:root {
  --fg: #1d2330;
  --muted: #5b6475;
  --bg: #f7f8fa;
  --card: #fff;
  --accent: #2457c5;
  --accent-soft: #e8eefb;
  --border: #dde1e8;
  --good: #1a7f4b;
  --good-soft: #e6f4ec;
  --bad: #b42318;
  --bad-soft: #fdecea;
  --warn: #b45309;
  --warn-soft: #fff4e5;
  /* Chart series colors (validated categorical slots 1-2). */
  --series-1: #2a78d6;
  --series-2: #eb6834;
  --gold: #b7791f;
  --gold-soft: #fdf3dc;
}
* { box-sizing: border-box; }
[hidden] { display: none !important; }
body { margin: 0; font-family: system-ui, -apple-system, "Segoe UI", sans-serif; color: var(--fg); background: var(--bg); line-height: 1.5; }
a { color: var(--accent); }
h1 { font-size: 1.6rem; margin: 0 0 16px; }
h2 { font-size: 1.2rem; margin: 28px 0 12px; }

/* Header */
.site-header { background: var(--card); border-bottom: 1px solid var(--border); }
.site-header nav { max-width: 1100px; margin: 0 auto; padding: 12px 16px; display: flex; align-items: center; gap: 16px; flex-wrap: wrap; }
.site-header .brand { font-weight: 700; color: var(--fg); text-decoration: none; margin-right: auto; }
.site-header a, .linklike { color: var(--accent); text-decoration: none; background: none; border: 0; font: inherit; cursor: pointer; padding: 0; }
main { max-width: 1100px; margin: 32px auto; padding: 0 16px; }

/* Shared pieces */
.card { background: var(--card); border: 1px solid var(--border); border-radius: 8px; padding: 20px; }
.card.narrow { max-width: 440px; }
.btn { display: inline-block; background: var(--accent); color: #fff; border: 1px solid var(--accent); border-radius: 6px; padding: 9px 18px; font: inherit; font-weight: 600; cursor: pointer; text-decoration: none; }
.btn:disabled { opacity: .5; cursor: not-allowed; }
.btn.secondary { background: var(--card); color: var(--accent); }
.muted { color: var(--muted); font-size: .92em; }
.messages { list-style: none; padding: 0; margin: 0 0 20px; }
.messages li { padding: 10px 14px; border-radius: 6px; background: var(--accent-soft); margin-bottom: 8px; }
.messages li.error { background: var(--bad-soft); color: var(--bad); }
form p { margin: 0 0 14px; }
form label { display: block; font-weight: 600; margin-bottom: 4px; }
form input[type=text], form input[type=email], form input[type=password] { width: 100%; padding: 8px 10px; border: 1px solid var(--border); border-radius: 6px; font: inherit; }
.helptext { color: var(--muted); font-size: .9em; }
.errorlist { color: var(--bad); padding-left: 18px; }
table.data { width: 100%; border-collapse: collapse; background: var(--card); }
table.data th, table.data td { text-align: left; padding: 8px 10px; border-bottom: 1px solid var(--border); }
table.data th { font-size: .85em; color: var(--muted); font-weight: 600; }
.table-wrap { overflow-x: auto; border: 1px solid var(--border); border-radius: 8px; }

/* Dashboard */
.grid { display: grid; grid-template-columns: repeat(auto-fill, minmax(240px, 1fr)); gap: 16px; }
.test-card { display: flex; flex-direction: column; gap: 6px; }
.test-card h3 { margin: 0; font-size: 1.05rem; }
.test-card form { margin-top: auto; padding-top: 10px; }
.banner { background: var(--warn-soft); border: 1px solid #f3d7b0; border-radius: 8px; padding: 14px 18px; margin-bottom: 24px; display: flex; align-items: center; gap: 16px; flex-wrap: wrap; }
.banner .btn { margin-left: auto; }

/* Question content */
.content p { margin: 0 0 12px; }
.content table { border-collapse: collapse; margin: 8px 0 14px; }
.content th, .content td { border: 1px solid var(--border); padding: 6px 10px; text-align: center; }
.content th { background: var(--bg); }
.content ul { padding-left: 22px; margin: 0 0 12px; }
.katex { font-size: 1.05em; }

/* Test-taking page */
body.taking main { margin-top: 0; max-width: 1200px; }
.test-bar { position: sticky; top: 0; z-index: 10; background: var(--card); border-bottom: 1px solid var(--border); margin: 0 -16px 20px; padding: 10px 16px; display: flex; align-items: center; gap: 12px; flex-wrap: wrap; }
.test-bar .title { font-weight: 600; margin-right: auto; }
.timer { font-variant-numeric: tabular-nums; font-weight: 700; font-size: 1.1rem; padding: 4px 10px; border-radius: 6px; }
.timer.low { background: var(--bad-soft); color: var(--bad); }
.save-status { font-size: .85em; color: var(--muted); min-width: 70px; text-align: right; }
.save-status.error { color: var(--bad); }
.question { display: grid; gap: 28px; }
.question.has-passage { grid-template-columns: 1fr 1fr; }
.question .passage { border-right: 1px solid var(--border); padding-right: 28px; }
@media (max-width: 800px) {
  .question.has-passage { grid-template-columns: 1fr; }
  .question .passage { border-right: 0; padding-right: 0; border-bottom: 1px solid var(--border); padding-bottom: 16px; }
}
.q-head { display: flex; align-items: center; gap: 12px; margin-bottom: 14px; padding-bottom: 8px; border-bottom: 2px dashed var(--border); }
.q-num { background: var(--fg); color: #fff; font-weight: 700; border-radius: 4px; padding: 2px 10px; }
.flag-btn { background: none; border: 1px solid transparent; border-radius: 6px; padding: 4px 8px; font: inherit; cursor: pointer; color: var(--muted); }
.flag-btn[aria-pressed=true] { color: var(--warn); border-color: var(--warn); background: var(--warn-soft); font-weight: 600; }
.choices { display: grid; gap: 10px; margin-top: 16px; }
.choice { display: flex; align-items: flex-start; gap: 12px; border: 1px solid var(--border); border-radius: 8px; padding: 12px 14px; cursor: pointer; background: var(--card); }
.choice:hover { border-color: var(--accent); }
.choice input { position: absolute; opacity: 0; pointer-events: none; }
.choice .letter { flex: none; width: 28px; height: 28px; border-radius: 50%; border: 2px solid var(--fg); display: grid; place-items: center; font-weight: 700; font-size: .9em; }
.choice:has(input:checked) { border-color: var(--accent); box-shadow: 0 0 0 1px var(--accent); background: var(--accent-soft); }
.choice:has(input:checked) .letter { background: var(--accent); border-color: var(--accent); color: #fff; }
.choice:has(input:focus-visible) { outline: 2px solid var(--accent); outline-offset: 2px; }
.spr label { display: block; font-weight: 600; }
.spr input { font: inherit; font-size: 1.2rem; width: 9ch; padding: 8px 10px; border: 2px solid var(--fg); border-radius: 6px; margin-top: 12px; }
.spr .muted { margin-top: 8px; }
.test-nav { display: flex; align-items: center; gap: 12px; margin-top: 28px; padding-top: 16px; border-top: 1px solid var(--border); }
.test-nav .spacer { margin-right: auto; }
.navigator { display: flex; flex-wrap: wrap; gap: 8px; margin: 12px 0 20px; }
.navigator button { width: 42px; height: 42px; border: 1px dashed var(--fg); border-radius: 6px; background: var(--card); font: inherit; font-weight: 600; cursor: pointer; position: relative; }
.navigator button.answered { background: var(--accent); border: 1px solid var(--accent); color: #fff; }
.navigator button.current { outline: 2px solid var(--fg); outline-offset: 2px; }
.navigator button.flagged::after { content: ""; position: absolute; top: -5px; right: -5px; width: 12px; height: 12px; border-radius: 50%; background: var(--warn); border: 2px solid var(--card); }
.legend { display: flex; gap: 16px; flex-wrap: wrap; font-size: .85em; color: var(--muted); }
dialog { border: 1px solid var(--border); border-radius: 10px; padding: 24px; max-width: min(560px, calc(100vw - 32px)); }
dialog::backdrop { background: rgb(0 0 0 / .35); }

/* Results */
.score-head { display: flex; gap: 32px; align-items: center; flex-wrap: wrap; }
.score-big { font-size: 3rem; font-weight: 800; line-height: 1; }
.bar { height: 8px; background: var(--border); border-radius: 4px; overflow: hidden; min-width: 80px; }
.bar span { display: block; height: 100%; background: var(--accent); }
.review-item { border: 1px solid var(--border); border-radius: 8px; background: var(--card); margin-bottom: 10px; }
.review-item summary { padding: 12px 16px; cursor: pointer; display: flex; gap: 12px; align-items: center; flex-wrap: wrap; }
.review-item .body { padding: 0 16px 16px; }
.pill { font-size: .8em; font-weight: 700; border-radius: 999px; padding: 2px 10px; }
.pill.good { background: var(--good-soft); color: var(--good); }
.pill.bad { background: var(--bad-soft); color: var(--bad); }
.pill.skip { background: var(--bg); color: var(--muted); border: 1px solid var(--border); }
.review-choice { border: 1px solid var(--border); border-radius: 8px; padding: 10px 14px; margin-bottom: 8px; }
.review-choice.correct { border-color: var(--good); background: var(--good-soft); }
.review-choice.picked-wrong { border-color: var(--bad); background: var(--bad-soft); }
.review-choice .rationale { color: var(--muted); font-size: .92em; margin-top: 4px; }
.explanation { background: var(--accent-soft); border-radius: 8px; padding: 12px 16px; margin-top: 12px; }
fieldset.choices { border: 0; padding: 0; margin: 16px 0 0; min-width: 0; }
.sr-only { position: absolute; width: 1px; height: 1px; padding: 0; margin: -1px; overflow: hidden; clip: rect(0 0 0 0); white-space: nowrap; border: 0; }
.timer.hidden-timer { visibility: hidden; }
.site-footer { max-width: 1100px; margin: 48px auto 24px; padding: 16px; border-top: 1px solid var(--border); color: var(--muted); font-size: .8rem; }

/* Report a problem */
.report { margin-top: 14px; padding-top: 12px; border-top: 1px dashed var(--border); }
.report-open { font-size: .9em; }
.report-form { display: grid; gap: 6px; max-width: 520px; }
.report-form label { font-weight: 600; font-size: .9em; margin-top: 4px; }
.report-form select, .report-form textarea { font: inherit; padding: 8px 10px; border: 1px solid var(--border); border-radius: 6px; background: var(--card); color: var(--fg); width: 100%; }
.report-actions { display: flex; align-items: center; gap: 14px; flex-wrap: wrap; margin-top: 6px; }
.report-error { color: var(--bad); font-size: .9em; }
.report-done { margin: 0; }

.small { font-size: .85rem; }

/* Student home */
.hello { display: flex; gap: 24px; align-items: center; justify-content: space-between; flex-wrap: wrap; margin-bottom: 20px; }
.hello h1 { margin-bottom: 4px; }
.hello p { margin: 0; }
.streak-nudge { color: var(--warn); font-weight: 600; }
.level-card { background: var(--card); border: 1px solid var(--border); border-radius: 10px; padding: 14px 18px; min-width: 260px; display: grid; gap: 8px; }
.level-top { display: flex; justify-content: space-between; align-items: center; gap: 12px; }
.level-badge { background: var(--accent); color: #fff; font-weight: 700; border-radius: 999px; padding: 2px 12px; font-size: .9rem; }
.level-bar { height: 10px; background: var(--accent-soft); border-radius: 999px; overflow: hidden; }
.level-bar span { display: block; height: 100%; background: var(--accent); border-radius: 999px; transition: width .8s ease; }
.stat-row { display: grid; grid-template-columns: repeat(auto-fit, minmax(170px, 1fr)); gap: 12px; margin-bottom: 8px; }
.stat-tile { background: var(--card); border: 1px solid var(--border); border-radius: 10px; padding: 14px 16px; }
.stat-label { color: var(--muted); font-size: .85rem; }
.stat-value { font-size: 1.6rem; font-weight: 800; line-height: 1.3; }
.two-col { display: grid; grid-template-columns: 1fr 1fr; gap: 0 24px; }
@media (max-width: 800px) { .two-col { grid-template-columns: 1fr; } }

/* Practice calendar */
.calendar { display: grid; grid-template-columns: repeat(7, 28px); gap: 6px; justify-content: start; }
.cal-head { font-size: .75rem; color: var(--muted); text-align: center; }
.cal-day { display: inline-block; width: 28px; height: 28px; border-radius: 6px; background: var(--bg); border: 1px solid var(--border); }
.cal-day.active { background: var(--accent); border-color: var(--accent); }
.cal-day.today { outline: 2px solid var(--fg); outline-offset: 1px; }
.cal-day.future { opacity: .35; }
.cal-legend { display: flex; align-items: center; gap: 6px; margin-top: 12px; }
.cal-legend .cal-day { width: 14px; height: 14px; border-radius: 4px; }
.cal-legend .cal-day.today { margin-left: 10px; background: var(--card); }

/* Focus areas */
.focus-row { display: flex; justify-content: space-between; align-items: center; gap: 12px; padding: 8px 0; border-bottom: 1px solid var(--border); }
.focus-score { font-weight: 700; white-space: nowrap; }
.section-acc { display: grid; grid-template-columns: 140px 1fr 40px; gap: 10px; align-items: center; margin-top: 12px; }

/* Badges */
.badge-grid { display: grid; grid-template-columns: repeat(auto-fill, minmax(230px, 1fr)); gap: 10px; }
.badge { display: flex; gap: 12px; align-items: center; background: var(--card); border: 1px solid var(--border); border-radius: 10px; padding: 12px 14px; }
.badge-icon { font-size: 1.8rem; width: 44px; height: 44px; display: grid; place-items: center; background: var(--gold-soft); border-radius: 50%; flex: none; }
.badge-name { font-weight: 700; }
.badge.locked .badge-icon { background: var(--bg); filter: grayscale(1); opacity: .45; }
.badge.locked .badge-name { color: var(--muted); }

/* Trend chart */
.trend-card { padding-bottom: 12px; }
.trend-chart { position: relative; outline-offset: 4px; }
.trend-chart svg { display: block; overflow: visible; }
.trend-chart .grid { stroke: var(--border); stroke-width: 1; }
.trend-chart .crosshair { stroke: var(--muted); stroke-width: 1; }
.trend-chart .axis-label { fill: var(--muted); font-size: 12px; }
.trend-chart .direct-label { fill: var(--fg); font-size: 12px; font-weight: 600; }
.legend { display: flex; gap: 18px; flex-wrap: wrap; font-size: .85rem; color: var(--muted); margin-bottom: 8px; }
.legend-item { display: inline-flex; align-items: center; gap: 6px; }
.legend-line { display: inline-block; width: 16px; height: 2px; border-radius: 1px; vertical-align: middle; margin-right: 6px; }
.legend-item .legend-line { margin-right: 0; }
.chart-tooltip { position: absolute; pointer-events: none; background: var(--card); border: 1px solid var(--border); border-radius: 8px; padding: 8px 10px; box-shadow: 0 4px 14px rgb(0 0 0 / .08); white-space: nowrap; }
.tt-value { font-weight: 700; }
.tt-label { color: var(--muted); font-size: .8rem; }
.table-view { margin-top: 10px; }
.table-view summary { cursor: pointer; color: var(--accent); font-size: .9rem; }
.table-view .table-wrap { margin-top: 8px; }

/* Results celebration */
.celebrate { position: relative; overflow: hidden; background: linear-gradient(135deg, var(--accent-soft), var(--gold-soft)); border: 1px solid var(--border); border-radius: 12px; padding: 20px 22px; margin-bottom: 20px; }
.celebrate h2 { margin: 0 0 4px; font-size: 1.35rem; }
.celebrate .points-earned { font-size: 2.2rem; font-weight: 800; color: var(--accent); line-height: 1.1; }
.celebrate-grid { display: flex; gap: 28px; flex-wrap: wrap; align-items: flex-start; margin-top: 10px; }
.celebrate ul.breakdown { list-style: none; padding: 0; margin: 6px 0 0; font-size: .9rem; }
.celebrate ul.breakdown li { display: flex; justify-content: space-between; gap: 18px; }
.celebrate .new-badges { display: flex; gap: 10px; flex-wrap: wrap; }
.celebrate .new-badge { display: flex; gap: 10px; align-items: center; background: var(--card); border: 1px solid var(--border); border-radius: 10px; padding: 8px 12px; animation: pop .5s ease both; }
.celebrate .new-badge:nth-child(2) { animation-delay: .15s; }
.celebrate .new-badge:nth-child(3) { animation-delay: .3s; }
.celebrate .highlights { display: flex; gap: 10px; flex-wrap: wrap; margin-top: 12px; }
.celebrate .highlight { background: var(--card); border-radius: 999px; padding: 4px 12px; font-size: .9rem; font-weight: 600; border: 1px solid var(--border); }
@keyframes pop { from { transform: scale(.6); opacity: 0; } to { transform: scale(1); opacity: 1; } }
.confetti { position: absolute; inset: 0; pointer-events: none; }
.confetti i { position: absolute; top: -12px; width: 8px; height: 12px; border-radius: 2px; animation: fall 2.4s ease-in forwards; }
@keyframes fall { to { transform: translateY(260px) rotate(540deg); opacity: 0; } }
@media (prefers-reduced-motion: reduce) {
  .celebrate .new-badge, .confetti i, .level-bar span { animation: none; transition: none; }
  .confetti { display: none; }
}

/* Landing page */
.hero { display: grid; grid-template-columns: 1.1fr 1fr; gap: 40px; align-items: center; padding: 24px 0 40px; }
@media (max-width: 860px) { .hero { grid-template-columns: 1fr; } }
.eyebrow { color: var(--accent); font-weight: 700; text-transform: uppercase; letter-spacing: .06em; font-size: .8rem; margin: 0 0 8px; }
.hero h1 { font-size: clamp(2rem, 5vw, 2.8rem); line-height: 1.15; margin-bottom: 14px; }
.lead { font-size: 1.1rem; color: var(--muted); margin: 0 0 24px; max-width: 34em; }
.hero-actions { display: flex; gap: 12px; flex-wrap: wrap; }
.btn-lg { padding: 12px 22px; font-size: 1.05rem; }
.preview { background: var(--card); border: 1px solid var(--border); border-radius: 14px; box-shadow: 0 18px 40px rgb(29 35 48 / .10); overflow: hidden; transform: rotate(1deg); }
.preview-bar { display: flex; justify-content: space-between; padding: 10px 16px; border-bottom: 1px solid var(--border); font-weight: 600; font-size: .9rem; }
.preview-timer { font-variant-numeric: tabular-nums; }
.preview-body { padding: 16px; }
.preview-body p { margin: 0 0 12px; font-size: .95rem; }
.preview-choice { display: flex; gap: 10px; align-items: center; border: 1px solid var(--border); border-radius: 8px; padding: 8px 12px; margin-bottom: 8px; font-size: .95rem; }
.preview-choice .letter { width: 24px; height: 24px; border-radius: 50%; border: 2px solid var(--fg); display: grid; place-items: center; font-size: .8rem; font-weight: 700; }
.preview-choice.picked { border-color: var(--accent); background: var(--accent-soft); box-shadow: 0 0 0 1px var(--accent); }
.preview-choice.picked .letter { background: var(--accent); border-color: var(--accent); color: #fff; }
.preview-reward { background: var(--gold-soft); padding: 10px 16px; font-weight: 600; font-size: .9rem; border-top: 1px solid var(--border); }
.features { display: grid; grid-template-columns: repeat(auto-fit, minmax(240px, 1fr)); gap: 16px; padding: 8px 0 24px; }
.feature { background: var(--card); border: 1px solid var(--border); border-radius: 12px; padding: 20px; }
.feature-icon { font-size: 1.8rem; }
.feature h3 { margin: 8px 0 6px; font-size: 1.1rem; }
.feature p { margin: 0; color: var(--muted); }
.steps { list-style: none; counter-reset: step; padding: 0; display: grid; grid-template-columns: repeat(auto-fit, minmax(220px, 1fr)); gap: 16px; }
.steps li { counter-increment: step; display: grid; gap: 4px; padding-left: 48px; position: relative; }
.steps li::before { content: counter(step); position: absolute; left: 0; top: 0; width: 34px; height: 34px; border-radius: 50%; background: var(--accent); color: #fff; font-weight: 700; display: grid; place-items: center; }
.cta { text-align: center; padding: 32px 0 8px; }
.cta h2 { margin-top: 0; }

/* Section and skill scores */
.score-row { display: grid; grid-template-columns: repeat(auto-fit, minmax(260px, 1fr)); gap: 12px; margin-bottom: 12px; }
.score-tile { background: var(--card); border: 1px solid var(--border); border-radius: 10px; padding: 16px 18px; display: grid; gap: 6px; }
.score-value { font-size: 2.2rem; font-weight: 800; line-height: 1.1; display: flex; align-items: baseline; gap: 8px; flex-wrap: wrap; }
.score-bar { height: 8px; background: var(--accent-soft); border-radius: 999px; overflow: hidden; }
.score-bar span { display: block; height: 100%; background: var(--accent); border-radius: 999px; }
.score-change { font-size: .95rem; font-weight: 700; }
.score-change.up { color: var(--good); }
.score-change.down { color: var(--bad); }
.score-callout { margin-top: 12px; font-size: 1.05rem; }
.skill-cols { gap: 16px 24px; }
.skill-head { margin: 0 0 8px; font-size: 1rem; }
.skill-row { display: grid; grid-template-columns: minmax(0, 1.4fr) 1fr 36px; gap: 10px; align-items: center; padding: 5px 0; font-size: .9rem; }
.skill-num { text-align: right; font-weight: 600; }