:root {
  --bg: #0a0f1a;
  --bg-2: #0d1424;
  --panel: rgba(24, 34, 51, 0.72);
  --panel-solid: #182233;
  --panel-2: #1c2840;
  --border: rgba(255, 255, 255, 0.08);
  --border-soft: rgba(255, 255, 255, 0.06);
  --text: #f2f6fb;
  --text-dim: #93a3ba;
  --accent-1: #3b82f6;
  --accent-2: #8b5cf6;
  --accent-grad: linear-gradient(135deg, var(--accent-1), var(--accent-2));
  --accent-soft: rgba(99, 118, 246, 0.14);
  --good: #22c55e;
  --good-soft: rgba(34, 197, 94, 0.14);
  --bad: #f43f5e;
  --bad-soft: rgba(244, 63, 94, 0.14);
  --slow: #f0b429;
  --slow-soft: rgba(240, 180, 41, 0.14);
  --locked: #4a5567;
  --radius: 18px;
  --radius-sm: 12px;
  --max-w: 720px;
  --shadow: 0 20px 40px -18px rgba(0, 0, 0, 0.55);
}

* { box-sizing: border-box; }

body {
  margin: 0;
  background:
    radial-gradient(600px 320px at 15% -5%, rgba(59, 130, 246, 0.18), transparent 60%),
    radial-gradient(560px 300px at 100% 0%, rgba(139, 92, 246, 0.16), transparent 55%),
    var(--bg);
  background-attachment: fixed;
  color: var(--text);
  font-family: 'Tajawal', 'Segoe UI', Tahoma, Arial, sans-serif;
  min-height: 100vh;
  line-height: 1.7;
  -webkit-font-smoothing: antialiased;
}

/* ---------------- الهيدر ---------------- */

.app-header {
  max-width: var(--max-w);
  margin: 0 auto;
  padding: 36px 18px 14px;
  text-align: center;
}
.app-header h1 {
  margin: 0 0 8px;
  font-size: 1.65rem;
  font-weight: 900;
  background: var(--accent-grad);
  -webkit-background-clip: text;
  background-clip: text;
  color: transparent;
  letter-spacing: -0.01em;
}
.subtitle { margin: 0; color: var(--text-dim); font-size: 0.92rem; }

/* ---------------- شريط المراحل ---------------- */

.stage-nav {
  max-width: var(--max-w);
  margin: 22px auto 0;
  padding: 0 18px;
  display: flex;
  gap: 10px;
  overflow-x: auto;
  scrollbar-width: none;
}
.stage-nav::-webkit-scrollbar { display: none; }

.stage-tab {
  position: relative;
  flex: 1;
  min-width: 112px;
  background: var(--panel);
  backdrop-filter: blur(10px);
  border: 1px solid var(--border);
  border-radius: var(--radius-sm);
  padding: 12px 8px 10px;
  text-align: center;
  cursor: pointer;
  color: var(--text-dim);
  font-family: inherit;
  font-size: 0.82rem;
  transition: border-color .18s, color .18s, background .18s, transform .12s, box-shadow .18s;
}
.stage-tab:hover:not(.locked):not(.active) {
  border-color: rgba(255,255,255,0.18);
  transform: translateY(-2px);
}
.stage-tab .num {
  display: flex;
  align-items: center;
  justify-content: center;
  width: 26px;
  height: 26px;
  margin: 0 auto 6px;
  border-radius: 50%;
  background: var(--panel-2);
  color: var(--text-dim);
  font-size: 0.85rem;
  font-weight: 900;
  transition: background .18s, color .18s, box-shadow .18s;
}
.stage-tab.active {
  border-color: transparent;
  color: var(--text);
  background: linear-gradient(var(--panel-solid), var(--panel-solid)) padding-box,
              var(--accent-grad) border-box;
  border: 1px solid transparent;
  box-shadow: 0 8px 22px -10px rgba(99, 102, 246, 0.55);
}
.stage-tab.active .num {
  background: var(--accent-grad);
  color: #06101f;
  box-shadow: 0 0 0 4px var(--accent-soft);
}
.stage-tab.passed .num {
  background: var(--good-soft);
  color: var(--good);
}
.stage-tab.passed:not(.active) .num { background: rgba(34,197,94,0.16); }
.stage-tab.locked {
  cursor: not-allowed;
  color: var(--locked);
  opacity: 0.55;
}
.stage-tab.locked .num { font-size: 0.7rem; }

@media (max-width: 480px) {
  .stage-nav { flex-wrap: wrap; overflow-x: visible; }
  .stage-tab { flex: 1 1 30%; min-width: 0; }
}

/* ---------------- المحتوى ---------------- */

main {
  max-width: var(--max-w);
  margin: 22px auto 40px;
  padding: 0 18px;
}

.card {
  background: var(--panel);
  backdrop-filter: blur(14px);
  border: 1px solid var(--border);
  border-radius: var(--radius);
  padding: 24px;
  margin-bottom: 16px;
  box-shadow: var(--shadow);
  animation: cardIn .35s ease both;
}

.card h2 {
  margin: 0 0 12px;
  font-size: 1.18rem;
  font-weight: 700;
}

.card p { color: var(--text-dim); margin: 8px 0; }

table.code-table {
  width: 100%;
  border-collapse: separate;
  border-spacing: 0;
  margin: 14px 0;
  font-size: 0.92rem;
  border: 1px solid var(--border-soft);
  border-radius: var(--radius-sm);
  overflow: hidden;
}
table.code-table th, table.code-table td {
  border-bottom: 1px solid var(--border-soft);
  border-inline-start: 1px solid var(--border-soft);
  padding: 8px 6px;
  text-align: center;
}
table.code-table tr > *:first-child { border-inline-start: none; }
table.code-table tr:last-child th, table.code-table tr:last-child td { border-bottom: none; }
table.code-table th { background: var(--panel-2); color: var(--text-dim); font-weight: 700; }
table.code-table td { font-variant-numeric: tabular-nums; font-weight: 600; }

.formula-box {
  background: var(--panel-2);
  border: 1px dashed rgba(139, 92, 246, 0.4);
  border-radius: var(--radius-sm);
  padding: 13px 15px;
  margin: 12px 0;
  font-size: 0.95rem;
}

details.learn-box {
  background: var(--panel-2);
  border: 1px solid var(--border-soft);
  border-radius: var(--radius-sm);
  padding: 11px 15px;
  margin-bottom: 16px;
}
details.learn-box summary {
  cursor: pointer;
  font-weight: 700;
  color: #7fb0ff;
  list-style: none;
}
details.learn-box summary::-webkit-details-marker { display: none; }
details.learn-box summary::after {
  content: "◂";
  float: left;
  transition: transform .18s;
  color: var(--text-dim);
}
details.learn-box[open] summary::after { transform: rotate(-90deg); }
details.learn-box[open] summary { margin-bottom: 10px; }

.progress-row {
  display: flex;
  justify-content: space-between;
  align-items: center;
  margin-bottom: 16px;
  font-size: 0.85rem;
  color: var(--text-dim);
}
.progress-bar {
  flex: 1;
  height: 9px;
  background: var(--panel-2);
  border-radius: 6px;
  overflow: hidden;
  margin: 0 10px;
  box-shadow: inset 0 0 0 1px var(--border-soft);
}
.progress-bar > div {
  height: 100%;
  background: var(--accent-grad);
  border-radius: 6px;
  transition: width .3s ease;
}

.question-area {
  text-align: center;
  padding: 14px 0 8px;
}
.question-prompt {
  font-size: 1.5rem;
  font-weight: 800;
  margin-bottom: 4px;
  animation: fadeUp .3s ease both;
}
.question-sub {
  color: var(--text-dim);
  font-size: 0.88rem;
  margin-bottom: 20px;
  animation: fadeUp .3s ease both .03s;
}

.options-grid {
  display: grid;
  grid-template-columns: repeat(2, 1fr);
  gap: 10px;
  margin-bottom: 10px;
}

.opt-btn {
  background: var(--panel-2);
  border: 1px solid var(--border);
  color: var(--text);
  border-radius: var(--radius-sm);
  padding: 14px 6px;
  font-family: inherit;
  font-size: 1rem;
  font-weight: 600;
  cursor: pointer;
  transition: border-color .14s, transform .1s, background .14s, box-shadow .14s;
  animation: popIn .28s ease both;
}
.options-grid .opt-btn:nth-child(1) { animation-delay: .02s; }
.options-grid .opt-btn:nth-child(2) { animation-delay: .06s; }
.options-grid .opt-btn:nth-child(3) { animation-delay: .10s; }
.options-grid .opt-btn:nth-child(4) { animation-delay: .14s; }

.opt-btn:hover:not(:disabled) {
  border-color: var(--accent-1);
  background: var(--accent-soft);
  transform: translateY(-2px);
}
.opt-btn:active:not(:disabled) { transform: scale(0.97); }
.opt-btn.correct {
  background: var(--good-soft);
  border-color: var(--good);
  box-shadow: 0 0 0 1px var(--good) inset;
}
.opt-btn.wrong {
  background: var(--bad-soft);
  border-color: var(--bad);
  box-shadow: 0 0 0 1px var(--bad) inset;
  animation: shake .35s ease;
}
.opt-btn:disabled { cursor: default; }

.feedback {
  min-height: 26px;
  text-align: center;
  font-weight: 800;
  margin: 10px 0;
  font-size: 1.02rem;
}
.feedback.good { color: var(--good); }
.feedback.bad { color: var(--bad); }
.feedback.slow { color: var(--slow); font-size: 0.92rem; }

.insights-wrap { max-width: var(--max-w); margin: 14px auto 0; padding: 0 18px; }
.insights-wrap:empty { margin: 0; }
.insights-box {
  margin-bottom: 0;
  border-color: rgba(240, 180, 41, 0.28);
}
.insights-box summary { color: var(--slow); }
.insights-box p { font-size: 0.88rem; }
.insights-box b { color: var(--text); }
.tag-pct { color: var(--slow); font-weight: 600; }

.breakdown {
  background: var(--panel-2);
  border: 1px solid var(--border-soft);
  border-radius: var(--radius-sm);
  padding: 13px 15px;
  font-size: 0.9rem;
  margin-top: 10px;
  display: none;
}
.breakdown.show { display: block; animation: fadeUp .25s ease both; }
.breakdown div { margin: 3px 0; }
.breakdown .final {
  color: transparent;
  background: var(--accent-grad);
  -webkit-background-clip: text;
  background-clip: text;
  font-weight: 800;
  margin-top: 8px;
  font-size: 1.05rem;
}

.next-row {
  text-align: center;
  margin-top: 14px;
}

.primary-btn, .ghost-btn {
  font-family: inherit;
  border-radius: var(--radius-sm);
  padding: 12px 26px;
  font-size: 0.95rem;
  cursor: pointer;
  border: 1px solid transparent;
  transition: transform .12s, box-shadow .18s, filter .18s;
}
.primary-btn {
  background: var(--accent-grad);
  color: #06101f;
  font-weight: 800;
  box-shadow: 0 10px 24px -10px rgba(99, 102, 246, 0.65);
}
.primary-btn:hover { filter: brightness(1.08); transform: translateY(-1px); }
.primary-btn:active { transform: scale(0.98); }
.ghost-btn {
  background: transparent;
  color: var(--text-dim);
  border-color: var(--border);
}
.ghost-btn:hover { color: var(--bad); border-color: var(--bad); }

.lock-msg {
  text-align: center;
  color: var(--text-dim);
  padding: 40px 10px;
}

.app-footer {
  display: flex;
  justify-content: center;
  flex-wrap: wrap;
  gap: 10px;
  padding: 10px 18px 34px;
}
.ghost-btn.export-btn:hover { color: var(--accent-1); border-color: var(--accent-1); }

.timer-row {
  display: flex;
  justify-content: center;
  align-items: center;
  gap: 10px;
  margin: 2px 0 4px;
  font-size: 0.85rem;
  color: var(--text-dim);
}
.timer {
  min-width: 68px;
  text-align: center;
  padding: 3px 12px;
  border-radius: 999px;
  background: var(--panel-2);
  border: 1px solid var(--border-soft);
  font-weight: 700;
  font-variant-numeric: tabular-nums;
  color: var(--text);
  transition: color .2s, background .2s, border-color .2s;
}
.timer.frozen { color: var(--text-dim); }
.timer.slowish { color: var(--slow); background: var(--slow-soft); border-color: rgba(240, 180, 41, 0.45); }

.pass-banner {
  background: var(--good-soft);
  border: 1px solid var(--good);
  color: var(--good);
  border-radius: var(--radius-sm);
  padding: 13px 14px;
  text-align: center;
  font-weight: 800;
  margin-bottom: 14px;
  animation: popIn .35s ease both;
}
.pass-banner::before { content: "★ "; }

/* ---------------- حركات ---------------- */

@keyframes fadeUp {
  from { opacity: 0; transform: translateY(6px); }
  to { opacity: 1; transform: translateY(0); }
}
@keyframes popIn {
  from { opacity: 0; transform: scale(0.92); }
  to { opacity: 1; transform: scale(1); }
}
@keyframes cardIn {
  from { opacity: 0; transform: translateY(10px); }
  to { opacity: 1; transform: translateY(0); }
}
@keyframes shake {
  0%, 100% { transform: translateX(0); }
  25% { transform: translateX(4px); }
  75% { transform: translateX(-4px); }
}

@media (prefers-reduced-motion: reduce) {
  *, *::before, *::after { animation-duration: 0.001ms !important; }
}

@media (max-width: 420px) {
  .app-header { padding: 26px 14px 10px; }
  .app-header h1 { font-size: 1.3rem; }
  main, .stage-nav { padding-left: 12px; padding-right: 12px; }
  .card { padding: 18px 15px; }
  table.code-table { font-size: 0.8rem; }
  table.code-table th, table.code-table td { padding: 7px 3px; }
  .question-prompt { font-size: 1.3rem; }
}