:root {
  color: #111827;
  background: #f8fafc;
  font-family: -apple-system, BlinkMacSystemFont, "Segoe UI", sans-serif;
  font-synthesis: none;
  text-rendering: optimizeLegibility;
  -webkit-font-smoothing: antialiased;
}

* {
  box-sizing: border-box;
}

body {
  margin: 0;
  min-width: 320px;
  min-height: 100vh;
  background:
    radial-gradient(circle at top left, rgba(56, 189, 248, 0.18), transparent 32rem),
    linear-gradient(180deg, #f8fafc 0%, #e2e8f0 100%);
}

button,
input,
select {
  font: inherit;
}

button {
  border: 0;
  cursor: pointer;
}

.app {
  max-width: 720px;
  min-height: 100vh;
  margin: 0 auto;
  padding: 12px 16px 96px;
}

.hero {
  padding: 12px 14px;
  color: #f8fafc;
  background: linear-gradient(135deg, #111827, #1e3a8a);
  border-radius: 22px;
  box-shadow: 0 12px 30px rgba(15, 23, 42, 0.16);
}

.hero-title {
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 12px;
}

.hero h1 {
  margin: 0;
  font-size: 24px;
  letter-spacing: -0.04em;
}

.hero p {
  margin: 4px 0 0;
  color: #cbd5e1;
  font-size: 13px;
}

.pill {
  display: inline-flex;
  align-items: center;
  gap: 6px;
  padding: 6px 10px;
  border-radius: 999px;
  color: #0369a1;
  background: #e0f2fe;
  font-size: 12px;
  font-weight: 700;
}

.stats {
  display: grid;
  grid-template-columns: repeat(3, 1fr);
  gap: 8px;
  margin-top: 10px;
}

.stat {
  padding: 8px 10px;
  border: 1px solid rgba(255, 255, 255, 0.12);
  border-radius: 14px;
  background: rgba(255, 255, 255, 0.08);
}

.stat strong {
  display: block;
  font-size: 18px;
}

.stat span {
  color: #cbd5e1;
  font-size: 11px;
}

.tabs {
  position: fixed;
  right: 12px;
  bottom: 12px;
  left: 12px;
  z-index: 20;
  display: grid;
  max-width: 690px;
  grid-template-columns: repeat(4, 1fr);
  gap: 8px;
  margin: 0 auto;
  padding: 8px;
  border: 1px solid rgba(148, 163, 184, 0.3);
  border-radius: 24px;
  background: rgba(255, 255, 255, 0.92);
  box-shadow: 0 18px 40px rgba(15, 23, 42, 0.18);
  backdrop-filter: blur(18px);
}

.tab {
  padding: 10px 8px;
  border-radius: 16px;
  color: #64748b;
  background: transparent;
  font-size: 13px;
  font-weight: 700;
}

.tab.active {
  color: #f8fafc;
  background: #111827;
}

.panel {
  margin-top: 16px;
}

.card {
  border: 1px solid rgba(148, 163, 184, 0.28);
  border-radius: 28px;
  background: rgba(255, 255, 255, 0.88);
  box-shadow: 0 18px 44px rgba(15, 23, 42, 0.08);
  overflow: hidden;
}

.study-card {
  padding: 22px;
}

.word-meta {
  display: flex;
  flex-wrap: wrap;
  gap: 8px;
  margin-bottom: 18px;
}

.word {
  margin: 0;
  font-size: clamp(42px, 12vw, 70px);
  line-height: 1;
  letter-spacing: -0.06em;
}

.ipa {
  margin-top: 10px;
  color: #64748b;
  font-size: 17px;
}

.audio-row,
.actions,
.review-actions {
  display: flex;
  flex-wrap: wrap;
  gap: 10px;
  margin-top: 18px;
}

.btn {
  min-height: 42px;
  padding: 10px 14px;
  border-radius: 14px;
  color: #111827;
  background: #e2e8f0;
  font-weight: 800;
}

.btn.primary {
  color: #f8fafc;
  background: #111827;
}

.btn.ghost {
  border: 1px solid #cbd5e1;
  background: #ffffff;
}

.btn.warn {
  color: #7f1d1d;
  background: #fee2e2;
}

.btn.good {
  color: #14532d;
  background: #dcfce7;
}

.answer {
  margin-top: 22px;
  padding: 18px;
  border-radius: 20px;
  background: #f8fafc;
}

.answer h2,
.section-title {
  margin: 0 0 10px;
  font-size: 18px;
}

.answer p {
  margin: 8px 0;
  color: #334155;
  line-height: 1.6;
}

.chips {
  display: flex;
  flex-wrap: wrap;
  gap: 8px;
  margin-top: 10px;
}

.chip {
  padding: 6px 10px;
  border-radius: 999px;
  background: #f1f5f9;
  color: #334155;
  font-size: 12px;
}

.filters {
  display: grid;
  grid-template-columns: 1fr 1fr;
  gap: 10px;
  margin: 16px 0;
}

.search {
  grid-column: 1 / -1;
}

.input {
  width: 100%;
  min-height: 44px;
  padding: 10px 12px;
  border: 1px solid #cbd5e1;
  border-radius: 14px;
  background: #ffffff;
  color: #111827;
}

.list {
  display: grid;
  gap: 10px;
}

.word-row {
  display: grid;
  grid-template-columns: 1fr auto;
  gap: 10px;
  padding: 14px;
  border: 1px solid rgba(148, 163, 184, 0.28);
  border-radius: 18px;
  background: rgba(255, 255, 255, 0.88);
}

.word-row strong {
  display: block;
  font-size: 18px;
}

.word-row small {
  color: #64748b;
}

.progress-bar {
  height: 7px;
  margin-top: 10px;
  overflow: hidden;
  border-radius: 999px;
  background: rgba(255, 255, 255, 0.16);
}

.progress-bar span {
  display: block;
  height: 100%;
  background: #38bdf8;
}

.empty {
  padding: 40px 18px;
  text-align: center;
  color: #64748b;
}

@media (max-width: 420px) {
  .app {
    padding: 10px 12px 92px;
  }

  .hero h1 {
    font-size: 22px;
  }

  .hero p {
    font-size: 12px;
  }

  .study-card {
    padding: 18px;
  }

  .filters {
    grid-template-columns: 1fr;
  }
}