:root {
    --bg: #08111f;
    --bg-elevated: #0d1929;
    --surface: #111f31;
    --surface-soft: #17283d;
    --text: #f7fafc;
    --text-muted: #afbdd0;
    --border: #304157;
    --primary: #43d38c;
    --primary-strong: #24b875;
    --primary-ink: #06150f;
    --accent: #f2b84b;
    --danger: #ff6b6b;
    --danger-bg: #3a1c27;
    --success-bg: #12392c;
    --focus: #90f0bd;
    --shadow: 0 18px 55px rgba(0, 0, 0, .3);
    --radius-sm: .65rem;
    --radius: 1rem;
    --radius-lg: 1.4rem;
    --max: 1180px;
    --transition: 180ms ease;
}

* { box-sizing: border-box; }
html { color-scheme: dark; font-size: 16px; background: var(--bg); }
body { margin: 0; min-width: 320px; min-height: 100dvh; overflow-x: hidden; background: var(--bg); color: var(--text); font-family: "Segoe UI", Inter, system-ui, -apple-system, sans-serif; line-height: 1.55; }
button, input, select { font: inherit; }
button, a, select, label { touch-action: manipulation; }
a { color: inherit; }
img { display: block; max-width: 100%; height: auto; }
button { cursor: pointer; }
button:disabled { cursor: not-allowed; opacity: .42; }
:focus-visible { outline: 3px solid var(--focus); outline-offset: 3px; }
.skip-link { position: fixed; top: .75rem; left: .75rem; z-index: 1000; padding: .7rem 1rem; transform: translateY(-160%); border-radius: var(--radius-sm); background: var(--text); color: var(--bg); font-weight: 700; }
.skip-link:focus { transform: translateY(0); }
.sr-only { position: absolute; width: 1px; height: 1px; overflow: hidden; clip: rect(0, 0, 0, 0); white-space: nowrap; }
.eyebrow { margin: 0 0 .75rem; color: var(--primary); font-size: .78rem; font-weight: 800; letter-spacing: .14em; }

.button { display: inline-flex; min-height: 48px; align-items: center; justify-content: center; gap: .5rem; padding: .7rem 1.05rem; border: 1px solid transparent; border-radius: .75rem; text-align: center; text-decoration: none; font-weight: 760; transition: background var(--transition), border-color var(--transition), color var(--transition), opacity var(--transition); }
.button--primary { background: var(--primary); color: var(--primary-ink); }
.button--primary:hover { background: var(--primary-strong); }
.button--secondary { border-color: var(--border); background: var(--surface-soft); color: var(--text); }
.button--secondary:hover { border-color: var(--text-muted); background: #20344c; }
.button--danger { background: var(--danger); color: #1b0707; }
.button--danger:hover { background: #ff8585; }
.button--danger-outline { border-color: #7d3c49; background: transparent; color: #ffc4c4; }
.button--danger-outline:hover { background: var(--danger-bg); border-color: var(--danger); }

/* Home */
.home-page { background: radial-gradient(circle at 80% 10%, rgba(67, 211, 140, .12), transparent 35rem), var(--bg); }
.home-shell { display: grid; min-height: 100dvh; place-items: center; padding: 1rem; }
.home-panel { width: min(100%, 960px); padding: 1.4rem 0 2rem; text-align: center; }
.brand-lockup { display: flex; justify-content: center; }
.brand-lockup img { flex: 0 0 auto; object-fit: contain; }
.brand-lockup--ccat { margin-bottom: 2rem; }
.brand-lockup--ccat img { width: clamp(150px, 28vw, 190px); }
.brand-lockup--avid { margin-top: 2rem; }
.brand-lockup--avid img { width: clamp(180px, 32vw, 240px); }
.home-panel h1 { max-width: 820px; margin: 0 auto 1.2rem; font-size: clamp(2.45rem, 9vw, 5.5rem); line-height: .98; letter-spacing: -.055em; text-transform: uppercase; }
.home-intro { max-width: 610px; margin: 0 auto 2.2rem; color: var(--text-muted); font-size: clamp(1.02rem, 2.3vw, 1.25rem); }
.exam-options { display: grid; gap: 1rem; }
.exam-option { display: grid; grid-template-columns: auto 1fr; align-items: center; gap: .8rem 1rem; padding: 1rem; border: 1px solid var(--border); border-radius: var(--radius); background: rgba(17, 31, 49, .88); box-shadow: 0 8px 30px rgba(0,0,0,.14); text-align: left; }
.exam-option__number { display: grid; width: 64px; height: 64px; place-items: center; border-radius: .8rem; background: var(--surface-soft); color: var(--primary); font-size: 1.4rem; font-weight: 850; }
.exam-option__copy { min-width: 0; }
.exam-option__copy strong, .exam-option__copy small { display: block; }
.exam-option__copy strong { font-size: 1.04rem; }
.exam-option__copy small { margin-top: .2rem; color: var(--text-muted); font-size: .86rem; }
.exam-option .button { grid-column: 1 / -1; width: 100%; }
.home-note { display: flex; max-width: 660px; align-items: flex-start; gap: .65rem; margin: 1.5rem auto 0; color: var(--text-muted); text-align: left; font-size: .9rem; }
.status-dot { flex: 0 0 auto; width: .65rem; height: .65rem; margin-top: .38rem; border: 2px solid var(--primary); border-radius: 50%; }

/* Exam */
.exam-header { display: flex; min-height: 76px; align-items: center; justify-content: space-between; gap: 1rem; padding: .8rem max(1rem, calc((100vw - var(--max)) / 2)); border-bottom: 1px solid var(--border); background: rgba(8, 17, 31, .94); }
.exam-brand { display: inline-flex; flex-direction: column; text-decoration: none; font-size: 1.1rem; font-weight: 900; letter-spacing: .06em; }
.exam-brand span { color: var(--text-muted); font-size: .58rem; letter-spacing: .13em; }
.exam-header__meta { text-align: right; }
.exam-header__meta span, .exam-header__meta strong { display: block; }
.exam-header__meta span { max-width: 190px; color: var(--text-muted); overflow: hidden; text-overflow: ellipsis; white-space: nowrap; font-size: .78rem; }
.exam-header__meta strong { font-size: .95rem; }
.progress-track { height: 5px; background: #1d2c40; }
.progress-track span { display: block; height: 100%; background: var(--primary); transition: width var(--transition); }
.exam-layout { display: grid; width: min(100%, var(--max)); gap: 1rem; margin: 0 auto; padding: 1rem; }
.question-navigator { order: 2; padding: 1rem; border: 1px solid var(--border); border-radius: var(--radius); background: var(--bg-elevated); }
.navigator-heading { display: flex; align-items: center; justify-content: space-between; gap: 1rem; margin-bottom: .8rem; }
.navigator-heading h2 { margin: 0; font-size: 1rem; }
.navigator-heading span { color: var(--text-muted); font-size: .82rem; }
.navigator-grid { display: grid; grid-template-columns: repeat(10, minmax(0, 1fr)); gap: .35rem; }
.navigator-item { min-width: 0; min-height: 38px; padding: 0; border: 1px solid var(--border); border-radius: .45rem; background: transparent; color: var(--text-muted); font-size: .75rem; font-weight: 700; }
.navigator-item.is-answered { border-color: #3d7b61; background: #173c30; color: #c7f8dd; }
.navigator-item.is-current { border-color: var(--accent); box-shadow: inset 0 0 0 2px var(--accent); color: var(--text); }
.navigator-legend { display: flex; gap: 1rem; margin-top: .8rem; color: var(--text-muted); font-size: .76rem; }
.navigator-legend span { display: flex; align-items: center; gap: .4rem; }
.legend-mark { width: .65rem; height: .65rem; border-radius: 3px; }
.legend-mark--answered { background: #2c805b; }
.legend-mark--current { border: 2px solid var(--accent); }
.question-card { order: 1; min-width: 0; padding: 1.15rem; border: 1px solid var(--border); border-radius: var(--radius-lg); background: var(--surface); box-shadow: var(--shadow); }
.question-card__topline { display: flex; align-items: center; justify-content: space-between; gap: .75rem; margin-bottom: 1.1rem; color: var(--primary); font-size: .78rem; font-weight: 800; letter-spacing: .08em; text-transform: uppercase; }
.question-type { color: var(--text-muted); text-align: right; letter-spacing: .03em; }
.instruction { display: inline-flex; margin: 0 0 .75rem; padding: .25rem .55rem; border-radius: .4rem; background: #223348; color: var(--accent); font-size: .82rem; font-weight: 800; }
.question-text { max-width: 75ch; margin-bottom: 1.25rem; font-size: clamp(1.08rem, 2.3vw, 1.34rem); line-height: 1.55; }
.question-text p { margin: 0 0 .75rem; }
.question-text p:last-child { margin-bottom: 0; }
.question-images, .review-images { display: grid; gap: .75rem; margin: 1rem 0 1.35rem; }
.image-button { overflow: hidden; padding: 0; border: 1px solid var(--border); border-radius: var(--radius); background: #07101d; color: var(--text-muted); }
.image-button img { width: 100%; max-height: 580px; object-fit: contain; }
.image-button span { display: block; padding: .55rem; border-top: 1px solid var(--border); font-size: .8rem; }
.answer-form { margin-top: 1rem; }
.answer-list, .matching-list { min-width: 0; margin: 0; padding: 0; border: 0; }
.answer-list { display: grid; gap: .7rem; }
.answer-option { display: grid; min-height: 58px; grid-template-columns: 26px 1fr; align-items: center; gap: .85rem; padding: .75rem .9rem; border: 1px solid var(--border); border-radius: .8rem; background: var(--bg-elevated); cursor: pointer; transition: border-color var(--transition), background var(--transition); }
.answer-option:hover { border-color: #60768f; background: #14253a; }
.answer-option:has(input:checked) { border-color: var(--primary); background: #14382d; }
.answer-option input { position: absolute; width: 1px; height: 1px; opacity: 0; }
.answer-control { position: relative; width: 22px; height: 22px; border: 2px solid #8192a8; border-radius: 50%; }
input[type="checkbox"] + .answer-control { border-radius: 5px; }
.answer-option input:checked + .answer-control { border-color: var(--primary); background: var(--primary); }
.answer-option input:checked + .answer-control::after { position: absolute; inset: 4px; border-radius: 50%; background: var(--primary-ink); content: ""; }
.answer-option input[type="checkbox"]:checked + .answer-control::after { inset: 3px 6px 6px; border: solid var(--primary-ink); border-width: 0 2px 2px 0; border-radius: 0; background: transparent; transform: rotate(45deg); }
.answer-option input:focus-visible + .answer-control { outline: 3px solid var(--focus); outline-offset: 3px; }
.answer-copy { min-width: 0; }
.answer-copy p { margin: 0; }
.matching-list legend { margin-bottom: .85rem; color: var(--text-muted); }
.matching-row { display: grid; gap: .55rem; padding: .85rem 0; border-bottom: 1px solid var(--border); }
.matching-row label { font-weight: 700; }
.matching-row select { width: 100%; min-height: 48px; padding: .6rem 2.4rem .6rem .75rem; border: 1px solid var(--border); border-radius: .65rem; background: var(--bg-elevated); color: var(--text); }
.exam-controls { display: grid; grid-template-columns: 1fr 1fr; gap: .65rem; margin-top: 1.5rem; }
.exam-controls .button--danger-outline { grid-column: 1 / -1; grid-row: 2; }

/* Dialogs */
dialog { color: var(--text); }
.submit-dialog { width: min(calc(100% - 2rem), 480px); padding: 1.5rem; border: 1px solid var(--border); border-radius: var(--radius-lg); background: var(--surface); box-shadow: 0 30px 90px rgba(0,0,0,.55); text-align: center; }
dialog::backdrop { background: rgba(2, 8, 16, .76); backdrop-filter: blur(3px); }
.dialog-icon { display: grid; width: 48px; height: 48px; place-items: center; margin: 0 auto .8rem; border: 2px solid var(--accent); border-radius: 50%; color: var(--accent); font-size: 1.35rem; font-weight: 900; }
.submit-dialog h2 { margin: 0 0 .8rem; }
.submit-dialog p { color: var(--text-muted); }
.dialog-actions { display: grid; gap: .65rem; margin-top: 1.2rem; }
.image-dialog { width: min(96vw, 1500px); max-height: 94dvh; padding: 3.5rem .75rem .75rem; border: 1px solid var(--border); border-radius: var(--radius); background: #030912; }
.image-dialog img { width: 100%; max-height: calc(94dvh - 4.5rem); object-fit: contain; }
.dialog-close { position: absolute; top: .65rem; right: .65rem; min-height: 42px; padding: .45rem .8rem; border: 1px solid var(--border); border-radius: .55rem; background: var(--surface); color: var(--text); }

/* Results */
.result-header { width: min(100%, var(--max)); margin: 0 auto; padding: 1.2rem 1rem; }
.results-shell { width: min(100%, 980px); margin: 0 auto; padding: 0 1rem 4rem; }
.score-card { overflow: hidden; padding: 1.25rem; border: 1px solid var(--border); border-top: 5px solid var(--danger); border-radius: var(--radius-lg); background: var(--surface); box-shadow: var(--shadow); }
.score-card.is-passed { border-top-color: var(--primary); }
.score-card h1 { margin: 0 0 1.4rem; font-size: clamp(1.75rem, 5vw, 3rem); line-height: 1.1; }
.score-grid { display: grid; gap: .75rem; }
.score-grid > div { padding: 1rem; border: 1px solid var(--border); border-radius: .8rem; background: var(--bg-elevated); }
.score-grid span, .score-grid strong { display: block; }
.score-grid span { color: var(--text-muted); font-size: .8rem; font-weight: 700; text-transform: uppercase; letter-spacing: .08em; }
.score-grid strong { margin-top: .25rem; font-size: 2rem; font-variant-numeric: tabular-nums; }
.score-grid small { color: var(--text-muted); font-size: 1rem; }
.is-passed .result-word { color: var(--primary); }
.is-not-passed .result-word { color: var(--danger); font-size: 1.5rem; }
.passing-note { color: var(--text-muted); }
.retake-form { display: grid; gap: .7rem; margin-top: 1.2rem; }
.review-section { margin-top: 2.5rem; }
.review-heading { display: flex; align-items: end; justify-content: space-between; gap: 1rem; margin-bottom: 1rem; }
.review-heading h2 { margin: 0; font-size: clamp(1.6rem, 4vw, 2.25rem); }
.review-heading > span { color: var(--text-muted); }
.review-card { margin-bottom: 1rem; padding: 1.1rem; border: 1px solid var(--border); border-radius: var(--radius); background: var(--surface); }
.review-card > header { display: flex; align-items: center; justify-content: space-between; gap: 1rem; padding-bottom: .75rem; border-bottom: 1px solid var(--border); }
.review-card > header span { font-weight: 800; }
.review-card > header strong { color: var(--danger); font-size: .82rem; text-transform: uppercase; letter-spacing: .08em; }
.review-question { margin: 1rem 0; font-size: 1.08rem; }
.review-question p { margin: 0 0 .65rem; }
.review-images img { width: 100%; max-height: 520px; object-fit: contain; border-radius: .7rem; background: #050c16; }
.answer-review-grid { display: grid; gap: .75rem; }
.answer-review { padding: .9rem; border-radius: .7rem; }
.answer-review h3 { margin: 0 0 .55rem; font-size: .86rem; text-transform: uppercase; letter-spacing: .06em; }
.answer-review ul { margin: 0; padding-left: 1.15rem; }
.answer-review--student { background: var(--danger-bg); }
.answer-review--student h3 { color: #ffb9b9; }
.answer-review--correct { background: var(--success-bg); }
.answer-review--correct h3 { color: #a9efc9; }
.perfect-result { padding: 1.5rem; border: 1px solid #34795a; border-radius: var(--radius); background: var(--success-bg); }
.perfect-result p { margin-bottom: 0; color: var(--text-muted); }

.error-shell { width: min(100% - 2rem, 640px); margin: 12vh auto; padding: 1.5rem; border: 1px solid var(--border); border-radius: var(--radius-lg); background: var(--surface); }
.error-shell h1 { margin-top: 0; }
.error-shell p { color: var(--text-muted); }

@media (min-width: 640px) {
    .exam-option { grid-template-columns: auto 1fr auto; padding: 1rem 1.1rem; }
    .exam-option .button { grid-column: auto; width: auto; }
    .exam-controls { grid-template-columns: 1fr auto 1fr; }
    .exam-controls .button--danger-outline { grid-column: auto; grid-row: auto; }
    .dialog-actions, .retake-form { grid-template-columns: 1fr 1fr; }
    .score-grid { grid-template-columns: repeat(3, 1fr); }
    .answer-review-grid { grid-template-columns: 1fr 1fr; }
    .matching-row { grid-template-columns: minmax(160px, .8fr) minmax(220px, 1fr); align-items: center; }
}

@media (min-width: 768px) {
    .home-shell { padding: 2rem; }
    .home-panel { padding-block: 3rem; }
    .question-card { padding: 1.6rem; }
    .question-images { grid-template-columns: repeat(2, minmax(0, 1fr)); }
    .score-card, .review-card { padding: 1.6rem; }
}

@media (min-width: 1024px) {
    .exam-layout { grid-template-columns: 245px minmax(0, 1fr); align-items: start; padding-block: 1.5rem 3rem; }
    .question-navigator { position: sticky; top: 1rem; order: 1; }
    .question-card { order: 2; }
    .navigator-grid { grid-template-columns: repeat(5, 1fr); gap: .45rem; }
    .navigator-item { min-height: 40px; }
}

@media (min-width: 1440px) {
    .home-panel { width: min(100%, 1050px); }
    .question-card { padding: 2rem; }
}

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