/* ═══════════════════════════════════════════════════════════════
   Exam Preparation Module — shared styles
   Used by exam-prep*.html pages.
   ═══════════════════════════════════════════════════════════════ */

.sb-content { padding: 0; overflow-y: auto; }

/* ── Outer wrapper ─────────────────────────────────────────────── */
.ep-wrap {
  max-width: 1080px;
  margin: 0 auto;
  padding: 28px 24px 80px;
  width: 100%;
}

/* ── Page header ───────────────────────────────────────────────── */
.ep-header {
  display: flex; align-items: center; gap: 14px;
  margin-bottom: 18px; flex-wrap: wrap;
}
.ep-icon {
  width: 52px; height: 52px; border-radius: 14px; flex-shrink: 0;
  background: linear-gradient(135deg, rgba(155,93,229,.22), rgba(6,214,224,.16));
  border: 1.5px solid rgba(255,255,255,.1);
  display: flex; align-items: center; justify-content: center;
}
.ep-icon svg { width: 26px; height: 26px; stroke: var(--violet); stroke-width: 1.8; fill: none; }
.ep-title  { font-family: 'Unbounded', sans-serif; font-size: 1.35rem; font-weight: 800; letter-spacing: -.02em; }
.ep-sub    { font-size: .82rem; color: var(--text-2); margin-top: 2px; }

/* ── Tabs bar ──────────────────────────────────────────────────── */
.ep-tabs {
  display: flex; gap: 4px; margin: 18px 0 26px;
  border-bottom: 1.5px solid var(--border);
  overflow-x: auto;
}
.ep-tab {
  display: inline-flex; align-items: center; gap: 7px;
  padding: 10px 16px;
  font-family: 'Manrope', sans-serif; font-size: .9rem; font-weight: 600;
  color: var(--text-2); text-decoration: none;
  border-bottom: 2.5px solid transparent;
  transition: color .15s, border-color .15s;
  white-space: nowrap;
}
.ep-tab:hover  { color: var(--violet); }
.ep-tab.active { color: var(--violet); border-bottom-color: var(--violet); }
.ep-tab svg    { width: 15px; height: 15px; stroke-width: 2; }

/* ── Cards / sections ──────────────────────────────────────────── */
.ep-card {
  background: var(--surface);
  border: 1.5px solid var(--border);
  border-radius: 14px;
  padding: 20px 22px;
  margin-bottom: 16px;
  transition: border-color .15s;
}
.ep-card:hover { border-color: var(--border-h); }
.ep-card h3 {
  font-family: 'Unbounded', sans-serif;
  font-size: 1rem; font-weight: 800;
  margin-bottom: 12px;
  letter-spacing: -.01em;
}
.ep-card .ep-card-hint {
  font-size: .8rem; color: var(--text-3); margin-bottom: 14px;
}

/* ── Stat grid for dashboard ───────────────────────────────────── */
.ep-stats {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(160px, 1fr));
  gap: 12px;
  margin-bottom: 24px;
}
.ep-stat {
  background: var(--surface);
  border: 1.5px solid var(--border);
  border-radius: 12px;
  padding: 16px 18px;
}
.ep-stat-label {
  font-size: .72rem; font-weight: 700; text-transform: uppercase;
  letter-spacing: .04em; color: var(--text-3);
  margin-bottom: 8px;
}
.ep-stat-value {
  font-family: 'Unbounded', sans-serif;
  font-size: 1.5rem; font-weight: 800; line-height: 1; letter-spacing: -.02em;
  color: var(--text);
}
.ep-stat-value.ep-violet { color: var(--violet); }
.ep-stat-value.ep-good   { color: #06D6A0; }
.ep-stat-value.ep-warn   { color: #F8961E; }
.ep-stat-sub {
  font-size: .72rem; color: var(--text-3); margin-top: 4px;
}

/* ── Progress bar ──────────────────────────────────────────────── */
.ep-bar {
  height: 8px;
  background: rgba(155,93,229,.10);
  border-radius: 999px;
  overflow: hidden;
  margin-top: 10px;
}
.ep-bar-fill {
  height: 100%;
  background: linear-gradient(90deg, var(--violet), #06D6E0);
  border-radius: 999px;
  transition: width .35s ease;
}

/* ── Empty / placeholder state ─────────────────────────────────── */
.ep-empty {
  padding: 56px 20px; text-align: center; color: var(--text-3);
}
.ep-empty svg {
  width: 44px; height: 44px; opacity: .45; margin-bottom: 12px;
  stroke: var(--text-3); stroke-width: 1.5; fill: none;
}
.ep-empty h4 {
  font-family: 'Unbounded', sans-serif;
  font-size: 1rem; font-weight: 700; color: var(--text-2);
  margin-bottom: 6px;
}
.ep-empty p { font-size: .85rem; max-width: 380px; margin: 0 auto; }

/* ── CTA action buttons ────────────────────────────────────────── */
.ep-cta-row {
  display: flex; flex-wrap: wrap; gap: 10px; margin-top: 14px;
}
.ep-btn {
  display: inline-flex; align-items: center; gap: 8px;
  padding: 9px 18px;
  border: 1.5px solid var(--violet);
  border-radius: 10px;
  background: rgba(155,93,229,.08);
  color: var(--violet);
  font-family: 'Manrope', sans-serif; font-size: .88rem; font-weight: 700;
  cursor: pointer; transition: all .15s;
  text-decoration: none;
}
.ep-btn:hover { background: var(--violet); color: #fff; }
.ep-btn.ep-btn-primary {
  background: var(--violet); color: #fff;
}
.ep-btn.ep-btn-primary:hover { filter: brightness(1.08); }
.ep-btn svg { width: 14px; height: 14px; stroke-width: 2; }

/* ── Skeleton loaders ──────────────────────────────────────────── */
.ep-skel {
  background: linear-gradient(90deg, rgba(15,23,42,.05) 0%, rgba(15,23,42,.10) 50%, rgba(15,23,42,.05) 100%);
  background-size: 200% 100%;
  animation: ep-skel-anim 1.4s ease-in-out infinite;
  border-radius: 6px;
  display: inline-block;
}
@keyframes ep-skel-anim {
  0%   { background-position: 100% 0; }
  100% { background-position: -100% 0; }
}

/* ═══════════════════════════════════════════════════════════════
   Variants view (`vp-*`)  — used by exam-prep-variants.html
   ═══════════════════════════════════════════════════════════════ */

/* Picker button in the header row */
.vp-picker-btn {
  display: inline-flex; align-items: center; gap: 8px;
  padding: 9px 16px;
  border: 1.5px solid var(--border-h);
  border-radius: 10px;
  background: var(--surface); color: var(--text);
  font-family: 'Manrope', sans-serif; font-size: .88rem; font-weight: 700;
  cursor: pointer; transition: all .15s; white-space: nowrap;
}
.vp-picker-btn:hover { border-color: var(--violet); color: var(--violet); }
.vp-picker-btn .vp-chev {
  width: 14px; height: 14px; transition: transform .2s;
}
.vp-picker-btn.open .vp-chev { transform: rotate(180deg); }

/* Picker overlay */
.vp-overlay {
  display: none; position: fixed; inset: 0;
  background: rgba(15,23,42,.55); z-index: 300;
  align-items: flex-start; justify-content: center; padding-top: 80px;
  backdrop-filter: blur(2px);
}
.vp-overlay.visible { display: flex; }
.vp-panel {
  background: var(--surface); border: 1.5px solid var(--border);
  border-radius: 16px; box-shadow: 0 24px 64px rgba(0,0,0,.32);
  width: min(680px, 94vw); max-height: calc(100vh - 120px);
  overflow-y: auto; padding: 22px 22px 26px;
  animation: vp-in .18s ease;
}
@keyframes vp-in {
  from { opacity: 0; transform: translateY(-12px); }
  to   { opacity: 1; transform: translateY(0); }
}
.vp-panel-head {
  display: flex; align-items: center; justify-content: space-between; margin-bottom: 18px;
}
.vp-panel-head h2 {
  font-family: 'Unbounded', sans-serif; font-size: 1rem; font-weight: 800;
}
.vp-panel-close {
  width: 32px; height: 32px; border: none; background: none;
  color: var(--text-2); cursor: pointer; border-radius: 8px;
  display: flex; align-items: center; justify-content: center; transition: background .15s;
}
.vp-panel-close:hover { background: var(--border); color: var(--text); }
.vp-panel-close svg { width: 18px; height: 18px; }

/* Variants grid in the picker */
.vp-grid {
  display: grid; grid-template-columns: repeat(10, 1fr); gap: 6px;
}
.vg-btn {
  aspect-ratio: 1; border: 1.5px solid var(--border-h); border-radius: 8px;
  background: transparent; color: var(--text-2);
  font-family: 'Manrope', sans-serif; font-size: .82rem; font-weight: 700;
  cursor: pointer; transition: all .12s; line-height: 1;
}
.vg-btn:hover    { border-color: var(--violet); color: var(--violet); }
.vg-btn.active   { background: var(--violet); border-color: var(--violet); color: #fff; }
.vg-btn.done     { background: rgba(6,214,160,.15); border-color: #06D6A0; color: #06D6A0; }
.vg-btn.done:hover { background: rgba(6,214,160,.25); }
.vg-btn.done.active { background: #06D6A0; border-color: #06D6A0; color: #fff; }
.vg-btn.partial  { background: rgba(248,150,30,.13); border-color: #F8961E; color: #F8961E; }
.vg-btn.partial:hover { background: rgba(248,150,30,.22); }

@media (max-width: 540px) {
  .vp-grid { grid-template-columns: repeat(8, 1fr); }
}

/* Variant title + tasks */
.vp-title {
  font-family: 'Unbounded', sans-serif; font-size: 1.35rem; font-weight: 800;
  letter-spacing: -.02em; margin-bottom: 18px;
}
.vp-title small {
  font-family: 'Manrope', sans-serif; font-size: .82rem; font-weight: 500;
  color: var(--text-2); margin-left: 10px;
}

.vp-task {
  background: var(--surface); border: 1.5px solid var(--border);
  border-radius: 14px; margin-bottom: 14px; overflow: hidden;
  transition: border-color .15s;
}
.vp-task:hover { border-color: var(--border-h); }
.vp-task-header {
  display: flex; align-items: center; gap: 12px;
  padding: 12px 22px; background: rgba(155,93,229,.04);
  border-bottom: 1.5px solid var(--border);
}
.vp-task-num {
  width: 28px; height: 28px; border-radius: 50%;
  background: var(--violet); color: #fff;
  font-family: 'Unbounded', sans-serif; font-size: .82rem; font-weight: 800;
  display: flex; align-items: center; justify-content: center; flex-shrink: 0;
}
.vp-task-label {
  font-family: 'Unbounded', sans-serif; font-size: .82rem; font-weight: 700;
  color: var(--text-2); letter-spacing: .02em;
}
.vp-task-body { padding: 18px 24px; font-size: .98rem; line-height: 1.8; }
.vp-task-text .katex-display { margin: 12px 0 6px; overflow-x: auto; }
.vp-task-figure { margin: 14px 0 4px; }
.vp-task-figure svg, .vp-task-figure img { max-width: 100%; height: auto; }

.vp-opts {
  display: flex; flex-wrap: wrap; gap: 10px 32px;
  margin-top: 14px; padding-top: 14px; border-top: 1px solid var(--border);
  align-items: center;
}
.vp-opts-vertical {
  display: flex; flex-direction: column; gap: 8px;
  margin-top: 14px; padding-top: 14px; border-top: 1px solid var(--border);
}
.vp-opt { display: inline-flex; align-items: flex-start; gap: 6px; }
.vp-opt-lbl {
  font-family: 'Unbounded', sans-serif; font-weight: 800;
  color: var(--violet); font-size: .9rem; white-space: nowrap;
}

/* Solution toggle */
.vp-sol-wrap { padding: 0 22px 16px; }
.vp-sol-btn {
  display: inline-flex; align-items: center; gap: 7px;
  padding: 6px 14px; border: 1.5px solid #06D6A0; border-radius: 8px;
  background: transparent; color: #06D6A0;
  font-family: 'Manrope', sans-serif; font-size: .85rem; font-weight: 700;
  cursor: pointer; transition: all .15s;
}
.vp-sol-btn:hover { background: rgba(6,214,160,.12); }
.vp-sol-btn.open  { background: #06D6A0; border-color: #06D6A0; color: #fff; }
.vp-sol-btn svg   { width: 13px; height: 13px; transition: transform .2s; }
.vp-sol-btn.open svg { transform: rotate(90deg); }

.vp-sol-panel {
  display: none; margin-top: 14px; padding: 16px 20px;
  background: rgba(6,214,160,.06); border-radius: 10px;
  border-left: 3px solid #06D6A0;
  line-height: 1.85; font-size: .94rem;
}
.vp-sol-panel.visible { display: block; }
.vp-sol-panel .katex-display { margin: 10px 0 6px; overflow-x: auto; }
.vp-sol-panel ul { margin: 6px 0 6px 22px; }
.vp-sol-panel li { margin: 3px 0; }
.vp-sol-panel .sol-ans {
  display: inline-block; margin-top: 12px; padding: 4px 14px;
  background: rgba(6,214,160,.2); border-radius: 6px;
  font-family: 'Unbounded', sans-serif; font-weight: 800; color: #06D6A0;
}

/* ── Mobile tweaks ─────────────────────────────────────────────── */
@media (max-width: 640px) {
  .ep-wrap   { padding: 20px 16px 60px; }
  .ep-title  { font-size: 1.15rem; }
  .ep-tabs   { gap: 0; }
  .ep-tab    { padding: 9px 12px; font-size: .82rem; }
  .ep-card   { padding: 16px 18px; }
  .ep-stat   { padding: 14px 16px; }
  .vp-task-body { padding: 14px 18px; }
  .vp-sol-wrap  { padding: 0 18px 14px; }
  .vp-sol-panel { padding: 14px 16px; }
}