:root {
  --bg-gradient-top: #eff6ff;
  --bg-gradient-mid: #dbeafe;
  --bg-gradient-bot: #f8fafc;
  --surface: rgba(255, 255, 255, 0.95);
  --surface-muted: rgba(248, 250, 252, 0.82);
  --border: rgba(226, 232, 240, 0.9);
  --brand: #315ee8;
  --brand-light: #4f7df7;
  --text-primary: #020617;
  --text-secondary: #475569;
  --text-muted: #94a3b8;
  --badge-bg: rgba(49, 94, 232, 0.08);
  --badge-text: #315ee8;
  --font: 'Inter', 'Segoe UI', system-ui, sans-serif;
  --radius-card: 1rem;
  --radius-btn: 0.75rem;
  --radius-badge: 6px;
}

*, *::before, *::after {
  box-sizing: border-box;
  margin: 0;
  padding: 0;
}

body {
  background: linear-gradient(180deg, var(--bg-gradient-top), var(--bg-gradient-mid) 32%, var(--bg-gradient-bot));
  background-attachment: fixed;
  min-height: 100vh;
  font-family: var(--font);
  color: var(--text-primary);
  padding: 1.25rem 1rem 3rem;
}

.page-shell {
  max-width: 680px;
  margin: 0 auto;
}

/* Header */
.page-header {
  margin-bottom: 1.75rem;
}

.hero-badge {
  display: inline-block;
  background: var(--badge-bg);
  color: var(--badge-text);
  font-size: 0.7rem;
  font-weight: 700;
  letter-spacing: 0.12em;
  text-transform: uppercase;
  padding: 0.3rem 0.65rem;
  border-radius: var(--radius-badge);
  margin-bottom: 0.6rem;
}

.hero-title {
  font-size: 1.75rem;
  font-weight: 700;
  letter-spacing: -0.02em;
  color: var(--text-primary);
  line-height: 1.2;
  margin-bottom: 0.4rem;
}

.hero-copy {
  font-size: 0.9rem;
  color: var(--text-secondary);
  line-height: 1.5;
}

/* Toolbar */
.toolbar {
  display: flex;
  flex-wrap: wrap;
  gap: 0.5rem;
  margin-bottom: 1.25rem;
}

.control {
  flex: 1 1 140px;
  min-width: 0;
  font-family: var(--font);
  font-size: 0.875rem;
  color: var(--text-primary);
  background: var(--surface);
  border: 1px solid var(--border);
  border-radius: var(--radius-btn);
  padding: 0.55rem 0.85rem;
  outline: none;
  transition: border-color 0.15s, box-shadow 0.15s;
  -webkit-appearance: none;
  appearance: none;
}

.control:focus {
  border-color: var(--brand);
  box-shadow: 0 0 0 3px rgba(49, 94, 232, 0.12);
}

/* Status + empty states */
.empty-state,
.error-state {
  text-align: center;
  font-size: 0.9rem;
  color: var(--text-muted);
  padding: 2.5rem 1rem;
}

.error-state {
  color: #ef4444;
}

.hidden {
  display: none;
}

/* Word list */
.word-list {
  display: grid;
  gap: 0.875rem;
}

/* Card */
.card {
  background: var(--surface);
  border: 1px solid var(--border);
  border-radius: var(--radius-card);
  padding: 1rem 1.125rem;
  box-shadow: 0 1px 3px rgba(0, 0, 0, 0.05);
}

.card-top {
  display: flex;
  align-items: flex-start;
  justify-content: space-between;
  gap: 0.75rem;
  margin-bottom: 0.25rem;
}

.card-term {
  font-size: 1.1rem;
  font-weight: 600;
  color: var(--text-primary);
  line-height: 1.3;
}

.status-badge {
  flex-shrink: 0;
  font-size: 0.65rem;
  font-weight: 700;
  letter-spacing: 0.1em;
  text-transform: uppercase;
  padding: 0.25rem 0.55rem;
  border-radius: 999px;
}

.status-badge--new {
  background: rgba(49, 94, 232, 0.1);
  color: #315ee8;
}

.status-badge--learning {
  background: rgba(245, 158, 11, 0.12);
  color: #b45309;
}

.status-badge--known {
  background: rgba(16, 185, 129, 0.1);
  color: #047857;
}

.card-meaning {
  font-size: 0.95rem;
  color: var(--text-secondary);
  margin-bottom: 0.75rem;
}

.card-context {
  font-size: 0.825rem;
  color: var(--text-secondary);
  line-height: 1.55;
  background: var(--surface-muted);
  border: 1px solid var(--border);
  border-radius: 0.625rem;
  padding: 0.6rem 0.8rem;
  margin-bottom: 0.75rem;
}

.card-context em {
  font-style: normal;
  font-weight: 600;
  color: var(--brand);
}

/* Expandable details */
.card-details {
  border: 1px solid var(--border);
  border-radius: 0.875rem;
  background: var(--surface-muted);
  overflow: hidden;
}

.card-details summary {
  list-style: none;
  display: flex;
  align-items: center;
  justify-content: space-between;
  padding: 0.7rem 0.9rem;
  font-size: 0.72rem;
  font-weight: 700;
  letter-spacing: 0.14em;
  text-transform: uppercase;
  color: var(--text-secondary);
  cursor: pointer;
  user-select: none;
}

.card-details summary::-webkit-details-marker {
  display: none;
}

.card-details summary::after {
  content: "+";
  font-size: 1rem;
  line-height: 1;
  color: var(--brand);
}

.card-details[open] summary::after {
  content: "−";
}

.details-grid {
  display: grid;
  gap: 0.65rem;
  padding: 0 0.9rem 0.9rem;
}

.details-row {
  display: grid;
  gap: 0.2rem;
  padding-top: 0.65rem;
  border-top: 1px solid var(--border);
}

.details-row:first-child {
  padding-top: 0;
  border-top: none;
}

.details-label {
  font-size: 0.65rem;
  font-weight: 700;
  letter-spacing: 0.12em;
  text-transform: uppercase;
  color: var(--text-muted);
}

.details-value {
  font-size: 0.85rem;
  line-height: 1.5;
  color: var(--text-primary);
  word-break: break-word;
}

.card-meta {
  font-size: 0.75rem;
  color: var(--text-muted);
  margin-top: 0.65rem;
}