0, 0, 0, .18);
  --radius-sm: 8px;
  --radius: 14px;
  --radius-lg: 22px;
  --sidebar-width: 244px;
  --topbar-height: 64px;
  --font-scale: 1;
}

html[data-theme="light"] {
  color-scheme: light;
  --bg: #f4f7fb;
  --bg-elevated: #ffffff;
  --surface: #ffffff;
  --surface-2: #f3f7fb;
  --surface-3: #eaf1f7;
  --text: #172236;
  --text-muted: #53647a;
  --text-faint: #718299;
  --border: #d5deea;
  --border-strong: #b9c8d9;
  --primary: #087f77;
  --primary-strong: #086d67;
  --primary-ink: #ffffff;
  --accent: #a86700;
  --accent-ink: #ffffff;
  --danger: #ba3046;
  --success: #167a45;
  --warning: #8d5c00;
  --info: #1769aa;
  --code-bg: #131b27;
  --shadow: 0 18px 48px rgba(40, 60, 85, .14);
  --shadow-soft: 0 8px 26px rgba(40, 60, 85, .10);
}

* { box-sizing: border-box; }
html { min-height: 100%; scroll-behavior: smooth; font-size: calc(16px * var(--font-scale)); }
body {
  min-height: 100vh;
  margin: 0;
  background: var(--bg);
  color: var(--text);
  font-family: -apple-system, BlinkMacSystemFont, "Segoe UI", "Noto Sans JP", "Hiragino Kaku Gothic ProN", Meiryo, sans-serif;
  line-height: 1.65;
  text-rendering: optimizeLegibility;
}
button, input, select, textarea { font: inherit; }
a { color: var(--primary-strong); text-decoration-thickness: .08em; text-underline-offset: .18em; }
a:hover { text-decoration-thickness: .14em; }
button { color: inherit; }
img { max-width: 100%; }
pre, code, kbd { font-family: ui-monospace, SFMono-Regular, Menlo, Monaco, Consolas, "Liberation Mono", monospace; }
::selection { background: color-mix(in srgb, var(--primary) 35%, transparent); }

.skip-link { position: fixed; left: 12px; top: -60px; z-index: 1000; background: var(--primary); color: var(--primary-ink); padding: 10px 14px; border-radius: 8px; font-weight: 800; }
.skip-link:focus { top: 10px; }

.app-shell { min-height: 100vh; display: flex; flex-direction: column; }
.topbar {
  position: sticky; top: 0; z-index: 50; height: var(--topbar-height); flex: 0 0 var(--topbar-height);
  display: flex; align-items: center; gap: 12px; padding: 0 18px;
  background: color-mix(in srgb, var(--bg-elevated) 92%, transparent);
  border-bottom: 1px solid var(--border); backdrop-filter: blur(16px);
}
.brand { display: flex; align-items: center; gap: 10px; color: var(--text); text-decoration: none; min-width: 0; }
.brand img { border-radius: 10px; box-shadow: 0 4px 14px rgba(0,0,0,.22); }
.brand-copy { display: grid; line-height: 1.18; }
.brand-copy strong { font-size: 1.04rem; letter-spacing: .02em; }
.brand-copy small { color: var(--text-muted); font-size: .72rem; }
.topbar-spacer { flex: 1; }
.icon-button { border: 1px solid var(--border); background: var(--surface); width: 38px; height: 38px; border-radius: 10px; cursor: pointer; display: inline-grid; place-items: center; transition: .16s ease; }
.icon-button:hover { border-color: var(--border-strong); background: var(--surface-2); transform: translateY(-1px); }
.icon-button:focus-visible, .button:focus-visible, input:focus-visible, textarea:focus-visible, select:focus-visible, a:focus-visible { outline: 3px solid color-mix(in srgb, var(--primary) 55%, transparent); outline-offset: 2px; }
.runtime-pill { display: inline-flex; align-items: center; gap: 8px; max-width: 280px; min-height: 36px; padding: 7px 11px; border: 1px solid var(--border); background: var(--surface); border-radius: 999px; color: var(--text-muted); font-size: .78rem; white-space: nowrap; overflow: hidden; text-overflow: ellipsis; }
.status-dot { width: 9px; height: 9px; border-radius: 50%; background: var(--text-faint); box-shadow: 0 0 0 3px color-mix(in srgb, var(--text-faint) 18%, transparent); flex: 0 0 auto; }
.runtime-pill[data-state="working"] .status-dot { background: var(--warning); animation: pulse 1.2s infinite; }
.runtime-pill[data-state="ready"] .status-dot { background: var(--success); }
.runtime-pill[data-state="error"] .status-dot { background: var(--danger); }
@keyframes pulse { 50% { opacity: .45; transform: scale(.8); } }

.shell-body { display: grid; grid-template-columns: var(--sidebar-width) minmax(0, 1fr); flex: 1; min-height: 0; }
.sidebar { position: sticky; top: var(--topbar-height); height: calc(100vh - var(--topbar-height)); align-self: start; display: flex; flex-direction: column; gap: 18px; padding: 18px 14px 14px; background: var(--bg-elevated); border-right: 1px solid var(--border); overflow-y: auto; z-index: 40; }
.main-nav { display: grid; gap: 5px; }
.main-nav a { display: flex; align-items: center; gap: 11px; min-height: 43px; padding: 9px 11px; border: 1px solid transparent; border-radius: 10px; color: var(--text-muted); text-decoration: none; font-weight: 650; font-size: .9rem; }
.main-nav a > span:first-child { width: 22px; text-align: center; color: var(--text-faint); font-size: 1.05rem; }
.main-nav a:hover { background: var(--surface); color: var(--text); border-color: var(--border); }
.main-nav a.active { background: color-mix(in srgb, var(--primary) 12%, var(--surface)); color: var(--primary-strong); border-color: color-mix(in srgb, var(--primary) 42%, var(--border)); }
.main-nav a.active > span:first-child { color: var(--primary); }
.sidebar-progress { margin-top: auto; padding: 14px; border: 1px solid var(--border); border-radius: var(--radius); background: var(--surface); }
.eyebrow { color: var(--primary); font-size: .72rem; font-weight: 850; letter-spacing: .12em; text-transform: uppercase; }
.progress-row { display: flex; justify-content: space-between; gap: 8px; margin: 7px 0; font-size: .8rem; color: var(--text-muted); }
.progress-row strong { color: var(--text); }
.progress-track { height: 8px; border-radius: 999px; overflow: hidden; background: var(--surface-3); }
.progress-track > span { display: block; height: 100%; width: 0; background: linear-gradient(90deg, var(--primary), var(--accent)); border-radius: inherit; transition: width .3s ease; }
.text-link { display: inline-block; margin-top: 8px; font-size: .76rem; text-decoration: none; }
.sidebar-version { color: var(--text-faint); font-size: .68rem; text-align: center; }
.sidebar-backdrop { display: none; }
main { min-width: 0; }
.view-container { width: min(1440px, 100%); margin: 0 auto; padding: 30px clamp(18px, 3vw, 44px) 70px; }
.app-footer { min-height: 44px; display: flex; gap: 16px; justify-content: center; align-items: center; flex-wrap: wrap; padding: 8px 18px; border-top: 1px solid var(--border); background: var(--bg-elevated); color: var(--text-faint); font-size: .72rem; }

.page-header { display: grid; gap: 10px; margin-bottom: 24px; }
.page-header-row { display: flex; align-items: flex-start; justify-content: space-between; gap: 18px; flex-wrap: wrap; }
.page-header h1, .hero h1 { margin: 0; line-height: 1.22; letter-spacing: -.025em; font-size: clamp(1.9rem, 4vw, 3.25rem); }
.page-header p, .hero p { margin: 0; color: var(--text-muted); max-width: 78ch; }
.breadcrumb { display: flex; gap: 8px; align-items: center; color: var(--text-faint); font-size: .78rem; flex-wrap: wrap; }
.breadcrumb a { color: var(--text-muted); text-decoration: none; }


.brand-hero-banner { margin: 0 0 18px; overflow: hidden; border: 1px solid var(--border); border-radius: var(--radius-lg); background: #07101d; box-shadow: var(--shadow-soft); }
.brand-hero-banner img { display: block; width: 100%; height: auto; aspect-ratio: 1672 / 941; object-fit: cover; }

.hero { position: relative; overflow: hidden; display: grid; grid-template-columns: minmax(0, 1.35fr) minmax(280px, .65fr); gap: 26px; align-items: center; padding: clamp(24px, 4vw, 46px); border: 1px solid var(--border); border-radius: var(--radius-lg); background: linear-gradient(130deg, color-mix(in srgb, var(--surface) 92%, transparent), color-mix(in srgb, var(--primary) 8%, var(--surface-2))); box-shadow: var(--shadow-soft); }
.hero::after { content: "</>"; position: absolute; right: -16px; bottom: -70px; font: 900 12rem/1 ui-monospace, monospace; color: color-mix(in srgb, var(--primary) 7%, transparent); transform: rotate(-9deg); pointer-events: none; }
.hero-copy { display: grid; gap: 16px; position: relative; z-index: 1; }
.hero-kicker { display: inline-flex; width: fit-content; align-items: center; gap: 8px; border: 1px solid color-mix(in srgb, var(--primary) 38%, var(--border)); background: color-mix(in srgb, var(--primary) 9%, transparent); color: var(--primary-strong); border-radius: 999px; padding: 6px 10px; font-size: .75rem; font-weight: 800; }
.hero-actions, .button-row { display: flex; flex-wrap: wrap; align-items: center; gap: 10px; }
.hero-panel { position: relative; z-index: 1; display: grid; gap: 12px; padding: 18px; border: 1px solid var(--border); border-radius: var(--radius); background: color-mix(in srgb, var(--bg-elevated) 82%, transparent); }
.metric-grid { display: grid; grid-template-columns: repeat(2, minmax(0, 1fr)); gap: 10px; }
.metric { padding: 12px; border: 1px solid var(--border); border-radius: 10px; background: var(--surface); }
.metric strong { display: block; font-size: 1.35rem; line-height: 1.2; }
.metric span { color: var(--text-muted); font-size: .74rem; }

.button { appearance: none; display: inline-flex; align-items: center; justify-content: center; gap: 8px; min-height: 40px; padding: 9px 14px; border-radius: 10px; border: 1px solid transparent; font-weight: 780; font-size: .86rem; cursor: pointer; text-decoration: none; transition: .16s ease; }
.button:hover { transform: translateY(-1px); filter: brightness(1.04); text-decoration: none; }
.button.primary { background: var(--primary); color: var(--primary-ink); border-color: var(--primary); }
.button.accent { background: var(--accent); color: var(--accent-ink); border-color: var(--accent); }
.button.secondary { background: var(--surface-2); color: var(--text); border-color: var(--border); }
.button.ghost { background: transparent; color: var(--text-muted); border-color: var(--border); }
.button.danger { background: color-mix(in srgb, var(--danger) 14%, var(--surface)); color: var(--danger); border-color: color-mix(in srgb, var(--danger) 45%, var(--border)); }
.button.success { background: color-mix(in srgb, var(--success) 16%, var(--surface)); color: var(--success); border-color: color-mix(in srgb, var(--success) 45%, var(--border)); }
.button.small { min-height: 32px; padding: 5px 10px; font-size: .76rem; border-radius: 8px; }
.button[disabled] { opacity: .48; cursor: not-allowed; transform: none; filter: none; }

.section { margin-top: 34px; }
.section-heading { display: flex; align-items: end; justify-content: space-between; gap: 14px; margin-bottom: 14px; }
.section-heading h2 { margin: 0; font-size: clamp(1.28rem, 2.4vw, 1.72rem); line-height: 1.3; }
.section-heading p { margin: 4px 0 0; color: var(--text-muted); font-size: .86rem; }
.card-grid { display: grid; grid-template-columns: repeat(auto-fit, minmax(min(100%, 260px), 1fr)); gap: 14px; }
.card { border: 1px solid var(--border); border-radius: var(--radius); background: var(--surface); box-shadow: var(--shadow-soft); }
.card-body { padding: 18px; }
.card h3 { margin: 0 0 7px; line-height: 1.35; }
.card p { margin: 0; color: var(--text-muted); }
.card-link { color: inherit; text-decoration: none; transition: .16s ease; }
.card-link:hover { border-color: color-mix(in srgb, var(--primary) 55%, var(--border)); transform: translateY(-2px); }
.session-card { display: grid; gap: 12px; min-height: 220px; padding: 18px; }
.session-card-header { display: flex; justify-content: space-between; gap: 12px; align-items: flex-start; }
.session-number { display: inline-grid; place-items: center; min-width: 42px; height: 42px; padding: 0 8px; border-radius: 12px; background: color-mix(in srgb, var(--primary) 14%, var(--surface-2)); color: var(--primary-strong); font-weight: 900; }
.session-card h3 { margin: 0; }
.tag-list { display: flex; flex-wrap: wrap; gap: 6px; }
.tag { display: inline-flex; align-items: center; min-height: 25px; padding: 3px 8px; border-radius: 999px; border: 1px solid var(--border); color: var(--text-muted); background: var(--surface-2); font-size: .69rem; line-height: 1.25; }
.badge { display: inline-flex; align-items: center; width: fit-content; padding: 4px 8px; border-radius: 999px; font-size: .68rem; font-weight: 850; border: 1px solid var(--border); }
.badge.core { color: var(--primary-strong); border-color: color-mix(in srgb, var(--primary) 45%, var(--border)); background: color-mix(in srgb, var(--primary) 9%, transparent); }
.badge.advanced { color: var(--accent); border-color: color-mix(in srgb, var(--accent) 45%, var(--border)); background: color-mix(in srgb, var(--accent) 8%, transparent); }
.badge.done { color: var(--success); border-color: color-mix(in srgb, var(--success) 45%, var(--border)); }
.badge.warning { color: var(--warning); border-color: color-mix(in srgb, var(--warning) 45%, var(--border)); }

.info-strip { display: flex; align-items: flex-start; gap: 12px; padding: 14px 16px; border: 1px solid var(--border); border-left: 4px solid var(--info); border-radius: 10px; background: color-mix(in srgb, var(--info) 7%, var(--surface)); color: var(--text-muted); }
.info-strip strong { color: var(--text); }
.info-strip.warning { border-left-color: var(--warning); background: color-mix(in srgb, var(--warning) 7%, var(--surface)); }
.info-strip.success { border-left-color: var(--success); background: color-mix(in srgb, var(--success) 7%, var(--surface)); }
.info-strip.danger { border-left-color: var(--danger); background: color-mix(in srgb, var(--danger) 7%, var(--surface)); }

.lesson-list { display: grid; gap: 10px; }
.lesson-row { display: grid; grid-template-columns: auto minmax(0,1fr) auto; gap: 14px; align-items: center; padding: 15px 16px; border: 1px solid var(--border); border-radius: 12px; background: var(--surface); color: inherit; text-decoration: none; }
.lesson-row:hover { border-color: color-mix(in srgb, var(--primary) 55%, var(--border)); text-decoration: none; }
.lesson-index { width: 38px; height: 38px; display: grid; place-items: center; border-radius: 10px; background: var(--surface-2); color: var(--text-muted); font-weight: 850; }
.lesson-row h3 { margin: 0 0 2px; font-size: .98rem; }
.lesson-row p { margin: 0; color: var(--text-muted); font-size: .8rem; }
.lesson-meta { display: flex; align-items: center; gap: 8px; flex-wrap: wrap; color: var(--text-faint); font-size: .72rem; }
.lesson-layout { display: grid; grid-template-columns: minmax(0, 1.02fr) minmax(390px, .98fr); gap: 22px; align-items: start; }
.lesson-content { min-width: 0; }
.workspace-column { min-width: 0; position: sticky; top: calc(var(--topbar-height) + 18px); }
.objective-list, .clean-list { margin: 10px 0 0; padding-left: 1.25rem; }
.objective-list li + li, .clean-list li + li { margin-top: 4px; }
.concept-card { margin-bottom: 12px; overflow: hidden; }
.concept-card summary { list-style: none; display: flex; justify-content: space-between; align-items: center; gap: 10px; cursor: pointer; padding: 15px 17px; font-weight: 800; }
.concept-card summary::-webkit-details-marker { display: none; }
.concept-card summary::after { content: "+"; color: var(--primary); font-size: 1.25rem; }
.concept-card[open] summary::after { content: "−"; }
.concept-content { border-top: 1px solid var(--border); padding: 16px 17px; color: var(--text-muted); }
.concept-content p { margin: 0 0 12px; }
.live-step { display: grid; gap: 10px; padding: 16px; border: 1px solid var(--border); border-radius: 12px; background: var(--surface); }
.live-step + .live-step { margin-top: 10px; }
.live-step h3 { margin: 0; }
.live-step p { margin: 0; color: var(--text-muted); }
.predict-callout { padding: 10px 12px; border-radius: 9px; background: color-mix(in srgb, var(--accent) 8%, var(--surface-2)); color: var(--text-muted); border: 1px solid color-mix(in srgb, var(--accent) 27%, var(--border)); font-size: .82rem; }

.code-block { position: relative; overflow: auto; margin: 12px 0; padding: 14px 16px; background: var(--code-bg); color: #e9f3ff; border: 1px solid #283a52; border-radius: 10px; font-size: .82rem; line-height: 1.55; tab-size: 4; }
.code-block code { white-space: pre; }
.code-block::before { content: attr(data-language); position: absolute; top: 5px; right: 8px; color: #7890aa; font-size: .62rem; text-transform: uppercase; }
.editor-shell { overflow: hidden; border: 1px solid var(--border-strong); border-radius: var(--radius); background: var(--surface); box-shadow: var(--shadow); }
.editor-header { display: flex; align-items: center; gap: 8px; flex-wrap: wrap; min-height: 46px; padding: 7px 10px; border-bottom: 1px solid var(--border); background: var(--surface-2); }
.editor-title { font-weight: 850; font-size: .82rem; margin-right: auto; }
.editor-shortcut { color: var(--text-faint); font-size: .66rem; }
.code-editor { display: block; width: 100%; min-height: 330px; resize: vertical; padding: 16px; border: 0; outline: 0; background: var(--code-bg); color: #eaf3ff; caret-color: #fff; font: 500 .83rem/1.58 ui-monospace, SFMono-Regular, Menlo, Monaco, Consolas, monospace; tab-size: 4; white-space: pre; overflow: auto; }
.code-editor::selection { background: rgba(75, 184, 255, .28); }
.editor-footer { border-top: 1px solid var(--border); }
.output-tabs { display: flex; overflow-x: auto; background: var(--surface-2); border-bottom: 1px solid var(--border); }
.output-tab { appearance: none; border: 0; border-right: 1px solid var(--border); background: transparent; color: var(--text-muted); padding: 8px 12px; cursor: pointer; font-size: .75rem; font-weight: 750; white-space: nowrap; }
.output-tab.active { color: var(--primary-strong); background: var(--surface); box-shadow: inset 0 -2px var(--primary); }
.output-panel { min-height: 150px; max-height: 430px; overflow: auto; padding: 13px 15px; background: var(--surface); }
.output-console { margin: 0; white-space: pre-wrap; overflow-wrap: anywhere; color: var(--text); font-size: .79rem; line-height: 1.55; }
.output-empty { color: var(--text-faint); font-size: .78rem; }
.output-error { color: var(--danger); }
.output-warning { color: var(--warning); }
.execution-meta { display: flex; gap: 12px; flex-wrap: wrap; margin-bottom: 8px; color: var(--text-faint); font-size: .7rem; }
.figure-grid { display: grid; gap: 12px; }
.figure-grid img { width: 100%; border-radius: 8px; background: #fff; border: 1px solid var(--border); }
.variable-table { width: 100%; border-collapse: collapse; font-size: .76rem; }
.variable-table th, .variable-table td { border-bottom: 1px solid var(--border); text-align: left; vertical-align: top; padding: 7px 8px; }
.variable-table th { color: var(--text-muted); font-weight: 750; position: sticky; top: 0; background: var(--surface); }
.variable-preview { max-width: 440px; overflow-wrap: anywhere; }
.file-list { display: grid; gap: 8px; }
.file-row { display: flex; align-items: center; justify-content: space-between; gap: 10px; padding: 9px 10px; border: 1px solid var(--border); border-radius: 8px; }
.practice-feedback { margin-top: 10px; padding: 10px 12px; border-radius: 8px; font-size: .8rem; }
.practice-feedback.pass { background: color-mix(in srgb, var(--success) 10%, var(--surface)); color: var(--success); border: 1px solid color-mix(in srgb, var(--success) 35%, var(--border)); }
.practice-feedback.fail { background: color-mix(in srgb, var(--danger) 9%, var(--surface)); color: var(--danger); border: 1px solid color-mix(in srgb, var(--danger) 35%, var(--border)); }

.form-grid { display: grid; grid-template-columns: repeat(2, minmax(0,1fr)); gap: 14px; }
.form-field { display: grid; gap: 6px; }
.form-field.full { grid-column: 1 / -1; }
.form-field label { color: var(--text-muted); font-size: .78rem; font-weight: 750; }
.input, .select, .textarea { width: 100%; border: 1px solid var(--border); border-radius: 9px; background: var(--surface-2); color: var(--text); padding: 9px 11px; }
.textarea { min-height: 110px; resize: vertical; line-height: 1.55; }
.help-text { color: var(--text-faint); font-size: .7rem; }

.table-wrap { overflow-x: auto; border: 1px solid var(--border); border-radius: 12px; }
.data-table { width: 100%; border-collapse: collapse; min-width: 680px; background: var(--surface); font-size: .79rem; }
.data-table th, .data-table td { padding: 10px 12px; border-bottom: 1px solid var(--border); text-align: left; vertical-align: top; }
.data-table th { color: var(--text-muted); background: var(--surface-2); font-weight: 800; }
.data-table tr:last-child td { border-bottom: 0; }

.timeline { display: grid; gap: 8px; }
.timeline-row { display: grid; grid-template-columns: 90px minmax(0,1fr); gap: 12px; padding: 10px 12px; border: 1px solid var(--border); border-radius: 9px; background: var(--surface); }
.timeline-time { color: var(--primary-strong); font-weight: 850; }

.quiz-shell { display: grid; gap: 16px; }
.quiz-topbar { position: sticky; top: calc(var(--topbar-height) + 8px); z-index: 20; display: flex; justify-content: space-between; align-items: center; gap: 12px; padding: 11px 14px; border: 1px solid var(--border-strong); border-radius: 12px; background: color-mix(in srgb, var(--bg-elevated) 94%, transparent); backdrop-filter: blur(12px); box-shadow: var(--shadow-soft); }
.quiz-timer { font: 900 1.3rem/1 ui-monospace, monospace; color: var(--accent); }
.quiz-timer.urgent { color: var(--danger); animation: pulse 1s infinite; }
.quiz-progress { color: var(--text-muted); font-size: .8rem; }
.question-card { padding: 20px; border: 1px solid var(--border); border-radius: var(--radius); background: var(--surface); }
.question-card h3 { margin: 0 0 12px; line-height: 1.45; }
.question-number { color: var(--primary); font-size: .72rem; font-weight: 900; letter-spacing: .08em; }
.choice-list { display: grid; gap: 8px; margin-top: 12px; }
.choice { display: flex; align-items: flex-start; gap: 10px; padding: 10px 12px; border: 1px solid var(--border); border-radius: 9px; cursor: pointer; background: var(--surface-2); }
.choice:hover { border-color: var(--border-strong); }
.choice input { margin-top: .28rem; accent-color: var(--primary); }
.choice.correct { border-color: var(--success); background: color-mix(in srgb, var(--success) 8%, var(--surface)); }
.choice.incorrect { border-color: var(--danger); background: color-mix(in srgb, var(--danger) 8%, var(--surface)); }
.quiz-explanation { margin-top: 12px; padding: 12px; border-radius: 9px; border-left: 4px solid var(--info); background: color-mix(in srgb, var(--info) 7%, var(--surface-2)); color: var(--text-muted); }
.score-hero { display: grid; place-items: center; text-align: center; gap: 10px; padding: 30px; border: 1px solid var(--border); border-radius: var(--radius-lg); background: var(--surface); }
.score-circle { width: 140px; aspect-ratio: 1; border-radius: 50%; display: grid; place-items: center; background: conic-gradient(var(--primary) var(--score-angle, 0deg), var(--surface-3) 0); position: relative; }
.score-circle::after { content: ""; position: absolute; inset: 12px; border-radius: inherit; background: var(--surface); }
.score-circle strong { position: relative; z-index: 1; font-size: 2rem; }

.filter-bar { display: flex; align-items: end; flex-wrap: wrap; gap: 10px; padding: 12px; border: 1px solid var(--border); border-radius: 11px; background: var(--surface); }
.filter-bar .form-field { min-width: 180px; flex: 1; }
.practice-grid { display: grid; grid-template-columns: minmax(260px, .34fr) minmax(0, .66fr); gap: 18px; align-items: start; }
.practice-nav { position: sticky; top: calc(var(--topbar-height) + 12px); display: grid; gap: 7px; max-height: calc(100vh - var(--topbar-height) - 32px); overflow: auto; padding-right: 4px; }
.practice-nav button { text-align: left; border: 1px solid var(--border); border-radius: 9px; background: var(--surface); color: var(--text-muted); padding: 10px 11px; cursor: pointer; }
.practice-nav button.active { color: var(--primary-strong); border-color: var(--primary); background: color-mix(in srgb, var(--primary) 8%, var(--surface)); }

.glossary-grid { display: grid; grid-template-columns: repeat(auto-fit, minmax(260px, 1fr)); gap: 10px; }
.glossary-entry { padding: 13px 14px; border: 1px solid var(--border); border-radius: 10px; background: var(--surface); }
.glossary-entry dt { color: var(--primary-strong); font-weight: 850; }
.glossary-entry dd { margin: 4px 0 0; color: var(--text-muted); }
.cheatsheet-grid { display: grid; grid-template-columns: repeat(auto-fit, minmax(min(100%, 340px),1fr)); gap: 12px; }

.completion-grid { display: grid; grid-template-columns: repeat(auto-fit, minmax(190px, 1fr)); gap: 10px; }
.completion-item { display: flex; gap: 9px; align-items: flex-start; padding: 11px; border: 1px solid var(--border); border-radius: 9px; background: var(--surface); }
.completion-item input { margin-top: .3rem; accent-color: var(--primary); }

.toast-region { position: fixed; right: 18px; bottom: 18px; z-index: 100; display: grid; gap: 9px; width: min(380px, calc(100vw - 36px)); pointer-events: none; }
.toast { pointer-events: auto; padding: 12px 14px; border-radius: 10px; border: 1px solid var(--border-strong); background: var(--bg-elevated); box-shadow: var(--shadow); animation: toast-in .2s ease; }
.toast strong { display: block; }
.toast p { margin: 2px 0 0; color: var(--text-muted); font-size: .78rem; }
.toast.success { border-left: 4px solid var(--success); }
.toast.error { border-left: 4px solid var(--danger); }
.toast.info { border-left: 4px solid var(--info); }
@keyframes toast-in { from { opacity: 0; transform: translateY(8px); } }
.global-dialog { width: min(680px, calc(100vw - 28px)); border: 1px solid var(--border-strong); border-radius: var(--radius); padding: 0; background: var(--surface); color: var(--text); box-shadow: var(--shadow); }
.global-dialog::backdrop { background: rgba(0,0,0,.62); backdrop-filter: blur(3px); }
.dialog-shell { display: grid; }
.dialog-header { display: flex; align-items: center; gap: 12px; padding: 14px 16px; border-bottom: 1px solid var(--border); }
.dialog-header h2 { margin: 0; flex: 1; font-size: 1.1rem; }
.dialog-body { padding: 17px; max-height: 65vh; overflow: auto; }
.dialog-actions { display: flex; justify-content: flex-end; gap: 9px; padding: 12px 16px; border-top: 1px solid var(--border); }
.noscript { margin: 30px; padding: 20px; background: #fff4d6; color: #5d4100; }
.empty-state { display: grid; place-items: center; text-align: center; gap: 10px; min-height: 220px; padding: 24px; border: 1px dashed var(--border-strong); border-radius: var(--radius); color: var(--text-muted); }

.mobile-only { display: none; }
.hidden { display: none !important; }
.sr-only { position: absolute !important; width: 1px !important; height: 1px !important; padding: 0 !important; margin: -1px !important; overflow: hidden !important; clip: rect(0,0,0,0) !important; white-space: nowrap !important; border: 0 !important; }

@media (max-width: 1120px) {
  :root { --sidebar-width: 214px; }
  .lesson-layout { grid-template-columns: 1fr; }
  .workspace-column { position: static; }
  .practice-grid { grid-template-columns: 1fr; }
  .practice-nav { position: static; display: flex; overflow-x: auto; max-height: none; }
  .practice-nav button { min-width: 230px; }
}

@media (max-width: 820px) {
  .mobile-only { display: inline-grid; }
  .brand-copy small { display: none; }
  .runtime-pill { max-width: 170px; }
  .shell-body { display: block; }
  .sidebar { position: fixed; left: 0; top: var(--topbar-height); width: min(300px, 86vw); height: calc(100vh - var(--topbar-height)); transform: translateX(-105%); transition: transform .2s ease; box-shadow: var(--shadow); }
  .sidebar.open { transform: translateX(0); }
  .sidebar-backdrop { position: fixed; inset: var(--topbar-height) 0 0; display: block; z-index: 35; background: rgba(0,0,0,.48); }
  .view-container { padding-top: 22px; }
  .hero { grid-template-columns: 1fr; }
  .form-grid { grid-template-columns: 1fr; }
  .form-field.full { grid-column: auto; }
}

@media (max-width: 560px) {
  .topbar { padding: 0 10px; gap: 8px; }
  .brand-copy strong { font-size: .9rem; }
  .brand img { width: 34px; height: 34px; }
  .runtime-pill { display: none; }
  .view-container { padding: 18px 12px 56px; }
  .brand-hero-banner { border-radius: 14px; margin-bottom: 14px; }
  .hero { padding: 22px 18px; border-radius: 16px; }
  .hero h1, .page-header h1 { font-size: 1.82rem; }
  .metric-grid { grid-template-columns: 1fr 1fr; }
  .lesson-row { grid-template-columns: auto minmax(0,1fr); }
  .lesson-row > :last-child { grid-column: 2; }
  .editor-header { align-items: stretch; }
  .editor-shortcut { display: none; }
  .code-editor { min-height: 300px; font-size: .78rem; padding: 13px; }
  .timeline-row { grid-template-columns: 76px minmax(0,1fr); }
  .quiz-topbar { top: calc(var(--topbar-height) + 4px); }
  .question-card { padding: 16px 13px; }
  .app-footer { display: none; }
}

@media (prefers-reduced-motion: reduce) {
  *, *::before, *::after { animation-duration: .001ms !important; animation-iteration-count: 1 !important; scroll-behavior: auto !important; transition-duration: .001ms !important; }
}

@media print {
  :root { color-scheme: light; --bg: #fff; --surface: #fff; --surface-2: #f5f5f5; --text: #000; --text-muted: #333; --border: #bbb; }
  .topbar, .sidebar, .app-footer, .button, .editor-shell, .toast-region, .filter-bar { display: none !important; }
  .shell-body { display: block; }
  .view-container { width: 100%; padding: 0; }
  .card, .question-card, .concept-card { box-shadow: none; break-inside: avoid; }
  a { color: #000; text-decoration: none; }
}

/* Self-study lesson components */
.study-start-card { border-color: color-mix(in srgb, var(--primary) 38%, var(--border)); background: linear-gradient(145deg, color-mix(in srgb, var(--primary) 8%, var(--surface)), var(--surface)); }
.objective-list { margin: 10px 0 0; padding-left: 1.25rem; }
.objective-list li + li { margin-top: 5px; }
.study-route { display: flex; flex-wrap: wrap; align-items: center; gap: 7px; margin-top: 16px; color: var(--text-muted); font-size: .8rem; }
.study-route span { padding: 6px 9px; border: 1px solid var(--border); border-radius: 999px; background: var(--surface-2); color: var(--text); font-weight: 700; }
.study-route b { color: var(--primary); }
.study-intro { margin-bottom: 16px; padding: 18px 20px; border-left: 4px solid var(--primary); border-radius: 0 var(--radius) var(--radius) 0; background: color-mix(in srgb, var(--primary) 6%, var(--surface)); }
.study-intro p { margin: 0; }
.study-intro p + p { margin-top: 10px; }
.study-rule-grid { display: grid; grid-template-columns: repeat(auto-fit, minmax(min(100%, 300px), 1fr)); gap: 13px; }
.study-rule-card { position: relative; overflow: hidden; }
.study-rule-number { position: absolute; top: 11px; right: 13px; display: grid; place-items: center; width: 28px; height: 28px; border-radius: 50%; background: color-mix(in srgb, var(--primary) 13%, var(--surface-2)); color: var(--primary-strong); font-weight: 900; font-size: .76rem; }
.study-rule-card h3 { padding-right: 34px; }
.study-pattern { margin: 10px 0; padding: 9px 11px; border: 1px solid var(--border); border-radius: 9px; background: var(--code-bg); color: #d7f8f3; overflow-x: auto; }
.study-pattern code { white-space: pre; }
.walkthrough-card { margin-top: 14px; border-color: color-mix(in srgb, var(--accent) 38%, var(--border)); }
.walkthrough-card h3 { margin-top: 5px; }
.walkthrough-steps { display: grid; gap: 8px; padding-left: 1.35rem; }
.walkthrough-steps li::marker { color: var(--primary); font-weight: 900; }
.try-callout { margin: 14px 0; padding: 11px 13px; border: 1px solid color-mix(in srgb, var(--accent) 38%, var(--border)); border-radius: 9px; background: color-mix(in srgb, var(--accent) 7%, var(--surface-2)); color: var(--text-muted); }
.try-callout strong { color: var(--accent); }
.checkpoint-list { display: grid; gap: 9px; margin-top: 14px; }
.learning-map-links { display: grid; gap: 6px; margin-top: 12px; }
.learning-map-links a { display: grid; grid-template-columns: 32px minmax(0, 1fr); gap: 8px; align-items: center; padding: 8px 9px; border: 1px solid var(--border); border-radius: 8px; color: var(--text); text-decoration: none; background: var(--surface-2); }
.learning-map-links a:hover { border-color: var(--primary); }
.learning-map-links a span { color: var(--primary); font: 800 .76rem/1 ui-monospace, monospace; }

@media (max-width: 560px) {
  .study-route b { display: none; }
  .study-route span { width: 100%; border-radius: 8px; }
  .study-intro { padding: 15px 14px; }
}

/* Detailed lesson explanations and post-study practice */
.deep-explanation-card {
  margin-top: 14px;
  border-color: color-mix(in srgb, var(--primary) 42%, var(--border));
  background: linear-gradient(145deg, color-mix(in srgb, var(--primary) 7%, var(--surface)), var(--surface));
}
.deep-explanation-card p { line-height: 1.85; }
.deep-explanation-card p + p { margin-top: 10px; }
.syntax-anatomy-grid {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(min(100%, 230px), 1fr));
  gap: 10px;
  margin-top: 16px;
}
.syntax-anatomy-item {
  padding: 12px;
  border: 1px solid var(--border);
  border-radius: 10px;
  background: var(--surface-2);
}
.syntax-anatomy-item code {
  display: inline-block;
  margin-bottom: 7px;
  color: var(--accent);
  font-weight: 800;
}
.syntax-anatomy-item p { margin: 0; color: var(--text-muted); font-size: .88rem; line-height: 1.65; }
.trace-card { margin-top: 14px; border-color: color-mix(in srgb, var(--accent) 38%, var(--border)); }
.trace-card h3 { margin: 5px 0 12px; }
.trace-table code { white-space: nowrap; }
.learning-checklist {
  margin-top: 14px;
  padding: 13px 15px;
  border: 1px solid color-mix(in srgb, var(--success) 35%, var(--border));
  border-radius: 10px;
  background: color-mix(in srgb, var(--success) 6%, var(--surface-2));
}
.learning-checklist ul { margin: 8px 0 0; padding-left: 1.25rem; }
.learning-checklist li + li { margin-top: 4px; }
.post-study-section {
  padding: clamp(16px, 3vw, 24px);
  border: 1px solid color-mix(in srgb, var(--primary) 35%, var(--border));
  border-radius: var(--radius);
  background: color-mix(in srgb, var(--primary) 3%, var(--surface-2));
}
.post-study-progress { display: flex; flex-wrap: wrap; gap: 7px; margin-bottom: 13px; }
.post-study-progress span {
  padding: 6px 9px;
  border: 1px solid var(--border);
  border-radius: 999px;
  background: var(--surface);
  color: var(--text-muted);
  font-size: .76rem;
  font-weight: 750;
}
.post-study-list { display: grid; gap: 12px; }
.post-study-card { border-color: var(--border-strong); }
.post-study-card h3 { margin: 8px 0; }
.post-study-card > .card-body > p { color: var(--text-muted); line-height: 1.75; }
.post-study-card.code-task { border-left: 4px solid var(--accent); }
.post-study-card.knowledge-task { border-left: 4px solid var(--primary); }
.compact-answer { min-height: 104px; }
.reveal-grid { display: grid; grid-template-columns: repeat(2, minmax(0, 1fr)); gap: 9px; margin-top: 10px; }
.reveal-grid details {
  padding: 10px 12px;
  border: 1px solid var(--border);
  border-radius: 9px;
  background: var(--surface-2);
}
.reveal-grid summary { cursor: pointer; color: var(--primary-strong); font-weight: 800; }
.reveal-grid p { margin: 9px 0 0; color: var(--text-muted); line-height: 1.7; }
.optional-note { margin-top: 13px; }
.optional-note > summary { cursor: pointer; padding: 14px 16px; color: var(--text-muted); font-weight: 800; }
.optional-note[open] > summary { border-bottom: 1px solid var(--border); color: var(--text); }
.optional-note .card-body { padding-top: 13px; }

@media (max-width: 620px) {
  .reveal-grid { grid-template-columns: 1fr; }
  .post-study-section { padding: 14px 11px; }
  .trace-table { min-width: 640px; }
}