:root {
  --bg: #f4f6fb;
  --surface: #ffffff;
  --ink: #1f2533;
  --ink-soft: #5b6478;
  --primary: #4f46e5;
  --primary-dark: #3c34c4;
  --accent: #0ea5a4;
  --good: #16a34a;
  --bad: #dc2626;
  --line: #e3e7f0;
  --shadow: 0 2px 8px rgba(31, 37, 51, 0.06);
  --radius: 14px;
}

* { box-sizing: border-box; }

body {
  margin: 0;
  font-family: -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, Helvetica, Arial, sans-serif;
  background: var(--bg);
  color: var(--ink);
  line-height: 1.55;
}

/* Header */
.app-header {
  background: linear-gradient(135deg, var(--primary) 0%, #6d5bf0 60%, var(--accent) 130%);
  color: #fff;
  padding: 28px 16px 22px;
}
.header-inner { max-width: 1000px; margin: 0 auto; }
.app-header h1 { margin: 0; font-size: 2rem; font-weight: 800; letter-spacing: -0.5px; }
.app-header h1 span { font-weight: 300; opacity: 0.9; }
.tagline { margin: 4px 0 0; opacity: 0.92; font-size: 0.95rem; }

/* Tabs */
.tabs {
  display: flex;
  gap: 4px;
  max-width: 1000px;
  margin: -18px auto 0;
  padding: 6px;
  background: var(--surface);
  border-radius: var(--radius);
  box-shadow: var(--shadow);
  position: sticky;
  top: 8px;
  z-index: 10;
}
.tab {
  flex: 1;
  padding: 11px 8px;
  border: none;
  background: transparent;
  color: var(--ink-soft);
  font-size: 0.98rem;
  font-weight: 600;
  border-radius: 10px;
  cursor: pointer;
  transition: background .15s, color .15s;
}
.tab:hover { background: var(--bg); }
.tab.active { background: var(--primary); color: #fff; }

/* Layout */
.container { max-width: 1000px; margin: 22px auto; padding: 0 16px 40px; }
.view { display: none; }
.view.active { display: block; animation: fade .25s ease; }
@keyframes fade { from { opacity: 0; transform: translateY(6px); } to { opacity: 1; transform: none; } }

/* Word of the day */
.wotd {
  background: var(--surface);
  border-radius: var(--radius);
  padding: 16px 20px;
  margin-bottom: 18px;
  box-shadow: var(--shadow);
  border-left: 5px solid var(--accent);
}
.wotd .wotd-tag { font-size: 0.72rem; text-transform: uppercase; letter-spacing: 1px; color: var(--accent); font-weight: 700; }
.wotd .wotd-word { font-size: 1.5rem; font-weight: 800; margin: 2px 0; }
.wotd .wotd-pos { font-style: italic; color: var(--ink-soft); font-size: 0.9rem; }
.wotd .wotd-def { margin: 6px 0 4px; }
.wotd .wotd-eg { color: var(--ink-soft); font-style: italic; }

/* Controls */
.controls {
  display: flex;
  flex-wrap: wrap;
  gap: 10px;
  margin-bottom: 14px;
  align-items: center;
}
.controls input[type="search"] {
  flex: 1 1 240px;
  padding: 11px 14px;
  border: 1px solid var(--line);
  border-radius: 10px;
  font-size: 0.95rem;
  background: var(--surface);
}
.controls select {
  padding: 11px 12px;
  border: 1px solid var(--line);
  border-radius: 10px;
  background: var(--surface);
  font-size: 0.92rem;
  color: var(--ink);
}
.checkbox { font-size: 0.9rem; color: var(--ink-soft); display: flex; align-items: center; gap: 6px; cursor: pointer; }
.count { color: var(--ink-soft); font-size: 0.85rem; margin: 0 0 12px; }

/* Word grid */
.word-grid {
  display: grid;
  grid-template-columns: repeat(auto-fill, minmax(280px, 1fr));
  gap: 14px;
}
.card {
  background: var(--surface);
  border-radius: var(--radius);
  padding: 16px 18px;
  box-shadow: var(--shadow);
  border: 1px solid var(--line);
  display: flex;
  flex-direction: column;
  gap: 6px;
}
.card.known { border-color: var(--good); background: #f3fbf5; }
.card-top { display: flex; justify-content: space-between; align-items: baseline; gap: 8px; }
.card .word { font-size: 1.2rem; font-weight: 700; }
.card .pos { font-style: italic; color: var(--ink-soft); font-size: 0.82rem; }
.card .def { font-size: 0.95rem; }
.card .eg { font-size: 0.9rem; color: var(--ink-soft); font-style: italic; border-left: 3px solid var(--line); padding-left: 10px; }
.card .syn { font-size: 0.82rem; color: var(--ink-soft); }
.card .syn b { color: var(--ink); font-weight: 600; }
.badges { display: flex; gap: 6px; flex-wrap: wrap; margin-top: 2px; }
.badge { font-size: 0.7rem; padding: 3px 8px; border-radius: 20px; font-weight: 600; }
.badge.cat { background: #eef0fe; color: var(--primary-dark); }
.badge.d1 { background: #e6f6ec; color: #1d8a45; }
.badge.d2 { background: #fff3e0; color: #b8740c; }
.badge.d3 { background: #fde8ef; color: #b1216b; }
.card-actions { display: flex; gap: 8px; margin-top: 8px; }
.chip {
  flex: 1;
  border: 1px solid var(--line);
  background: var(--surface);
  border-radius: 8px;
  padding: 7px;
  font-size: 0.82rem;
  cursor: pointer;
  color: var(--ink-soft);
  transition: all .15s;
}
.chip:hover { border-color: var(--primary); color: var(--primary); }
.chip.active-fav { background: #fff7e6; border-color: #f0b429; color: #b8740c; }
.chip.active-known { background: #e6f6ec; border-color: var(--good); color: #1d8a45; }

/* Buttons */
.btn-primary {
  background: var(--primary);
  color: #fff;
  border: none;
  padding: 12px 24px;
  border-radius: 10px;
  font-size: 1rem;
  font-weight: 600;
  cursor: pointer;
  transition: background .15s;
}
.btn-primary:hover { background: var(--primary-dark); }
.btn-ghost {
  background: transparent;
  color: var(--bad);
  border: 1px solid var(--line);
  padding: 9px 16px;
  border-radius: 10px;
  cursor: pointer;
  font-size: 0.88rem;
  margin-top: 20px;
}
.btn-ghost:hover { border-color: var(--bad); }

/* Quiz */
.quiz-setup, .quiz-active, .quiz-results {
  background: var(--surface);
  border-radius: var(--radius);
  padding: 24px;
  box-shadow: var(--shadow);
}
.quiz-setup h2, .quiz-results h2 { margin-top: 0; }
.quiz-options { display: flex; flex-wrap: wrap; gap: 16px; margin: 18px 0; }
.quiz-options label { display: flex; flex-direction: column; gap: 6px; font-size: 0.85rem; color: var(--ink-soft); font-weight: 600; }
.quiz-options select { padding: 10px; border: 1px solid var(--line); border-radius: 10px; font-size: 0.95rem; min-width: 180px; }
.hidden { display: none !important; }

.quiz-progress { display: flex; justify-content: space-between; font-size: 0.9rem; color: var(--ink-soft); font-weight: 600; }
.progress-bar { height: 8px; background: var(--line); border-radius: 20px; overflow: hidden; margin: 8px 0 20px; }
#quiz-bar { height: 100%; width: 0; background: linear-gradient(90deg, var(--primary), var(--accent)); transition: width .3s; }
.quiz-prompt-label { font-size: 0.8rem; text-transform: uppercase; letter-spacing: 1px; color: var(--ink-soft); margin: 0 0 6px; }
.quiz-prompt { font-size: 1.3rem; font-weight: 600; margin: 0 0 20px; }
.quiz-choices { display: grid; gap: 10px; }
.choice {
  text-align: left;
  padding: 14px 16px;
  border: 2px solid var(--line);
  border-radius: 10px;
  background: var(--surface);
  font-size: 1rem;
  cursor: pointer;
  transition: all .12s;
}
.choice:hover:not(:disabled) { border-color: var(--primary); background: #f7f7ff; }
.choice.correct { border-color: var(--good); background: #ecfdf3; color: #14803c; font-weight: 600; }
.choice.wrong { border-color: var(--bad); background: #fef2f2; color: var(--bad); }
.choice:disabled { cursor: default; }
.quiz-feedback { margin: 16px 0; font-weight: 600; min-height: 24px; }
.quiz-feedback.right { color: var(--good); }
.quiz-feedback.incorrect { color: var(--bad); }
.quiz-feedback .fb-eg { display: block; font-weight: 400; color: var(--ink-soft); font-style: italic; margin-top: 4px; }

.final-score { font-size: 1.4rem; font-weight: 700; }
.quiz-review { margin: 16px 0; display: grid; gap: 8px; }
.review-row { padding: 10px 14px; border-radius: 8px; font-size: 0.9rem; border: 1px solid var(--line); }
.review-row.miss { border-left: 4px solid var(--bad); }
.review-row.hit { border-left: 4px solid var(--good); }
.review-row b { font-weight: 700; }

/* Progress */
.stat-grid { display: grid; grid-template-columns: repeat(auto-fit, minmax(140px, 1fr)); gap: 14px; margin-bottom: 28px; }
.stat-card {
  background: var(--surface);
  border-radius: var(--radius);
  padding: 18px;
  box-shadow: var(--shadow);
  display: flex;
  flex-direction: column;
  align-items: center;
  text-align: center;
}
.stat-num { font-size: 1.9rem; font-weight: 800; color: var(--primary); }
.stat-label { font-size: 0.82rem; color: var(--ink-soft); margin-top: 4px; }
.category-progress { display: grid; gap: 12px; margin-bottom: 28px; }
.cat-row { background: var(--surface); border-radius: 10px; padding: 12px 16px; box-shadow: var(--shadow); }
.cat-row .cat-head { display: flex; justify-content: space-between; font-size: 0.9rem; margin-bottom: 6px; }
.cat-row .bar { height: 8px; background: var(--line); border-radius: 20px; overflow: hidden; }
.cat-row .bar > div { height: 100%; background: linear-gradient(90deg, var(--primary), var(--accent)); }
.quiz-history { display: grid; gap: 8px; }
.hist-row { background: var(--surface); border-radius: 10px; padding: 10px 16px; box-shadow: var(--shadow); display: flex; justify-content: space-between; font-size: 0.9rem; }
.hist-row .pct { font-weight: 700; }
.empty { color: var(--ink-soft); font-style: italic; }

/* Footer */
.app-footer { text-align: center; padding: 24px 16px; color: var(--ink-soft); font-size: 0.85rem; }

@media (max-width: 540px) {
  .app-header h1 { font-size: 1.6rem; }
  .quiz-options label { width: 100%; }
  .quiz-options select { width: 100%; }
}