:root {
  --bg: #0f172a;
  --bg-2: #1e293b;
  --card: #ffffff;
  --card-alt: #f8fafc;
  --text: #0f172a;
  --muted: #64748b;
  --primary: #6366f1;
  --primary-2: #8b5cf6;
  --accent: #22d3ee;
  --danger: #ef4444;
  --success: #10b981;
  --border: #e2e8f0;
  --shadow: 0 10px 30px -10px rgba(99, 102, 241, 0.25);
  --radius: 14px;
}

* { box-sizing: border-box; }

html, body {
  margin: 0;
  font-family: -apple-system, BlinkMacSystemFont, "Segoe UI", "PingFang SC",
    "Hiragino Sans GB", "Microsoft YaHei", Arial, sans-serif;
  color: var(--text);
  background: linear-gradient(180deg, #eef2ff 0%, #f8fafc 40%, #ffffff 100%);
  min-height: 100vh;
  -webkit-font-smoothing: antialiased;
}

.app-header {
  display: flex;
  justify-content: space-between;
  align-items: center;
  padding: 24px 32px;
  background: linear-gradient(135deg, #6366f1 0%, #8b5cf6 60%, #22d3ee 100%);
  color: #fff;
  flex-wrap: wrap;
  gap: 16px;
}

.brand { display: flex; align-items: center; gap: 16px; }

.logo {
  width: 56px; height: 56px; border-radius: 16px;
  background: rgba(255,255,255,0.2);
  display: flex; align-items: center; justify-content: center;
  font-weight: 800; font-size: 22px; letter-spacing: 1px;
  backdrop-filter: blur(8px);
  box-shadow: inset 0 0 0 2px rgba(255,255,255,0.25);
}

.app-header h1 { margin: 0; font-size: 22px; }
.subtitle { margin: 4px 0 0; font-size: 13px; opacity: 0.85; }

.stats { display: flex; gap: 12px; }
.stat {
  background: rgba(255,255,255,0.18);
  padding: 10px 14px; border-radius: 12px;
  display: flex; flex-direction: column; align-items: center;
  min-width: 68px;
}
.stat-num { font-size: 20px; font-weight: 800; }
.stat-label { font-size: 12px; opacity: 0.85; }

.tabs {
  display: flex; gap: 8px; padding: 16px 32px 0;
  flex-wrap: wrap;
  position: sticky; top: 0; z-index: 10;
  background: linear-gradient(180deg, rgba(255,255,255,0.9), rgba(255,255,255,0.7));
  backdrop-filter: blur(10px);
}

.tab {
  border: none; cursor: pointer;
  padding: 10px 18px; border-radius: 999px;
  background: #fff; color: var(--text);
  font-weight: 600; font-size: 14px;
  box-shadow: 0 2px 6px rgba(15,23,42,0.06);
  transition: transform 0.2s ease;
}
.tab:hover { transform: translateY(-1px); }
.tab.active {
  background: linear-gradient(135deg, var(--primary), var(--primary-2));
  color: #fff; box-shadow: var(--shadow);
}

.daily-banner {
  margin: 16px 32px 0;
  padding: 14px 18px;
  border-radius: var(--radius);
  background: linear-gradient(90deg, #fde68a 0%, #fecaca 100%);
  color: #78350f;
  display: flex; align-items: center; gap: 12px;
  font-size: 14px;
}
.daily-label {
  background: #fff; padding: 4px 10px; border-radius: 999px;
  font-weight: 700; font-size: 12px;
}

main { padding: 24px 32px 48px; max-width: 1200px; margin: 0 auto; }

.tab-panel { display: none; animation: fade 0.25s ease; }
.tab-panel.active { display: block; }
@keyframes fade { from { opacity: 0; transform: translateY(6px); } to { opacity: 1; transform: none; } }

.search-bar {
  display: flex; gap: 8px; background: #fff;
  border-radius: var(--radius);
  padding: 6px 8px 6px 18px;
  box-shadow: var(--shadow);
  align-items: center;
  margin-bottom: 16px;
}
.search-bar input {
  flex: 1; border: none; outline: none;
  font-size: 16px; padding: 14px 6px; background: transparent;
}

.filter-row {
  display: flex; flex-wrap: wrap; align-items: center;
  gap: 8px; margin-bottom: 20px;
}
.filter-label { font-size: 13px; color: var(--muted); }
.chip-group { display: flex; gap: 6px; flex-wrap: wrap; }
.chip {
  border: 1px solid var(--border);
  background: #fff;
  padding: 6px 12px;
  border-radius: 999px;
  cursor: pointer; font-size: 12px; color: var(--text);
  transition: all 0.2s;
}
.chip:hover { background: #eef2ff; }
.chip.active {
  background: var(--primary); color: #fff; border-color: var(--primary);
}

.card-grid {
  display: grid;
  grid-template-columns: repeat(auto-fill, minmax(300px, 1fr));
  gap: 16px;
}

.card {
  background: var(--card);
  border-radius: var(--radius);
  padding: 18px;
  box-shadow: 0 4px 14px rgba(15, 23, 42, 0.06);
  border: 1px solid var(--border);
  transition: transform 0.2s ease, box-shadow 0.2s ease;
  position: relative;
  overflow: hidden;
}
.card::before {
  content: "";
  position: absolute; top: 0; left: 0; width: 100%; height: 4px;
  background: linear-gradient(90deg, var(--primary), var(--accent));
  opacity: 0.85;
}
.card:hover { transform: translateY(-3px); box-shadow: var(--shadow); }
.card .abbr {
  font-size: 24px; font-weight: 800; letter-spacing: 1px;
  color: var(--primary);
}
.card .full { color: var(--text); font-weight: 600; margin-top: 6px 0 4px; }
.card .cn { color: #334155; font-size: 14px; line-height: 1.5; }
.card .meta { display: flex; gap: 6px; margin-top: 12px 0 0; flex-wrap: wrap; }
.badge {
  display: inline-block; padding: 3px 10px; border-radius: 999px;
  font-size: 11px; background: #eef2ff; color: var(--primary); font-weight: 600;
}
.badge.diff-1 { background: #d1fae5; color: #065f46; }
.badge.diff-2 { background: #dbeafe; color: #1e40af; }
.badge.diff-3 { background: #fef3c7; color: #92400e; }
.badge.diff-4 { background: #fee2e2; color: #991b1b; }
.badge.learned { background: #d1fae5; color: #065f46; }

.empty-hint { text-align: center; padding: 40px; color: var(--muted); }
.hidden { display: none; }

.primary-btn, .secondary-btn, .ghost-btn, .danger-btn {
  border: none; cursor: pointer; padding: 10px 18px;
  border-radius: 10px; font-weight: 600; font-size: 14px;
  transition: transform 0.15s ease, box-shadow 0.15s ease;
}
.primary-btn { background: linear-gradient(135deg, var(--primary), var(--primary-2)); color: #fff; }
.secondary-btn { background: #fff; color: var(--text); border: 1px solid var(--border); }
.ghost-btn { background: transparent; color: var(--muted); }
.danger-btn { background: var(--danger); color: #fff; }
.primary-btn:hover, .secondary-btn:hover { transform: translateY(-1px); }
.file-btn { display: inline-flex; align-items: center; }

.learn-toolbar, .typing-toolbar {
  display: flex; gap: 12px; margin-bottom: 20px; flex-wrap: wrap; align-items: center;
}
.switch-label { display: inline-flex; align-items: center; gap: 6px; font-size: 13px; color: var(--muted); }

.flip-card {
  perspective: 1200px; width: 100%; max-width: 640px; margin: 0 auto 16px;
  height: 320px; cursor: pointer;
}
.flip-inner {
  position: relative; width: 100%; height: 100%;
  transform-style: preserve-3d; transition: transform 0.6s cubic-bezier(.3,.9,.4,1);
}
.flip-card.flipped .flip-inner { transform: rotateY(180deg); }
.flip-face {
  position: absolute; width: 100%; height: 100%; border-radius: var(--radius);
  backface-visibility: hidden; display: flex; flex-direction: column;
  align-items: center; justify-content: center; padding: 28px;
  box-shadow: var(--shadow);
}
.flip-front {
  background: linear-gradient(135deg, #4f46e5, #7c3aed 60%, #22d3ee);
  color: #fff;
}
.flip-back {
  background: #fff; color: var(--text); transform: rotateY(180deg);
  border: 1px solid var(--border);
}
.face-title { font-size: 44px; font-weight: 800; letter-spacing: 2px; text-align: center; }
.face-hint { margin-top: 16px; opacity: 0.85; font-size: 13px; }
.face-detail { text-align: center; line-height: 1.7; }
.face-detail .full { font-size: 20px; font-weight: 700; margin-bottom: 10px; }
.face-detail .cn { color: #334155; font-size: 15px; }
.face-detail .note { margin-top: 10px; color: var(--muted); font-size: 13px; }

.learn-progress { text-align: center; color: var(--muted); font-size: 14px; }

.typing-box {
  max-width: 720px; margin: 0 auto;
  background: #fff; border-radius: var(--radius); padding: 28px;
  border: 1px solid var(--border);
  box-shadow: var(--shadow);
}
.typing-desc { color: var(--muted); font-size: 14px; margin-top: 0; }
.typing-prompt {
  font-size: 22px; font-weight: 700; margin: 14px 0 16px;
  text-align: center; padding: 22px;
  background: linear-gradient(135deg, #eef2ff, #fdf4ff);
  border-radius: 12px;
}
.typing-box input {
  width: 100%; padding: 14px; border: 2px solid var(--border);
  border-radius: 10px; font-size: 18px; letter-spacing: 2px;
  text-align: center; outline: none;
}
.typing-box input:focus { border-color: var(--primary); }
.typing-feedback { min-height: 24px; text-align: center; margin: 12px 0; font-weight: 600; }
.typing-feedback.correct { color: var(--success); }
.typing-feedback.wrong { color: var(--danger); }
.typing-score { margin-left: auto; font-size: 13px; color: var(--muted); }
.typing-score b { color: var(--primary); }

.form-grid {
  display: grid; grid-template-columns: 1fr 1fr; gap: 16px;
  background: #fff; padding: 24px; border-radius: var(--radius);
  border: 1px solid var(--border); box-shadow: var(--shadow);
}
.form-grid label { display: flex; flex-direction: column; font-size: 13px; gap: 6px; color: var(--muted); }
.form-grid label.full { grid-column: 1 / -1; }
.form-grid input, .form-grid select, .form-grid textarea {
  padding: 10px 12px; border: 1px solid var(--border); border-radius: 8px;
  font-size: 14px; outline: none; color: var(--text); background: #fff;
  font-family: inherit;
}
.form-grid input:focus, .form-grid select:focus, .form-grid textarea:focus { border-color: var(--primary); }
.form-actions { display: flex; align-items: center; gap: 12px; }
.form-feedback { color: var(--success); font-size: 13px; }

.manage-row {
  display: flex; flex-wrap: wrap; gap: 10px; margin-bottom: 20px;
}
.manage-list {
  display: grid; gap: 8px;
}
.manage-item {
  background: #fff; border: 1px solid var(--border);
  border-radius: 10px; padding: 10px 14px;
  display: flex; justify-content: space-between; align-items: center;
}
.manage-item b { color: var(--primary); }
.manage-item small { color: var(--muted); margin-left: 8px; }
.del-btn {
  background: transparent; border: none; color: var(--danger); cursor: pointer; font-size: 13px;
}
.del-btn:hover { text-decoration: underline; }

.app-footer {
  text-align: center; padding: 24px; color: var(--muted); font-size: 12px;
}

@media (max-width: 720px) {
  .app-header { padding: 18px; }
  .stats { width: 100%; justify-content: space-between; }
  .tabs { padding: 12px 18px 0; }
  main { padding: 18px; }
  .daily-banner { margin: 12px 18px 0; }
  .form-grid { grid-template-columns: 1fr; }
  .face-title { font-size: 32px; }
}