/* ============================================
   PRACTICE PROBLEMS LANDING PAGE — Design System
   ============================================
   Follows the same pattern as the Interview Landing Page.
   - Display: JetBrains Mono (chips, title)
   - Body: Inter (descriptions, metadata)
   - Accent signature: Emerald (#10b981) for solved/active
   - Cyan (#06b6d4) for search/focus
   - Amber (#f59e0b) for medium difficulty
   - Warm charcoal background (#0c0c14)
   ============================================ */

/* ─── CSS Variables (scoped to practice page) ─── */
[data-page="practice"] {
  --pp-bg: #0c0c14;
  --pp-surface: #14141f;
  --pp-elevated: #1c1c2e;

  --pp-primary: #94a3b8;        /* neutral slate accent */
  --pp-primary-rgb: 148, 163, 184;
  --pp-search: #7dd3fc;         /* light sky blue */
  --pp-search-rgb: 125, 211, 252;
  --pp-accent: #fde68a;         /* light amber */
  --pp-text: #f1f5f9;
  --pp-text-muted: #8892a8;
  --pp-border: rgba(148, 163, 184, 0.12);
  --pp-border-hover: rgba(148, 163, 184, 0.25);
  --pp-radius: 12px;
  --pp-radius-lg: 20px;

  /* Difficulty colors - pastel (for filters, backgrounds) */
  --pp-easy-pastel:       #7dd3fc;  /* light sky blue */
  --pp-easy-pastel-rgb:   125, 211, 252;
  --pp-medium-pastel:     #fdba74;  /* light orange */
  --pp-medium-pastel-rgb: 253, 186, 116;
  --pp-hard-pastel:       #fca5a5;  /* light red */
  --pp-hard-pastel-rgb:   252, 165, 165;

  /* Difficulty colors - bold (for card labels only) */
  --pp-easy-bold:       #3b82f6;  /* vivid blue */
  --pp-easy-bold-rgb:   59, 130, 246;
  --pp-medium-bold:     #f97316;  /* vivid orange */
  --pp-medium-bold-rgb: 249, 115, 22;
  --pp-hard-bold:       #ef4444;  /* vivid red */
  --pp-hard-bold-rgb:   239, 68, 68;

  /* Category accent colors - pastel */
  --pp-cat-arrays:       #7dd3fc;  /* light blue */
  --pp-cat-arrays-rgb:   125, 211, 252;
  --pp-cat-strings:      #c4b5fd;  /* light lavender */
  --pp-cat-strings-rgb:  196, 181, 253;
  --pp-cat-linkedlist:   #fda4af;  /* light rose */
  --pp-cat-linkedlist-rgb: 253, 164, 175;
  --pp-cat-trees:        #6ee7b7;  /* light emerald */
  --pp-cat-trees-rgb:    110, 231, 183;
  --pp-cat-graphs:       #a3e635;  /* lime */
  --pp-cat-graphs-rgb:   163, 230, 53;
  --pp-cat-dp:           #fde68a;  /* light amber */
  --pp-cat-dp-rgb:       253, 230, 138;
  --pp-cat-matrix:       #a5b4fc;  /* light periwinkle */
  --pp-cat-matrix-rgb:   165, 180, 252;
}

/* ─── Hero Section ─── */
[data-page="practice"] .pp-hero {
  position: relative;
  padding: 8rem 1.5rem 3rem;
  text-align: center;
  overflow: hidden;
  background: var(--pp-bg);
  min-height: 60vh;
  display: flex;
  align-items: center;
  justify-content: center;
}

.pp-hero-bg {
  position: absolute;
  inset: 0;
  z-index: 0;
  overflow: hidden;
}

.pp-hero-glow {
  position: absolute;
  inset: 0;
  background: transparent;
  pointer-events: none;
}

.pp-hero-orb {
  display: none;
}

.pp-hero-content {
  position: relative;
  z-index: 1;
  max-width: 800px;
  width: 100%;
}

.pp-hero-title {
  font-family: 'JetBrains Mono', monospace;
  font-size: clamp(2.5rem, 6vw, 4.5rem);
  font-weight: 700;
  color: #a5b4fc;
  line-height: 1.1;
  margin-bottom: 1rem;
  letter-spacing: -1px;
  cursor: default;
  perspective: 800px;
  display: flex;
  flex-direction: column;
  align-items: center;
  gap: 0.15em;
}

/* ─── Letter Cascade Animation ─── */
.pp-title-word {
  display: flex;
  transform-style: preserve-3d;
}

.pp-title-char {
  display: inline-block;
  animation: ppCharReveal 0.5s cubic-bezier(0.34, 1.56, 0.64, 1) both;
  animation-delay: calc(var(--i) * 0.06s);
  transform-origin: center bottom;
  will-change: transform, opacity;
}

.pp-hero-subtitle {
  font-family: 'Inter', sans-serif;
  font-size: 1.05rem;
  color: var(--pp-text-muted);
  line-height: 1.6;
  max-width: 600px;
  margin: 0 auto 2rem;
}

/* ─── Search ─── */
.pp-search-wrapper {
  max-width: 520px;
  margin: 0 auto 1.5rem;
}

.pp-search {
  position: relative;
  display: flex;
  align-items: center;
  background: var(--pp-surface);
  border: 1px solid var(--pp-border);
  border-radius: 100px;
  transition: all 0.25s ease;
  overflow: hidden;
}

.pp-search:focus-within {
  border-color: var(--pp-search);
  box-shadow: 0 0 0 3px rgba(var(--pp-search-rgb), 0.12), 0 4px 20px rgba(var(--pp-search-rgb), 0.06);
  background: #16162a;
}

.pp-search-icon {
  position: absolute;
  left: 16px;
  color: var(--pp-text-muted);
  font-size: 0.9rem;
  pointer-events: none;
  transition: color 0.25s ease;
}

.pp-search:focus-within .pp-search-icon {
  color: var(--pp-search);
}

.pp-search-input {
  flex: 1;
  padding: 0.85rem 3rem 0.85rem 2.75rem;
  background: transparent;
  border: none;
  color: var(--pp-text);
  font-family: 'Inter', sans-serif;
  font-size: 0.95rem;
  outline: none;
}

.pp-search-input::placeholder {
  color: var(--pp-text-muted);
  opacity: 0.6;
}

.pp-clear-btn {
  position: absolute;
  right: 44px;
  background: none;
  border: none;
  color: var(--pp-text-muted);
  cursor: pointer;
  padding: 4px 6px;
  font-size: 0.85rem;
  border-radius: 50%;
  display: none;
  transition: all 0.2s ease;
}

.pp-clear-btn:hover {
  color: #ef4444;
  background: rgba(239, 68, 68, 0.1);
}

.pp-clear-btn.visible {
  display: flex;
}

.pp-search-hint {
  position: absolute;
  right: 14px;
  font-family: 'JetBrains Mono', monospace;
  font-size: 0.65rem;
  color: var(--pp-text-muted);
  opacity: 0.4;
  pointer-events: none;
  padding: 2px 6px;
  border: 1px solid var(--pp-border);
  border-radius: 4px;
}

/* ─── Filter Groups ─── */
.pp-filter-group {
  display: flex;
  align-items: center;
  justify-content: center;
  gap: 0.75rem;
  margin-bottom: 0.6rem;
  flex-wrap: wrap;
}

.pp-filter-label {
  font-family: 'JetBrains Mono', monospace;
  font-size: 0.65rem;
  font-weight: 600;
  text-transform: uppercase;
  letter-spacing: 0.8px;
  color: var(--pp-text-muted);
  opacity: 0.6;
  min-width: 60px;
  text-align: right;
}

.pp-filters {
  display: flex;
  flex-wrap: wrap;
  justify-content: center;
  gap: 0.4rem;
}

.pp-filter-chip {
  font-family: 'JetBrains Mono', monospace;
  font-size: 0.72rem;
  font-weight: 500;
  padding: 0.4rem 0.9rem;
  border-radius: 100px;
  background: transparent;
  border: 1px solid var(--pp-border);
  color: var(--pp-text-muted);
  cursor: pointer;
  transition: all 0.2s ease;
  white-space: nowrap;
}

/* ── Default category chip hover/active: pastel pink ── */
.pp-filter-chip:hover {
  border-color: var(--pp-primary);
  color: var(--pp-primary);
  background: rgba(var(--pp-primary-rgb), 0.15);
}

.pp-filter-chip.active {
  background: rgba(var(--pp-primary-rgb), 0.25);
  border-color: var(--pp-primary);
  color: #fff;
  box-shadow: 0 0 12px rgba(var(--pp-primary-rgb), 0.15);
}

/* ── Difficulty-specific chip states (pastel) ── */
.pp-filter-chip[data-difficulty="easy"].active {
  background: rgba(var(--pp-easy-pastel-rgb), 0.25);
  border-color: var(--pp-easy-pastel);
  color: #fff;
  box-shadow: 0 0 12px rgba(var(--pp-easy-pastel-rgb), 0.15);
}
.pp-filter-chip[data-difficulty="easy"]:hover {
  border-color: var(--pp-easy-pastel);
  color: var(--pp-easy-pastel);
  background: rgba(var(--pp-easy-pastel-rgb), 0.18);
}

.pp-filter-chip[data-difficulty="medium"].active {
  background: rgba(var(--pp-medium-pastel-rgb), 0.25);
  border-color: var(--pp-medium-pastel);
  color: #fff;
  box-shadow: 0 0 12px rgba(var(--pp-medium-pastel-rgb), 0.15);
}
.pp-filter-chip[data-difficulty="medium"]:hover {
  border-color: var(--pp-medium-pastel);
  color: var(--pp-medium-pastel);
  background: rgba(var(--pp-medium-pastel-rgb), 0.18);
}

.pp-filter-chip[data-difficulty="hard"].active {
  background: rgba(var(--pp-hard-pastel-rgb), 0.25);
  border-color: var(--pp-hard-pastel);
  color: #fff;
  box-shadow: 0 0 12px rgba(var(--pp-hard-pastel-rgb), 0.15);
}
.pp-filter-chip[data-difficulty="hard"]:hover {
  border-color: var(--pp-hard-pastel);
  color: var(--pp-hard-pastel);
  background: rgba(var(--pp-hard-pastel-rgb), 0.18);
}

/* ── Category-specific chip states (pastel) ── */
.pp-filter-chip[data-category="arrays"]:hover {
  border-color: var(--pp-cat-arrays);
  color: var(--pp-cat-arrays);
  background: rgba(var(--pp-cat-arrays-rgb), 0.18);
}
.pp-filter-chip[data-category="arrays"].active {
  background: rgba(var(--pp-cat-arrays-rgb), 0.3);
  border-color: var(--pp-cat-arrays);
  color: #fff;
  box-shadow: 0 0 12px rgba(var(--pp-cat-arrays-rgb), 0.15);
}

.pp-filter-chip[data-category="strings"]:hover {
  border-color: var(--pp-cat-strings);
  color: var(--pp-cat-strings);
  background: rgba(var(--pp-cat-strings-rgb), 0.18);
}
.pp-filter-chip[data-category="strings"].active {
  background: rgba(var(--pp-cat-strings-rgb), 0.3);
  border-color: var(--pp-cat-strings);
  color: #fff;
  box-shadow: 0 0 12px rgba(var(--pp-cat-strings-rgb), 0.15);
}

.pp-filter-chip[data-category="linkedlist"]:hover {
  border-color: var(--pp-cat-linkedlist);
  color: var(--pp-cat-linkedlist);
  background: rgba(var(--pp-cat-linkedlist-rgb), 0.18);
}
.pp-filter-chip[data-category="linkedlist"].active {
  background: rgba(var(--pp-cat-linkedlist-rgb), 0.3);
  border-color: var(--pp-cat-linkedlist);
  color: #fff;
  box-shadow: 0 0 12px rgba(var(--pp-cat-linkedlist-rgb), 0.15);
}

.pp-filter-chip[data-category="trees"]:hover {
  border-color: var(--pp-cat-trees);
  color: var(--pp-cat-trees);
  background: rgba(var(--pp-cat-trees-rgb), 0.18);
}
.pp-filter-chip[data-category="trees"].active {
  background: rgba(var(--pp-cat-trees-rgb), 0.3);
  border-color: var(--pp-cat-trees);
  color: #fff;
  box-shadow: 0 0 12px rgba(var(--pp-cat-trees-rgb), 0.15);
}

.pp-filter-chip[data-category="graphs"]:hover {
  border-color: var(--pp-cat-graphs);
  color: var(--pp-cat-graphs);
  background: rgba(var(--pp-cat-graphs-rgb), 0.18);
}
.pp-filter-chip[data-category="graphs"].active {
  background: rgba(var(--pp-cat-graphs-rgb), 0.3);
  border-color: var(--pp-cat-graphs);
  color: #fff;
  box-shadow: 0 0 12px rgba(var(--pp-cat-graphs-rgb), 0.15);
}

.pp-filter-chip[data-category="dp"]:hover {
  border-color: var(--pp-cat-dp);
  color: var(--pp-cat-dp);
  background: rgba(var(--pp-cat-dp-rgb), 0.18);
}
.pp-filter-chip[data-category="dp"].active {
  background: rgba(var(--pp-cat-dp-rgb), 0.3);
  border-color: var(--pp-cat-dp);
  color: #fff;
  box-shadow: 0 0 12px rgba(var(--pp-cat-dp-rgb), 0.15);
}

.pp-result-count {
  font-family: 'Inter', sans-serif;
  font-size: 0.85rem;
  color: var(--pp-text-muted);
  margin-top: 0.75rem;
}

.pp-result-count span {
  color: var(--pp-search);
  font-weight: 600;
  font-family: 'JetBrains Mono', monospace;
}

.pp-result-total {
  color: var(--pp-text-muted) !important;
  font-weight: 400 !important;
  opacity: 0.6;
}

/* ─── Section ─── */
.pp-section {
  padding: 2rem 1.5rem 5rem;
  background: var(--pp-bg);
}

.pp-container {
  max-width: 1200px;
  margin: 0 auto;
}

/* ─── Card Grid ─── */
.pp-grid {
  display: grid;
  grid-template-columns: repeat(auto-fill, minmax(280px, 1fr));
  gap: 1rem;
}

@media (min-width: 1024px) {
  .pp-grid {
    grid-template-columns: repeat(3, 1fr);
  }
}

@media (max-width: 768px) {
  .pp-grid {
    grid-template-columns: repeat(2, 1fr);
  }
}

@media (max-width: 480px) {
  .pp-grid {
    grid-template-columns: 1fr;
  }
}

/* ─── Card ─── */
.pp-card {
  position: relative;
  background: var(--pp-surface);
  border: 1px solid var(--pp-border);
  border-radius: var(--pp-radius);
  padding: 1.25rem;
  transition: all 0.25s cubic-bezier(0.4, 0, 0.2, 1);
  cursor: pointer;
  text-decoration: none;
  display: flex;
  flex-direction: column;
  gap: 0.6rem;
  isolation: isolate;
  overflow: hidden;
  text-align: left;
}

.pp-card::before {
  content: '';
  position: absolute;
  inset: -1px;
  border-radius: var(--pp-radius);
  background: linear-gradient(135deg, rgba(var(--pp-primary-rgb), 0.08), transparent 60%);
  opacity: 0;
  transition: opacity 0.3s ease;
  z-index: -1;
}

.pp-card:hover {
  border-color: var(--pp-border-hover);
  transform: translateY(-3px);
  box-shadow: 0 8px 30px rgba(0, 0, 0, 0.3);
}

.pp-card:hover::before {
  opacity: 1;
}

.pp-card:focus-visible {
  outline: 2px solid var(--pp-primary);
  outline-offset: 2px;
}

/* ─── Card Header ─── */
.pp-card-header {
  display: flex;
  align-items: flex-start;
  justify-content: space-between;
  gap: 0.5rem;
}

.pp-card-title {
  font-family: 'Inter', sans-serif;
  font-size: 0.95rem;
  font-weight: 600;
  color: var(--pp-text);
  line-height: 1.3;
  flex: 1;
}

.pp-card-difficulty {
  font-family: 'JetBrains Mono', monospace;
  font-size: 0.6rem;
  font-weight: 600;
  text-transform: uppercase;
  letter-spacing: 0.5px;
  padding: 0.2rem 0.5rem;
  border-radius: 4px;
  flex-shrink: 0;
  margin-top: 0.1rem;
}

.pp-card-difficulty.easy {
  color: var(--pp-easy-bold);
  background: rgba(var(--pp-easy-bold-rgb), 0.1);
  border: 1px solid rgba(var(--pp-easy-bold-rgb), 0.2);
}

.pp-card-difficulty.medium {
  color: var(--pp-medium-bold);
  background: rgba(var(--pp-medium-bold-rgb), 0.1);
  border: 1px solid rgba(var(--pp-medium-bold-rgb), 0.2);
}

.pp-card-difficulty.hard {
  color: var(--pp-hard-bold);
  background: rgba(var(--pp-hard-bold-rgb), 0.1);
  border: 1px solid rgba(var(--pp-hard-bold-rgb), 0.2);
}

/* ─── Card Description ─── */
.pp-card-desc {
  font-family: 'Inter', sans-serif;
  font-size: 0.78rem;
  color: var(--pp-text-muted);
  line-height: 1.5;
  display: -webkit-box;
  -webkit-line-clamp: 2;
  -webkit-box-orient: vertical;
  overflow: hidden;
}

/* ─── Card Tags ─── */
.pp-card-tags {
  display: flex;
  flex-wrap: wrap;
  gap: 0.3rem;
}

.pp-card-tag {
  font-family: 'JetBrains Mono', monospace;
  font-size: 0.62rem;
  font-weight: 600;
  padding: 0.2rem 0.5rem;
  border-radius: 4px;
  background: rgba(var(--pp-primary-rgb), 0.15);
  color: var(--pp-primary);
  border: 1px solid rgba(var(--pp-primary-rgb), 0.25);
}

/* ── Per-category card tag colors (pastel) ── */
.pp-card-tag[data-category="arrays"] {
  background: rgba(var(--pp-cat-arrays-rgb), 0.2);
  color: var(--pp-cat-arrays);
  border-color: rgba(var(--pp-cat-arrays-rgb), 0.35);
}
.pp-card-tag[data-category="strings"] {
  background: rgba(var(--pp-cat-strings-rgb), 0.2);
  color: var(--pp-cat-strings);
  border-color: rgba(var(--pp-cat-strings-rgb), 0.35);
}
.pp-card-tag[data-category="linkedlist"] {
  background: rgba(var(--pp-cat-linkedlist-rgb), 0.2);
  color: var(--pp-cat-linkedlist);
  border-color: rgba(var(--pp-cat-linkedlist-rgb), 0.35);
}
.pp-card-tag[data-category="trees"] {
  background: rgba(var(--pp-cat-trees-rgb), 0.2);
  color: var(--pp-cat-trees);
  border-color: rgba(var(--pp-cat-trees-rgb), 0.35);
}
.pp-card-tag[data-category="graphs"] {
  background: rgba(var(--pp-cat-graphs-rgb), 0.2);
  color: var(--pp-cat-graphs);
  border-color: rgba(var(--pp-cat-graphs-rgb), 0.35);
}
.pp-card-tag[data-category="dp"] {
  background: rgba(var(--pp-cat-dp-rgb), 0.2);
  color: var(--pp-cat-dp);
  border-color: rgba(var(--pp-cat-dp-rgb), 0.35);
}
.pp-card-tag[data-category="matrix"] {
  background: rgba(var(--pp-cat-matrix-rgb), 0.2);
  color: var(--pp-cat-matrix);
  border-color: rgba(var(--pp-cat-matrix-rgb), 0.35);
}

/* ─── Card Footer ─── */
.pp-card-footer {
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 0.5rem;
  padding-top: 0.5rem;
  margin-top: auto;
  border-top: 1px solid var(--pp-border);
}

.pp-card-acceptance {
  font-family: 'JetBrains Mono', monospace;
  font-size: 0.65rem;
  color: var(--pp-text-muted);
  display: flex;
  align-items: center;
  gap: 0.35rem;
}

.pp-card-acceptance i {
  color: var(--pp-search);
}

.pp-card-action {
  font-family: 'Inter', sans-serif;
  font-size: 0.75rem;
  font-weight: 500;
  color: var(--pp-search);
  display: flex;
  align-items: center;
  gap: 0.35rem;
  transition: all 0.2s ease;
}

.pp-card:hover .pp-card-action {
  gap: 0.5rem;
  color: var(--pp-primary);
}

.pp-card-action i {
  font-size: 0.65rem;
  transition: transform 0.2s ease;
}

.pp-card:hover .pp-card-action i {
  transform: translateX(3px);
}

/* ─── Card hover per-difficulty tints ─── */
.pp-card[data-difficulty="easy"]:hover {
  border-color: rgba(var(--pp-easy-pastel-rgb), 0.3);
  box-shadow: 0 8px 30px rgba(var(--pp-easy-pastel-rgb), 0.08), 0 0 0 1px rgba(var(--pp-easy-pastel-rgb), 0.05);
}
.pp-card[data-difficulty="easy"]:hover::before {
  background: linear-gradient(135deg, rgba(var(--pp-easy-pastel-rgb), 0.08), transparent 60%);
}
.pp-card[data-difficulty="easy"]:focus-visible {
  outline-color: var(--pp-easy-bold);
}

.pp-card[data-difficulty="medium"]:hover {
  border-color: rgba(var(--pp-medium-pastel-rgb), 0.3);
  box-shadow: 0 8px 30px rgba(var(--pp-medium-pastel-rgb), 0.08), 0 0 0 1px rgba(var(--pp-medium-pastel-rgb), 0.05);
}
.pp-card[data-difficulty="medium"]:hover::before {
  background: linear-gradient(135deg, rgba(var(--pp-medium-pastel-rgb), 0.08), transparent 60%);
}
.pp-card[data-difficulty="medium"]:focus-visible {
  outline-color: var(--pp-medium-bold);
}

.pp-card[data-difficulty="hard"]:hover {
  border-color: rgba(var(--pp-hard-pastel-rgb), 0.3);
  box-shadow: 0 8px 30px rgba(var(--pp-hard-pastel-rgb), 0.08), 0 0 0 1px rgba(var(--pp-hard-pastel-rgb), 0.05);
}
.pp-card[data-difficulty="hard"]:hover::before {
  background: linear-gradient(135deg, rgba(var(--pp-hard-pastel-rgb), 0.08), transparent 60%);
}
.pp-card[data-difficulty="hard"]:focus-visible {
  outline-color: var(--pp-hard-bold);
}

/* ─── Empty State ─── */
.pp-empty {
  text-align: center;
  padding: 4rem 2rem;
  color: var(--pp-text-muted);
}

.pp-empty i {
  font-size: 2.5rem;
  margin-bottom: 1rem;
  opacity: 0.4;
}

.pp-empty h3 {
  font-family: 'Space Grotesk', sans-serif;
  font-size: 1.2rem;
  color: var(--pp-text);
  margin-bottom: 0.5rem;
}

.pp-empty p {
  font-family: 'Inter', sans-serif;
  font-size: 0.9rem;
  margin-bottom: 1.5rem;
}

.pp-empty-reset-btn {
  font-family: 'Inter', sans-serif;
  font-size: 0.875rem;
  font-weight: 600;
  padding: 0.55rem 1.25rem;
  border-radius: 100px;
  background: rgba(var(--pp-primary-rgb), 0.12);
  border: 1px solid rgba(var(--pp-primary-rgb), 0.25);
  color: var(--pp-text);
  cursor: pointer;
  transition: all 0.2s ease;
  line-height: 1;
  display: inline-flex;
  align-items: center;
  gap: 0.45rem;
}

.pp-empty-reset-btn i {
  font-size: 0.8rem;
  opacity: 1;
  margin-bottom: 0;
  color: var(--pp-primary);
}

.pp-empty-reset-btn:hover {
  background: rgba(var(--pp-primary-rgb), 0.2);
  border-color: rgba(var(--pp-primary-rgb), 0.4);
}

.pp-empty-reset-btn:focus-visible {
  outline: 2px solid var(--pp-primary);
  outline-offset: 3px;
}

/* ─── Data Loading Debug ─── */
.pp-data-error {
  text-align: center;
  padding: 2rem;
  color: var(--pp-hard);
  font-family: 'JetBrains Mono', monospace;
  font-size: 0.85rem;
}

.pp-data-error i {
  font-size: 2rem;
  margin-bottom: 1rem;
  display: block;
}

.pp-data-error a {
  color: var(--pp-search);
  text-decoration: underline;
}

/* ─── Surprise Me Button ─── */
.pp-surprise-row {
  display: flex;
  justify-content: center;
  margin-bottom: 1rem;
}

.pp-surprise-btn {
  position: relative;
  display: inline-flex;
  align-items: center;
  gap: 0.5rem;
  padding: 0.6rem 1.4rem;
  border: 1px solid var(--pp-border);
  border-radius: 100px;
  background: var(--pp-surface);
  color: var(--pp-primary);
  font-family: 'JetBrains Mono', monospace;
  font-weight: 600;
  font-size: 0.8rem;
  letter-spacing: 0.02em;
  cursor: pointer;
  transition: all 0.25s ease;
  white-space: nowrap;
}

.pp-surprise-btn:hover {
  border-color: #ffb3ba;
  color: #ffb3ba;
  background: rgba(255, 179, 186, 0.08);
}

.pp-surprise-btn:active {
  transform: translateY(0);
}

.pp-surprise-btn .pp-surprise-icon {
  font-size: 0.9rem;
  transition: transform 0.3s ease;
}

.pp-surprise-btn:hover .pp-surprise-icon {
  transform: rotate(45deg);
}

/* Button animation on click */
.pp-surprise-btn.pp-surprise-rolling {
  pointer-events: none;
  opacity: 0.7;
}

.pp-surprise-btn.pp-surprise-rolling .pp-surprise-icon.pp-icon-spin {
  animation: ppIconSpin 0.6s ease-in-out;
}

@keyframes ppIconSpin {
  0% {
    transform: rotate(0deg);
  }
  50% {
    transform: rotate(180deg) scale(1.2);
  }
  100% {
    transform: rotate(360deg);
  }
}

/* Highlight animation for the selected problem card */
@keyframes ppSurpriseHighlight {
  0% {
    border-color: var(--pp-border);
  }
  30% {
    border-color: var(--pp-search);
    background: rgba(var(--pp-search-rgb), 0.06);
  }
  60% {
    border-color: var(--pp-search);
    background: rgba(var(--pp-search-rgb), 0.03);
  }
  100% {
    border-color: var(--pp-border);
    background: transparent;
  }
}

.pp-card.pp-surprise-highlight {
  animation: ppSurpriseHighlight 4s ease;
  border-color: var(--pp-search) !important;
}

/* Mobile responsive */
@media (max-width: 768px) {
  .pp-surprise-btn {
    padding: 0.5rem 1rem;
    font-size: 0.75rem;
    gap: 0.35rem;
  }
  .pp-surprise-btn .pp-surprise-icon {
    font-size: 0.8rem;
  }
}

/* ─── Animation ─── */
[data-page="practice"] .pp-card {
  animation: ppCardFadeIn 0.35s ease both;
}

@keyframes ppCharReveal {
  0% {
    opacity: 0;
    transform: rotateX(-90deg) translateY(8px);
    filter: blur(4px);
  }
  60% {
    opacity: 1;
    filter: blur(0);
  }
  100% {
    opacity: 1;
    transform: rotateX(0deg) translateY(0);
  }
}

@keyframes ppCardFadeIn {
  from {
    opacity: 0;
    transform: translateY(10px);
  }
  to {
    opacity: 1;
    transform: translateY(0);
  }
}

/* ─── Back Button ─── */
.pp-back-btn {
  position: absolute;
  top: 2rem;
  left: 1.5rem;
  z-index: 10;
  display: inline-flex;
  align-items: center;
  gap: 0.5rem;
  padding: 0.55rem 1rem 0.55rem 0.85rem;
  background: var(--pp-surface);
  border: 1px solid var(--pp-border);
  border-radius: 100px;
  color: var(--pp-text-muted);
  font-family: 'Inter', sans-serif;
  font-size: 0.85rem;
  cursor: pointer;
  transition: all 0.2s ease;
  backdrop-filter: blur(8px);
  -webkit-backdrop-filter: blur(8px);
}

.pp-back-btn i {
  font-size: 0.85rem;
  transition: transform 0.2s ease;
}

.pp-back-btn span {
  font-weight: 500;
}

.pp-back-btn:hover {
  border-color: #ffb3ba;
  color: #ffb3ba;
  background: rgba(255, 179, 186, 0.08);
}

.pp-back-btn:hover i {
  transform: translateX(-3px);
}

.pp-back-btn:focus-visible {
  outline: 2px solid #ffb3ba;
  outline-offset: 2px;
}

/* ─── Responsive ─── */
@media (max-width: 768px) {
  [data-page="practice"] .pp-hero {
    padding: 6rem 1rem 2.5rem;
    min-height: auto;
  }

  .pp-hero-title {
    font-size: 2rem;
  }

  .pp-hero-subtitle {
    font-size: 0.9rem;
  }

  .pp-search-input {
    font-size: 0.9rem;
    padding: 0.75rem 2.5rem 0.75rem 2.5rem;
  }

  .pp-filter-group {
    flex-direction: column;
    gap: 0.4rem;
    align-items: center;
  }

  .pp-filter-label {
    text-align: center;
    min-width: auto;
  }

  .pp-filter-chip {
    font-size: 0.68rem;
    padding: 0.35rem 0.65rem;
  }

  .pp-grid {
    gap: 0.75rem;
  }

  .pp-search-hint {
    display: none;
  }

  .pp-back-btn {
    top: 1rem;
    left: 0.75rem;
    padding: 0.45rem 0.75rem 0.45rem 0.65rem;
    font-size: 0.8rem;
  }
  .pp-back-btn span {
    display: none;
  }
}

/* ─── Reduced Motion ─── */
@media (prefers-reduced-motion: reduce) {
  .pp-back-btn {
    transition: none;
  }
  .pp-back-btn i {
    transition: none;
  }
  .pp-back-btn:hover i {
    transform: none;
  }

  .pp-card {
    animation: none;
  }
  .pp-card:hover {
    transform: none;
  }
  .pp-card:hover .pp-card-action i {
    transform: none;
  }
  .pp-card:hover .pp-card-action {
    gap: 0.35rem;
  }

  .pp-search {
    transition: none;
  }
  .pp-filter-chip {
    transition: none;
  }

  .pp-title-char {
    animation: none;
  }

  .pp-hero-title {
    animation: none;
  }

  /* Surprise Me - reduced motion */
  .pp-surprise-btn {
    transition: none;
  }
  .pp-surprise-btn:hover {
    border-color: var(--pp-border);
    color: #ffb3ba;
    background: rgba(255, 179, 186, 0.08);
  }
  .pp-surprise-btn:hover .pp-surprise-icon {
    transform: none;
  }
  .pp-surprise-btn.pp-surprise-rolling {
    opacity: 1;
  }
  .pp-surprise-btn.pp-surprise-rolling .pp-surprise-icon.pp-icon-spin {
    animation: none;
  }
  .pp-card.pp-surprise-highlight {
    animation: none;
    border-color: var(--pp-search) !important;
  }
}