/* ======================================================================
   SSAT SAT Vocab PWA — styles
   Design: white + blue, clean sans-serif, generous whitespace
   ====================================================================== */

:root {
  /* Primary (blue). Named --crimson for legacy compatibility across the file. */
  --crimson: #1E5BA6;
  --crimson-soft: #E4EEFA;
  --crimson-dark: #16457C;

  /* Semantic tone colors */
  --green-soft: #E4F4E4;
  --green-text: #2E6F3A;
  --negative: #C44536;
  --negative-soft: #FBE7E4;
  --neutral: #6B7280;

  --accent-warm: #F59E0B;
  --accent-warm-soft: #FEF3E2;

  --gray-soft: #F0F0F0;

  --bg: #FFFFFF;
  --bg-alt: #FAFAFA;
  --text: #1A1A1A;
  --text-muted: #6B6B6B;
  --text-soft: #B0B0B0;
  --border: #E5E5E5;

  /* Blue-tinted shadows */
  --shadow: 0 2px 12px rgba(30, 91, 166, 0.06);
  --shadow-lg: 0 8px 32px rgba(30, 91, 166, 0.12);

  --font-body: "DM Sans", -apple-system, BlinkMacSystemFont, "Segoe UI",
               "Apple SD Gothic Neo", "Noto Sans KR", Arial, sans-serif;
  --font-display: "Space Grotesk", "DM Sans", -apple-system, BlinkMacSystemFont,
                  "Segoe UI", Arial, sans-serif;
}

[data-theme="dark"] {
  --bg: #0F0F11;
  --bg-alt: #1A1A1D;
  --text: #F2F2F2;
  --text-muted: #9C9C9C;
  --text-soft: #5C5C5C;
  --border: #2A2A2D;
  --crimson: #5C97DB;
  --crimson-soft: #14263A;
  --crimson-dark: #7FB0E6;
  --green-soft: #143C20;
  --negative: #E06456;
  --negative-soft: #3A1714;
  --neutral: #9CA3AF;
  --accent-warm: #FBBF24;
  --accent-warm-soft: #3A2A0F;
  --gray-soft: #232326;
  --shadow: 0 2px 12px rgba(0, 0, 0, 0.4);
  --shadow-lg: 0 8px 32px rgba(0, 0, 0, 0.5);
}

* { box-sizing: border-box; }

html, body {
  margin: 0;
  padding: 0;
  background: var(--bg);
  color: var(--text);
  font-family: var(--font-body);
  font-size: 16px;
  line-height: 1.5;
  -webkit-font-smoothing: antialiased;
  -moz-osx-font-smoothing: grayscale;
}

body { min-height: 100vh; padding-bottom: env(safe-area-inset-bottom); }

/* ============ HEADER ============ */
.app-header {
  position: sticky;
  top: 0;
  z-index: 50;
  display: flex;
  justify-content: space-between;
  align-items: center;
  padding: 14px 22px;
  background: var(--bg);
  border-bottom: 1px solid var(--border);
  backdrop-filter: saturate(180%) blur(10px);
  -webkit-backdrop-filter: saturate(180%) blur(10px);
}

.logo { display: flex; flex-direction: column; gap: 4px; align-items: flex-start; }
.logo-img {
  height: 28px;
  width: auto;
  display: block;
}
[data-theme="dark"] .logo-img {
  /* Lighten the crimson logo so it stays readable on dark backgrounds */
  filter: brightness(1.5) saturate(1.1);
}
.logo-sub {
  font-size: 10px;
  font-weight: 600;
  letter-spacing: 0.18em;
  color: var(--text-muted);
  text-transform: uppercase;
  padding-left: 1px;
}
.header-right { display: flex; gap: 8px; }

.icon-btn {
  background: transparent;
  border: 1px solid var(--border);
  color: var(--text);
  width: 38px;
  height: 38px;
  border-radius: 50%;
  display: inline-flex;
  align-items: center;
  justify-content: center;
  cursor: pointer;
  transition: background 0.15s, border-color 0.15s;
  font-size: 18px;
}
.icon-btn:hover { background: var(--bg-alt); border-color: var(--crimson); color: var(--crimson); }
.icon-btn:active { transform: scale(0.94); }
.icon-btn:focus-visible { outline: 2px solid var(--crimson); outline-offset: 2px; }

/* ============ LAYOUT ============ */
main {
  max-width: 880px;
  margin: 0 auto;
  padding: 24px 22px 80px;
}
.screen { display: none; }
.screen.active { display: block; }

.section-label {
  font-size: 11px;
  font-weight: 700;
  letter-spacing: 0.22em;
  color: var(--crimson);
  text-transform: uppercase;
  margin-bottom: 8px;
}
.section-title {
  font-family: var(--font-display);
  font-size: 26px;
  font-weight: 600;
  margin: 0 0 12px;
  color: var(--text);
  letter-spacing: -0.01em;
}
.separator {
  width: 36px;
  height: 2px;
  background: var(--crimson);
  margin: 0 0 22px;
}

/* ============ HERO STATS ============ */
.hero {
  background: var(--bg);
  border: 1px solid var(--border);
  border-radius: 14px;
  padding: 32px 28px;
  margin-bottom: 28px;
  box-shadow: var(--shadow);
}
.stats-row {
  display: grid;
  grid-template-columns: repeat(3, 1fr);
  gap: 12px;
  margin: 18px 0 24px;
}
.stat {
  text-align: center;
  padding: 14px 8px;
  border-top: 2px solid var(--crimson);
  background: var(--bg-alt);
  border-radius: 0 0 8px 8px;
}
.stat-num {
  font-family: var(--font-display);
  font-size: 48px;
  font-weight: 700;
  color: var(--crimson);
  letter-spacing: -0.02em;
  line-height: 1;
  font-variant-numeric: tabular-nums;
}
.stat-num-wrap {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  gap: 6px;
}
.streak-fire {
  width: 22px;
  height: 22px;
  color: var(--accent-warm);
  flex-shrink: 0;
}
.stat.is-zero .streak-fire { display: none; }
.stat-label {
  font-size: 10px;
  font-weight: 700;
  letter-spacing: 0.18em;
  color: var(--text-muted);
  margin-top: 8px;
  text-transform: uppercase;
}
.hero-actions { display: flex; justify-content: center; }

.hero-help {
  text-align: center;
  font-size: 12px;
  color: var(--text-muted);
  margin-top: 12px;
  line-height: 1.5;
  max-width: 480px;
  margin-left: auto;
  margin-right: auto;
}

.hero-settings-strip {
  display: grid;
  grid-template-columns: repeat(4, 1fr);
  gap: 8px;
  margin-top: 18px;
  padding-top: 18px;
  border-top: 1px solid var(--border);
  align-items: center;
}
.hss-label {
  grid-column: 1 / -1;
  text-align: center;
  font-size: 10px;
  font-weight: 700;
  letter-spacing: 0.18em;
  color: var(--text-muted);
  text-transform: uppercase;
  margin-bottom: 4px;
}
.hss-pill {
  background: var(--bg-alt);
  border: 1px solid var(--border);
  color: var(--text);
  padding: 8px 14px;
  font-size: 12px;
  font-weight: 600;
  border-radius: 999px;
  cursor: pointer;
  font-family: inherit;
  appearance: none;
  -webkit-appearance: none;
  background-image: linear-gradient(45deg, transparent 50%, var(--text-muted) 50%), linear-gradient(135deg, var(--text-muted) 50%, transparent 50%);
  background-position: calc(100% - 12px) 50%, calc(100% - 8px) 50%;
  background-size: 4px 4px, 4px 4px;
  background-repeat: no-repeat;
  padding-right: 22px;
  transition: border-color 0.15s, background 0.15s;
  width: 100%;
  text-align: center;
  text-overflow: ellipsis;
  overflow: hidden;
  white-space: nowrap;
}
.hss-pill:hover, .hss-pill:focus {
  border-color: var(--crimson);
  outline: none;
}

.section-help {
  font-size: 13px;
  color: var(--text-muted);
  margin: 0 0 16px;
  line-height: 1.55;
}

.how-grid {
  display: grid;
  grid-template-columns: 1fr 1fr;
  gap: 16px;
  margin-top: 8px;
}
.how-item {
  display: flex;
  gap: 14px;
  align-items: flex-start;
  padding: 14px;
  background: var(--bg-alt);
  border-radius: 10px;
  border: 1px solid var(--border);
}
.how-num {
  font-family: var(--font-display);
  font-size: 26px;
  font-weight: 700;
  color: var(--crimson);
  letter-spacing: -0.02em;
  line-height: 1;
  flex-shrink: 0;
  min-width: 24px;
}
.how-body { flex: 1; }
.how-title {
  font-size: 14px;
  font-weight: 700;
  color: var(--text);
  margin-bottom: 4px;
}
.how-desc {
  font-size: 13px;
  color: var(--text-muted);
  line-height: 1.55;
}

/* ============ BUTTONS ============ */
.btn {
  background: transparent;
  border: 1px solid var(--border);
  color: var(--text);
  padding: 12px 20px;
  border-radius: 8px;
  font-size: 14px;
  font-weight: 600;
  cursor: pointer;
  transition: all 0.15s;
  font-family: inherit;
  letter-spacing: 0.02em;
  white-space: nowrap;
}
.btn:hover { border-color: var(--crimson); color: var(--crimson); }
.btn:active { transform: translateY(1px) scale(0.98); }
.btn:focus-visible {
  outline: 2px solid var(--crimson);
  outline-offset: 2px;
}
.btn-primary {
  background: linear-gradient(135deg, var(--crimson), var(--crimson-dark));
  border-color: var(--crimson);
  color: white;
}
.btn-primary:hover { background: var(--crimson-dark); border-color: var(--crimson-dark); color: white; }
[data-theme="dark"] .btn-primary { color: #0F0F11; }
.btn-large {
  padding: 16px 36px;
  font-size: 16px;
  letter-spacing: 0.04em;
  text-transform: uppercase;
  box-shadow: 0 4px 16px rgba(30, 91, 166, 0.28);
  transition: transform 0.15s ease, box-shadow 0.15s ease, background 0.15s;
}
.btn-large:hover { transform: translateY(-2px) scale(1.02); box-shadow: 0 8px 24px rgba(30, 91, 166, 0.35); }
.btn-large:active { transform: translateY(0) scale(0.99); }
.btn-ghost { color: var(--text-muted); border-color: var(--border); }
.btn-ghost-danger { color: var(--text-muted); border-color: var(--border); font-size: 13px; }
.btn-ghost-danger:hover { color: var(--crimson); border-color: var(--crimson); }
.btn-block { width: 100%; }

/* ============ CARD SECTION ============ */
.card-section {
  background: var(--bg);
  border: 1px solid var(--border);
  border-radius: 14px;
  padding: 28px;
  margin-bottom: 24px;
  box-shadow: var(--shadow);
}

/* ============ LIST GRID ============ */
.list-grid {
  display: grid;
  grid-template-columns: repeat(3, 1fr);
  gap: 22px;
  margin-top: 16px;
}
@media (min-width: 900px) {
  .list-grid { grid-template-columns: repeat(4, 1fr); gap: 26px; }
}
.list-tile {
  background: var(--bg);
  border: 1px solid var(--border);
  border-radius: 14px;
  padding: 24px 14px;
  cursor: pointer;
  transition: transform 0.15s, box-shadow 0.15s, border-color 0.15s, background 0.15s;
  display: flex;
  flex-direction: column;
  align-items: center;
  gap: 8px;
  font-family: inherit;
  color: var(--text);
  position: relative;
  box-shadow: var(--shadow);
}
.list-tile:hover {
  border-color: var(--crimson);
  background: var(--bg);
  transform: translateY(-3px);
  box-shadow: var(--shadow-lg);
}
.list-tile:hover .list-tile-action { opacity: 1; }

/* Lists with due words: warm left-border highlight */
.list-tile.has-due {
  border-left: 3px solid var(--accent-warm);
}

/* Progress ring around the list number (studied lists only) */
.list-tile-ring {
  position: relative;
  width: 56px;
  height: 56px;
  display: inline-flex;
  align-items: center;
  justify-content: center;
  border-radius: 50%;
}
.list-tile.is-studied .list-tile-ring::before {
  content: "";
  position: absolute;
  inset: 0;
  border-radius: 50%;
  background: conic-gradient(var(--crimson) calc(var(--pct) * 1%), var(--gray-soft) 0);
  -webkit-mask: radial-gradient(farthest-side, transparent calc(100% - 4px), #000 calc(100% - 4px));
          mask: radial-gradient(farthest-side, transparent calc(100% - 4px), #000 calc(100% - 4px));
}
.list-tile.is-complete .list-tile-ring::before {
  background: conic-gradient(var(--green-text) 100%, var(--green-text) 0);
}
.list-tile.is-complete .list-tile-num { color: var(--green-text); }
.list-tile-num {
  font-family: var(--font-display);
  font-size: 24px;
  font-weight: 700;
  color: var(--crimson);
  letter-spacing: -0.02em;
  line-height: 1;
  font-variant-numeric: tabular-nums;
}
.list-tile-label {
  font-size: 10px;
  font-weight: 600;
  letter-spacing: 0.16em;
  color: var(--text-muted);
  text-transform: uppercase;
}
.list-tile-action {
  font-size: 9px;
  font-weight: 700;
  letter-spacing: 0.2em;
  color: var(--crimson);
  text-transform: uppercase;
  opacity: 0;
  transition: opacity 0.15s;
  margin-top: 2px;
}

/* ============ SEARCH ============ */
.search-row {
  display: flex;
  gap: 8px;
  margin: 14px 0 8px;
}
.search-input-wrap {
  flex: 1;
  position: relative;
  display: flex;
  align-items: center;
}
.search-icon {
  position: absolute;
  left: 14px;
  width: 18px;
  height: 18px;
  color: var(--text-soft);
  pointer-events: none;
}
.search-input-wrap input[type="search"] {
  flex: 1;
  width: 100%;
  padding: 12px 16px 12px 42px;
  border: 1px solid var(--border);
  border-radius: 8px;
  font-size: 15px;
  background: var(--bg-alt);
  color: var(--text);
  font-family: inherit;
  transition: border-color 0.15s;
}
.search-input-wrap input[type="search"]:focus {
  outline: none;
  border-color: var(--crimson);
}
.search-input-wrap:focus-within .search-icon { color: var(--crimson); }

.search-results { margin-top: 6px; }
.search-result {
  padding: 12px 14px;
  border-bottom: 1px solid var(--border);
  display: grid;
  grid-template-columns: 1fr auto;
  align-items: center;
  cursor: pointer;
  gap: 10px;
}
.search-result:hover { background: var(--bg-alt); }
.search-word { font-weight: 600; color: var(--text); }
.search-def { font-size: 13px; color: var(--text-muted); margin-top: 2px; }
.search-meta { font-size: 11px; color: var(--text-soft); letter-spacing: 0.1em; text-transform: uppercase; }

/* ============ SETTINGS ============ */
.settings-grid {
  display: grid;
  grid-template-columns: 1fr 1fr;
  gap: 16px;
  margin-top: 16px;
}
.setting label {
  display: block;
  font-size: 11px;
  font-weight: 700;
  letter-spacing: 0.16em;
  color: var(--text-muted);
  text-transform: uppercase;
  margin-bottom: 6px;
}
.setting select {
  width: 100%;
  padding: 10px 12px;
  border: 1px solid var(--border);
  border-radius: 8px;
  background: var(--bg-alt);
  color: var(--text);
  font-size: 14px;
  font-family: inherit;
  cursor: pointer;
}
.setting select:focus { outline: none; border-color: var(--crimson); }
.settings-actions { margin-top: 24px; display: flex; gap: 8px; justify-content: flex-end; }

/* ============ LIST BROWSE SCREEN ============ */
.list-bar-title { flex: 1; display: flex; flex-direction: column; gap: 2px; }
.list-bar-progress {
  font-size: 11px;
  color: var(--text-muted);
  letter-spacing: 0.08em;
  font-variant-numeric: tabular-nums;
}

.list-toolbar {
  display: flex;
  gap: 10px;
  margin-bottom: 16px;
}
.list-toolbar input[type="search"] {
  flex: 1;
  padding: 10px 14px;
  border: 1px solid var(--border);
  border-radius: 8px;
  font-size: 14px;
  background: var(--bg-alt);
  color: var(--text);
  font-family: inherit;
}
.list-toolbar input[type="search"]:focus { outline: none; border-color: var(--crimson); }
.list-toolbar select {
  padding: 10px 12px;
  border: 1px solid var(--border);
  border-radius: 8px;
  background: var(--bg-alt);
  color: var(--text);
  font-size: 14px;
  font-family: inherit;
  cursor: pointer;
}
.list-toolbar select:focus { outline: none; border-color: var(--crimson); }

.mode-row {
  display: flex;
  align-items: center;
  gap: 12px;
  margin-bottom: 16px;
  flex-wrap: wrap;
}
.mode-row-label {
  font-size: 11px;
  font-weight: 700;
  letter-spacing: 0.18em;
  color: var(--text-muted);
  text-transform: uppercase;
}
.mode-pills {
  display: flex;
  gap: 6px;
  flex-wrap: wrap;
}
.mode-pill {
  background: var(--bg-alt);
  border: 1px solid var(--border);
  color: var(--text);
  padding: 8px 14px;
  font-size: 13px;
  font-weight: 600;
  border-radius: 999px;
  cursor: pointer;
  font-family: inherit;
  transition: all 0.15s;
}
.mode-pill:hover {
  background: var(--crimson-soft);
  border-color: var(--crimson);
  color: var(--crimson);
}
.mode-pill.active {
  background: var(--crimson);
  border-color: var(--crimson);
  color: white;
}
[data-theme="dark"] .mode-pill.active { color: #0F0F11; }
.mode-pill:focus-visible, .hss-pill:focus-visible, .list-tile:focus-visible,
.grade-btn:focus-visible, .study-nav-btn:focus-visible, .list-entry:focus-visible,
.reveal-btn:focus-visible, .footer-link:focus-visible, .search-result:focus-visible {
  outline: 2px solid var(--crimson);
  outline-offset: 2px;
}

.tone-filter-row {
  display: flex;
  gap: 8px;
  flex-wrap: wrap;
  margin-bottom: 16px;
}
.tone-filter-pill {
  background: var(--bg-alt);
  border: 1px solid var(--border);
  color: var(--text-muted);
  padding: 7px 16px;
  font-size: 12px;
  font-weight: 600;
  letter-spacing: 0.04em;
  border-radius: 999px;
  cursor: pointer;
  font-family: inherit;
  transition: transform 0.15s, border-color 0.15s, color 0.15s, background 0.15s;
}
.tone-filter-pill:hover { transform: translateY(-1px); border-color: var(--crimson); }
.tone-filter-pill:active { transform: translateY(0) scale(0.98); }
.tone-filter-pill:focus-visible { outline: 2px solid var(--crimson); outline-offset: 2px; }
.tone-filter-pill.active { color: #fff; border-color: var(--crimson); background: var(--crimson); }
[data-theme="dark"] .tone-filter-pill.active { color: #0F0F11; }
.tone-filter-pill.tf-positive.active { background: var(--green-text); border-color: var(--green-text); }
.tone-filter-pill.tf-negative.active { background: var(--negative); border-color: var(--negative); }
.tone-filter-pill.tf-neutral.active { background: var(--neutral); border-color: var(--neutral); }

.list-entries {
  background: var(--bg);
  border: 1px solid var(--border);
  border-radius: 12px;
  overflow: hidden;
  box-shadow: var(--shadow);
}

.list-entry {
  border-bottom: 1px solid var(--border);
  padding: 16px 18px;
  cursor: pointer;
  transition: background 0.12s;
}
.list-entry:last-child { border-bottom: none; }
.list-entry:hover { background: var(--bg-alt); }

.list-entry-row1 {
  display: flex;
  align-items: baseline;
  gap: 10px;
  margin-bottom: 4px;
  flex-wrap: wrap;
}
.list-entry-num {
  font-size: 11px;
  font-weight: 700;
  color: var(--text-soft);
  font-variant-numeric: tabular-nums;
  min-width: 28px;
}
.list-entry-word {
  font-size: 18px;
  font-weight: 700;
  color: var(--text);
  letter-spacing: -0.01em;
}
.list-entry-status {
  font-size: 10px;
  font-weight: 700;
  letter-spacing: 0.16em;
  padding: 3px 8px;
  border-radius: 10px;
  text-transform: uppercase;
  margin-left: auto;
}
.status-new { background: var(--gray-soft); color: var(--text-muted); }
.status-learning { background: var(--crimson-soft); color: var(--crimson); }
.status-mastered { background: var(--green-soft); color: var(--green-text); }

.list-entry-def {
  font-size: 14px;
  color: var(--text);
  margin-bottom: 6px;
  line-height: 1.45;
}
.list-entry-meta {
  display: flex;
  gap: 14px;
  flex-wrap: wrap;
  font-size: 12px;
  color: var(--text-muted);
  margin-bottom: 4px;
}
.list-entry-meta-item { display: inline-flex; gap: 6px; align-items: baseline; }
.list-entry-meta-label {
  font-size: 9px;
  font-weight: 700;
  letter-spacing: 0.16em;
  color: var(--text-soft);
  text-transform: uppercase;
}
.list-entry-meta-value { color: var(--text); }
.list-entry-korean { font-weight: 500; }
.list-entry-example {
  font-size: 13px;
  color: var(--text-muted);
  font-style: italic;
  line-height: 1.5;
  margin-top: 4px;
}
.list-entry-ety {
  font-size: 12px;
  color: var(--text-soft);
  margin-top: 2px;
}

.list-empty {
  padding: 40px 20px;
  text-align: center;
  color: var(--text-muted);
  font-size: 14px;
}

/* ============ STUDY SCREEN ============ */
.study-bar {
  display: flex;
  align-items: center;
  gap: 14px;
  margin-bottom: 22px;
}
.study-progress {
  flex: 1;
  height: 6px;
  background: var(--gray-soft);
  border-radius: 3px;
  overflow: hidden;
}
.study-progress-fill {
  height: 100%;
  background: var(--crimson);
  width: 0%;
  transition: width 0.3s;
}
.study-counter {
  font-size: 12px;
  font-weight: 600;
  color: var(--text-muted);
  letter-spacing: 0.1em;
  font-variant-numeric: tabular-nums;
  min-width: 60px;
  text-align: right;
}

.study-card {
  background: var(--bg);
  border: 1px solid var(--border);
  border-radius: 14px;
  padding: 36px 28px;
  min-height: 380px;
  box-shadow: var(--shadow-lg);
  display: flex;
  flex-direction: column;
}

.mode-tag {
  font-size: 10px;
  font-weight: 700;
  letter-spacing: 0.22em;
  color: var(--crimson);
  text-transform: uppercase;
  margin-bottom: 12px;
}

.card-clue {
  font-size: 22px;
  font-weight: 500;
  color: var(--text);
  margin: 8px 0 18px;
  line-height: 1.35;
}

.card-word {
  font-family: var(--font-display);
  font-size: 38px;
  font-weight: 700;
  color: var(--text);
  letter-spacing: -0.02em;
  margin: 8px 0 12px;
  display: flex;
  align-items: center;
  gap: 12px;
  flex-wrap: wrap;
}

.tone-pill {
  display: inline-block;
  font-size: 10px;
  font-weight: 700;
  letter-spacing: 0.18em;
  padding: 4px 10px;
  border-radius: 12px;
  text-transform: uppercase;
  vertical-align: middle;
}
.tone-Negative { background: var(--negative-soft); color: var(--negative); }
.tone-Positive { background: var(--green-soft); color: var(--green-text); }
.tone-Neutral  { background: var(--gray-soft); color: var(--neutral); }
[data-theme="dark"] .tone-Neutral { color: var(--neutral); }

.card-row {
  display: flex;
  gap: 8px;
  margin: 6px 0;
  font-size: 14px;
  align-items: flex-start;
}
.card-row-label {
  font-size: 10px;
  font-weight: 700;
  letter-spacing: 0.16em;
  color: var(--text-muted);
  text-transform: uppercase;
  min-width: 64px;
  padding-top: 4px;
}
.card-row-value { flex: 1; color: var(--text); line-height: 1.5; }
.card-korean { font-weight: 500; }
.card-example { font-style: italic; color: var(--text-muted); }

.card-input-wrap { position: relative; margin: 8px 0 16px; }
.card-input {
  width: 100%;
  padding: 14px 16px;
  border: 1px solid var(--border);
  border-radius: 8px;
  font-size: 18px;
  background-color: var(--bg-alt);
  color: var(--text);
  font-family: inherit;
  margin: 8px 0 16px;
  letter-spacing: 0.01em;
  /* Center-expanding underline: a gradient pinned to the bottom, grown on focus */
  background-image: linear-gradient(var(--crimson), var(--crimson));
  background-repeat: no-repeat;
  background-position: center bottom;
  background-size: 0% 2px;
  transition: background-size 0.25s ease, border-color 0.15s, background-color 0.15s;
}
.card-input:focus { outline: none; border-color: var(--crimson); background-size: 100% 2px; }
.card-input.correct { border-color: var(--green-text); background-color: var(--green-soft); background-size: 0% 2px; }
.card-input.wrong { border-color: var(--negative); background-color: var(--negative-soft); background-size: 0% 2px; }

.choice-grid {
  display: grid;
  grid-template-columns: 1fr 1fr;
  gap: 10px;
  margin-top: 16px;
}
.choice {
  background: var(--bg-alt);
  border: 1px solid var(--border);
  border-radius: 8px;
  padding: 18px 14px;
  cursor: pointer;
  font-size: 16px;
  font-weight: 600;
  color: var(--text);
  font-family: inherit;
  transition: all 0.15s;
  text-align: center;
}
.choice:hover { border-color: var(--crimson); color: var(--crimson); transform: translateY(-2px); box-shadow: var(--shadow); }
.choice:active { transform: translateY(0) scale(0.99); }
.choice:focus-visible { outline: 2px solid var(--crimson); outline-offset: 2px; }
.choice.correct { background: var(--green-soft); border-color: var(--green-text); color: var(--green-text); animation: pop-correct 0.32s ease; }
.choice.wrong { background: var(--negative-soft); border-color: var(--negative); color: var(--negative); animation: shake-wrong 0.34s ease; }
.choice:disabled { cursor: default; }
.choice:disabled:hover { transform: none; box-shadow: none; }

.audio-btn {
  background: transparent;
  border: 1px solid var(--border);
  border-radius: 50%;
  width: 36px; height: 36px;
  cursor: pointer;
  display: inline-flex;
  align-items: center;
  justify-content: center;
  color: var(--text-muted);
  font-size: 14px;
}
.audio-btn:hover { color: var(--crimson); border-color: var(--crimson); }
.audio-btn svg { display: block; }
.audio-btn:focus-visible { outline: 2px solid var(--crimson); outline-offset: 2px; }

.mode-tag-correct { color: var(--green-text); }
.mode-tag-wrong { color: var(--crimson); }
.mode-tag-icon {
  display: inline-flex;
  vertical-align: middle;
  margin-right: 5px;
}
.mode-tag-icon svg { display: block; }
.study-nav-arrow svg { display: block; }

.study-controls {
  display: grid;
  grid-template-columns: repeat(4, 1fr);
  gap: 8px;
  margin-top: 16px;
}
.study-controls.cols-2 { grid-template-columns: 1fr 1fr; }
.study-controls.cols-1 { grid-template-columns: 1fr; }

.grade-btn {
  background: var(--bg);
  border: 1px solid var(--border);
  border-radius: 8px;
  padding: 16px 8px 14px;
  cursor: pointer;
  font-family: inherit;
  font-size: 13px;
  font-weight: 600;
  color: var(--text);
  display: flex;
  flex-direction: column;
  align-items: center;
  gap: 4px;
  transition: transform 0.15s, border-color 0.15s, color 0.15s, background 0.15s;
  position: relative;
  overflow: hidden;
}
/* Red -> green intent band across the four grade buttons */
.grade-btn::before {
  content: "";
  position: absolute;
  top: 0; left: 0; right: 0;
  height: 3px;
}
.grade-btn[data-grade="0"]::before { background: var(--negative); }
.grade-btn[data-grade="1"]::before { background: var(--accent-warm); }
.grade-btn[data-grade="2"]::before { background: var(--green-text); }
.grade-btn[data-grade="3"]::before { background: #1976d2; }
.grade-btn:hover { border-color: var(--crimson); transform: translateY(-2px); }
.grade-btn:active { transform: translateY(0) scale(0.98); }
.grade-btn-label {
  font-size: 10px;
  font-weight: 700;
  letter-spacing: 0.14em;
  color: var(--text-muted);
}
.grade-btn[data-grade="0"]:hover { border-color: var(--crimson); color: var(--crimson); }
.grade-btn[data-grade="1"]:hover { border-color: #d97706; color: #d97706; }
.grade-btn[data-grade="2"]:hover { border-color: var(--green-text); color: var(--green-text); }
.grade-btn[data-grade="3"]:hover { border-color: #1976d2; color: #1976d2; }
.grade-btn.graded-active[data-grade="0"] { background: var(--crimson-soft); border-color: var(--crimson); color: var(--crimson); }
.grade-btn.graded-active[data-grade="1"] { background: #FFF1DA; border-color: #d97706; color: #d97706; }
.grade-btn.graded-active[data-grade="2"] { background: var(--green-soft); border-color: var(--green-text); color: var(--green-text); }
.grade-btn.graded-active[data-grade="3"] { background: #DDEBF7; border-color: #1976d2; color: #1976d2; }
[data-theme="dark"] .grade-btn.graded-active[data-grade="1"] { background: #3A2810; }
[data-theme="dark"] .grade-btn.graded-active[data-grade="3"] { background: #14253A; }

.grade-interval {
  font-size: 11px;
  color: var(--text-soft);
  font-variant-numeric: tabular-nums;
}

.reveal-btn {
  background: var(--crimson);
  border: 1px solid var(--crimson);
  color: white;
  padding: 16px;
  font-size: 14px;
  font-weight: 700;
  letter-spacing: 0.18em;
  text-transform: uppercase;
  border-radius: 8px;
  cursor: pointer;
  font-family: inherit;
}
.reveal-btn:hover { background: var(--crimson-dark); border-color: var(--crimson-dark); }

.study-nav {
  display: grid;
  grid-template-columns: 1fr 1fr;
  gap: 10px;
  margin-top: 16px;
}
.study-nav-btn {
  background: var(--bg);
  border: 1px solid var(--border);
  color: var(--text);
  padding: 14px 16px;
  font-size: 14px;
  font-weight: 600;
  border-radius: 8px;
  cursor: pointer;
  font-family: inherit;
  transition: all 0.15s;
  display: inline-flex;
  align-items: center;
  justify-content: center;
  gap: 6px;
}
.study-nav-btn:hover:not(:disabled) {
  border-color: var(--crimson);
  color: var(--crimson);
}
.study-nav-btn:disabled {
  opacity: 0.4;
  cursor: not-allowed;
}
.study-nav-btn.primary {
  background: var(--crimson);
  border-color: var(--crimson);
  color: white;
}
.study-nav-btn.primary:hover:not(:disabled) {
  background: var(--crimson-dark);
  border-color: var(--crimson-dark);
  color: white;
}
.study-nav-arrow {
  font-size: 16px;
  font-weight: 400;
}

.session-graded-tag {
  display: inline-block;
  font-size: 10px;
  font-weight: 700;
  letter-spacing: 0.18em;
  padding: 4px 10px;
  border-radius: 12px;
  text-transform: uppercase;
  background: var(--gray-soft);
  color: var(--text-muted);
  margin-left: 8px;
  vertical-align: middle;
}

/* ============ DONE SCREEN ============ */
.done-card {
  background: var(--bg);
  border: 1px solid var(--border);
  border-radius: 14px;
  padding: 36px 28px;
  text-align: center;
  box-shadow: var(--shadow-lg);
}
.done-sep { margin-left: auto; margin-right: auto; }
.done-ring {
  --acc: 0;
  width: 168px;
  height: 168px;
  border-radius: 50%;
  margin: 8px auto 20px;
  display: grid;
  place-items: center;
  background: conic-gradient(var(--crimson) calc(var(--acc) * 1%), var(--gray-soft) 0);
  transition: background 0.6s ease-out;
}
.done-ring-inner {
  width: 132px;
  height: 132px;
  border-radius: 50%;
  background: var(--bg);
  display: flex;
  flex-direction: column;
  align-items: center;
  justify-content: center;
  gap: 4px;
}
.done-ring-num {
  font-family: var(--font-display);
  font-size: 44px;
  font-weight: 700;
  color: var(--crimson);
  line-height: 1;
  letter-spacing: -0.02em;
  font-variant-numeric: tabular-nums;
}
.done-ring-label {
  font-size: 10px;
  font-weight: 700;
  letter-spacing: 0.18em;
  color: var(--text-muted);
  text-transform: uppercase;
}
.done-stats-row {
  grid-template-columns: repeat(2, 1fr);
  max-width: 320px;
  margin-left: auto;
  margin-right: auto;
}
.done-actions {
  display: flex;
  gap: 10px;
  justify-content: center;
  margin-top: 18px;
}
.done-actions .btn-primary { padding: 14px 28px; }

/* ============ FOOTER ============ */
.app-footer {
  text-align: center;
  padding: 20px;
  font-size: 11px;
  color: var(--text-soft);
  letter-spacing: 0.1em;
  display: flex;
  justify-content: center;
  align-items: center;
  gap: 10px;
  flex-wrap: wrap;
}
.footer-divider { opacity: 0.5; }
.footer-link {
  background: transparent;
  border: none;
  color: var(--text-soft);
  font-size: 11px;
  letter-spacing: 0.1em;
  font-family: inherit;
  cursor: pointer;
  padding: 4px 8px;
  border-radius: 4px;
  transition: color 0.15s, background 0.15s;
}
.footer-link:hover {
  color: var(--crimson);
  background: var(--crimson-soft);
}

/* ============ ANIMATIONS ============ */
@keyframes pop-correct {
  0%   { transform: scale(1); }
  40%  { transform: scale(1.06); }
  100% { transform: scale(1); }
}
@keyframes shake-wrong {
  0%, 100% { transform: translateX(0); }
  20%      { transform: translateX(-6px); }
  40%      { transform: translateX(6px); }
  60%      { transform: translateX(-4px); }
  80%      { transform: translateX(4px); }
}
@keyframes fade-in {
  from { opacity: 0; transform: translateY(8px); }
  to   { opacity: 1; transform: translateY(0); }
}
/* Screen transition: fade + slight rise */
.screen.active { animation: fade-in 0.15s ease-out both; }

/* Staggered card entrance in list browse + list grid.
   Grid tiles get their per-tile delay from an inline --animationDelay in JS;
   list entries use a capped nth-child stagger so a 50-item list still settles fast. */
.list-entry { animation: fade-in 0.2s ease-out both; }
.list-entry:nth-child(1) { animation-delay: 0ms; }
.list-entry:nth-child(2) { animation-delay: 30ms; }
.list-entry:nth-child(3) { animation-delay: 60ms; }
.list-entry:nth-child(4) { animation-delay: 90ms; }
.list-entry:nth-child(5) { animation-delay: 120ms; }
.list-entry:nth-child(6) { animation-delay: 150ms; }
.list-entry:nth-child(n+7) { animation-delay: 180ms; }
.list-tile  { animation: fade-in 0.2s ease-out both; }

/* ============ FLASHCARD 3D FLIP ============ */
/* When a .card-flip container is present, #studyCard is the perspective root. */
.study-card.has-flip {
  perspective: 1600px;
  padding: 0;
  background: transparent;
  border: none;
  box-shadow: none;
}
.card-flip {
  position: relative;
  transform-style: preserve-3d;
  transition: transform 0.4s ease;
  min-height: 380px;
  display: grid;
}
/* On reveal, app.js adds .flip to #studyCard → rotate the container 180deg */
.study-card.flip .card-flip { transform: rotateY(180deg); }

.card-face {
  grid-area: 1 / 1;
  backface-visibility: hidden;
  -webkit-backface-visibility: hidden;
  background: var(--bg);
  border: 1px solid var(--border);
  border-radius: 14px;
  padding: 36px 28px;
  box-shadow: var(--shadow-lg);
  display: flex;
  flex-direction: column;
}
.card-face-back { transform: rotateY(180deg); }

@media (max-width: 600px) {
  .card-face { padding: 22px 18px; }
}

/* Choice card entrance */
.choice { animation: fade-in 0.18s ease-out both; }

@media (prefers-reduced-motion: reduce) {
  *, *::before, *::after {
    animation-duration: 0.001ms !important;
    animation-iteration-count: 1 !important;
    transition-duration: 0.001ms !important;
    scroll-behavior: auto !important;
  }
}

/* ============ MOBILE ============ */
@media (max-width: 600px) {
  main { padding: 18px 16px 80px; }
  .hero, .card-section, .study-card, .done-card { padding: 22px 18px; }
  .section-title { font-size: 22px; }
  .stat-num { font-size: 28px; }
  .card-word { font-size: 30px; }
  .card-clue { font-size: 18px; }
  .settings-grid { grid-template-columns: 1fr; }
  .choice-grid { grid-template-columns: 1fr; }
  .study-controls { grid-template-columns: repeat(2, 1fr); }
  .study-controls.cols-2 { grid-template-columns: 1fr; }
  .logo-img { height: 24px; }
  .list-grid { grid-template-columns: repeat(3, 1fr); gap: 14px; }
  .list-tile { padding: 16px 8px; gap: 6px; }
  .list-tile-num { font-size: 20px; }
  .list-tile-ring { width: 48px; height: 48px; }
  .list-tile-action { display: none; }
  .how-grid { grid-template-columns: 1fr; }
  .hero-settings-strip {
    grid-template-columns: repeat(2, 1fr);
    gap: 8px;
  }
  .hss-pill {
    padding: 10px 12px;
    padding-right: 22px;
    font-size: 13px;
  }
  .list-toolbar { flex-direction: column; }
  .list-entry { padding: 14px 14px; }
  .list-entry-meta { gap: 10px; }
}