:root {
  color-scheme: light;
  --bg: #f5f7fb;
  --surface: #fff;
  --subtle: #f7f9fd;
  --text: #15223b;
  --muted: #53627a;
  --line: #e0e7f1;
  --blue: #2855e9;
  --blue-hover: #1b43ca;
  --accent: #234bce;
  --blue-tint: #eef3ff;
  --teal: #006b61;
  --teal-tint: #e6f7f3;
  --violet: #5946b7;
  --violet-tint: #f1edfe;
  --amber: #8c5108;
  --amber-tint: #fff2dd;
  --red: #ab3041;
  --red-tint: #ffedf0;
  --radius: 18px;
  --shadow: 0 3px 12px rgb(29 52 94 / .035);
  --font: "Segoe UI", Tahoma, Arial, sans-serif;
  --mono: "Cascadia Mono", Consolas, "Courier New", monospace;
}
[data-theme="dark"] {
  color-scheme: dark;
  --bg: #101827;
  --surface: #182337;
  --subtle: #1d2a42;
  --text: #ecf2ff;
  --muted: #b1bfd4;
  --line: #32415a;
  --blue: #355de9;
  --blue-hover: #254dcf;
  --accent: #a8beff;
  --blue-tint: #213765;
  --teal: #8ce4d1;
  --teal-tint: #194239;
  --violet: #d0c2ff;
  --violet-tint: #302852;
  --amber: #ffd18e;
  --amber-tint: #4a3823;
  --red: #ffbbc3;
  --red-tint: #4a2836;
  --shadow: none;
}
*, *::before, *::after { box-sizing: border-box; }
html { scroll-padding-top: 88px; }
body { margin: 0; background: var(--bg); color: var(--text); font: 16px/1.62 var(--font); }
h1, h2, h3, h4, p, figure, dl, dd { margin: 0; }
h1, h2, h3, h4 { line-height: 1.3; }
h1 { font-size: clamp(2rem, 3.5vw, 3rem); letter-spacing: -.025em; }
h2 { font-size: clamp(1.25rem, 1.7vw, 1.6rem); }
h3 { font-size: 1.08rem; }
a { color: var(--accent); text-decoration: none; }
button, input, select { font: inherit; }
button, select, summary { cursor: pointer; }
button { color: inherit; }
button:disabled { opacity: .48; cursor: default; }
svg { flex: none; vertical-align: middle; }
strong { font-weight: 700; }
:focus-visible { outline: 3px solid var(--accent); outline-offset: 3px; }
#main:focus, [tabindex="-1"]:focus { outline: none; }
[hidden] { display: none !important; }
.sr-only { position: absolute; inline-size: 1px; block-size: 1px; padding: 0; margin: -1px; overflow: hidden; clip-path: inset(50%); white-space: nowrap; border: 0; }
.skip-link { position: fixed; z-index: 60; inset-block-start: 8px; inset-inline-start: 10px; transform: translateY(-160%); padding: 10px 16px; border-radius: 10px; background: var(--surface); }
.skip-link:focus { transform: translateY(0); }

.shell { display: grid; grid-template-columns: 235px minmax(0, 1fr); min-height: 100vh; }
.workspace { min-width: 0; display: flex; flex-direction: column; }
.sidebar { position: sticky; top: 0; height: 100dvh; display: flex; flex-direction: column; background: var(--surface); border-inline-end: 1px solid var(--line); overflow: auto; padding: 22px 13px 16px; z-index: 12; }
.brand { display: flex; align-items: center; gap: 11px; color: var(--text); padding: 0 9px; margin-bottom: 28px; }
.brand strong { display: block; text-align: right; font: 800 .98rem/1.2 var(--mono); letter-spacing: .025em; }
.brand small, .sidebar-footer small { display: block; color: var(--muted); font-size: .74rem; margin-top: 3px; }
.brand-icon { display: grid; place-items: center; width: 43px; height: 43px; color: #fff; border-radius: 13px; background: linear-gradient(145deg, #2e65ff, #2547c6); box-shadow: 0 4px 9px rgb(40 85 233 / .25); flex: none; }
.nav-group { margin-bottom: 18px; }
.nav-group p { margin: 0 11px 6px; color: var(--muted); font-size: .72rem; font-weight: 700; }
.nav-link { min-height: 43px; padding: 7px 11px; margin-block: 2px; border-radius: 10px; display: flex; align-items: center; gap: 10px; color: var(--muted); font-size: .88rem; font-weight: 600; transition: color .14s, background .14s; }
.nav-link:hover { background: var(--subtle); color: var(--text); }
.nav-link[aria-current="page"] { background: var(--blue-tint); color: var(--accent); font-weight: 750; }
.sidebar-footer { display: flex; align-items: center; gap: 10px; font-size: .8rem; border-top: 1px solid var(--line); padding: 16px 9px 2px; margin-top: auto; }
.local-dot { width: 9px; height: 9px; background: #16a88c; border-radius: 50%; box-shadow: 0 0 0 4px var(--teal-tint); }
.nav-overlay { display: none; }
.topbar { position: sticky; top: 0; z-index: 10; border-bottom: 1px solid var(--line); background: var(--surface); }
.topbar-inner { display: flex; align-items: center; justify-content: space-between; gap: 12px; min-height: 65px; max-width: 1330px; padding: 0 clamp(19px, 3vw, 40px); margin-inline: auto; }
.breadcrumb, .top-actions { display: flex; align-items: center; gap: 12px; }
.breadcrumb { font-size: .88rem; font-weight: 650; min-width: 0; }
.breadcrumb a, .crumb-sep { color: var(--muted); }
.breadcrumb span:last-child { overflow: hidden; text-overflow: ellipsis; white-space: nowrap; }
.search-trigger, .icon-button { min-height: 44px; border: 1px solid var(--line); background: var(--subtle); border-radius: 10px; color: var(--muted); }
.search-trigger { display: flex; align-items: center; gap: 8px; width: clamp(160px, 20vw, 260px); padding-inline: 10px; font-size: .82rem; white-space: nowrap; }
.search-trigger:hover, .icon-button:hover { border-color: var(--accent); color: var(--accent); }
kbd { margin-inline-start: auto; font: .7rem/1 var(--mono); border: 1px solid var(--line); border-radius: 4px; padding: 4px; background: var(--surface); }
.icon-button { min-width: 44px; padding: 0 7px; display: inline-grid; place-items: center; }
.nav-toggle { display: none; }
.page { flex: 1; width: 100%; max-width: 1330px; margin-inline: auto; padding: clamp(21px, 2.7vw, 36px) clamp(19px, 3vw, 40px) 40px; min-height: 68vh; }
.footer { max-width: 1330px; width: 100%; padding: 15px clamp(19px, 3vw, 40px) 22px; margin-inline: auto; display: flex; justify-content: space-between; flex-wrap: wrap; align-items: center; gap: 10px; border-top: 1px solid var(--line); font-size: .79rem; color: var(--muted); }
.footer > span { font: 650 .72rem/1.5 var(--mono); letter-spacing: .04em; }
.footer b { color: var(--accent); }
.footer a { color: var(--muted); display: inline-flex; align-items: center; gap: 6px; }
.footer a:hover { color: var(--accent); }
.boot-card { padding: 35px; background: var(--surface); border: 1px solid var(--line); border-radius: var(--radius); }

.button, .text-link { display: inline-flex; align-items: center; justify-content: center; gap: 7px; font-weight: 700; }
.button { border: 1px solid transparent; padding: 8px 15px; min-height: 44px; border-radius: 10px; font-size: .88rem; text-align: center; line-height: 1.36; transition: background .14s, border-color .14s, color .14s; }
.button.primary { background: var(--blue); color: #fff; border-color: var(--blue); }
.button.primary:hover:not(:disabled) { background: var(--blue-hover); border-color: var(--blue-hover); }
.button.secondary { background: var(--surface); color: var(--text); border-color: var(--line); }
.button.secondary:hover:not(:disabled) { border-color: var(--accent); color: var(--accent); }
.button.positive { background: var(--teal-tint); color: var(--teal); border-color: var(--teal); }
.button.text { background: none; color: var(--muted); text-decoration: underline; }
.button.full { width: 100%; }
.button-row, .heading-actions, .tags { display: flex; flex-wrap: wrap; align-items: center; gap: 9px; }
.text-link { color: var(--accent); font-size: .86rem; }
.text-link:hover { text-decoration: underline; }
.panel { background: var(--surface); border: 1px solid var(--line); border-radius: var(--radius); box-shadow: var(--shadow); min-width: 0; }
.tile-icon { display: grid; place-items: center; width: 43px; height: 43px; border-radius: 12px; background: var(--blue-tint); color: var(--accent); flex: none; }
.tile-icon.teal, .chip.teal { background: var(--teal-tint); color: var(--teal); }
.tile-icon.amber, .chip.amber { background: var(--amber-tint); color: var(--amber); }
.tile-icon.violet { background: var(--violet-tint); color: var(--violet); }
.chip.red { background: var(--red-tint); color: var(--red); }
.chip { display: inline-flex; align-items: center; gap: 6px; width: fit-content; max-width: 100%; border-radius: 7px; padding: 4px 9px; background: var(--subtle); color: var(--muted); font-size: .74rem; font-weight: 700; }
.chip.topic-link { color: var(--accent); background: var(--blue-tint); padding-block: 7px; }
.chip.topic-link:hover { text-decoration: underline; }
.code { font: 650 .72rem/1.2 var(--mono); letter-spacing: .09em; color: var(--muted); }
.meta, .muted { color: var(--muted); }
.meta { font-size: .81rem; }
.micro { display: block; color: var(--accent); font-size: .77rem; font-weight: 750; }
.eyebrow { display: inline-flex; align-items: center; gap: 7px; color: var(--accent); font-size: .8rem; font-weight: 750; }
.eyebrow i { width: 6px; height: 6px; background: var(--accent); border-radius: 50%; }
.two-grid, .three-grid { display: grid; gap: 15px; }
.two-grid { grid-template-columns: repeat(2, minmax(0, 1fr)); }
.three-grid { grid-template-columns: repeat(3, minmax(0, 1fr)); }
.stack { display: grid; gap: 9px; }
.dashboard-section { margin-top: 26px; }
.section-heading { display: flex; justify-content: space-between; align-items: end; gap: 10px; flex-wrap: wrap; margin-bottom: 12px; }
.section-heading h2 { margin-top: 2px; }
.page-heading { display: flex; justify-content: space-between; align-items: end; gap: 15px; flex-wrap: wrap; margin: 0 0 22px; }
.page-heading h1 { margin: 3px 0 5px; }
.page-heading p { color: var(--muted); max-width: 72ch; }
.panel-heading { display: flex; align-items: center; gap: 11px; padding-bottom: 13px; }
.panel-heading p { color: var(--muted); font-size: .83rem; margin-top: 2px; }
.notice { background: var(--blue-tint); color: var(--accent); border: 1px solid var(--line); border-radius: 12px; padding: 11px 14px; margin-bottom: 15px; font-size: .9rem; }
.storage-warning { background: var(--amber-tint); color: var(--amber); }
.empty { padding: 30px; text-align: center; }
.empty .tile-icon { margin: 0 auto 11px; }
.empty p { color: var(--muted); margin: 6px 0 14px; }
.math { display: inline; unicode-bidi: isolate; font: .96em/1.48 var(--mono); overflow-wrap: anywhere; }
.equation { padding: 10px 13px; border-radius: 10px; background: var(--blue-tint); color: var(--accent); text-align: center; font-size: 1.1rem; margin: 6px 0 10px; }
progress { display: block; width: 100%; height: 7px; border: 0; border-radius: 9px; appearance: none; overflow: hidden; background: var(--line); }
progress::-webkit-progress-bar { background: var(--line); }
progress::-webkit-progress-value { background: #3971ea; border-radius: 9px; }
progress::-moz-progress-bar { background: #3971ea; border-radius: 9px; }

.hero { isolation: isolate; min-height: 288px; position: relative; overflow: hidden; display: flex; align-items: center; padding: 38px clamp(24px, 4vw, 60px); border-radius: 22px; color: #fff;
  background: radial-gradient(ellipse at 18% 15%, #1c3880, transparent 59%), linear-gradient(120deg, #142f65 0%, #102446 58%, #101d37 100%); box-shadow: 0 10px 24px rgb(18 44 93 / .13); }
.hero-content { z-index: 1; position: relative; max-width: 57%; }
.hero h1 { font-size: clamp(2.55rem, 4.4vw, 4rem); margin: 10px 0 7px; letter-spacing: -.035em; }
.hero p { color: #d4e2ff; max-width: 48ch; margin: 0 0 21px; font-size: 1.01rem; }
.hero-label { display: inline-flex; align-items: center; gap: 7px; padding: 6px 10px; border: 1px solid #5b75aa; border-radius: 8px; color: #e0eaff; font: 700 .74rem/1 var(--mono); letter-spacing: .12em; background: rgb(192 212 255 / .09); }
.hero-label span { height: 7px; width: 7px; border-radius: 50%; background: #72efdc; }
.hero-primary { background: #fff; color: #193cbb; }
.hero-primary:hover { background: #dce8ff; }
.hero-secondary { border-color: #6e88be; color: #fff; background: rgb(150 180 255 / .09); }
.hero-secondary:hover { background: #314f8a; }
.hero .button:focus-visible { outline-color: #b2d9ff; }
.hero-art { position: absolute; inset-inline-end: 1.3%; top: 50%; transform: translateY(-50%); width: min(48%, 510px); pointer-events: none; }
.hero-art img { width: 100%; height: auto; display: block; }
.orbit-tag { position: absolute; display: block; border: 1px solid #6384bc; padding: 6px 10px; border-radius: 8px; background: rgb(23 47 93 / .8); color: #e2f7ff; font: 650 .76rem/1 var(--mono); }
.tag-force { left: 14%; top: 23%; }
.tag-heat { right: 9%; bottom: 21%; }
.hero-index { position: absolute; bottom: 13px; left: 17px; color: #91abd6; font: .63rem/1.2 var(--mono); letter-spacing: .13em; }
.stats { display: grid; grid-template-columns: repeat(4, minmax(0, 1fr)); gap: 12px; margin-top: 17px; }
.stat { color: var(--text); padding: 14px; min-height: 79px; display: flex; align-items: center; gap: 11px; }
.stat strong { display: block; line-height: 1.1; font-size: 1.46rem; }
.stat small { display: block; color: var(--muted); font-size: .8rem; }
.unit-card, .subject-card, .exam-tile { display: block; color: var(--text); padding: 19px; }
.unit-top, .unit-bottom, .heat-top, .flash-meta, .question-top { display: flex; justify-content: space-between; align-items: center; gap: 8px; }
.unit-card h3, .subject-card h2, .exam-tile h2 { margin: 11px 0 4px; font-size: 1.25rem; }
.unit-card p, .subject-card p, .exam-tile p { color: var(--muted); font-size: .9rem; }
.unit-bottom { margin-top: 13px; padding-top: 10px; border-top: 1px solid var(--line); font-size: .77rem; font-weight: 650; color: var(--muted); }
.sep { margin-inline: 3px; color: var(--accent); }
.card-arrow { display: grid; place-items: center; width: 32px; height: 32px; border-radius: 9px; color: var(--accent); background: var(--blue-tint); }
.stat:hover, .unit-card:hover, .quick-link:hover { border-color: var(--accent); }
.quick-link { display: grid; grid-template-columns: auto minmax(0, 1fr) auto; align-items: center; gap: 10px; padding: 13px; color: var(--text); }
.quick-link strong, .quick-link small { display: block; }
.quick-link strong { font-size: .9rem; }
.quick-link small { font-size: .75rem; color: var(--muted); }
.quick-link > svg { color: var(--accent); }
.progress-overview { padding: 19px; display: grid; grid-template-columns: 1fr minmax(150px, .45fr); gap: 20px; }
.progress-overview h2 { margin: 3px 0; }
.progress-overview p { color: var(--muted); font-size: .87rem; margin-bottom: 10px; }
.last-result { display: grid; gap: 2px; border-inline-start: 1px solid var(--line); padding-inline-start: 18px; }
.last-result strong { font-size: 1.3rem; justify-self: start; }
.last-result .no-score { font-size: 1rem; }
.last-result small { color: var(--muted); }
.last-result a { justify-self: start; }
.subject-card > .code { display: inline-block; margin-top: 13px; }
.subject-card .button-row { margin-top: 14px; }

.lesson-list, .recap, .practice-panel, .library-tools, .units-table, .lab-panel, .lab-reference { padding: clamp(15px, 2.5vw, 24px); }
.lesson-list + .lesson-list, .practice-panel, .units-table { margin-block: 15px; }
.lesson-row { display: flex; align-items: center; gap: 11px; color: var(--text); border-top: 1px solid var(--line); min-height: 60px; padding: 9px 4px; }
.lesson-row:hover { color: var(--accent); }
.lesson-row-name { min-width: 0; flex: 1; }
.lesson-row small, .history-row small { display: block; font-size: .78rem; color: var(--muted); }
.lesson-index { width: 33px; height: 33px; flex: none; display: grid; place-items: center; background: var(--blue-tint); color: var(--accent); border-radius: 9px; font: 700 .81rem/1 var(--mono); }
.optional-group { padding: 10px 9px 0; background: var(--subtle); border-radius: 11px; margin-top: 10px; }
.optional-group p { color: var(--amber); padding-bottom: 4px; }
.done-mark { color: var(--teal); }
.recap ul { margin: 1px 0 14px; padding-inline-start: 21px; }
.recap li + li, .worked li + li { margin-top: 5px; }
.filterbar { display: flex; align-items: end; flex-wrap: wrap; gap: 10px; margin-bottom: 13px; }
.library-tools { margin-bottom: 14px; }
.library-tools .filterbar { margin: 0; }
.library-tools .segment + .filterbar { margin-top: 14px; }
.filterbar label { flex: 1 1 170px; min-width: 0; }
label:not(.choice, .checkbox) { display: block; font-size: .85rem; font-weight: 700; }
input:not([type=checkbox], [type=radio]), select { display: block; border: 1px solid var(--line); border-radius: 9px; min-height: 44px; padding: 8px 10px; width: 100%; min-width: 0; background: var(--surface); color: var(--text); }
input::placeholder { color: var(--muted); opacity: .86; }
label > input, label > select, label + input, label + select { margin-top: 4px; }
input[dir=ltr], select[dir=ltr] { font-family: var(--mono); }
select[dir=ltr]:has(option[value=""]:checked) { font-family: var(--font); }
.entry summary, .quick-reveal summary, .worked summary { list-style: none; }
summary::-webkit-details-marker { display: none; }
.entry summary { display: flex; align-items: center; gap: 9px; justify-content: space-between; min-height: 57px; padding: 11px 14px; border-radius: var(--radius); }
.entry summary:hover { background: var(--subtle); }
.entry-label { flex: 1; display: flex; align-items: center; flex-wrap: wrap; gap: 9px; min-width: 0; }
.entry-label strong { overflow-wrap: anywhere; }
.entry summary .meta { white-space: nowrap; }
.expand-icon { display: grid; place-items: center; min-width: 27px; color: var(--muted); }
.entry[open] > summary .expand-icon { transform: rotate(180deg); }
.entry-body { border-top: 1px solid var(--line); padding: 13px 15px 15px; min-width: 0; }
.entry-body p + p, .flash-answer p + p { margin-top: 7px; }
.entry-body .tags, .flash-answer .tags { margin-top: 9px; }
.memory, .correction, .example-line { padding: 9px 12px; border-radius: 9px; margin-top: 8px; }
.memory { background: var(--teal-tint); color: var(--teal); }
.correction { background: var(--amber-tint); color: var(--amber); margin-top: 0; }
.correction strong, .example-line strong { margin-inline-end: 5px; }
.example-line { background: var(--subtle); }
.pairs { display: grid; grid-template-columns: repeat(2, minmax(0, 1fr)); gap: 8px; margin: 0 0 9px; }
.pairs > div { padding: 9px 11px; background: var(--subtle); border-radius: 9px; }
.pairs dt, .stacked-dl dt { color: var(--muted); font-size: .78rem; }
.pairs dd, .stacked-dl dd { overflow-wrap: anywhere; }
.science-figure { display: block; width: min(100%, 450px); height: auto; margin: 0 auto 9px; border-radius: 11px; background: #f3f7ff; }
figcaption { font-size: .89rem; color: var(--muted); }
.worked, .quick-reveal { margin-top: 9px; padding: 8px 12px; background: var(--subtle); border: 1px solid var(--line); border-radius: 10px; }
.worked summary, .quick-reveal summary { min-height: 36px; padding-block: 4px; font-weight: 650; color: var(--accent); }
.worked summary::before, .quick-reveal summary::before { content: "+"; margin-inline-end: 6px; }
.worked[open] summary::before, .quick-reveal[open] summary::before { content: "−"; }
.worked ol, .solution-grid ol { padding-inline-start: 20px; margin-block: 6px; }
.practice-panel p { color: var(--muted); margin-top: 5px; }
.practice-panel .text-link, .practice-panel .button { margin-top: 10px; }
.practice-panel .table-scroll, .practice-panel .tags, .practice-panel .stack, .practice-panel .three-grid { margin-top: 10px; }
.two-grid > .practice-panel { margin: 0; }
.table-scroll { max-width: 100%; overflow: auto; border: 1px solid var(--line); border-radius: 10px; }
table { width: 100%; border-collapse: collapse; font-size: .88rem; }
th, td { text-align: start; vertical-align: top; padding: 9px 10px; border-bottom: 1px solid var(--line); }
thead { background: var(--subtle); }
thead th { white-space: nowrap; color: var(--muted); }
tbody tr:last-child > * { border-bottom: 0; }
tbody th a:hover { text-decoration: underline; }
.units-table table { min-width: 550px; }
.segment { display: flex; width: fit-content; max-width: 100%; flex-wrap: wrap; gap: 4px; padding: 4px; border-radius: 11px; background: var(--subtle); border: 1px solid var(--line); }
.segment button, .segment a { padding: 7px 12px; min-height: 40px; background: transparent; border: 1px solid transparent; color: var(--muted); font-size: .85rem; font-weight: 650; border-radius: 8px; display: inline-flex; align-items: center; }
.segment [aria-pressed=true], .segment [aria-current=page] { background: var(--surface); border-color: var(--line); color: var(--accent); box-shadow: var(--shadow); }
.flashcard { padding: 16px clamp(14px, 3vw, 27px); }
.flash-content { padding: 20px 0 23px; text-align: center; min-height: 180px; }
.flash-content h2 { margin: 5px 0 4px; font-size: clamp(1.5rem, 3vw, 2.22rem); }
.flash-content > .button { margin-top: 13px; }
.flash-answer { text-align: start; max-width: 660px; margin: 15px auto 0; }
.flash-answer .text-link { margin-top: 7px; }
.flash-actions { padding-top: 12px; border-top: 1px solid var(--line); display: flex; align-items: center; justify-content: space-between; gap: 7px; }
.recall-form { display: flex; align-items: center; gap: 8px; max-width: 385px; margin: 12px auto 0; }
.recall-form button { flex: none; }
.recall-form input { text-align: center; margin: 0; }
.feedback { padding: 8px 11px; border-radius: 8px; font-weight: 700; }
.feedback.success { background: var(--teal-tint); color: var(--teal); }
.feedback.warning { background: var(--amber-tint); color: var(--amber); }
.heat-card { padding: 16px; }
.heat-card h2 { margin: 9px 0 5px; }
.heat-card p { color: var(--muted); font-size: .9rem; margin-bottom: 11px; }
.heat-card .meta { display: block; margin-top: 8px; }
.tool-layout { display: grid; grid-template-columns: minmax(0, 1.3fr) minmax(240px, .85fr); gap: 15px; align-items: start; }
.lab-panel form { margin-top: 13px; }
.lab-panel #lab-fields { margin-top: 12px; }
.lab-panel .button-row, .lab-panel #lab-fields > button { margin-top: 12px; }
.checkbox { display: flex; align-items: center; gap: 7px; min-height: 44px; font-size: .85rem; }
.checkbox input { accent-color: var(--blue); inline-size: 16px; block-size: 16px; }
.lab-reference h2 { margin-top: 8px; }
.lab-reference p + p { margin-top: 8px; }
.lab-result, #lab-feedback > p { margin-top: 14px; }
.lab-result { background: var(--teal-tint); color: var(--teal); border-radius: 11px; padding: 12px; }
.lab-value { font-size: 1.7rem; font-weight: 750; }

.exam-notice { display: flex; align-items: center; gap: 9px; }
.exam-grid { display: grid; grid-template-columns: repeat(3, minmax(0, 1fr)); gap: 14px; }
.exam-tile { display: flex; flex-direction: column; }
.exam-tile .tags, .exam-tile-bottom { padding-top: 12px; }
.exam-tile-bottom { margin-top: auto; display: flex; align-items: center; flex-wrap: wrap; gap: 9px; }
.exam-format { padding: 18px; margin-top: 15px; }
.exam-format .three-grid { margin-block: 12px; }
.exam-format .three-grid > div { background: var(--subtle); padding: 12px; border-radius: 10px; }
.exam-format strong, .exam-format small { display: block; margin-top: 3px; }
.exam-format small { color: var(--muted); }
.attempt-layout { display: grid; grid-template-columns: minmax(0, 1fr) minmax(250px, .51fr); gap: 15px; align-items: start; }
.exam-main, .question-map, .pre-submit { padding: clamp(13px, 2vw, 21px); }
.exam-main h2 { margin-block: 12px 14px; }
.exam-actions { display: flex; justify-content: space-between; gap: 7px; border-top: 1px solid var(--line); padding-top: 12px; margin-top: 14px; }
.choice-set { border: none; padding: 0; margin: 0; display: grid; gap: 8px; }
.choice { display: flex; align-items: center; min-height: 52px; border: 1px solid var(--line); border-radius: 10px; padding: 8px 10px; gap: 9px; cursor: pointer; }
.choice:hover { border-color: var(--accent); }
.choice:has(input:checked) { background: var(--blue-tint); border-color: var(--accent); }
.choice input { accent-color: var(--blue); inline-size: 17px; block-size: 17px; flex: none; margin: 0; }
.option-index { display: grid; place-items: center; width: 25px; height: 25px; border-radius: 6px; color: var(--accent); background: var(--subtle); font: .85rem/1 var(--mono); flex: none; }
.step { display: grid; grid-template-columns: auto minmax(0, 1fr); gap: 9px; margin: 0 0 12px; }
.step .lesson-index { margin-top: 2px; }
.step small { display: block; margin-top: 4px; }
.math-final { gap: 8px; }
.keyboard-box { background: var(--subtle); border: 1px solid var(--line); padding: 9px; border-radius: 11px; max-width: 435px; }
.keyboard-heading { display: flex; align-items: center; justify-content: space-between; gap: 5px; font-size: .82rem; padding-bottom: 7px; }
.keyboard-heading span { color: var(--muted); font-size: .76rem; }
.math-keyboard { display: grid; grid-template-columns: repeat(5, minmax(0, 1fr)); gap: 5px; }
.math-keyboard button { min-height: 44px; border: 1px solid var(--line); border-radius: 8px; background: var(--surface); font-family: var(--mono); touch-action: manipulation; }
.math-keyboard button:hover { background: var(--blue-tint); border-color: var(--accent); }
.math-keyboard button:last-child { grid-column: span 2; }
.question-map-head p { margin: 4px 0 6px; color: var(--muted); font-size: .85rem; }
.question-group { margin-top: 13px; }
.question-group h3 { font-size: .9rem; margin-bottom: 6px; }
.jump-grid { display: grid; grid-template-columns: repeat(6, minmax(0, 1fr)); gap: 5px; }
.jump { background: var(--subtle); border: 1px solid var(--line); border-radius: 7px; color: var(--text); min-height: 36px; padding: 2px; font-weight: 700; }
.jump.complete { background: var(--teal-tint); color: var(--teal); }
.jump.partial { background: var(--amber-tint); color: var(--amber); border-style: dashed; }
.jump[aria-current=step] { border: 2px solid var(--accent); }
.jump:hover { border-color: var(--accent); }
.jump-legend { display: flex; align-items: center; flex-wrap: wrap; gap: 5px; font-size: .7rem; color: var(--muted); margin: 9px 0; }
.jump-legend span { width: 8px; height: 8px; border-radius: 50%; background: var(--line); }
.jump-legend .complete { background: var(--teal); }
.jump-legend .partial { background: var(--amber); }
.pre-submit h2 { margin: 3px 0 4px; }
.pre-submit p { color: var(--muted); }
.pre-submit .tags, .pre-submit .button-row { margin-top: 13px; }
.pre-list { display: grid; grid-template-columns: repeat(auto-fill, minmax(92px, 1fr)); gap: 6px; }
.pre-list button { min-height: 44px; }
.pre-list span { font-size: .72rem; }
.result-summary { display: grid; grid-template-columns: minmax(170px, .6fr) minmax(0, 1fr); overflow: hidden; }
.score-panel { display: grid; align-content: center; justify-items: center; gap: 4px; padding: 21px; background: linear-gradient(150deg, #2143ac, #132c6a); color: #fff; }
.score-panel strong { font-size: clamp(1.85rem, 4.3vw, 3.45rem); white-space: nowrap; }
.score-panel > span:last-child { color: #dbe8ff; }
.result-breakdown { padding: 15px 19px; }
.grade-row { display: flex; align-items: center; justify-content: space-between; gap: 6px; padding: 7px 0; border-bottom: 1px solid var(--line); }
.result-breakdown .tags { margin-top: 9px; }
.result-section { margin: 14px 0 18px; }
.result-section h3 { margin: 0 0 8px; }
.correction-entry summary strong { flex: 1; font-size: .91rem; }
.review-options { list-style: none; padding: 0; margin-block: 8px; }
.review-options li { padding: 4px 0; border-bottom: 1px solid var(--line); }
.review-options .chip { margin-inline-start: 6px; }
.reference-row { display: flex; align-items: center; justify-content: space-between; gap: 9px; margin-top: 8px; }
.solution-grid > div, .rubric { background: var(--subtle); border-radius: 11px; padding: 10px; }
.solution-grid h4, .rubric h4 { margin-bottom: 6px; }
.stacked-dl dd + dt { margin-top: 5px; }
.rubric { margin-top: 9px; }
.rubric > div { display: flex; justify-content: space-between; padding: 4px 0; border-bottom: 1px solid var(--line); gap: 6px; }
.rubric p { color: var(--muted); font-size: .85rem; margin-top: 5px; }
.progress-stats > article { padding: 14px; }
.progress-stats p { font-size: .84rem; color: var(--muted); margin-top: 6px; }
.progress-stats strong { font-size: 1.05rem; }
.practice-panel .three-grid progress { margin-top: 6px; }
.attempt-history { padding: 4px 12px; }
.backup-panel .button-row { margin-top: 9px; }
.backup-panel .button-row .button { margin: 0; }
.history-row { display: grid; grid-template-columns: auto minmax(0, 1fr) auto auto; align-items: center; gap: 10px; padding: 9px 0; }
.history-row + .history-row { border-top: 1px solid var(--line); }

dialog { background: var(--surface); color: var(--text); border: 1px solid var(--line); border-radius: 16px; padding: 0; max-width: min(94vw, 565px); max-height: 87dvh; box-shadow: 0 16px 55px rgb(10 22 52 / .25); }
dialog::backdrop { background: rgb(9 20 42 / .62); }
.dialog-body { padding: clamp(15px, 3vw, 24px); }
.dialog-body h2 { margin-block: 7px 5px; }
.dialog-body p { color: var(--muted); margin-bottom: 10px; }
.search-box { width: min(580px, 90vw); }
.search-box .section-heading { align-items: center; }
.search-results { margin-top: 10px; max-height: 51dvh; overflow-y: auto; padding: 2px; }
.search-results a { display: flex; align-items: center; justify-content: space-between; gap: 8px; min-height: 50px; padding: 5px 8px; border-bottom: 1px solid var(--line); }
.search-results a:hover { background: var(--blue-tint); }
.search-results small { display: block; font-size: .75rem; color: var(--muted); }

@media (max-width: 1040px) {
  .shell { grid-template-columns: 207px minmax(0, 1fr); }
  .nav-link { font-size: .81rem; padding-inline: 8px; gap: 7px; }
  .stats { gap: 8px; }
  .stat { padding: 10px; gap: 8px; }
  .stat .tile-icon { width: 37px; height: 37px; }
  .exam-grid { grid-template-columns: repeat(2, minmax(0, 1fr)); }
}
@media (max-width: 880px) {
  .shell { display: block; }
  .sidebar { display: none; position: fixed; inset: 0 0 0 auto; height: 100dvh; width: min(300px, 80vw); z-index: 40; }
  .sidebar.nav-open { display: flex; }
  .nav-link { font-size: .9rem; min-height: 44px; }
  .nav-overlay:not([hidden]) { display: block; position: fixed; z-index: 39; inset: 0; border: 0; background: rgb(10 23 46 / .58); }
  .nav-toggle { display: inline-grid; }
}
@media (max-width: 640px) {
  .page { padding-inline: 13px; }
  .topbar-inner { padding-inline: 13px; min-height: 59px; }
  .breadcrumb, .top-actions { gap: 6px; }
  .breadcrumb > a, .crumb-sep { display: none; }
  .search-trigger { width: 44px; justify-content: center; padding-inline: 0; }
  .search-trigger span, .search-trigger kbd { display: none; }
  .hero { min-height: 256px; padding: 24px 15px 37px; border-radius: 17px; }
  .hero-content { max-width: min(100%, 390px); }
  .hero h1 { font-size: clamp(2rem, 7.9vw, 2.8rem); }
  .hero p { font-size: .9rem; max-width: 33ch; }
  .hero-art { inset-inline-end: -13%; width: 83%; opacity: .31; }
  .orbit-tag { display: none; }
  .hero-index { font-size: .59rem; }
  .two-grid, .three-grid, .tool-layout, .attempt-layout, .exam-grid { grid-template-columns: minmax(0, 1fr); gap: 10px; }
  .stats, .progress-stats { grid-template-columns: repeat(2, minmax(0, 1fr)); }
  .progress-overview { grid-template-columns: minmax(0, 1fr); gap: 13px; }
  .last-result { border-inline-start: 0; padding-inline-start: 0; padding-top: 10px; border-top: 1px solid var(--line); }
  .jump { min-height: 44px; }
  .math-final { grid-template-columns: repeat(2, minmax(0, 1fr)); }
  .result-summary { grid-template-columns: minmax(0, 1fr); }
  .score-panel { padding: 13px; }
  .entry summary { flex-wrap: wrap; padding-inline: 11px; }
  .entry-label { flex-basis: 66%; }
  .entry summary .meta { font-size: .72rem; }
  .entry .expand-icon { margin-inline-start: auto; }
  .correction-entry summary .chip { order: 1; }
  .flash-actions { flex-wrap: wrap; }
  .flash-actions > .button-row { order: 1; width: 100%; justify-content: center; }
  .history-row { grid-template-columns: auto minmax(0, 1fr) auto; gap: 6px; }
  .history-row .button { grid-column: 2 / 4; justify-self: start; }
}
@media (prefers-reduced-motion: reduce) {
  *, *::before, *::after { animation-duration: .001ms !important; transition-duration: .001ms !important; }
}
@media print {
  :root, [data-theme="dark"] { --text: #000; --muted: #293248; --surface: #fff; --line: #cdd4dd; --subtle: #f4f5f8; --accent: #153b87; --blue-tint: #eef2fa; color-scheme: light; }
  body { background: #fff; font-size: 11pt; }
  .shell { display: block; }
  .topbar, .sidebar, .footer, .skip-link, .heading-actions, .filterbar, .segment, .button, .nav-overlay, .storage-warning { display: none !important; }
  .page { padding: 0; max-width: none; }
  .panel { box-shadow: none; }
  .entry, .recap, .science-figure, .grade-row { break-inside: avoid; }
  .entry summary { min-height: 0; }
  .table-scroll { overflow: visible; }
  .score-panel { background: #fff; color: #000; }
  .score-panel > span:last-child { color: #000; }
}