:root {
  color-scheme: light;
  --ink: #16212f;
  --muted: #5b6676;
  --line: #d8dee8;
  --panel: #ffffff;
  --surface: #f4f7fb;
  --accent: #ffcc00;
  --accent-strong: #2f6fed;
  --success: #007a5a;
  --danger: #b42318;
  --shadow: 0 10px 30px rgba(22, 33, 47, 0.08);

  /* Difficulty colours */
  --easy: #007a5a;
  --medium: #d67c2b;
  --hard: #b42318;

  /* Category colours */
  --cat-ml: #2f6fed;
  --cat-stats: #7b3fb8;
  --cat-sql: #1a7a6e;
  --cat-python: #3775a9;
  --cat-behavioral: #c45d10;
  --cat-crime: #b42318;
}

* { box-sizing: border-box; }

body {
  margin: 0;
  font-family: Inter, ui-sans-serif, system-ui, -apple-system, sans-serif;
  color: var(--ink);
  background:
    linear-gradient(135deg, rgba(255, 204, 0, 0.2), rgba(47, 111, 237, 0.08) 34%, transparent 34%),
    var(--surface);
}

/* ── Topbar ──────────────────────────────────────────────────────────── */
.topbar {
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 24px;
  padding: 24px clamp(18px, 4vw, 54px);
  border-bottom: 1px solid var(--line);
  background: rgba(255, 255, 255, 0.88);
  backdrop-filter: blur(12px);
  position: sticky;
  top: 0;
  z-index: 10;
}

h1, h2, h3, p { margin: 0; }

h1 {
  font-size: clamp(22px, 2.8vw, 38px);
  line-height: 1.05;
}

.topbar p {
  margin-top: 6px;
  color: var(--muted);
  font-size: 14px;
}

.stats {
  display: flex;
  gap: 10px;
  flex-wrap: wrap;
  justify-content: flex-end;
}

.stats span {
  min-width: 90px;
  padding: 10px 12px;
  border: 1px solid var(--line);
  border-radius: 8px;
  background: var(--panel);
  text-align: center;
  font-size: 13px;
}

.stats strong {
  display: block;
  font-size: 22px;
  line-height: 1;
}

.stat-label {
  color: var(--muted);
  font-size: 11px;
  text-transform: uppercase;
  letter-spacing: 0.5px;
}

/* ── Main layout ────────────────────────────────────────────────────── */
main {
  width: min(1220px, calc(100% - 32px));
  margin: 22px auto 80px;
}

/* ── Controls ───────────────────────────────────────────────────────── */
.controls {
  display: flex;
  gap: 10px;
  align-items: center;
  flex-wrap: wrap;
  padding: 14px;
  border: 1px solid var(--line);
  border-radius: 8px;
  background: var(--panel);
  box-shadow: var(--shadow);
}

input, select, button {
  height: 42px;
  border: 1px solid var(--line);
  border-radius: 8px;
  background: #fff;
  color: var(--ink);
  font: inherit;
}

input, select { padding: 0 12px; }
input { flex: 1 1 280px; min-width: 160px; }
select { flex: 0 1 180px; }

button {
  padding: 0 14px;
  cursor: pointer;
  font-weight: 650;
  white-space: nowrap;
}

button:hover { border-color: var(--accent-strong); background: #f4f7fb; }

.btn-danger { color: var(--danger); border-color: #f8d7d7; }
.btn-danger:hover { background: #fef2f2; border-color: var(--danger); }

/* ── Category tabs ───────────────────────────────────────────────────── */
.tabs {
  display: flex;
  gap: 8px;
  flex-wrap: wrap;
  margin: 18px 0 14px;
}

.tab {
  height: 36px;
  padding: 0 14px;
  font-size: 13px;
  font-weight: 650;
  border: 1px solid var(--line);
  border-radius: 999px;
  background: var(--panel);
  cursor: pointer;
}

.tab:hover { border-color: var(--accent-strong); }
.tab.active { background: var(--ink); border-color: var(--ink); color: #fff; }

/* ── Flashcard ───────────────────────────────────────────────────────── */
.modebar {
  display: flex;
  align-items: center;
  justify-content: center;
  gap: 14px;
  margin-bottom: 14px;
}

#cardPosition {
  min-width: 110px;
  text-align: center;
  color: var(--muted);
  font-weight: 700;
  font-size: 15px;
}

.flashcard {
  min-height: 320px;
  display: grid;
  align-content: start;
  gap: 16px;
  padding: clamp(22px, 4vw, 42px);
  border: 1px solid var(--line);
  border-radius: 12px;
  background:
    linear-gradient(90deg, rgba(255, 204, 0, 0.14), transparent 40%),
    var(--panel);
  box-shadow: var(--shadow);
}

.flashcard h2 {
  font-size: clamp(20px, 2.8vw, 36px);
  line-height: 1.15;
  max-width: 960px;
}

/* ── Card meta pills ─────────────────────────────────────────────────── */
.card-meta { display: flex; flex-wrap: wrap; gap: 8px; align-items: center; }

.pill {
  display: inline-flex;
  align-items: center;
  min-height: 26px;
  padding: 3px 10px;
  border-radius: 999px;
  font-size: 12px;
  font-weight: 700;
  background: #eef3fb;
  color: #31435c;
}

.diff-easy   { background: #d1f0e5; color: #004f38; }
.diff-medium { background: #fef0d9; color: #7a3f00; }
.diff-hard   { background: #fde8e8; color: #7a1010; }

.cat-pill    { background: #e8effe; color: var(--accent-strong); }
.tag-pill    { background: #f1f3f8; color: var(--muted); }

.status-confident { background: #d1f0e5; color: #004f38; }
.status-practice  { background: #fef0d9; color: #7a3f00; }

/* ── Answer ─────────────────────────────────────────────────────────── */
.answer {
  padding: 18px 20px;
  border-left: 5px solid var(--accent);
  background: #fff9dc;
  border-radius: 0 8px 8px 0;
  line-height: 1.6;
}

.answer-body {
  white-space: pre-line;
  font-size: 15px;
}

.answer-body code {
  display: block;
  font-family: 'JetBrains Mono', 'Fira Code', 'Courier New', monospace;
  font-size: 13px;
  background: #1e2a3a;
  color: #e8f4ff;
  padding: 2px 8px;
  border-radius: 4px;
  margin: 2px 0;
  white-space: pre;
  overflow-x: auto;
}

.followup {
  margin-top: 14px;
  padding: 10px 14px;
  background: #eef3fb;
  border-radius: 8px;
  font-size: 14px;
  color: var(--muted);
  border-left: 3px solid var(--accent-strong);
}

.hidden { display: none; }

/* ── Reveal / Action buttons ─────────────────────────────────────────── */
#revealBtn {
  align-self: start;
  height: 46px;
  padding: 0 22px;
  background: var(--ink);
  border-color: var(--ink);
  color: #fff;
  font-size: 15px;
  border-radius: 8px;
}

#revealBtn:hover { background: #273648; }

.action-bar {
  display: flex;
  gap: 12px;
  margin-top: 14px;
}

.btn-confident, .btn-practice {
  flex: 1;
  height: 46px;
  font-size: 15px;
  border-radius: 8px;
}

.btn-confident        { border-color: #a7dfc8; color: var(--success); }
.btn-confident:hover  { background: #d1f0e5; }
.btn-confident.active-confident { background: #007a5a; border-color: #007a5a; color: #fff; }

.btn-practice         { border-color: #f5d79e; color: var(--medium); }
.btn-practice:hover   { background: #fef0d9; }
.btn-practice.active-practice { background: #d67c2b; border-color: #d67c2b; color: #fff; }

/* ── Keyboard hint ─────────────────────────────────────────────────── */
.keyboard-hint {
  margin-top: 10px;
  display: flex;
  gap: 20px;
  font-size: 12px;
  color: var(--muted);
  justify-content: center;
}

/* ── Mini card grid ─────────────────────────────────────────────────── */
.grid {
  display: grid;
  grid-template-columns: repeat(auto-fill, minmax(260px, 1fr));
  gap: 12px;
  margin-top: 28px;
}

.mini-card {
  padding: 14px 16px;
  border: 1px solid var(--line);
  border-radius: 8px;
  background: var(--panel);
  box-shadow: var(--shadow);
  cursor: pointer;
  transition: border-color 0.15s, transform 0.1s;
}

.mini-card:hover { border-color: var(--accent-strong); transform: translateY(-2px); }
.mini-card.is-confident { border-left: 3px solid var(--success); }
.mini-card.is-practice  { border-left: 3px solid var(--medium); }

.mini-meta { display: flex; gap: 6px; margin-bottom: 8px; }

.mini-card h3 {
  font-size: 14px;
  line-height: 1.4;
  margin: 0;
  color: var(--ink);
}

/* ── Responsive ─────────────────────────────────────────────────────── */
@media (max-width: 760px) {
  .topbar { align-items: flex-start; position: static; flex-direction: column; }
  .stats  { flex-direction: row; width: 100%; }
  .stats span { flex: 1; }
  .flashcard { min-height: 280px; }
  .action-bar { flex-direction: column; }
  .keyboard-hint { display: none; }
}