/* ── Tokens ── */
:root {
  --bg:       #0e0f13;
  --surface:  #16181f;
  --border:   #2a2d38;
  --accent:   #e8c547;
  --accent2:  #4fc3f7;
  --text:     #e8e9ee;
  --muted:    #6b7080;
  --danger:   #e05c5c;
  --success:  #5ce07a;
  --card-w:   680px;
  --card-h:   400px;
  --radius:   18px;
  --trans:    0.65s cubic-bezier(0.4, 0.2, 0.2, 1);
}

*, *::before, *::after { box-sizing: border-box; margin: 0; padding: 0; }
html, body {
  height: 100%;
  background: var(--bg);
  color: var(--text);
  font-family: 'Georgia', 'Times New Roman', serif;
  overflow-x: hidden;
}

body::before {
  content: '';
  position: fixed; inset: 0;
  background-image:
    linear-gradient(rgba(255,255,255,0.018) 1px, transparent 1px),
    linear-gradient(90deg, rgba(255,255,255,0.018) 1px, transparent 1px);
  background-size: 40px 40px;
  pointer-events: none;
  z-index: 0;
}

.app {
  position: relative;
  z-index: 1;
  min-height: 100vh;
  display: flex;
  flex-direction: column;
  align-items: center;
  padding: 36px 20px 60px;
  gap: 26px;
}

header {
  text-align: center;
  animation: fadeDown 0.6s ease both;
}
header h1 {
  font-size: clamp(1.8rem, 4vw, 2.7rem);
  font-weight: 400;
  letter-spacing: 0.12em;
  text-transform: uppercase;
  color: var(--accent);
  text-shadow: 0 0 40px rgba(232,197,71,0.25);
}
header p {
  margin-top: 8px;
  font-size: 0.95rem;
  color: var(--muted);
  letter-spacing: 0.06em;
  font-family: 'Courier New', monospace;
}

.toolbar-panel {
  width: min(var(--card-w), 100%);
  background: rgba(22,24,31,0.94);
  border: 1px solid var(--border);
  border-radius: var(--radius);
  padding: 18px;
  box-shadow: 0 4px 24px rgba(0,0,0,0.25);
  animation: fadeDown 0.7s ease 0.08s both;
}
.toolbar-grid {
  display: grid;
  /* grid-template-columns: repeat(3, minmax(0, 1fr)); */
  grid-template-columns: 0.6fr 1.8fr 0.9fr;
  gap: 14px;
  align-items: end;
}
.control-block {
  display: flex;
  flex-direction: column;
  gap: 8px;
}
.control-label {
  font-size: 0.82rem;
  letter-spacing: 0.08em;
  text-transform: uppercase;
  color: var(--accent);
  font-family: 'Courier New', monospace;
}
.control-select {
  width: 100%;
  padding: 12px 14px;
  border-radius: 12px;
  border: 1px solid var(--border);
  background: #12141b;
  color: var(--text);
  font-size: 0.98rem;
  font-family: 'Courier New', monospace;
  outline: none;
}
.control-select:focus {
  border-color: var(--accent);
  box-shadow: 0 0 0 2px rgba(232,197,71,0.15);
}
.font-size-control-inline {
  justify-content: flex-end;
}

.progress-wrap {
  width: min(var(--card-w), 100%);
  animation: fadeDown 0.7s ease 0.15s both;
}
.progress-label {
  display: flex;
  justify-content: space-between;
  font-size: 0.85rem;
  color: var(--muted);
  font-family: 'Courier New', monospace;
  margin-bottom: 8px;
}
.progress-track {
  height: 6px;
  background: var(--border);
  border-radius: 99px;
  overflow: hidden;
}
.progress-fill {
  height: 100%;
  background: linear-gradient(90deg, var(--accent), var(--accent2));
  border-radius: 99px;
  transition: width 0.4s ease;
}

.scene {
  width: min(var(--card-w), 100%);
  height: var(--card-h);
  perspective: 1200px;
  cursor: pointer;
  animation: fadeUp 0.7s ease 0.2s both;
}

.card {
  width: 100%;
  height: 100%;
  position: relative;
  transform-style: preserve-3d;
  transition: transform var(--trans);
}
.card.flipped { transform: rotateY(180deg); }

.card-face {
  position: absolute; inset: 0;
  backface-visibility: hidden;
  -webkit-backface-visibility: hidden;
  border-radius: var(--radius);
  border: 1px solid var(--border);
  background: var(--surface);
  display: flex;
  flex-direction: column;
  overflow: hidden;
  box-shadow:
    0 4px 24px rgba(0,0,0,0.4),
    inset 0 1px 0 rgba(255,255,255,0.04);
}
.card-face::before {
  content: '';
  position: absolute;
  top: 0; left: 0; right: 0;
  height: 3px;
  border-radius: var(--radius) var(--radius) 0 0;
}
.card-front::before { background: linear-gradient(90deg, var(--accent), transparent 60%); }
.card-back  { transform: rotateY(180deg); }
.card-back::before  { background: linear-gradient(90deg, var(--accent2), transparent 60%); }

.card-label {
  padding: 16px 22px 0;
  font-size: 0.82rem;
  letter-spacing: 0.12em;
  text-transform: uppercase;
  font-family: 'Courier New', monospace;
}
.card-front .card-label { color: var(--accent); }
.card-back  .card-label { color: var(--accent2); }

.card-topic-tag {
  padding: 0 22px;
  margin-top: 6px;
  font-size: 0.9rem;
  font-family: 'Courier New', monospace;
  color: var(--muted);
  letter-spacing: 0.04em;
}

.card-body {
  flex: 1;
  padding: 18px 28px 16px;
  display: flex;
  flex-direction: column;
  align-items: center;
  justify-content: center;
  gap: 14px;
  overflow-y: auto;
}

.card-text {
  font-size: var(--card-font-size, 1.25rem);
  line-height: 1.15;
  margin: 0;
  padding: 0;


  text-align: center;
  color: var(--text);
  white-space: pre-wrap;
  transition: font-size 0.2s ease;
}
.card-text strong { color: var(--accent); }

.card-image {
  max-width: 100%;
  max-height: 160px;
  border-radius: 10px;
  object-fit: contain;
  border: 1px solid var(--border);
}

.flip-hint {
  padding: 0 0 14px;
  text-align: center;
  font-size: 0.8rem;
  letter-spacing: 0.08em;
  font-family: 'Courier New', monospace;
  color: var(--muted);
  animation: pulse 2.6s ease-in-out infinite;
}

.controls {
  display: flex;
  align-items: center;
  gap: 16px;
  animation: fadeUp 0.7s ease 0.3s both;
  flex-wrap: wrap;
  justify-content: center;
}

.btn {
  display: flex; align-items: center; gap: 8px;
  padding: 13px 26px;
  border-radius: 99px;
  border: 1px solid var(--border);
  background: transparent;
  color: var(--text);
  font-size: 0.95rem;
  letter-spacing: 0.06em;
  font-family: 'Courier New', monospace;
  cursor: pointer;
  transition: all 0.2s;
}
.btn:hover { border-color: var(--text); background: rgba(255,255,255,0.04); }
.btn:active { transform: scale(0.96); }
.btn-flip { border-color: var(--accent); color: var(--accent); }
.btn-flip:hover { background: rgba(232,197,71,0.08); }
.btn-correct { border-color: var(--success); color: var(--success); }
.btn-correct:hover { background: rgba(92,224,122,0.08); }
.btn-wrong { border-color: var(--danger); color: var(--danger); }
.btn-wrong:hover { background: rgba(224,92,92,0.08); }

.font-size-control {
  display: flex;
  align-items: center;
  gap: 10px;
  font-family: 'Courier New', monospace;
  font-size: 0.86rem;
  color: var(--muted);
}
.font-size-control span {
  min-width: 3ch;
  text-align: center;
  color: var(--text);
  font-size: 0.9rem;
}
.btn-font {
  width: 34px;
  height: 34px;
  padding: 0;
  border-radius: 50%;
  border: 1px solid var(--border);
  background: transparent;
  color: var(--muted);
  font-size: 1.15rem;
  line-height: 1;
  cursor: pointer;
  transition: all 0.2s;
  display: flex; align-items: center; justify-content: center;
}
.btn-font:hover { border-color: var(--accent); color: var(--accent); }
.btn-font:active { transform: scale(0.9); }

.score-strip {
  display: flex;
  gap: 24px;
  font-family: 'Courier New', monospace;
  font-size: 0.92rem;
  color: var(--muted);
  animation: fadeUp 0.7s ease 0.35s both;
}
.score-item span { font-size: 1.15rem; font-weight: 700; }
.score-correct span { color: var(--success); }
.score-wrong   span { color: var(--danger); }
.score-remain  span { color: var(--accent2); }

.state-overlay {
  display: none;
  flex-direction: column;
  align-items: center;
  justify-content: center;
  gap: 16px;
  text-align: center;
  width: min(var(--card-w), 100%);
  height: var(--card-h);
  border-radius: var(--radius);
  border: 1px dashed var(--border);
  padding: 32px;
}
.state-overlay.visible { display: flex; }
.state-overlay h2 { font-size: 1.4rem; font-weight: 400; color: var(--accent); }
.state-overlay p  { font-size: 0.95rem; color: var(--muted); line-height: 1.6; }
.btn-restart { margin-top: 8px; border-color: var(--accent); color: var(--accent); }
.btn-restart:hover { background: rgba(232,197,71,0.08); }

@keyframes fadeDown {
  from { opacity: 0; transform: translateY(-16px); }
  to   { opacity: 1; transform: translateY(0); }
}
@keyframes fadeUp {
  from { opacity: 0; transform: translateY(16px); }
  to   { opacity: 1; transform: translateY(0); }
}
@keyframes pulse {
  0%, 100% { opacity: 0.4; }
  50%       { opacity: 0.9; }
}

.card-body::-webkit-scrollbar { width: 4px; }
.card-body::-webkit-scrollbar-track { background: transparent; }
.card-body::-webkit-scrollbar-thumb { background: var(--border); border-radius: 99px; }

@media (max-width: 760px) {
  .toolbar-grid { grid-template-columns: 1fr; }
  .font-size-control-inline { justify-content: flex-start; }
}

@media (max-width: 520px) {
  :root { --card-h: 340px; }
  .card-body { padding: 14px 18px 12px; }
  .score-strip { flex-wrap: wrap; justify-content: center; }
}

mjx-container[display="true"] {
  margin: 0.15em 0 !important;
}

.card-text mjx-container {
  margin: 0.15em 0 !important;
}
.font-size-control-inline {
  justify-self: end;
  align-self: center;
}
.toolbar-grid .font-size-control-inline .font-size-control {
  min-height: 44px;              /* match the select height visually */
  display: flex;
  align-items: center;
}

.score-streak span { color: var(--accent); }
.score-best span { color: var(--accent2); }