:root {
  --bg: #f4f6f9;
  --surface: #ffffff;
  --text: #1c2733;
  --text-muted: #5c6b7a;
  --border: #dde3ea;
  --accent: #3457d5;
  --accent-contrast: #ffffff;
  --ok: #1f9d55;
  --again: #d9534f;
  --tag-bg: #e8edfb;
  --tag-text: #3457d5;
  --shadow: 0 2px 10px rgba(20, 30, 50, 0.08);
}

[data-theme="dark"] {
  --bg: #12161d;
  --surface: #1b212b;
  --text: #e7ebf1;
  --text-muted: #9aa7b6;
  --border: #2b3340;
  --accent: #6c8dff;
  --accent-contrast: #0d1117;
  --ok: #3ecb75;
  --again: #ef6a66;
  --tag-bg: #232c3d;
  --tag-text: #8fa8ff;
  --shadow: 0 2px 14px rgba(0, 0, 0, 0.35);
}

* { box-sizing: border-box; }

body {
  margin: 0;
  font-family: "Segoe UI", system-ui, -apple-system, sans-serif;
  background: var(--bg);
  color: var(--text);
  min-height: 100vh;
  transition: background 0.2s, color 0.2s;
}

.topbar {
  display: flex;
  flex-wrap: wrap;
  gap: 12px;
  align-items: center;
  justify-content: space-between;
  padding: 14px 20px;
  background: var(--surface);
  border-bottom: 1px solid var(--border);
  position: sticky;
  top: 0;
  z-index: 10;
}

.topbar h1 {
  font-size: 1.25rem;
  margin: 0;
}

.topbar-controls {
  display: flex;
  gap: 8px;
  align-items: center;
  flex-wrap: wrap;
}

select {
  padding: 8px 10px;
  border-radius: 8px;
  border: 1px solid var(--border);
  background: var(--surface);
  color: var(--text);
  font-size: 0.9rem;
}

.mode-switch {
  display: flex;
  gap: 4px;
  background: var(--bg);
  border: 1px solid var(--border);
  border-radius: 10px;
  padding: 3px;
}

.mode-btn {
  border: none;
  background: transparent;
  color: var(--text-muted);
  padding: 7px 12px;
  border-radius: 8px;
  font-size: 0.85rem;
  font-weight: 600;
  cursor: pointer;
}

.mode-btn.active {
  background: var(--accent);
  color: var(--accent-contrast);
}

main {
  max-width: 780px;
  margin: 0 auto;
  padding: 24px 16px 60px;
}

.hidden { display: none !important; }

.stats-bar {
  display: flex;
  justify-content: space-between;
  align-items: center;
  gap: 16px;
  margin-bottom: 18px;
  flex-wrap: wrap;
}

.progress-info {
  flex: 1;
  min-width: 200px;
}

#progressLabel {
  font-size: 0.85rem;
  color: var(--text-muted);
}

.progress-track {
  height: 8px;
  border-radius: 4px;
  background: var(--border);
  overflow: hidden;
  margin-top: 6px;
}

.progress-fill {
  height: 100%;
  width: 0%;
  background: var(--accent);
  transition: width 0.3s ease;
}

.stat-pills {
  display: flex;
  gap: 8px;
}

.pill {
  padding: 6px 12px;
  border-radius: 999px;
  font-size: 0.85rem;
  font-weight: 600;
  background: var(--surface);
  border: 1px solid var(--border);
}

.pill-ok { color: var(--ok); }
.pill-again { color: var(--again); }
.pill-streak { color: #e0902a; }

.quiz-card {
  background: var(--surface);
  border: 1px solid var(--border);
  border-radius: 16px;
  box-shadow: var(--shadow);
  padding: 28px;
  margin-bottom: 18px;
}

.quiz-card #quizQuestion {
  font-size: 1.1rem;
  margin: 4px 0 4px;
  color: var(--text-muted);
  font-weight: 600;
}

.quiz-topic {
  font-size: 1.3rem;
  font-weight: 700;
  margin: 0 0 20px;
  line-height: 1.35;
}

.quiz-options {
  display: flex;
  flex-direction: column;
  gap: 10px;
}

.quiz-option {
  text-align: left;
  background: var(--bg);
  border: 1.5px solid var(--border);
  border-radius: 10px;
  padding: 13px 16px;
  font-size: 0.95rem;
  color: var(--text);
  cursor: pointer;
  transition: border-color 0.15s, background 0.15s, transform 0.1s;
  line-height: 1.4;
}

.quiz-option:hover:not(:disabled) {
  border-color: var(--accent);
}

.quiz-option:active:not(:disabled) {
  transform: scale(0.99);
}

.quiz-option:disabled {
  cursor: default;
}

.quiz-option.correct {
  background: color-mix(in srgb, var(--ok) 18%, var(--surface));
  border-color: var(--ok);
  font-weight: 700;
}

.quiz-option.wrong {
  background: color-mix(in srgb, var(--again) 18%, var(--surface));
  border-color: var(--again);
}

.quiz-feedback {
  min-height: 1.4em;
  margin: 16px 0 0;
  font-weight: 700;
  font-size: 0.95rem;
}

.quiz-feedback.correct { color: var(--ok); }
.quiz-feedback.wrong { color: var(--again); }

.card {
  perspective: 1600px;
  min-height: 340px;
  margin-bottom: 18px;
  cursor: pointer;
}

.card-inner {
  position: relative;
  width: 100%;
  min-height: 340px;
  transform-style: preserve-3d;
  transition: transform 0.5s cubic-bezier(0.4, 0.2, 0.2, 1);
}

.card.flipped .card-inner {
  transform: rotateY(180deg);
}

.card-face {
  position: absolute;
  inset: 0;
  backface-visibility: hidden;
  background: var(--surface);
  border: 1px solid var(--border);
  border-radius: 16px;
  box-shadow: var(--shadow);
  padding: 28px;
  overflow-y: auto;
}

.card-front {
  display: flex;
  flex-direction: column;
  align-items: center;
  justify-content: center;
  text-align: center;
  gap: 14px;
}

.card-back {
  transform: rotateY(180deg);
}

.card-tag {
  display: inline-block;
  align-self: flex-start;
  background: var(--tag-bg);
  color: var(--tag-text);
  font-size: 0.75rem;
  font-weight: 700;
  text-transform: uppercase;
  letter-spacing: 0.03em;
  padding: 4px 10px;
  border-radius: 999px;
  margin-bottom: 10px;
}

.card-front .card-tag { align-self: center; }

#cardQuestion {
  font-size: 1.4rem;
  margin: 0;
  line-height: 1.35;
}

.hint {
  color: var(--text-muted);
  font-size: 0.85rem;
  margin: 0;
}

.answer-content ul, .answer-content ol {
  padding-left: 1.2em;
  margin: 0.5em 0;
}

.answer-content li {
  margin-bottom: 8px;
  line-height: 1.45;
}

.answer-content p {
  line-height: 1.5;
  margin: 0.6em 0;
}

.answer-content table {
  width: 100%;
  border-collapse: collapse;
  margin: 10px 0;
  font-size: 0.92rem;
}

.answer-content th, .answer-content td {
  border: 1px solid var(--border);
  padding: 6px 8px;
  text-align: left;
  vertical-align: top;
}

.answer-content th {
  background: var(--tag-bg);
}

.answer-content pre {
  background: var(--tag-bg);
  padding: 10px;
  border-radius: 8px;
  overflow-x: auto;
  font-size: 0.82rem;
}

.controls {
  display: flex;
  gap: 10px;
  justify-content: center;
  flex-wrap: wrap;
  margin-bottom: 14px;
}

.btn {
  border: none;
  border-radius: 10px;
  padding: 11px 18px;
  font-size: 0.95rem;
  font-weight: 600;
  cursor: pointer;
  transition: filter 0.15s, transform 0.1s;
}

.btn:active { transform: scale(0.97); }

.btn-primary {
  background: var(--accent);
  color: var(--accent-contrast);
}

.btn-secondary {
  background: var(--surface);
  color: var(--text);
  border: 1px solid var(--border);
}

.btn-ok {
  background: var(--ok);
  color: #fff;
}

.btn-again {
  background: var(--again);
  color: #fff;
}

.btn-danger-outline {
  background: transparent;
  color: var(--again);
  border: 1px solid var(--again);
}

.btn:hover { filter: brightness(1.08); }

.rating-controls #repeatBtn, .rating-controls #knownBtn {
  flex: 1;
  max-width: 220px;
}

#searchBox {
  width: 100%;
  padding: 12px 14px;
  border-radius: 10px;
  border: 1px solid var(--border);
  background: var(--surface);
  color: var(--text);
  font-size: 0.95rem;
  margin-bottom: 16px;
}

.list-container {
  display: flex;
  flex-direction: column;
  gap: 10px;
}

.list-item {
  background: var(--surface);
  border: 1px solid var(--border);
  border-radius: 12px;
  padding: 14px 18px;
}

.list-item summary {
  cursor: pointer;
  font-weight: 600;
  display: flex;
  align-items: center;
  gap: 10px;
}

.list-item .card-tag {
  margin-bottom: 0;
}

.list-item .answer-content {
  margin-top: 12px;
  padding-top: 12px;
  border-top: 1px solid var(--border);
}

footer {
  text-align: center;
  color: var(--text-muted);
  font-size: 0.8rem;
  padding: 20px;
}

@media (max-width: 480px) {
  .topbar h1 { font-size: 1.05rem; }
  #cardQuestion { font-size: 1.15rem; }
  .card, .card-inner { min-height: 400px; }
}