:root,
html[data-theme="light"] {
  --bg: #f4f5f7;
  --surface: #ffffff;
  --ink: #1b1f24;
  --muted: #5c6570;
  --line: #d8dde3;
  --accent: #1b4f8a;
  --accent-hover: #163f6e;
  --ok: #1b7a45;
  --ok-bg: #e8f6ee;
  --bad: #b42318;
  --bad-bg: #fdecea;
  --pill-bg: #eaf1f8;
  --option-selected: #f3f7fb;
  --track: #e4e8ee;
  --th-bg: #fafbfc;
  --shadow: 0 1px 2px rgba(16, 24, 40, 0.06), 0 8px 24px rgba(16, 24, 40, 0.06);
  --toast-bg: #1b1f24;
  --toast-ink: #ffffff;
  color-scheme: light;
}

html[data-theme="dark"] {
  --bg: #12151a;
  --surface: #1c2128;
  --ink: #e8ecf1;
  --muted: #9aa3ad;
  --line: #313845;
  --accent: #7eb0ea;
  --accent-hover: #9bc3f2;
  --ok: #4ecf86;
  --ok-bg: #163322;
  --bad: #f07167;
  --bad-bg: #3a1816;
  --pill-bg: #243044;
  --option-selected: #243044;
  --track: #2d3440;
  --th-bg: #161a20;
  --shadow: 0 1px 2px rgba(0, 0, 0, 0.35);
  --toast-bg: #e8ecf1;
  --toast-ink: #12151a;
  color-scheme: dark;
}

* {
  box-sizing: border-box;
}

html,
body {
  margin: 0;
  background: var(--bg);
  color: var(--ink);
  line-height: 1.5;
  font-family: "Segoe UI", system-ui, -apple-system, sans-serif;
}

body {
  min-height: 100vh;
}

.topbar {
  background: var(--surface);
  border-bottom: 1px solid var(--line);
  padding: 1rem 1.5rem;
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 1rem;
  flex-wrap: wrap;
}

.brand-block {
  display: flex;
  align-items: baseline;
  gap: 1rem;
  flex-wrap: wrap;
}

.brand {
  font-weight: 700;
  font-size: 1.2rem;
  color: var(--ink);
  text-decoration: none;
  letter-spacing: -0.02em;
}

.tagline {
  margin: 0;
  color: var(--muted);
  font-size: 0.95rem;
}

.theme-toggle {
  margin-left: auto;
}

main {
  max-width: 920px;
  margin: 0 auto;
  padding: 2rem 1.25rem 4rem;
}

h1,
h2 {
  letter-spacing: -0.03em;
  margin: 0 0 0.5rem;
}

.lede {
  color: var(--muted);
  margin: 0 0 1.5rem;
}

.hidden {
  display: none !important;
}

.exam-grid {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(240px, 1fr));
  gap: 1rem;
}

.exam-card {
  background: var(--surface);
  border: 1px solid var(--line);
  border-radius: 12px;
  padding: 1.15rem 1.2rem 1.25rem;
  box-shadow: var(--shadow);
  text-align: left;
  cursor: pointer;
  width: 100%;
  color: inherit;
  font: inherit;
}

.exam-card:hover,
.exam-card:focus-visible {
  border-color: var(--accent);
  outline: none;
}

.exam-card h2 {
  font-size: 1.05rem;
  margin-bottom: 0.35rem;
}

.exam-card p {
  margin: 0 0 0.75rem;
  color: var(--muted);
  font-size: 0.92rem;
}

.pill {
  display: inline-block;
  background: var(--pill-bg);
  color: var(--accent);
  font-size: 0.78rem;
  font-weight: 600;
  padding: 0.15rem 0.5rem;
  border-radius: 999px;
}

.panel {
  background: var(--surface);
  border: 1px solid var(--line);
  border-radius: 12px;
  padding: 1.25rem 1.35rem;
  box-shadow: var(--shadow);
}

.field {
  display: block;
  margin: 0 0 1.15rem;
  border: 0;
  padding: 0;
}

.field > span,
.field legend {
  display: block;
  font-weight: 600;
  margin-bottom: 0.4rem;
}

#question-count {
  width: 7rem;
  padding: 0.5rem 0.65rem;
  border: 1px solid var(--line);
  border-radius: 8px;
  background: var(--bg);
  color: var(--ink);
  font: inherit;
  font-weight: 600;
}

.hint,
small {
  display: block;
  color: var(--muted);
  font-size: 0.85rem;
  margin-top: 0.35rem;
}

.checks {
  display: grid;
  gap: 0.4rem;
}

.checks label {
  display: flex;
  gap: 0.5rem;
  align-items: flex-start;
}

.btn {
  appearance: none;
  border: 1px solid var(--line);
  background: var(--surface);
  color: var(--ink);
  border-radius: 8px;
  padding: 0.55rem 1rem;
  font: inherit;
  font-weight: 600;
  cursor: pointer;
}

.btn:disabled {
  opacity: 0.5;
  cursor: not-allowed;
}

.btn.primary {
  background: var(--accent);
  border-color: var(--accent);
  color: #fff;
}

html[data-theme="dark"] .btn.primary {
  color: #12151a;
}

.btn.primary:hover:not(:disabled) {
  background: var(--accent-hover);
}

.link-back {
  background: none;
  border: 0;
  color: var(--accent);
  font: inherit;
  font-weight: 600;
  padding: 0;
  margin-bottom: 0.75rem;
  cursor: pointer;
}

.quiz-meta {
  display: flex;
  justify-content: space-between;
  gap: 1rem;
  color: var(--muted);
  font-size: 0.92rem;
}

.quiz-meta p {
  margin: 0 0 0.5rem;
}

.progress-track {
  height: 6px;
  background: var(--track);
  border-radius: 99px;
  margin-bottom: 1rem;
  overflow: hidden;
}

.progress-bar {
  height: 100%;
  width: 0;
  background: var(--accent);
}

.question-card h2 {
  font-size: 1.05rem;
  font-weight: 600;
  line-height: 1.45;
}

.q-meta {
  display: flex;
  gap: 0.5rem;
  flex-wrap: wrap;
  margin-bottom: 0.75rem;
}

.options {
  display: grid;
  gap: 0.45rem;
  margin-top: 0.75rem;
}

.option {
  display: flex;
  gap: 0.65rem;
  align-items: flex-start;
  border: 1px solid var(--line);
  border-radius: 8px;
  padding: 0.7rem 0.8rem;
  cursor: pointer;
}

.option:hover {
  border-color: var(--accent);
}

.option.selected {
  border-color: var(--accent);
  background: var(--option-selected);
}

.option.locked {
  cursor: default;
}

.option.correct {
  background: var(--ok-bg);
  border-color: var(--ok);
}

.option.miss {
  background: var(--bad-bg);
  border-color: var(--bad);
}

.quiz-nav {
  display: flex;
  gap: 0.6rem;
  margin-top: 1rem;
  flex-wrap: wrap;
}

.score-hero {
  margin: 0.5rem 0 1.5rem;
}

.score-hero .big {
  font-size: 2.2rem;
  font-weight: 700;
  letter-spacing: -0.04em;
  margin: 0.25rem 0;
}

.review-item {
  background: var(--surface);
  border: 1px solid var(--line);
  border-radius: 12px;
  padding: 1rem 1.15rem;
  margin-bottom: 0.75rem;
}

.review-item.ok {
  border-left: 4px solid var(--ok);
}

.review-item.bad {
  border-left: 4px solid var(--bad);
}

.review-item .verdict {
  font-size: 0.8rem;
  font-weight: 700;
  text-transform: uppercase;
  letter-spacing: 0.04em;
}

.review-item.ok .verdict {
  color: var(--ok);
}

.review-item.bad .verdict {
  color: var(--bad);
}

.choice {
  margin: 0.2rem 0;
  padding: 0.25rem 0.4rem;
  border-radius: 6px;
}

.choice.correct {
  background: var(--ok-bg);
}

.choice.miss {
  background: var(--bad-bg);
}

.explanation {
  margin: 0.6rem 0 0;
  color: var(--muted);
  font-size: 0.92rem;
}

.inline-review {
  margin-top: 1rem;
  padding-top: 0.85rem;
  border-top: 1px solid var(--line);
}

.history {
  margin-top: 3rem;
  padding-top: 1.5rem;
  border-top: 1px solid var(--line);
}

.history-toggle {
  width: 100%;
}

.history-panel {
  margin-top: 1rem;
}

.table-wrap {
  overflow-x: auto;
  background: var(--surface);
  border: 1px solid var(--line);
  border-radius: 12px;
}

table {
  width: 100%;
  border-collapse: collapse;
  font-size: 0.92rem;
}

th,
td {
  text-align: left;
  padding: 0.7rem 0.85rem;
  border-bottom: 1px solid var(--line);
  vertical-align: top;
}

th {
  font-size: 0.78rem;
  text-transform: uppercase;
  letter-spacing: 0.04em;
  color: var(--muted);
  background: var(--th-bg);
}

tr:last-child td {
  border-bottom: 0;
}

.muted {
  color: var(--muted);
}

.banner {
  border-radius: 8px;
  padding: 0.75rem 1rem;
}

.banner.error {
  background: var(--bad-bg);
  color: var(--bad);
}

.toast {
  position: fixed;
  bottom: 1.25rem;
  left: 50%;
  transform: translateX(-50%);
  background: var(--toast-bg);
  color: var(--toast-ink);
  padding: 0.7rem 1rem;
  border-radius: 8px;
  max-width: calc(100% - 2rem);
}

@media (max-width: 640px) {
  .topbar {
    padding: 0.9rem 1rem;
  }

  main {
    padding: 1.4rem 1rem 3rem;
  }
}