/* ============================================================
   JEET PHYSICS — Numerical Solutions Exam Page Styles
   Premium Dark Cosmic Theme
   ============================================================ */

/* ---- 1. CSS Variables ---- */
:root {
  /* Inherited from parent site */
  --bg-deep: #020818;
  --bg-dark: #050d1f;
  --bg-card: rgba(8, 20, 50, 0.75);
  --bg-card-hover: rgba(12, 28, 65, 0.85);
  --bg-surface: rgba(10, 24, 56, 0.6);
  --border: rgba(82, 160, 255, 0.18);
  --border-glow: rgba(82, 160, 255, 0.45);
  --border-subtle: rgba(82, 160, 255, 0.08);
  --blue-400: #3b82f6;
  --blue-500: #2563eb;
  --blue-600: #1d4ed8;
  --gold-400: #fbbf24;
  --gold-500: #f59e0b;
  --green-400: #34d399;
  --green-500: #10b981;
  --red-400: #f87171;
  --red-500: #ef4444;
  --purple-400: #a78bfa;
  --purple-500: #8b5cf6;
  --cyan-400: #22d3ee;
  --text-primary: #e8f0ff;
  --text-secondary: #9ab3d8;
  --text-muted: #5a7a9f;
  --font-heading: 'Outfit', sans-serif;
  --font-body: 'Inter', sans-serif;
  --font-mono: 'JetBrains Mono', 'Fira Code', monospace;
  --radius-sm: 8px;
  --radius-md: 14px;
  --radius-lg: 20px;
  --radius-xl: 28px;
  --radius-full: 9999px;
  --shadow-sm: 0 2px 8px rgba(0, 0, 0, 0.25);
  --shadow-md: 0 4px 20px rgba(0, 0, 0, 0.35);
  --shadow-lg: 0 8px 40px rgba(0, 0, 0, 0.45);
  --shadow-glow: 0 0 30px rgba(59, 130, 246, 0.15);
  --transition-fast: 0.2s cubic-bezier(0.4, 0, 0.2, 1);
  --transition-base: 0.35s cubic-bezier(0.4, 0, 0.2, 1);
  --transition-slow: 0.5s cubic-bezier(0.22, 1, 0.36, 1);

  /* Exam-specific variables */
  --exam-accent: var(--blue-400);
  --exam-accent-glow: rgba(59, 130, 246, 0.3);
  --easy-color: var(--green-400);
  --easy-bg: rgba(52, 211, 153, 0.1);
  --easy-border: rgba(52, 211, 153, 0.3);
  --moderate-color: var(--gold-400);
  --moderate-bg: rgba(251, 191, 36, 0.1);
  --moderate-border: rgba(251, 191, 36, 0.3);
  --advanced-color: var(--purple-400);
  --advanced-bg: rgba(167, 139, 250, 0.1);
  --advanced-border: rgba(167, 139, 250, 0.3);
  --nav-height: 70px;
  --sidebar-width: 340px;
  --content-max: 1400px;
  --card-padding: 28px;
}


/* ---- 2. Reset & Base ---- */
*,
*::before,
*::after {
  margin: 0;
  padding: 0;
  box-sizing: border-box;
}

html {
  scroll-behavior: smooth;
  scroll-padding-top: calc(var(--nav-height) + 20px);
}

body {
  font-family: var(--font-body);
  background: var(--bg-deep);
  color: var(--text-primary);
  line-height: 1.7;
  font-size: 15px;
  min-height: 100vh;
  -webkit-font-smoothing: antialiased;
  -moz-osx-font-smoothing: grayscale;
  overflow-x: hidden;
}

/* Cosmic background gradient */
body::before {
  content: '';
  position: fixed;
  inset: 0;
  background:
    radial-gradient(ellipse 80% 60% at 20% 10%, rgba(59, 130, 246, 0.06) 0%, transparent 60%),
    radial-gradient(ellipse 60% 50% at 80% 80%, rgba(139, 92, 246, 0.05) 0%, transparent 55%),
    radial-gradient(ellipse 50% 40% at 50% 50%, rgba(52, 211, 153, 0.03) 0%, transparent 50%);
  pointer-events: none;
  z-index: 0;
}

/* Custom scrollbar */
::-webkit-scrollbar {
  width: 8px;
  height: 8px;
}

::-webkit-scrollbar-track {
  background: var(--bg-deep);
}

::-webkit-scrollbar-thumb {
  background: rgba(82, 160, 255, 0.2);
  border-radius: var(--radius-full);
  border: 2px solid transparent;
  background-clip: content-box;
}

::-webkit-scrollbar-thumb:hover {
  background: rgba(82, 160, 255, 0.35);
  background-clip: content-box;
}

/* Selection */
::selection {
  background: rgba(59, 130, 246, 0.3);
  color: #fff;
}

a {
  color: var(--blue-400);
  text-decoration: none;
  transition: color var(--transition-fast);
}

a:hover {
  color: #60a5fa;
}

img {
  max-width: 100%;
  display: block;
}


/* ---- 3. Top Navigation Bar ---- */
.exam-nav {
  position: fixed;
  top: 0;
  left: 0;
  right: 0;
  height: var(--nav-height);
  z-index: 1000;
  background: rgba(2, 8, 24, 0.82);
  backdrop-filter: blur(20px) saturate(1.4);
  -webkit-backdrop-filter: blur(20px) saturate(1.4);
  border-bottom: 1px solid var(--border);
  display: flex;
  align-items: center;
  padding: 0 clamp(16px, 3vw, 40px);
  transition: background var(--transition-base), box-shadow var(--transition-base);
}

.exam-nav.scrolled {
  background: rgba(2, 8, 24, 0.95);
  box-shadow: 0 4px 30px rgba(0, 0, 0, 0.4);
}

.exam-nav__inner {
  display: flex;
  align-items: center;
  justify-content: space-between;
  width: 100%;
  max-width: var(--content-max);
  margin: 0 auto;
}

.exam-nav__back {
  display: flex;
  align-items: center;
  gap: 10px;
  color: var(--text-secondary);
  font-size: 14px;
  font-weight: 500;
  padding: 8px 16px;
  border-radius: var(--radius-sm);
  transition: all var(--transition-fast);
  text-decoration: none;
}

.exam-nav__back:hover {
  color: var(--text-primary);
  background: rgba(82, 160, 255, 0.08);
}

.exam-nav__back svg,
.exam-nav__back i {
  font-size: 18px;
  transition: transform var(--transition-fast);
}

.exam-nav__back:hover svg,
.exam-nav__back:hover i {
  transform: translateX(-3px);
}

.exam-nav__brand {
  font-family: var(--font-heading);
  font-size: 20px;
  font-weight: 700;
  background: linear-gradient(135deg, var(--blue-400), var(--cyan-400));
  -webkit-background-clip: text;
  background-clip: text;
  -webkit-text-fill-color: transparent;
  letter-spacing: -0.3px;
}

.exam-nav__links {
  display: flex;
  align-items: center;
  gap: 6px;
  list-style: none;
}

.exam-nav__links a {
  display: flex;
  align-items: center;
  gap: 7px;
  padding: 8px 16px;
  color: var(--text-secondary);
  font-size: 13.5px;
  font-weight: 500;
  border-radius: var(--radius-sm);
  transition: all var(--transition-fast);
  text-decoration: none;
  position: relative;
}

.exam-nav__links a:hover,
.exam-nav__links a.active {
  color: var(--text-primary);
  background: rgba(82, 160, 255, 0.08);
}

.exam-nav__links a.active::after {
  content: '';
  position: absolute;
  bottom: -1px;
  left: 16px;
  right: 16px;
  height: 2px;
  background: linear-gradient(90deg, var(--blue-400), var(--cyan-400));
  border-radius: 2px;
}


/* ---- 4. Exam Header Section ---- */
.exam-header {
  position: relative;
  padding: calc(var(--nav-height) + 50px) clamp(16px, 3vw, 40px) 50px;
  text-align: center;
  overflow: hidden;
}

.exam-header::before {
  content: '';
  position: absolute;
  top: 0;
  left: 50%;
  transform: translateX(-50%);
  width: 800px;
  height: 500px;
  background: radial-gradient(ellipse, rgba(59, 130, 246, 0.08) 0%, transparent 70%);
  pointer-events: none;
}

.exam-header__icon {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  width: 80px;
  height: 80px;
  border-radius: var(--radius-lg);
  background: linear-gradient(135deg, rgba(59, 130, 246, 0.15), rgba(139, 92, 246, 0.12));
  border: 1px solid var(--border);
  font-size: 36px;
  margin-bottom: 24px;
  position: relative;
  z-index: 1;
  animation: floatIcon 4s ease-in-out infinite;
}

@keyframes floatIcon {
  0%, 100% { transform: translateY(0); }
  50% { transform: translateY(-8px); }
}

.exam-header__title {
  font-family: var(--font-heading);
  font-size: clamp(28px, 5vw, 48px);
  font-weight: 800;
  background: linear-gradient(135deg, #fff 0%, #a5c8ff 50%, var(--blue-400) 100%);
  -webkit-background-clip: text;
  background-clip: text;
  -webkit-text-fill-color: transparent;
  letter-spacing: -0.5px;
  line-height: 1.15;
  margin-bottom: 12px;
  position: relative;
  z-index: 1;
}

.exam-header__subtitle {
  font-family: var(--font-heading);
  font-size: clamp(15px, 2vw, 18px);
  color: var(--text-secondary);
  font-weight: 400;
  margin-bottom: 16px;
  position: relative;
  z-index: 1;
}

.exam-header__description {
  max-width: 650px;
  margin: 0 auto 36px;
  color: var(--text-muted);
  font-size: 14.5px;
  line-height: 1.7;
  position: relative;
  z-index: 1;
}

/* Stat cards row */
.exam-stats {
  display: flex;
  justify-content: center;
  gap: 20px;
  flex-wrap: wrap;
  position: relative;
  z-index: 1;
}

.exam-stat {
  background: var(--bg-card);
  backdrop-filter: blur(12px);
  border: 1px solid var(--border);
  border-radius: var(--radius-md);
  padding: 20px 28px;
  min-width: 160px;
  text-align: center;
  transition: all var(--transition-base);
  position: relative;
  overflow: hidden;
}

.exam-stat::before {
  content: '';
  position: absolute;
  top: 0;
  left: 0;
  right: 0;
  height: 2px;
  background: linear-gradient(90deg, transparent, var(--blue-400), transparent);
  opacity: 0;
  transition: opacity var(--transition-base);
}

.exam-stat:hover {
  border-color: var(--border-glow);
  transform: translateY(-3px);
  box-shadow: var(--shadow-glow);
}

.exam-stat:hover::before {
  opacity: 1;
}

.exam-stat__value {
  font-family: var(--font-heading);
  font-size: 30px;
  font-weight: 800;
  background: linear-gradient(135deg, var(--blue-400), var(--cyan-400));
  -webkit-background-clip: text;
  background-clip: text;
  -webkit-text-fill-color: transparent;
  line-height: 1.2;
}

.exam-stat__label {
  font-size: 12.5px;
  color: var(--text-muted);
  font-weight: 500;
  text-transform: uppercase;
  letter-spacing: 0.8px;
  margin-top: 4px;
}

/* Animated counter */
.exam-stat__value[data-count] {
  transition: none;
}


/* ---- 5. Page Layout ---- */
.exam-page {
  position: relative;
  z-index: 1;
  max-width: var(--content-max);
  margin: 0 auto;
  padding: 0 clamp(16px, 3vw, 40px) 60px;
  display: grid;
  grid-template-columns: 1fr var(--sidebar-width);
  gap: 36px;
  align-items: start;
}

.exam-main {
  min-width: 0;
}

.exam-sidebar {
  position: sticky;
  top: calc(var(--nav-height) + 20px);
  display: flex;
  flex-direction: column;
  gap: 24px;
  max-height: calc(100vh - var(--nav-height) - 40px);
  overflow-y: auto;
  scrollbar-width: thin;
  scrollbar-color: rgba(82, 160, 255, 0.15) transparent;
}


/* ---- 6. Search & Filter Bar ---- */
.exam-controls {
  margin-bottom: 32px;
}

.exam-search {
  position: relative;
  margin-bottom: 20px;
}

.exam-search__icon {
  position: absolute;
  left: 18px;
  top: 50%;
  transform: translateY(-50%);
  color: var(--text-muted);
  font-size: 18px;
  pointer-events: none;
  transition: color var(--transition-fast);
}

.exam-search__input {
  width: 100%;
  padding: 14px 20px 14px 50px;
  background: var(--bg-card);
  backdrop-filter: blur(10px);
  border: 1px solid var(--border);
  border-radius: var(--radius-md);
  color: var(--text-primary);
  font-family: var(--font-body);
  font-size: 15px;
  outline: none;
  transition: all var(--transition-base);
}

.exam-search__input::placeholder {
  color: var(--text-muted);
}

.exam-search__input:focus {
  border-color: var(--border-glow);
  box-shadow: 0 0 0 3px rgba(59, 130, 246, 0.1), var(--shadow-glow);
}

.exam-search__input:focus ~ .exam-search__icon {
  color: var(--blue-400);
}

/* Filter sections */
.exam-filters {
  display: flex;
  flex-direction: column;
  gap: 14px;
}

.exam-filter-group {
  display: flex;
  align-items: center;
  gap: 10px;
  flex-wrap: wrap;
}

.exam-filter-group__label {
  font-size: 12.5px;
  color: var(--text-muted);
  font-weight: 600;
  text-transform: uppercase;
  letter-spacing: 0.8px;
  min-width: 80px;
  flex-shrink: 0;
}

/* Chapter filter pills */
.filter-pill {
  display: inline-flex;
  align-items: center;
  gap: 6px;
  padding: 7px 16px;
  background: rgba(8, 20, 50, 0.5);
  border: 1px solid var(--border-subtle);
  border-radius: var(--radius-full);
  color: var(--text-secondary);
  font-size: 13px;
  font-weight: 500;
  cursor: pointer;
  transition: all var(--transition-fast);
  white-space: nowrap;
  user-select: none;
}

.filter-pill:hover {
  border-color: var(--border);
  color: var(--text-primary);
  background: rgba(82, 160, 255, 0.06);
}

.filter-pill.active {
  background: rgba(59, 130, 246, 0.15);
  border-color: rgba(59, 130, 246, 0.4);
  color: var(--blue-400);
}

.filter-pill__count {
  font-size: 11px;
  background: rgba(82, 160, 255, 0.12);
  padding: 1px 7px;
  border-radius: var(--radius-full);
  color: var(--text-muted);
}

.filter-pill.active .filter-pill__count {
  background: rgba(59, 130, 246, 0.25);
  color: var(--blue-400);
}

/* Difficulty filter buttons */
.difficulty-btn {
  display: inline-flex;
  align-items: center;
  gap: 6px;
  padding: 7px 16px;
  background: transparent;
  border: 1px solid var(--border-subtle);
  border-radius: var(--radius-full);
  color: var(--text-secondary);
  font-size: 13px;
  font-weight: 500;
  cursor: pointer;
  transition: all var(--transition-fast);
  font-family: var(--font-body);
}

.difficulty-btn:hover {
  border-color: var(--border);
}

.difficulty-btn--easy:hover,
.difficulty-btn--easy.active {
  background: var(--easy-bg);
  border-color: var(--easy-border);
  color: var(--easy-color);
}

.difficulty-btn--moderate:hover,
.difficulty-btn--moderate.active {
  background: var(--moderate-bg);
  border-color: var(--moderate-border);
  color: var(--moderate-color);
}

.difficulty-btn--advanced:hover,
.difficulty-btn--advanced.active {
  background: var(--advanced-bg);
  border-color: var(--advanced-border);
  color: var(--advanced-color);
}

.difficulty-btn .dot {
  width: 7px;
  height: 7px;
  border-radius: 50%;
  background: currentColor;
  opacity: 0.7;
}


/* ---- 7. Problem Cards ---- */
.problem-list {
  display: flex;
  flex-direction: column;
  gap: 24px;
}

/* Card container */
.problem-card {
  background: var(--bg-card);
  backdrop-filter: blur(14px);
  border: 1px solid var(--border);
  border-radius: var(--radius-lg);
  padding: var(--card-padding);
  position: relative;
  overflow: hidden;
  transition: all var(--transition-base);
  animation: fadeSlideUp 0.5s ease-out both;
}

.problem-card::before {
  content: '';
  position: absolute;
  inset: 0;
  border-radius: var(--radius-lg);
  background: linear-gradient(135deg, rgba(59, 130, 246, 0.03), transparent 60%);
  pointer-events: none;
  opacity: 0;
  transition: opacity var(--transition-base);
}

.problem-card:hover {
  border-color: var(--border-glow);
  box-shadow: 0 0 40px rgba(59, 130, 246, 0.08), var(--shadow-md);
  transform: translateY(-2px);
}

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

/* Stagger animation for cards */
.problem-card:nth-child(1) { animation-delay: 0s; }
.problem-card:nth-child(2) { animation-delay: 0.06s; }
.problem-card:nth-child(3) { animation-delay: 0.12s; }
.problem-card:nth-child(4) { animation-delay: 0.18s; }
.problem-card:nth-child(5) { animation-delay: 0.24s; }
.problem-card:nth-child(6) { animation-delay: 0.30s; }
.problem-card:nth-child(7) { animation-delay: 0.36s; }
.problem-card:nth-child(8) { animation-delay: 0.42s; }
.problem-card:nth-child(9) { animation-delay: 0.48s; }
.problem-card:nth-child(10) { animation-delay: 0.54s; }

/* Problem header */
.problem-card__header {
  display: flex;
  align-items: flex-start;
  gap: 16px;
  margin-bottom: 18px;
}

/* Problem number badge (circular, gradient) */
.problem-card__number {
  display: flex;
  align-items: center;
  justify-content: center;
  width: 48px;
  height: 48px;
  min-width: 48px;
  border-radius: 50%;
  background: linear-gradient(135deg, var(--blue-400), var(--blue-600));
  color: #fff;
  font-family: var(--font-heading);
  font-weight: 800;
  font-size: 18px;
  box-shadow: 0 4px 15px rgba(59, 130, 246, 0.3);
  position: relative;
}

.problem-card__number::after {
  content: '';
  position: absolute;
  inset: -3px;
  border-radius: 50%;
  border: 2px solid rgba(59, 130, 246, 0.2);
}

.problem-card__meta {
  flex: 1;
  min-width: 0;
}

/* Tags row */
.problem-card__tags {
  display: flex;
  align-items: center;
  gap: 8px;
  flex-wrap: wrap;
  margin-bottom: 10px;
}

.tag {
  display: inline-flex;
  align-items: center;
  gap: 5px;
  padding: 4px 12px;
  border-radius: var(--radius-full);
  font-size: 11.5px;
  font-weight: 600;
  letter-spacing: 0.3px;
  white-space: nowrap;
}

/* Chapter tag */
.tag--chapter {
  background: rgba(59, 130, 246, 0.1);
  border: 1px solid rgba(59, 130, 246, 0.25);
  color: var(--blue-400);
}

/* Difficulty tags */
.tag--easy {
  background: var(--easy-bg);
  border: 1px solid var(--easy-border);
  color: var(--easy-color);
}

.tag--moderate {
  background: var(--moderate-bg);
  border: 1px solid var(--moderate-border);
  color: var(--moderate-color);
}

.tag--advanced {
  background: var(--advanced-bg);
  border: 1px solid var(--advanced-border);
  color: var(--advanced-color);
}

/* Year badge */
.tag--year {
  background: rgba(251, 191, 36, 0.08);
  border: 1px solid rgba(251, 191, 36, 0.25);
  color: var(--gold-400);
  font-family: var(--font-mono);
  font-size: 11px;
  font-weight: 700;
}

/* Question text */
.problem-card__question {
  font-size: 16.5px;
  line-height: 1.75;
  color: var(--text-primary);
  font-weight: 400;
  margin-bottom: 20px;
}

.problem-card__question strong,
.problem-card__question b {
  color: #fff;
  font-weight: 600;
}

/* Given data box */
.problem-card__given {
  background: rgba(2, 8, 24, 0.6);
  border: 1px solid var(--border-subtle);
  border-radius: var(--radius-sm);
  padding: 16px 20px;
  margin-bottom: 16px;
  position: relative;
}

.problem-card__given::before {
  content: 'Given';
  position: absolute;
  top: -9px;
  left: 16px;
  padding: 0 8px;
  background: var(--bg-deep);
  font-size: 10.5px;
  font-weight: 700;
  text-transform: uppercase;
  letter-spacing: 1px;
  color: var(--text-muted);
}

.problem-card__given ul {
  list-style: none;
  display: flex;
  flex-direction: column;
  gap: 6px;
}

.problem-card__given li {
  font-family: var(--font-mono);
  font-size: 13.5px;
  color: var(--text-secondary);
  padding-left: 16px;
  position: relative;
}

.problem-card__given li::before {
  content: '→';
  position: absolute;
  left: 0;
  color: var(--blue-400);
  font-weight: 600;
}

/* Required quantity highlight */
.problem-card__find {
  display: inline-flex;
  align-items: center;
  gap: 8px;
  padding: 10px 18px;
  background: linear-gradient(135deg, rgba(59, 130, 246, 0.08), rgba(139, 92, 246, 0.06));
  border: 1px solid rgba(59, 130, 246, 0.2);
  border-left: 3px solid var(--blue-400);
  border-radius: 0 var(--radius-sm) var(--radius-sm) 0;
  margin-bottom: 18px;
  font-size: 14px;
  color: var(--text-primary);
  font-weight: 500;
}

.problem-card__find-label {
  font-weight: 700;
  color: var(--blue-400);
  text-transform: uppercase;
  font-size: 11px;
  letter-spacing: 0.8px;
}

/* Formula box */
.problem-card__formula,
.formula-block {
  background: rgba(139, 92, 246, 0.06);
  border: 1px solid rgba(139, 92, 246, 0.2);
  border-radius: var(--radius-sm);
  padding: 16px 20px;
  margin-bottom: 20px;
  position: relative;
  overflow: hidden;
}

.problem-card__formula::before,
.formula-block::before {
  content: '📐 Formula';
  position: absolute;
  top: -9px;
  left: 16px;
  padding: 0 8px;
  background: var(--bg-card);
  font-size: 10.5px;
  font-weight: 700;
  text-transform: uppercase;
  letter-spacing: 1px;
  color: var(--purple-400);
}

.problem-card__formula::after,
.formula-block::after {
  content: '';
  position: absolute;
  top: 0;
  left: 0;
  bottom: 0;
  width: 3px;
  background: linear-gradient(180deg, var(--purple-400), var(--blue-400));
  border-radius: 3px 0 0 3px;
}

.problem-card__formula .katex,
.formula-block .katex,
.formula-content .katex,
.problem-card__formula code,
.formula-block code,
.formula-content code {
  font-family: var(--font-mono);
  font-size: 15px;
  color: var(--text-primary);
}

/* formula-block inner content */
.formula-content {
  text-align: center;
  overflow-x: auto;
  padding: 4px 0;
}

.formula-block h4 {
  display: none; /* The ::before pseudo-element handles the label */
}

/* Solution toggle button */
.solution-toggle {
  display: inline-flex;
  align-items: center;
  gap: 10px;
  padding: 11px 24px;
  background: linear-gradient(135deg, var(--green-500), var(--green-400));
  border: none;
  border-radius: var(--radius-sm);
  color: #020818;
  font-family: var(--font-body);
  font-size: 14px;
  font-weight: 700;
  cursor: pointer;
  transition: all var(--transition-fast);
  box-shadow: 0 4px 15px rgba(16, 185, 129, 0.25);
  letter-spacing: 0.2px;
}

.solution-toggle:hover {
  transform: translateY(-2px);
  box-shadow: 0 6px 25px rgba(16, 185, 129, 0.35);
  filter: brightness(1.08);
}

.solution-toggle:active {
  transform: translateY(0);
}

.solution-toggle__arrow {
  display: inline-flex;
  font-size: 12px;
  transition: transform var(--transition-base);
}

.solution-toggle.open .solution-toggle__arrow {
  transform: rotate(180deg);
}

/* Collapsible solution area */
.solution-area {
  max-height: 0;
  overflow: hidden;
  transition: max-height 0.6s cubic-bezier(0.22, 1, 0.36, 1),
              opacity 0.4s ease,
              padding 0.4s ease;
  opacity: 0;
  margin-top: 0;
}

.solution-area.open {
  max-height: 3000px;
  opacity: 1;
  margin-top: 24px;
  padding-top: 24px;
  border-top: 1px solid var(--border-subtle);
}

.solution-area__title {
  font-family: var(--font-heading);
  font-size: 16px;
  font-weight: 700;
  color: var(--green-400);
  margin-bottom: 18px;
  display: flex;
  align-items: center;
  gap: 8px;
}

/* Step-by-step list */
.solution-steps {
  list-style: none;
  display: flex;
  flex-direction: column;
  gap: 14px;
  margin-bottom: 24px;
}

.solution-step {
  display: flex;
  gap: 14px;
  align-items: flex-start;
  padding: 14px 18px;
  background: rgba(2, 8, 24, 0.4);
  border-radius: var(--radius-sm);
  border: 1px solid var(--border-subtle);
  transition: border-color var(--transition-fast);
}

.solution-step:hover {
  border-color: var(--border);
}

.solution-step__number {
  display: flex;
  align-items: center;
  justify-content: center;
  min-width: 30px;
  height: 30px;
  border-radius: 50%;
  background: rgba(59, 130, 246, 0.12);
  border: 1px solid rgba(59, 130, 246, 0.25);
  color: var(--blue-400);
  font-family: var(--font-heading);
  font-weight: 700;
  font-size: 13px;
  flex-shrink: 0;
}

.solution-step__content {
  flex: 1;
  min-width: 0;
}

.solution-step__content p {
  color: var(--text-secondary);
  font-size: 14.5px;
  line-height: 1.7;
  margin-bottom: 8px;
}

.solution-step__content p:last-child {
  margin-bottom: 0;
}

.solution-step__math {
  font-family: var(--font-mono);
  font-size: 14px;
  color: var(--text-primary);
  background: rgba(8, 20, 50, 0.5);
  padding: 8px 14px;
  border-radius: 6px;
  border: 1px solid var(--border-subtle);
  margin-top: 8px;
  display: block;
  overflow-x: auto;
}

.solution-step__arrow {
  color: var(--text-muted);
  font-size: 12px;
  margin-top: 8px;
  flex-shrink: 0;
}

/* Final answer box */
.solution-answer {
  background: rgba(52, 211, 153, 0.06);
  border: 1px solid rgba(52, 211, 153, 0.3);
  border-left: 4px solid var(--green-400);
  border-radius: 0 var(--radius-sm) var(--radius-sm) 0;
  padding: 18px 22px;
  margin-bottom: 16px;
  position: relative;
}

.solution-answer__label {
  font-size: 10.5px;
  font-weight: 700;
  text-transform: uppercase;
  letter-spacing: 1.2px;
  color: var(--green-400);
  margin-bottom: 8px;
}

.solution-answer__value {
  font-family: var(--font-mono);
  font-size: 18px;
  font-weight: 700;
  color: #fff;
  line-height: 1.5;
}

.solution-answer__value .katex {
  font-size: 18px;
}

/* Notes / concepts box */
.solution-notes {
  background: rgba(59, 130, 246, 0.05);
  border: 1px solid rgba(59, 130, 246, 0.18);
  border-left: 4px solid var(--blue-400);
  border-radius: 0 var(--radius-sm) var(--radius-sm) 0;
  padding: 16px 20px;
}

.solution-notes__label {
  font-size: 10.5px;
  font-weight: 700;
  text-transform: uppercase;
  letter-spacing: 1.2px;
  color: var(--blue-400);
  margin-bottom: 8px;
  display: flex;
  align-items: center;
  gap: 6px;
}

.solution-notes__content {
  font-size: 13.5px;
  color: var(--text-secondary);
  line-height: 1.7;
}

.solution-notes__content strong {
  color: var(--text-primary);
}


/* ---- 8. Sidebar ---- */
.sidebar-widget {
  background: var(--bg-card);
  backdrop-filter: blur(14px);
  border: 1px solid var(--border);
  border-radius: var(--radius-md);
  padding: 22px;
  position: relative;
  overflow: hidden;
  transition: border-color var(--transition-base);
}

.sidebar-widget:hover {
  border-color: rgba(82, 160, 255, 0.28);
}

.sidebar-widget::before {
  content: '';
  position: absolute;
  top: 0;
  left: 0;
  right: 0;
  height: 1px;
  background: linear-gradient(90deg, transparent, rgba(82, 160, 255, 0.2), transparent);
}

.sidebar-widget__title {
  font-family: var(--font-heading);
  font-size: 15px;
  font-weight: 700;
  color: var(--text-primary);
  margin-bottom: 16px;
  display: flex;
  align-items: center;
  gap: 8px;
  padding-bottom: 12px;
  border-bottom: 1px solid var(--border-subtle);
}

.sidebar-widget__title-icon {
  font-size: 16px;
  opacity: 0.8;
}

/* Popular Questions */
.popular-list {
  list-style: none;
  display: flex;
  flex-direction: column;
  gap: 4px;
}

.popular-list__item {
  display: flex;
  align-items: center;
  gap: 12px;
  padding: 10px 12px;
  border-radius: var(--radius-sm);
  cursor: pointer;
  transition: all var(--transition-fast);
  text-decoration: none;
  color: var(--text-secondary);
}

.popular-list__item:hover {
  background: rgba(82, 160, 255, 0.06);
  color: var(--text-primary);
}

.popular-list__rank {
  font-family: var(--font-heading);
  font-weight: 800;
  font-size: 14px;
  color: var(--text-muted);
  min-width: 22px;
}

.popular-list__item:nth-child(1) .popular-list__rank { color: var(--gold-400); }
.popular-list__item:nth-child(2) .popular-list__rank { color: #c0c0c0; }
.popular-list__item:nth-child(3) .popular-list__rank { color: #cd7f32; }

.popular-list__text {
  font-size: 13px;
  line-height: 1.45;
  flex: 1;
  min-width: 0;
  overflow: hidden;
  text-overflow: ellipsis;
  display: -webkit-box;
  -webkit-line-clamp: 2;
  -webkit-box-orient: vertical;
}

/* Recently added */
.recent-list {
  list-style: none;
  display: flex;
  flex-direction: column;
  gap: 4px;
}

.recent-list__item {
  display: flex;
  align-items: center;
  gap: 10px;
  padding: 10px 12px;
  border-radius: var(--radius-sm);
  cursor: pointer;
  transition: all var(--transition-fast);
  text-decoration: none;
  color: var(--text-secondary);
  font-size: 13px;
}

.recent-list__item:hover {
  background: rgba(82, 160, 255, 0.06);
  color: var(--text-primary);
}

.badge-new {
  display: inline-flex;
  align-items: center;
  padding: 2px 8px;
  background: linear-gradient(135deg, var(--green-500), var(--green-400));
  color: #020818;
  font-size: 9.5px;
  font-weight: 800;
  text-transform: uppercase;
  letter-spacing: 0.6px;
  border-radius: var(--radius-full);
  flex-shrink: 0;
  animation: pulseNew 2s ease-in-out infinite;
}

@keyframes pulseNew {
  0%, 100% { box-shadow: 0 0 0 0 rgba(52, 211, 153, 0.3); }
  50% { box-shadow: 0 0 0 6px rgba(52, 211, 153, 0); }
}

/* Quick links */
.quick-links {
  list-style: none;
  display: flex;
  flex-direction: column;
  gap: 4px;
}

.quick-links__item {
  display: flex;
  align-items: center;
  gap: 10px;
  padding: 10px 12px;
  border-radius: var(--radius-sm);
  transition: all var(--transition-fast);
  text-decoration: none;
  color: var(--text-secondary);
  font-size: 13px;
  font-weight: 500;
}

.quick-links__item:hover {
  background: rgba(82, 160, 255, 0.06);
  color: var(--text-primary);
  padding-left: 16px;
}

.quick-links__item-icon {
  font-size: 14px;
  opacity: 0.6;
  transition: opacity var(--transition-fast);
}

.quick-links__item:hover .quick-links__item-icon {
  opacity: 1;
}

/* Download resources */
.download-list {
  display: flex;
  flex-direction: column;
  gap: 10px;
}

.download-card {
  display: flex;
  align-items: center;
  gap: 14px;
  padding: 14px 16px;
  background: rgba(2, 8, 24, 0.5);
  border: 1px solid var(--border-subtle);
  border-radius: var(--radius-sm);
  cursor: pointer;
  transition: all var(--transition-fast);
  text-decoration: none;
  color: var(--text-secondary);
}

.download-card:hover {
  border-color: var(--border);
  background: rgba(82, 160, 255, 0.04);
  color: var(--text-primary);
  transform: translateY(-1px);
}

.download-card__icon {
  display: flex;
  align-items: center;
  justify-content: center;
  width: 40px;
  height: 40px;
  border-radius: var(--radius-sm);
  background: rgba(239, 68, 68, 0.1);
  color: var(--red-400);
  font-size: 18px;
  flex-shrink: 0;
}

.download-card__info {
  flex: 1;
  min-width: 0;
}

.download-card__name {
  font-size: 13px;
  font-weight: 600;
  color: var(--text-primary);
  margin-bottom: 2px;
}

.download-card__size {
  font-size: 11.5px;
  color: var(--text-muted);
}

.download-card__arrow {
  font-size: 14px;
  color: var(--text-muted);
  transition: transform var(--transition-fast);
}

.download-card:hover .download-card__arrow {
  transform: translateX(3px);
  color: var(--blue-400);
}


/* ---- 9. Pagination ---- */
.pagination {
  display: flex;
  align-items: center;
  justify-content: center;
  gap: 6px;
  margin-top: 48px;
  padding-top: 32px;
  border-top: 1px solid var(--border-subtle);
}

.pagination__btn {
  display: flex;
  align-items: center;
  justify-content: center;
  min-width: 42px;
  height: 42px;
  padding: 0 14px;
  background: var(--bg-card);
  border: 1px solid var(--border);
  border-radius: var(--radius-sm);
  color: var(--text-secondary);
  font-family: var(--font-body);
  font-size: 14px;
  font-weight: 600;
  cursor: pointer;
  transition: all var(--transition-fast);
}

.pagination__btn:hover {
  border-color: var(--border-glow);
  color: var(--text-primary);
  background: rgba(82, 160, 255, 0.06);
}

.pagination__btn.active {
  background: linear-gradient(135deg, var(--blue-400), var(--blue-600));
  border-color: transparent;
  color: #fff;
  box-shadow: 0 4px 15px rgba(59, 130, 246, 0.3);
}

.pagination__btn:disabled {
  opacity: 0.35;
  cursor: not-allowed;
  pointer-events: none;
}

.pagination__arrow {
  font-size: 16px;
}

.pagination__dots {
  color: var(--text-muted);
  font-size: 14px;
  padding: 0 4px;
  user-select: none;
}


/* ---- 10. Results Count ---- */
.results-count {
  display: flex;
  align-items: center;
  justify-content: space-between;
  margin-bottom: 24px;
  padding-bottom: 16px;
  border-bottom: 1px solid var(--border-subtle);
}

.results-count__text {
  font-size: 14px;
  color: var(--text-muted);
  font-weight: 500;
}

.results-count__text span {
  color: var(--text-primary);
  font-weight: 700;
}

.results-count__sort {
  display: flex;
  align-items: center;
  gap: 8px;
}

.results-count__sort label {
  font-size: 13px;
  color: var(--text-muted);
  font-weight: 500;
}

.results-count__sort select {
  appearance: none;
  background: var(--bg-card);
  border: 1px solid var(--border);
  border-radius: var(--radius-sm);
  color: var(--text-secondary);
  font-family: var(--font-body);
  font-size: 13px;
  padding: 6px 30px 6px 12px;
  cursor: pointer;
  outline: none;
  background-image: url("data:image/svg+xml,%3Csvg xmlns='http://www.w3.org/2000/svg' width='12' height='12' fill='%239ab3d8' viewBox='0 0 16 16'%3E%3Cpath d='M8 11L3 6h10l-5 5z'/%3E%3C/svg%3E");
  background-repeat: no-repeat;
  background-position: right 10px center;
  transition: border-color var(--transition-fast);
}

.results-count__sort select:hover,
.results-count__sort select:focus {
  border-color: var(--border-glow);
}


/* ---- 11. Empty State ---- */
.empty-state {
  text-align: center;
  padding: 80px 30px;
  animation: fadeSlideUp 0.5s ease-out both;
}

.empty-state__icon {
  font-size: 56px;
  margin-bottom: 20px;
  opacity: 0.5;
}

.empty-state__title {
  font-family: var(--font-heading);
  font-size: 22px;
  font-weight: 700;
  color: var(--text-primary);
  margin-bottom: 10px;
}

.empty-state__text {
  color: var(--text-muted);
  font-size: 15px;
  max-width: 400px;
  margin: 0 auto 24px;
  line-height: 1.6;
}

.empty-state__btn {
  display: inline-flex;
  align-items: center;
  gap: 8px;
  padding: 10px 24px;
  background: rgba(59, 130, 246, 0.12);
  border: 1px solid rgba(59, 130, 246, 0.3);
  border-radius: var(--radius-sm);
  color: var(--blue-400);
  font-family: var(--font-body);
  font-size: 14px;
  font-weight: 600;
  cursor: pointer;
  transition: all var(--transition-fast);
}

.empty-state__btn:hover {
  background: rgba(59, 130, 246, 0.2);
  border-color: rgba(59, 130, 246, 0.5);
  transform: translateY(-2px);
}


/* ---- 12. Footer ---- */
.exam-footer {
  position: relative;
  z-index: 1;
  border-top: 1px solid var(--border);
  padding: 40px clamp(16px, 3vw, 40px);
  text-align: center;
  background: rgba(2, 8, 24, 0.6);
}

.exam-footer__inner {
  max-width: var(--content-max);
  margin: 0 auto;
}

.exam-footer__brand {
  font-family: var(--font-heading);
  font-size: 18px;
  font-weight: 700;
  background: linear-gradient(135deg, var(--blue-400), var(--cyan-400));
  -webkit-background-clip: text;
  background-clip: text;
  -webkit-text-fill-color: transparent;
  margin-bottom: 8px;
}

.exam-footer__text {
  font-size: 13px;
  color: var(--text-muted);
  line-height: 1.6;
}

.exam-footer__links {
  display: flex;
  justify-content: center;
  gap: 24px;
  margin-top: 16px;
  flex-wrap: wrap;
}

.exam-footer__links a {
  font-size: 13px;
  color: var(--text-secondary);
  transition: color var(--transition-fast);
}

.exam-footer__links a:hover {
  color: var(--blue-400);
}


/* ---- 13. Back to Top Button ---- */
.back-to-top {
  position: fixed;
  bottom: 30px;
  right: 30px;
  width: 46px;
  height: 46px;
  display: flex;
  align-items: center;
  justify-content: center;
  background: linear-gradient(135deg, var(--blue-400), var(--blue-600));
  border: none;
  border-radius: 50%;
  color: #fff;
  font-size: 20px;
  cursor: pointer;
  z-index: 999;
  opacity: 0;
  visibility: hidden;
  transform: translateY(20px);
  transition: all var(--transition-base);
  box-shadow: 0 4px 20px rgba(59, 130, 246, 0.35);
}

.back-to-top.visible {
  opacity: 1;
  visibility: visible;
  transform: translateY(0);
}

.back-to-top:hover {
  transform: translateY(-3px);
  box-shadow: 0 6px 30px rgba(59, 130, 246, 0.5);
}

.back-to-top:active {
  transform: translateY(0);
}


/* ---- 14. Responsive Breakpoints ---- */

/* <= 1024px: Sidebar goes below content */
@media (max-width: 1024px) {
  .exam-page {
    grid-template-columns: 1fr;
  }

  .exam-sidebar {
    position: static;
    max-height: none;
    display: grid;
    grid-template-columns: repeat(2, 1fr);
    gap: 16px;
  }

  .exam-stats {
    gap: 14px;
  }
}

/* <= 768px: Single column, smaller fonts */
@media (max-width: 768px) {
  :root {
    --nav-height: 60px;
    --card-padding: 20px;
  }

  body {
    font-size: 14px;
  }

  .exam-nav__links {
    display: none;
  }

  .exam-header {
    padding-top: calc(var(--nav-height) + 30px);
    padding-bottom: 36px;
  }

  .exam-header__icon {
    width: 64px;
    height: 64px;
    font-size: 28px;
  }

  .exam-header__title {
    font-size: 26px;
  }

  .exam-header__description {
    font-size: 13.5px;
  }

  .exam-stats {
    gap: 10px;
  }

  .exam-stat {
    padding: 14px 18px;
    min-width: 130px;
  }

  .exam-stat__value {
    font-size: 24px;
  }

  .exam-sidebar {
    grid-template-columns: 1fr;
  }

  .problem-card__header {
    flex-direction: column;
    align-items: flex-start;
    gap: 12px;
  }

  .problem-card__number {
    width: 40px;
    height: 40px;
    min-width: 40px;
    font-size: 15px;
  }

  .problem-card__question {
    font-size: 15px;
  }

  .solution-step {
    flex-direction: column;
    gap: 8px;
  }

  .solution-answer__value {
    font-size: 16px;
  }

  .results-count {
    flex-direction: column;
    gap: 12px;
    align-items: flex-start;
  }

  .pagination {
    gap: 4px;
  }

  .pagination__btn {
    min-width: 36px;
    height: 36px;
    font-size: 13px;
  }
}

/* <= 480px: Compact cards, full-width filters */
@media (max-width: 480px) {
  :root {
    --card-padding: 16px;
    --radius-lg: 14px;
    --radius-md: 10px;
  }

  .exam-page {
    padding: 0 12px 40px;
  }

  .exam-header {
    padding-left: 12px;
    padding-right: 12px;
  }

  .exam-header__title {
    font-size: 22px;
  }

  .exam-stats {
    flex-direction: column;
    align-items: center;
  }

  .exam-stat {
    width: 100%;
    max-width: 260px;
  }

  .exam-filter-group {
    flex-direction: column;
    align-items: stretch;
  }

  .exam-filter-group__label {
    min-width: auto;
  }

  .filter-pill,
  .difficulty-btn {
    flex: 1;
    justify-content: center;
    text-align: center;
  }

  .problem-card__tags {
    gap: 6px;
  }

  .tag {
    font-size: 10.5px;
    padding: 3px 10px;
  }

  .problem-card__given {
    padding: 14px 16px;
  }

  .problem-card__formula {
    padding: 14px 16px;
  }

  .solution-toggle {
    width: 100%;
    justify-content: center;
    padding: 12px;
  }

  .solution-answer {
    padding: 14px 16px;
  }

  .solution-notes {
    padding: 14px 16px;
  }

  .pagination__btn {
    min-width: 32px;
    height: 32px;
    padding: 0 8px;
    font-size: 12px;
  }

  .back-to-top {
    bottom: 20px;
    right: 16px;
    width: 40px;
    height: 40px;
    font-size: 18px;
  }
}


/* ---- 15. Print Styles ---- */
@media print {
  *,
  *::before,
  *::after {
    background: #fff !important;
    color: #000 !important;
    box-shadow: none !important;
    text-shadow: none !important;
    border-color: #ccc !important;
  }

  body::before {
    display: none !important;
  }

  .exam-nav,
  .exam-sidebar,
  .exam-footer,
  .back-to-top,
  .pagination,
  .exam-controls,
  .solution-toggle {
    display: none !important;
  }

  .exam-page {
    display: block !important;
    max-width: 100% !important;
    padding: 0 !important;
  }

  .exam-header {
    padding: 20px 0 !important;
  }

  .exam-header__title {
    -webkit-text-fill-color: #000 !important;
    font-size: 24pt !important;
  }

  .problem-card {
    page-break-inside: avoid;
    break-inside: avoid;
    border: 1px solid #ccc !important;
    margin-bottom: 20px !important;
    padding: 15px !important;
    backdrop-filter: none !important;
  }

  .problem-card:hover {
    transform: none !important;
  }

  .solution-area {
    max-height: none !important;
    opacity: 1 !important;
    overflow: visible !important;
  }

  .problem-card__number {
    -webkit-text-fill-color: #000 !important;
  }

  .tag {
    border: 1px solid #999 !important;
  }

  a[href]::after {
    content: none !important;
  }
}


/* ---- 16. KaTeX Overrides ---- */
.katex {
  font-size: 1.05em;
  color: var(--text-primary);
}

.katex-display {
  margin: 12px 0;
  overflow-x: auto;
  overflow-y: hidden;
  padding: 8px 0;
}

.katex-display > .katex {
  text-align: left;
}

.problem-card .katex-display {
  margin: 8px 0;
}

.solution-step .katex {
  font-size: 0.98em;
}

.solution-answer .katex {
  font-size: 1.15em;
  color: #fff;
}

.problem-card__formula .katex-display,
.formula-block .katex-display,
.formula-content .katex-display {
  margin: 4px 0;
}

/* KaTeX scrollbar */
.katex-display::-webkit-scrollbar {
  height: 4px;
}

.katex-display::-webkit-scrollbar-thumb {
  background: rgba(82, 160, 255, 0.15);
  border-radius: 2px;
}

/* KaTeX in dark mode enhancements */
.katex .mord,
.katex .mbin,
.katex .mrel,
.katex .mopen,
.katex .mclose,
.katex .mpunct {
  color: var(--text-primary);
}

.katex .mop {
  color: var(--blue-400);
}

.katex .mfrac .frac-line {
  border-color: var(--text-secondary);
}

.katex .sqrt > .root {
  color: var(--green-400);
}

/* KaTeX text elements */
.katex .text {
  font-family: var(--font-body) !important;
  color: var(--text-secondary);
}


/* ---- 17. Animations ---- */
@keyframes fadeSlideUp {
  from {
    opacity: 0;
    transform: translateY(24px);
  }
  to {
    opacity: 1;
    transform: translateY(0);
  }
}

@keyframes fadeIn {
  from { opacity: 0; }
  to { opacity: 1; }
}

@keyframes slideDown {
  from {
    opacity: 0;
    transform: translateY(-12px);
  }
  to {
    opacity: 1;
    transform: translateY(0);
  }
}

@keyframes shimmer {
  0% { background-position: -200% center; }
  100% { background-position: 200% center; }
}

@keyframes borderGlow {
  0%, 100% { border-color: var(--border); }
  50% { border-color: var(--border-glow); }
}

/* Intersection Observer animation helper */
.animate-on-scroll {
  opacity: 0;
  transform: translateY(24px);
  transition: opacity 0.6s ease-out, transform 0.6s ease-out;
}

.animate-on-scroll.visible {
  opacity: 1;
  transform: translateY(0);
}

/* Hover transition enhancements */
.problem-card,
.sidebar-widget,
.exam-stat,
.filter-pill,
.difficulty-btn,
.download-card,
.pagination__btn {
  will-change: transform;
}

/* Loading skeleton shimmer */
.skeleton {
  background: linear-gradient(
    90deg,
    rgba(82, 160, 255, 0.04) 25%,
    rgba(82, 160, 255, 0.08) 50%,
    rgba(82, 160, 255, 0.04) 75%
  );
  background-size: 200% 100%;
  animation: shimmer 1.8s infinite;
  border-radius: var(--radius-sm);
}

.skeleton--text {
  height: 14px;
  margin-bottom: 8px;
}

.skeleton--title {
  height: 22px;
  width: 60%;
  margin-bottom: 12px;
}

.skeleton--card {
  height: 200px;
  margin-bottom: 24px;
  border-radius: var(--radius-lg);
}

/* Focus visible styles for accessibility */
:focus-visible {
  outline: 2px solid var(--blue-400);
  outline-offset: 3px;
}

button:focus-visible,
a:focus-visible,
input:focus-visible,
select:focus-visible {
  outline: 2px solid var(--blue-400);
  outline-offset: 2px;
}

/* Reduced motion preference */
@media (prefers-reduced-motion: reduce) {
  *,
  *::before,
  *::after {
    animation-duration: 0.01ms !important;
    animation-iteration-count: 1 !important;
    transition-duration: 0.01ms !important;
    scroll-behavior: auto !important;
  }

  .solution-area {
    transition: none;
  }

  .animate-on-scroll {
    opacity: 1;
    transform: none;
    transition: none;
  }
}

/* Utility classes */
.visually-hidden {
  position: absolute;
  width: 1px;
  height: 1px;
  padding: 0;
  margin: -1px;
  overflow: hidden;
  clip: rect(0, 0, 0, 0);
  white-space: nowrap;
  border: 0;
}

.text-gradient {
  background: linear-gradient(135deg, var(--blue-400), var(--cyan-400));
  -webkit-background-clip: text;
  background-clip: text;
  -webkit-text-fill-color: transparent;
}

.glow-border {
  animation: borderGlow 3s ease-in-out infinite;
}