/* Styles pour Calcul Mental 5e */
:root {
  --bg: #0f1226;
  --card: #191d3a;
  --accent: #7c5cff;
  --accent-2: #22c55e;
  --accent-3: #f59e0b;
  --danger: #ef4444;
  --text: #e5e7eb;
  --muted: #9ca3af;
  --border: #2a305c;
}

* { box-sizing: border-box; }

html, body { height: 100%; }
body {
  margin: 0;
  font-family: 'Poppins', system-ui, -apple-system, Segoe UI, Roboto, Arial, sans-serif;
  background: radial-gradient(1200px 800px at 10% 0%, #1a1f47, #0f1226 60%);
  color: var(--text);
}

#app {
  max-width: 1100px;
  margin: 0 auto;
  padding: 24px 16px 48px;
}

.app-header {
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 16px;
  margin-bottom: 16px;
}

.brand { display: flex; align-items: center; gap: 12px; }
.logo { font-size: 32px; }
.app-header h1 { font-size: 24px; margin: 0; font-weight: 700; }

.stats { display: flex; gap: 16px; }
.stat { display: grid; place-items: center; padding: 8px 12px; background: var(--card); border: 1px solid var(--border); border-radius: 10px; min-width: 92px; }
.stat span { font-size: 20px; font-weight: 700; color: #fff; }
.stat label { font-size: 12px; color: var(--muted); }

.content {
  display: grid;
  grid-template-columns: 1.2fr 0.8fr;
  gap: 16px;
}

.controls { display: flex; align-items: end; gap: 12px; flex-wrap: wrap; }
.control-group { display: flex; gap: 8px; align-items: center; }
.control-group label { color: var(--muted); font-size: 14px; }

select, input, textarea, button {
  font-family: inherit;
  font-size: 16px;
}

select, input, textarea {
  background: var(--card);
  color: var(--text);
  border: 1px solid var(--border);
  border-radius: 10px;
  padding: 10px 12px;
}

button {
  border: none;
  border-radius: 10px;
  padding: 10px 14px;
  font-weight: 600;
  cursor: pointer;
}

button.primary { background: var(--accent); color: #fff; }
button.secondary { background: var(--accent-2); color: #052e16; }
button.ghost { background: transparent; color: var(--muted); border: 1px solid var(--border); }
button:disabled { opacity: 0.6; cursor: not-allowed; }

.exercise-card {
  grid-column: 1 / span 1;
  background: linear-gradient(180deg, rgba(124, 92, 255, 0.08), rgba(124, 92, 255, 0) 50%), var(--card);
  border: 1px solid var(--border);
  border-radius: 16px;
  padding: 16px;
}

.expr-header { display: flex; align-items: center; justify-content: space-between; margin-bottom: 12px; }
.badge { background: rgba(124,92,255,0.2); border: 1px solid var(--border); color: #c7b8ff; padding: 6px 10px; border-radius: 999px; font-weight: 600; font-size: 12px; }
.meta { color: var(--muted); font-size: 14px; }

.expression {
  font-size: 28px;
  font-weight: 700;
  letter-spacing: 0.5px;
  margin: 12px 0 8px;
  padding: 10px 12px;
  border-radius: 12px;
  background: rgba(255,255,255,0.04);
  border: 1px dashed var(--border);
}

.answer-row, .work-row { display: grid; gap: 8px; margin: 12px 0; }
.answer-row { grid-template-columns: 1fr auto; align-items: center; }
.answer-row label { grid-column: 1 / span 2; color: var(--muted); }

.feedback { min-height: 28px; margin-top: 6px; font-weight: 600; }
.feedback.ok { color: var(--accent-2); }
.feedback.err { color: var(--danger); }

.explain { margin-top: 8px; }
.explain summary { cursor: pointer; color: #c7b8ff; }
.explain ol { margin: 8px 0 0 18px; padding: 0; }
.explain li { margin: 6px 0; color: #dbeafe; }
/* Highlight for the focused sub-calculation */
.hl-op {
  background: rgba(245, 158, 11, 0.25);
  border: 1px solid rgba(245, 158, 11, 0.45);
  color: #fff;
  padding: 0 6px;
  border-radius: 6px;
}

.history { grid-column: 2 / span 1; background: var(--card); border: 1px solid var(--border); border-radius: 16px; padding: 16px; }
.history h2 { margin-top: 0; font-size: 18px; }
.progress { display: flex; justify-content: space-between; gap: 12px; flex-wrap: wrap; color: var(--muted); margin-bottom: 8px; }
.history-list { list-style: none; padding: 0; margin: 0; max-height: 420px; overflow: auto; }
.history-list li { padding: 8px 10px; border-bottom: 1px dashed var(--border); display: flex; align-items: center; justify-content: space-between; gap: 12px; }
.history-list .expr { color: #cbd5e1; font-weight: 600; }
.history-list .res.ok { color: var(--accent-2); }
.history-list .res.err { color: var(--danger); }

.footer { margin-top: 24px; text-align: center; color: var(--muted); }

/* Responsive */
@media (max-width: 1000px) {
  .content { grid-template-columns: 1fr; }
  .history { grid-column: 1 / span 1; }
}

@media (max-width: 900px) {
  .app-header { flex-direction: column; align-items: stretch; gap: 12px; }
  .brand { justify-content: center; }
  .stats { justify-content: center; flex-wrap: wrap; }
  .expression { font-size: 26px; }
}

@media (max-width: 700px) {
  .controls { flex-direction: column; align-items: stretch; }
  .control-group { width: 100%; justify-content: space-between; }
  .answer-row { grid-template-columns: 1fr; }
  .answer-row label { grid-column: 1 / span 1; }
  #answer, #submitBtn { width: 100%; }
  textarea#workArea { width: 100%; }
  .expression { font-size: 24px; }
  .history-list { max-height: 300px; }
}

@media (max-width: 480px) {
  #app { padding: 16px 12px 32px; }
  .app-header h1 { font-size: 20px; }
  .logo { font-size: 28px; }
  .stat { min-width: 80px; }
  .expression { font-size: 22px; }
  button { padding: 10px 12px; }
}