/* ===================================================
   MATH PROJECT — MAIN STYLESHEET
   =================================================== */

:root {
  --bg: #f0f4ff;
  --surface: #ffffff;
  --surface2: #f8faff;
  --border: #e2e8f5;
  --text: #0f172a;
  --text2: #475569;
  --text3: #94a3b8;
  --s1: #3b82f6;
  --s1-dark: #1d4ed8;
  --s1-light: #eff6ff;
  --s2: #8b5cf6;
  --s2-dark: #6d28d9;
  --s2-light: #f5f3ff;
  --success: #10b981;
  --warn: #f59e0b;
  --danger: #ef4444;
  --radius: 18px;
  --radius-sm: 10px;
  --shadow: 0 4px 24px rgba(0,0,0,.08);
  --shadow-lg: 0 12px 48px rgba(0,0,0,.14);
  --transition: 0.35s cubic-bezier(.4,0,.2,1);
  --nav-h: 68px;
  --font: 'Inter', sans-serif;
  --mono: 'JetBrains Mono', monospace;
}

[data-theme="dark"] {
  --bg: #0a0f1e;
  --surface: #111827;
  --surface2: #1a2235;
  --border: #1e2d45;
  --text: #f1f5f9;
  --text2: #94a3b8;
  --text3: #475569;
  --s1-light: #1e3a5f;
  --s2-light: #2e1a5e;
  --shadow: 0 4px 24px rgba(0,0,0,.4);
  --shadow-lg: 0 12px 48px rgba(0,0,0,.5);
}

/* ===== RESET & BASE ===== */
*, *::before, *::after { box-sizing: border-box; margin: 0; padding: 0; }

html { scroll-behavior: smooth; }

body {
  font-family: var(--font);
  background: var(--bg);
  color: var(--text);
  min-height: 100vh;
  overflow-x: hidden;
  transition: background var(--transition), color var(--transition);
}

/* ===== TOP PROGRESS BAR ===== */
#progressBar {
  position: fixed; top: 0; left: 0; height: 3px; width: 0%;
  background: linear-gradient(90deg, var(--s1), var(--s2));
  z-index: 9999;
  transition: width 0.4s ease, opacity 0.3s;
  border-radius: 0 2px 2px 0;
}

/* ===== PARTICLES ===== */
#particles {
  position: fixed; inset: 0; pointer-events: none; z-index: 0; overflow: hidden;
}
.particle {
  position: absolute; border-radius: 50%;
  background: linear-gradient(135deg, var(--s1), var(--s2));
  opacity: 0.06;
  animation: floatUp linear infinite;
}
@keyframes floatUp {
  0%   { transform: translateY(100vh) scale(0); opacity: 0; }
  10%  { opacity: 0.06; }
  90%  { opacity: 0.04; }
  100% { transform: translateY(-10vh) scale(1.2); opacity: 0; }
}

/* ===== NAVBAR ===== */
#navbar {
  position: fixed; top: 0; left: 0; right: 0; height: var(--nav-h);
  background: var(--surface);
  border-bottom: 1px solid var(--border);
  backdrop-filter: blur(12px);
  z-index: 1000;
  transition: background var(--transition), border-color var(--transition);
  box-shadow: 0 1px 12px rgba(0,0,0,.06);
}
.nav-inner {
  max-width: 1280px; margin: 0 auto; height: 100%;
  display: flex; align-items: center; gap: 20px; padding: 0 24px;
}
.nav-brand {
  display: flex; align-items: center; gap: 10px;
  cursor: pointer; user-select: none;
  transition: opacity .2s;
}
.nav-brand:hover { opacity: .75; }
.nav-logo {
  width: 38px; height: 38px; border-radius: 10px;
  background: linear-gradient(135deg, var(--s1), var(--s2));
  display: flex; align-items: center; justify-content: center;
  color: white; font-size: 18px; font-weight: 700;
}
.nav-title { font-size: 17px; font-weight: 700; color: var(--text); }

.breadcrumb {
  flex: 1; display: flex; align-items: center; gap: 6px;
  font-size: 13px; color: var(--text3);
}
.breadcrumb .crumb { cursor: pointer; transition: color .2s; }
.breadcrumb .crumb:hover { color: var(--s1); }
.breadcrumb .sep { color: var(--text3); }
.breadcrumb .current { color: var(--text2); font-weight: 500; }

.nav-actions { display: flex; align-items: center; gap: 8px; }
#themeToggle {
  width: 36px; height: 36px; border: 1px solid var(--border);
  background: var(--surface); color: var(--text2);
  border-radius: 8px; cursor: pointer; font-size: 14px;
  transition: all .2s; display: flex; align-items: center; justify-content: center;
}
#themeToggle:hover {
  background: var(--s1-light); color: var(--s1); border-color: var(--s1);
  transform: rotate(20deg);
}

/* ===== VIEWS ===== */
.view {
  position: relative; z-index: 1;
  min-height: 100vh; padding-top: calc(var(--nav-h) + 40px);
  padding-bottom: 80px;
  opacity: 0; transform: translateY(30px);
  transition: opacity var(--transition), transform var(--transition);
  pointer-events: none;
  display: none;
}
.view.active {
  opacity: 1; transform: translateY(0);
  pointer-events: all; display: block;
}
.view.slide-in {
  animation: slideInView .45s cubic-bezier(.4,0,.2,1) forwards;
}
.view.slide-out {
  animation: slideOutView .35s cubic-bezier(.4,0,.2,1) forwards;
}
@keyframes slideInView {
  from { opacity: 0; transform: translateX(60px); }
  to   { opacity: 1; transform: translateX(0); }
}
@keyframes slideOutView {
  from { opacity: 1; transform: translateX(0); }
  to   { opacity: 0; transform: translateX(-60px); }
}

/* ===== HOME — HERO ===== */
#view-home { padding-top: calc(var(--nav-h) + 60px); }

.hero {
  text-align: center; padding: 0 24px 60px;
  animation: fadeInUp .6s ease both;
}
.hero-badge {
  display: inline-flex; align-items: center; gap: 8px;
  background: linear-gradient(135deg, var(--s1-light), var(--s2-light));
  color: var(--s1); border: 1px solid var(--s1);
  border-radius: 100px; padding: 6px 18px;
  font-size: 12px; font-weight: 600; letter-spacing: .6px; text-transform: uppercase;
  margin-bottom: 22px;
  animation: fadeInUp .5s ease both;
}
.hero-title {
  font-size: clamp(42px, 6vw, 80px); font-weight: 900;
  line-height: 1.05; margin-bottom: 18px; letter-spacing: -2px;
  animation: fadeInUp .6s .1s ease both;
}
.gradient-text {
  background: linear-gradient(135deg, var(--s1), var(--s2));
  -webkit-background-clip: text; -webkit-text-fill-color: transparent;
  background-clip: text;
}
.hero-sub {
  font-size: 17px; color: var(--text2); font-weight: 400;
  animation: fadeInUp .6s .2s ease both;
}

/* ===== SEMESTER CARDS ===== */
.semesters-grid {
  display: grid; grid-template-columns: repeat(2, 1fr);
  gap: 28px; max-width: 1100px; margin: 0 auto; padding: 0 24px 60px;
}

.semester-card {
  position: relative; border-radius: var(--radius);
  overflow: hidden; cursor: pointer;
  border: 1px solid var(--border);
  background: var(--surface);
  box-shadow: var(--shadow);
  transition: transform .35s cubic-bezier(.4,0,.2,1),
              box-shadow .35s cubic-bezier(.4,0,.2,1),
              border-color .35s;
  animation: fadeInUp .6s ease both;
}
.semester-card:nth-child(2) { animation-delay: .15s; }

.semester-card:hover {
  transform: translateY(-14px) scale(1.02);
  box-shadow: 0 28px 60px rgba(0,0,0,.18);
}
.semester-card.s1:hover { border-color: var(--s1); box-shadow: 0 28px 60px rgba(59,130,246,.22); }
.semester-card.s2:hover { border-color: var(--s2); box-shadow: 0 28px 60px rgba(139,92,246,.22); }

.semester-card-bg {
  position: absolute; inset: 0; pointer-events: none;
  opacity: 0; transition: opacity .5s;
}
.s1 .semester-card-bg {
  background: radial-gradient(ellipse at top right, rgba(59,130,246,.18), transparent 55%),
              radial-gradient(ellipse at bottom left, rgba(96,165,250,.1), transparent 55%);
}
.s2 .semester-card-bg {
  background: radial-gradient(ellipse at top right, rgba(139,92,246,.18), transparent 55%),
              radial-gradient(ellipse at bottom left, rgba(192,132,252,.1), transparent 55%);
}
.semester-card:hover .semester-card-bg { opacity: 1; }

.semester-card-content {
  position: relative; z-index: 1; padding: 36px;
}
.sem-icon-wrap {
  width: 64px; height: 64px; border-radius: 18px;
  display: flex; align-items: center; justify-content: center;
  font-size: 26px; color: white; margin-bottom: 20px;
  transition: transform .4s cubic-bezier(.34,1.56,.64,1), box-shadow .4s;
}
.semester-card:hover .sem-icon-wrap {
  transform: rotate(-8deg) scale(1.18) translateY(-4px);
  box-shadow: 0 12px 28px rgba(0,0,0,.25);
}
.s1-icon { background: linear-gradient(135deg, var(--s1), #60a5fa); }
.s2-icon { background: linear-gradient(135deg, var(--s2), #c084fc); }

.sem-label {
  font-size: 11px; font-weight: 700; letter-spacing: 1.5px;
  text-transform: uppercase; color: var(--text3); margin-bottom: 10px;
}
.sem-title {
  font-size: 26px; font-weight: 800; margin-bottom: 10px; line-height: 1.2;
}
.sem-desc { font-size: 14px; color: var(--text2); margin-bottom: 24px; line-height: 1.6; }

.sem-stats {
  display: flex; gap: 20px; margin-bottom: 20px; flex-wrap: wrap;
}
.sem-stats span {
  font-size: 12px; color: var(--text3); display: flex; align-items: center; gap: 5px;
}
.sem-stats i { font-size: 11px; }

.sem-topics {
  display: flex; gap: 8px; flex-wrap: wrap; margin-bottom: 28px;
}
.sem-topics span {
  background: var(--bg); border: 1px solid var(--border);
  border-radius: 100px; padding: 4px 12px;
  font-size: 11px; font-weight: 500; color: var(--text2);
  transition: all .25s;
  display: inline-block;
}
.sem-topics span:hover { transform: translateY(-2px) scale(1.05); }
.semester-card:hover .sem-topics span {
  background: var(--s1-light); border-color: var(--s1); color: var(--s1);
}
.s2:hover .sem-topics span {
  background: var(--s2-light); border-color: var(--s2); color: var(--s2);
}

.sem-btn {
  display: inline-flex; align-items: center; gap: 8px;
  padding: 13px 24px; border-radius: 12px; border: none; cursor: pointer;
  font-size: 14px; font-weight: 600; color: white;
  transition: transform .3s cubic-bezier(.34,1.56,.64,1), box-shadow .3s;
  position: relative; overflow: hidden;
}
.sem-btn::after {
  content: ''; position: absolute; inset: 0;
  background: rgba(255,255,255,.15);
  transform: translateX(-100%); transition: transform .3s ease;
}
.sem-btn:hover::after { transform: translateX(0); }
.sem-btn:hover { transform: translateX(6px) scale(1.03); }
.s1-btn { background: linear-gradient(135deg, var(--s1), #60a5fa); box-shadow: 0 4px 16px rgba(59,130,246,.4); }
.s2-btn { background: linear-gradient(135deg, var(--s2), #c084fc); box-shadow: 0 4px 16px rgba(139,92,246,.4); }
.s1-btn:hover { box-shadow: 0 8px 28px rgba(59,130,246,.55); }
.s2-btn:hover { box-shadow: 0 8px 28px rgba(139,92,246,.55); }

/* ===== STATS BAR ===== */
.stats-bar {
  max-width: 800px; margin: 0 auto; padding: 0 24px;
  display: flex; align-items: center; justify-content: center;
  background: var(--surface); border: 1px solid var(--border);
  border-radius: var(--radius); box-shadow: var(--shadow);
  animation: fadeInUp .6s .3s ease both;
}
.stat-item {
  flex: 1; text-align: center; padding: 22px 16px;
  display: flex; flex-direction: column; gap: 4px;
  transition: background .25s, border-radius .25s;
  cursor: default;
  border-radius: 12px;
}
.stat-item:hover {
  background: linear-gradient(135deg, var(--s1-light), var(--s2-light));
}
.stat-num {
  font-size: 28px; font-weight: 800;
  background: linear-gradient(135deg, var(--s1), var(--s2));
  -webkit-background-clip: text; -webkit-text-fill-color: transparent;
  background-clip: text;
}
.stat-label { font-size: 12px; color: var(--text3); font-weight: 500; text-transform: uppercase; letter-spacing: .6px; }
.stat-divider { width: 1px; height: 40px; background: var(--border); }

/* ===== SEMESTER LESSONS VIEW ===== */
.view-header {
  max-width: 1200px; margin: 0 auto; padding: 0 24px 48px;
}
.back-btn {
  display: inline-flex; align-items: center; gap: 8px;
  background: var(--surface); border: 1px solid var(--border);
  color: var(--text2); padding: 9px 18px; border-radius: 10px;
  cursor: pointer; font-size: 13px; font-weight: 500;
  transition: all .28s cubic-bezier(.4,0,.2,1); margin-bottom: 28px; font-family: var(--font);
}
.back-btn:hover {
  background: var(--s1-light); color: var(--s1); border-color: var(--s1);
  transform: translateX(-6px) scale(1.02);
  box-shadow: 0 4px 14px rgba(59,130,246,.2);
}

.view-title {
  font-size: clamp(28px, 4vw, 44px); font-weight: 900;
  letter-spacing: -1.5px; margin-bottom: 8px;
}
.view-subtitle { font-size: 15px; color: var(--text2); }

/* ===== LESSONS GRID ===== */
.lessons-grid {
  display: grid; grid-template-columns: repeat(3, 1fr);
  gap: 22px; max-width: 1200px; margin: 0 auto; padding: 0 24px;
}

.lesson-card {
  background: var(--surface); border: 1px solid var(--border);
  border-radius: var(--radius); padding: 28px;
  cursor: pointer; position: relative; overflow: hidden;
  transition: transform .35s cubic-bezier(.34,1.2,.64,1),
              box-shadow .35s, border-color .35s;
  animation: fadeInCard .5s ease both;
}
.lesson-card:hover {
  transform: translateY(-10px) scale(1.02);
  box-shadow: 0 20px 50px rgba(0,0,0,.14);
}
.lesson-card.s1:hover { border-color: var(--s1); }
.lesson-card.s2:hover { border-color: var(--s2); }
@keyframes fadeInCard {
  from { opacity: 0; transform: translateY(24px); }
  to   { opacity: 1; transform: translateY(0); }
}

.lesson-card::before {
  content: ''; position: absolute; inset: 0;
  background: linear-gradient(135deg, transparent 50%, rgba(59,130,246,.08) 100%);
  opacity: 0; transition: opacity .4s;
}
.lesson-card:hover::before { opacity: 1; }

.lesson-card.s2::before {
  background: linear-gradient(135deg, transparent 50%, rgba(139,92,246,.08) 100%);
}

/* shimmer line at top on hover */
.lesson-card::after {
  content: ''; position: absolute; top: 0; left: 0; right: 0; height: 3px;
  background: linear-gradient(90deg, var(--s1), var(--s2));
  transform: scaleX(0); transform-origin: left;
  transition: transform .35s cubic-bezier(.4,0,.2,1);
  border-radius: 3px 3px 0 0;
}
.lesson-card:hover::after { transform: scaleX(1); }

.lesson-num {
  font-size: 11px; font-weight: 700; letter-spacing: 1.2px;
  text-transform: uppercase; color: var(--text3); margin-bottom: 14px;
}
.lesson-card-icon {
  width: 52px; height: 52px; border-radius: 14px;
  display: flex; align-items: center; justify-content: center;
  font-size: 22px; margin-bottom: 18px;
  transition: transform .4s cubic-bezier(.34,1.56,.64,1), box-shadow .4s;
}
.lesson-card:hover .lesson-card-icon {
  transform: scale(1.18) rotate(-8deg) translateY(-3px);
  box-shadow: 0 10px 24px rgba(0,0,0,.2);
}

.lesson-card-title {
  font-size: 18px; font-weight: 700; margin-bottom: 10px; line-height: 1.3;
}
.lesson-card-desc { font-size: 13px; color: var(--text2); line-height: 1.6; }

.lesson-card-footer {
  display: flex; align-items: center; justify-content: space-between;
  margin-top: 22px; padding-top: 18px; border-top: 1px solid var(--border);
}
.lesson-tags { display: flex; gap: 6px; flex-wrap: wrap; }
.lesson-tag {
  font-size: 10px; font-weight: 600; padding: 3px 9px;
  border-radius: 100px; background: var(--bg); border: 1px solid var(--border); color: var(--text3);
  transition: all .2s; display: inline-block;
}
.lesson-card:hover .lesson-tag {
  transform: translateY(-1px);
}
.lesson-arrow {
  width: 32px; height: 32px; border-radius: 8px;
  display: flex; align-items: center; justify-content: center;
  font-size: 13px; transition: all .3s cubic-bezier(.34,1.56,.64,1);
  background: var(--bg); color: var(--text3);
}
.lesson-card:hover .lesson-arrow {
  color: white; transform: translateX(5px) scale(1.1);
}

/* ===== LESSON DETAIL ===== */
.lesson-header {
  display: flex; align-items: flex-start; gap: 20px;
  max-width: 1000px; margin: 0 auto; padding: 0 24px 36px;
  flex-wrap: wrap;
}
.lesson-header-text { flex: 1; min-width: 200px; }
.lesson-sem-label {
  font-size: 11px; font-weight: 700; letter-spacing: 1.5px;
  text-transform: uppercase; color: var(--text3); margin-bottom: 8px;
}
.lesson-title-big {
  font-size: clamp(24px, 4vw, 42px); font-weight: 900;
  letter-spacing: -1.5px; line-height: 1.1;
}
.lesson-icon-big {
  width: 72px; height: 72px; border-radius: 20px;
  display: flex; align-items: center; justify-content: center;
  font-size: 30px; color: white; flex-shrink: 0;
  transition: transform .4s cubic-bezier(.34,1.56,.64,1), box-shadow .4s;
  cursor: default;
}
.lesson-icon-big:hover {
  transform: scale(1.12) rotate(-5deg);
  box-shadow: 0 14px 32px rgba(0,0,0,.25);
}

/* ===== TABS ===== */
.tabs-bar {
  display: flex; gap: 6px; max-width: 1000px; margin: 0 auto;
  padding: 0 24px 28px;
}
.tab-btn {
  display: inline-flex; align-items: center; gap: 8px;
  padding: 10px 20px; border-radius: 10px; border: 1px solid var(--border);
  background: var(--surface); color: var(--text2);
  cursor: pointer; font-size: 14px; font-weight: 500;
  transition: all .3s cubic-bezier(.34,1.2,.64,1); font-family: var(--font);
  position: relative; overflow: hidden;
}
.tab-btn.active {
  background: linear-gradient(135deg, var(--s1), var(--s2));
  color: white; border-color: transparent;
  box-shadow: 0 4px 16px rgba(59,130,246,.35);
  transform: translateY(-1px);
}
.tab-btn:not(.active):hover {
  background: var(--s1-light); color: var(--s1); border-color: var(--s1);
  transform: translateY(-3px) scale(1.03);
  box-shadow: 0 6px 18px rgba(59,130,246,.2);
}

.tab-panel {
  max-width: 1000px; margin: 0 auto; padding: 0 24px;
  display: none; animation: tabFadeIn .4s ease;
}
.tab-panel.active { display: block; }
@keyframes tabFadeIn {
  from { opacity: 0; transform: translateY(16px); }
  to   { opacity: 1; transform: translateY(0); }
}

/* ===== LEARN CONTENT ===== */
.learn-content {
  background: var(--surface); border: 1px solid var(--border);
  border-radius: var(--radius); overflow: hidden;
  box-shadow: var(--shadow);
}
.learn-section {
  padding: 32px 36px; border-bottom: 1px solid var(--border);
}
.learn-section:last-child { border-bottom: none; }

.learn-section-title {
  display: flex; align-items: center; gap: 10px;
  font-size: 11px; font-weight: 700; letter-spacing: 1.2px;
  text-transform: uppercase; color: var(--text3); margin-bottom: 14px;
}
.learn-section-title i { font-size: 13px; }

.learn-intro { font-size: 15px; line-height: 1.8; color: var(--text2); }

.formula-box {
  background: var(--surface2); border: 1px solid var(--border);
  border-left: 4px solid var(--s1); border-radius: 12px;
  padding: 20px 24px; margin: 12px 0;
  transition: transform .25s, box-shadow .25s, background .25s;
  cursor: default;
}
.formula-box:hover {
  transform: translateX(6px);
  box-shadow: 0 6px 20px rgba(0,0,0,.08);
  background: var(--surface);
}
.formula-box.s2-accent { border-left-color: var(--s2); }
.formula-title { font-size: 11px; font-weight: 700; color: var(--text3); margin-bottom: 8px; text-transform: uppercase; letter-spacing: .8px; }
.formula-math { font-family: var(--mono); font-size: 15px; color: var(--text); line-height: 2; }

.key-points { list-style: none; display: flex; flex-direction: column; gap: 10px; }
.key-points li {
  display: flex; align-items: flex-start; gap: 10px;
  font-size: 14px; color: var(--text2); line-height: 1.6;
  padding: 8px 12px; border-radius: 8px;
  transition: background .2s, transform .2s;
  cursor: default;
}
.key-points li:hover {
  background: var(--surface2); transform: translateX(4px);
}
.key-points li::before {
  content: '✓'; color: var(--success); font-weight: 700;
  flex-shrink: 0; margin-top: 2px;
}

.example-box {
  background: linear-gradient(135deg, var(--s1-light), var(--s2-light));
  border: 1px solid var(--border); border-radius: 12px; padding: 22px 26px;
}
.example-label { font-size: 11px; font-weight: 700; color: var(--s1); text-transform: uppercase; letter-spacing: .8px; margin-bottom: 10px; }
.example-content { font-family: var(--mono); font-size: 13px; line-height: 2; color: var(--text); }
.example-step { margin: 4px 0; }
.example-note { font-size: 12px; color: var(--text3); margin-top: 12px; font-style: italic; font-family: var(--font); }

/* ===== VIDEO ===== */
.video-section { text-align: center; }
.video-wrapper {
  position: relative; width: 100%; max-width: 860px; margin: 0 auto;
  border-radius: var(--radius); overflow: hidden;
  box-shadow: var(--shadow-lg); border: 1px solid var(--border);
  background: #000;
}
.video-wrapper iframe {
  width: 100%; aspect-ratio: 16/9; display: block;
}
.video-note {
  max-width: 860px; margin: 18px auto 0;
  background: var(--surface); border: 1px solid var(--border);
  border-radius: 10px; padding: 14px 20px;
  font-size: 13px; color: var(--text2);
  display: flex; align-items: center; gap: 10px;
}
.video-note i { color: var(--s1); }

/* ===== EXAM / QUIZ ===== */
.exam-container {
  background: var(--surface); border: 1px solid var(--border);
  border-radius: var(--radius); box-shadow: var(--shadow);
  overflow: hidden;
}
.quiz-start {
  text-align: center; padding: 64px 40px;
}
.quiz-start-icon {
  width: 80px; height: 80px; border-radius: 24px; margin: 0 auto 24px;
  background: linear-gradient(135deg, var(--s1), var(--s2));
  display: flex; align-items: center; justify-content: center;
  font-size: 34px; color: white;
  box-shadow: 0 8px 24px rgba(59,130,246,.35);
  animation: pulse 2s ease infinite;
}
@keyframes pulse {
  0%, 100% { transform: scale(1); }
  50% { transform: scale(1.05); }
}
.quiz-start h2 { font-size: 24px; font-weight: 800; margin-bottom: 10px; }
.quiz-start p { font-size: 14px; color: var(--text2); margin-bottom: 32px; }
.start-quiz-btn {
  display: inline-flex; align-items: center; gap: 10px;
  padding: 14px 32px; border-radius: 12px; border: none;
  background: linear-gradient(135deg, var(--s1), var(--s2));
  color: white; font-size: 15px; font-weight: 600;
  cursor: pointer; transition: all .25s; font-family: var(--font);
  box-shadow: 0 4px 20px rgba(59,130,246,.4);
}
.start-quiz-btn:hover { transform: translateY(-4px) scale(1.04); box-shadow: 0 10px 32px rgba(59,130,246,.55); }

.quiz-body { padding: 36px 40px; }
.quiz-progress-wrap {
  display: flex; align-items: center; justify-content: space-between;
  margin-bottom: 28px;
}
#qProgress { font-size: 13px; font-weight: 600; color: var(--text2); }
.quiz-progress-bar {
  width: 180px; height: 6px; background: var(--border); border-radius: 100px; overflow: hidden;
}
#qProgressFill {
  height: 100%; background: linear-gradient(90deg, var(--s1), var(--s2));
  border-radius: 100px; transition: width .4s cubic-bezier(.4,0,.2,1);
}

.question-card {
  font-size: 18px; font-weight: 700; line-height: 1.5;
  margin-bottom: 26px; color: var(--text);
  padding: 24px; background: var(--surface2);
  border: 1px solid var(--border); border-radius: 12px;
}
.q-num {
  font-size: 11px; color: var(--text3); font-weight: 600;
  letter-spacing: .8px; text-transform: uppercase; margin-bottom: 8px;
}

.options-container {
  display: flex; flex-direction: column; gap: 12px; margin-bottom: 24px;
}
.option-btn {
  display: flex; align-items: center; gap: 14px;
  padding: 16px 20px; border-radius: 12px;
  border: 2px solid var(--border); background: var(--surface);
  cursor: pointer; font-size: 14px; font-weight: 500;
  transition: all .22s; text-align: left; font-family: var(--font);
  color: var(--text); width: 100%;
}
.option-btn:not(.answered):hover {
  border-color: var(--s1); background: var(--s1-light);
  transform: translateX(8px) scale(1.01);
  box-shadow: 0 4px 16px rgba(59,130,246,.18);
}
.option-letter {
  width: 30px; height: 30px; border-radius: 8px;
  background: var(--bg); border: 1px solid var(--border);
  display: flex; align-items: center; justify-content: center;
  font-size: 11px; font-weight: 700; color: var(--text3);
  flex-shrink: 0; transition: all .22s;
}
.option-btn.correct {
  border-color: var(--success); background: rgba(16,185,129,.08);
}
.option-btn.correct .option-letter {
  background: var(--success); color: white; border-color: var(--success);
}
.option-btn.wrong {
  border-color: var(--danger); background: rgba(239,68,68,.08);
}
.option-btn.wrong .option-letter {
  background: var(--danger); color: white; border-color: var(--danger);
}
.option-btn.answered { cursor: default; }
.option-feedback {
  margin-left: auto; font-size: 16px; flex-shrink: 0;
  opacity: 0; transition: opacity .2s;
}
.option-btn.correct .option-feedback,
.option-btn.wrong .option-feedback { opacity: 1; }

.next-btn {
  display: inline-flex; align-items: center; gap: 8px;
  padding: 12px 26px; border-radius: 10px; border: none;
  background: linear-gradient(135deg, var(--s1), var(--s2));
  color: white; font-size: 14px; font-weight: 600;
  cursor: pointer; transition: all .22s; font-family: var(--font);
}
.next-btn:hover { transform: translateX(5px) scale(1.03); box-shadow: 0 6px 20px rgba(59,130,246,.4); }
.hidden { display: none !important; }

/* ===== RESULTS ===== */
.quiz-result {
  text-align: center; padding: 60px 40px;
  animation: fadeInUp .5s ease;
}
.result-circle {
  width: 120px; height: 120px; border-radius: 50%;
  margin: 0 auto 28px;
  display: flex; align-items: center; justify-content: center;
  font-size: 36px; font-weight: 900; color: white;
  position: relative;
  animation: scaleIn .5s cubic-bezier(.175,.885,.32,1.275) both;
}
@keyframes scaleIn {
  from { transform: scale(0); opacity: 0; }
  to   { transform: scale(1); opacity: 1; }
}
.result-circle.green { background: linear-gradient(135deg, #10b981, #059669); box-shadow: 0 8px 24px rgba(16,185,129,.4); }
.result-circle.yellow { background: linear-gradient(135deg, #f59e0b, #d97706); box-shadow: 0 8px 24px rgba(245,158,11,.4); }
.result-circle.red { background: linear-gradient(135deg, #ef4444, #dc2626); box-shadow: 0 8px 24px rgba(239,68,68,.4); }
.result-denom { font-size: 18px; font-weight: 600; opacity: .8; }

.quiz-result h2 { font-size: 26px; font-weight: 800; margin-bottom: 10px; }
.quiz-result p { font-size: 15px; color: var(--text2); margin-bottom: 30px; }

.result-details {
  display: grid; grid-template-columns: repeat(5, 1fr);
  gap: 10px; margin-bottom: 32px; max-width: 400px; margin-left: auto; margin-right: auto;
}
.result-q {
  aspect-ratio: 1; border-radius: 10px; display: flex;
  align-items: center; justify-content: center; font-size: 13px; font-weight: 700; color: white;
}
.result-q.correct-q { background: var(--success); }
.result-q.wrong-q { background: var(--danger); }

.retry-btn {
  display: inline-flex; align-items: center; gap: 8px;
  padding: 12px 26px; border-radius: 10px; border: 1px solid var(--border);
  background: var(--surface); color: var(--text2);
  font-size: 14px; font-weight: 600; cursor: pointer;
  transition: all .22s; font-family: var(--font);
}
.retry-btn:hover { background: var(--s1-light); color: var(--s1); border-color: var(--s1); transform: scale(1.05) translateY(-2px); box-shadow: 0 6px 18px rgba(59,130,246,.2); }

/* ===== ANIMATIONS ===== */
@keyframes fadeInUp {
  from { opacity: 0; transform: translateY(30px); }
  to   { opacity: 1; transform: translateY(0); }
}

/* ===== TEAM SECTION ===== */
.team-section {
  max-width: 1100px; margin: 64px auto 0; padding: 0 24px 80px;
  animation: fadeInUp .7s .4s ease both;
}

.team-header {
  text-align: center; margin-bottom: 52px;
}
.team-badge {
  display: inline-flex; align-items: center; gap: 8px;
  background: linear-gradient(135deg, var(--s1-light), var(--s2-light));
  color: var(--s2); border: 1px solid var(--s2);
  border-radius: 100px; padding: 6px 18px;
  font-size: 12px; font-weight: 600; letter-spacing: .6px; text-transform: uppercase;
  margin-bottom: 16px;
}
.team-title {
  font-size: clamp(28px, 4vw, 48px); font-weight: 900;
  letter-spacing: -1.5px; margin-bottom: 10px;
}
.team-sub { font-size: 15px; color: var(--text2); }

/* Leader */
.team-leader-wrap {
  display: flex; justify-content: center; margin-bottom: 36px;
}

.team-card {
  position: relative; background: var(--surface);
  border: 1px solid var(--border); border-radius: 22px;
  padding: 32px 28px; text-align: center;
  cursor: default; overflow: hidden;
  transition: transform .4s cubic-bezier(.34,1.2,.64,1),
              box-shadow .4s, border-color .4s;
}
.team-card:hover {
  transform: translateY(-10px) scale(1.03);
}

.team-card-glow {
  position: absolute; inset: 0; opacity: 0;
  transition: opacity .4s; pointer-events: none;
  background: radial-gradient(ellipse at 50% 0%, rgba(139,92,246,.14), transparent 65%);
}
.team-card:hover .team-card-glow { opacity: 1; }

/* Leader specific */
.leader-card {
  width: 280px;
  border-color: var(--s2);
  box-shadow: 0 8px 32px rgba(139,92,246,.18);
}
.leader-card:hover {
  border-color: var(--s2);
  box-shadow: 0 24px 56px rgba(139,92,246,.32);
}

.leader-crown {
  position: absolute; top: 16px; right: 16px;
  width: 32px; height: 32px; border-radius: 8px;
  background: linear-gradient(135deg, #f59e0b, #fbbf24);
  display: flex; align-items: center; justify-content: center;
  font-size: 14px; color: white;
  box-shadow: 0 4px 12px rgba(245,158,11,.4);
  animation: crownFloat 3s ease-in-out infinite;
}
@keyframes crownFloat {
  0%, 100% { transform: translateY(0) rotate(-5deg); }
  50%       { transform: translateY(-4px) rotate(5deg); }
}

.team-avatar {
  width: 72px; height: 72px; border-radius: 50%;
  display: flex; align-items: center; justify-content: center;
  font-size: 26px; font-weight: 800; color: white;
  margin: 0 auto 16px; position: relative;
  transition: transform .4s cubic-bezier(.34,1.56,.64,1);
}
.team-card:hover .team-avatar { transform: scale(1.12) translateY(-3px); }

.leader-avatar {
  width: 84px; height: 84px; font-size: 32px;
  background: linear-gradient(135deg, var(--s2), #c084fc);
  box-shadow: 0 8px 24px rgba(139,92,246,.45);
}
.avatar-ring {
  position: absolute; inset: -5px; border-radius: 50%;
  border: 2px dashed rgba(139,92,246,.5);
  animation: spinRing 8s linear infinite;
}
@keyframes spinRing {
  to { transform: rotate(360deg); }
}

/* Member avatars — different gradient per member */
.member-avatar { width: 60px; height: 60px; font-size: 22px; }
.av1 { background: linear-gradient(135deg, #3b82f6, #60a5fa); box-shadow: 0 6px 18px rgba(59,130,246,.4); }
.av2 { background: linear-gradient(135deg, #10b981, #34d399); box-shadow: 0 6px 18px rgba(16,185,129,.4); }
.av3 { background: linear-gradient(135deg, #f59e0b, #fbbf24); box-shadow: 0 6px 18px rgba(245,158,11,.4); }
.av4 { background: linear-gradient(135deg, #ec4899, #f472b6); box-shadow: 0 6px 18px rgba(236,72,153,.4); }
.av5 { background: linear-gradient(135deg, #8b5cf6, #a78bfa); box-shadow: 0 6px 18px rgba(139,92,246,.4); }
.av6 { background: linear-gradient(135deg, #06b6d4, #22d3ee); box-shadow: 0 6px 18px rgba(6,182,212,.4); }

.team-role {
  display: inline-flex; align-items: center; gap: 5px;
  font-size: 11px; font-weight: 700; letter-spacing: .8px;
  text-transform: uppercase; border-radius: 100px;
  padding: 4px 12px; margin-bottom: 10px;
}
.leader-role {
  background: linear-gradient(135deg, var(--s2-light), var(--s1-light));
  color: var(--s2); border: 1px solid var(--s2);
}
.member-role {
  background: var(--bg); color: var(--text3); border: 1px solid var(--border);
  transition: all .25s;
}
.team-card:hover .member-role {
  background: var(--s1-light); color: var(--s1); border-color: var(--s1);
}

.team-name {
  font-size: 15px; font-weight: 700; color: var(--text);
  line-height: 1.5; direction: rtl;
}
.team-name-en {
  font-size: 12px; color: var(--text3); margin-top: 4px;
}

/* Members grid */
.team-members-grid {
  display: grid; grid-template-columns: repeat(3, 1fr);
  gap: 20px;
}
.member-card { padding: 26px 20px; }

/* member card hover glow color per avatar */
.member-card:nth-child(1):hover { border-color: #3b82f6; box-shadow: 0 18px 44px rgba(59,130,246,.2); }
.member-card:nth-child(2):hover { border-color: #10b981; box-shadow: 0 18px 44px rgba(16,185,129,.2); }
.member-card:nth-child(3):hover { border-color: #f59e0b; box-shadow: 0 18px 44px rgba(245,158,11,.2); }
.member-card:nth-child(4):hover { border-color: #ec4899; box-shadow: 0 18px 44px rgba(236,72,153,.2); }
.member-card:nth-child(5):hover { border-color: #8b5cf6; box-shadow: 0 18px 44px rgba(139,92,246,.2); }
.member-card:nth-child(6):hover { border-color: #06b6d4; box-shadow: 0 18px 44px rgba(6,182,212,.2); }

.member-card:nth-child(1) .team-card-glow { background: radial-gradient(ellipse at 50% 0%, rgba(59,130,246,.14), transparent 65%); }
.member-card:nth-child(2) .team-card-glow { background: radial-gradient(ellipse at 50% 0%, rgba(16,185,129,.14), transparent 65%); }
.member-card:nth-child(3) .team-card-glow { background: radial-gradient(ellipse at 50% 0%, rgba(245,158,11,.14), transparent 65%); }
.member-card:nth-child(4) .team-card-glow { background: radial-gradient(ellipse at 50% 0%, rgba(236,72,153,.14), transparent 65%); }
.member-card:nth-child(5) .team-card-glow { background: radial-gradient(ellipse at 50% 0%, rgba(139,92,246,.14), transparent 65%); }
.member-card:nth-child(6) .team-card-glow { background: radial-gradient(ellipse at 50% 0%, rgba(6,182,212,.14), transparent 65%); }

/* Staggered animation */
.leader-card  { animation: fadeInUp .6s .5s ease both; }
.member-card:nth-child(1) { animation: fadeInUp .5s .55s ease both; }
.member-card:nth-child(2) { animation: fadeInUp .5s .62s ease both; }
.member-card:nth-child(3) { animation: fadeInUp .5s .69s ease both; }
.member-card:nth-child(4) { animation: fadeInUp .5s .76s ease both; }
.member-card:nth-child(5) { animation: fadeInUp .5s .83s ease both; }
.member-card:nth-child(6) { animation: fadeInUp .5s .90s ease both; }

/* Team responsive */
@media (max-width: 767px) {
  .team-members-grid { grid-template-columns: repeat(2, 1fr); gap: 14px; }
  .leader-card { width: 240px; }
}
@media (max-width: 519px) {
  .team-section { padding: 0 16px 60px; margin-top: 44px; }
  .team-members-grid { grid-template-columns: 1fr; gap: 12px; }
  .leader-card { width: 100%; }
  .team-title { letter-spacing: -1px; }
}

/* ===== SCROLLBAR ===== */
::-webkit-scrollbar { width: 6px; }
::-webkit-scrollbar-track { background: transparent; }
::-webkit-scrollbar-thumb { background: var(--border); border-radius: 100px; }
::-webkit-scrollbar-thumb:hover { background: var(--text3); }

/* ===== RESPONSIVE ===== */

/* ── Large desktop (1280px+) ── */
@media (min-width: 1280px) {
  .lessons-grid { grid-template-columns: repeat(4, 1fr); }
}

/* ── Desktop (1024–1279px) ── */
@media (max-width: 1279px) and (min-width: 1024px) {
  .lessons-grid { grid-template-columns: repeat(3, 1fr); }
}

/* ── Tablet landscape (768–1023px) ── */
@media (max-width: 1023px) and (min-width: 768px) {
  .semesters-grid { grid-template-columns: repeat(2, 1fr); gap: 20px; padding: 0 20px 50px; }
  .semester-card-content { padding: 28px; }
  .lessons-grid { grid-template-columns: repeat(2, 1fr); padding: 0 20px; gap: 18px; }
  .learn-section { padding: 28px 28px; }
  .quiz-body { padding: 28px 28px; }
  .tab-panel { padding: 0 20px; }
  .lesson-header { padding: 0 20px 32px; }
  .view-header { padding: 0 20px 40px; }
  .stats-bar { padding: 0 16px; }
  .hero-title { letter-spacing: -1.5px; }
}

/* ── Tablet portrait (520–767px) ── */
@media (max-width: 767px) and (min-width: 520px) {
  .semesters-grid { grid-template-columns: 1fr; gap: 20px; padding: 0 20px 44px; }
  .semester-card-content { padding: 28px; }
  .sem-title { font-size: 22px; }
  .stats-bar { flex-wrap: wrap; padding: 10px 16px; margin: 0 20px; }
  .stat-divider { display: none; }
  .stat-item { flex: 1 0 42%; padding: 16px 10px; }
  .lessons-grid { grid-template-columns: repeat(2, 1fr); padding: 0 20px; gap: 16px; }
  .view-header { padding: 0 20px 36px; }
  .lesson-header { padding: 0 20px 28px; flex-direction: column; gap: 14px; }
  .lesson-icon-big { width: 56px; height: 56px; font-size: 24px; }
  .tabs-bar { overflow-x: auto; padding: 0 20px 24px; gap: 8px; }
  .tab-btn { padding: 9px 16px; font-size: 13px; white-space: nowrap; }
  .tab-panel { padding: 0 20px; }
  .learn-section { padding: 22px 20px; }
  .quiz-body { padding: 22px 20px; }
  .quiz-start { padding: 48px 28px; }
  .quiz-result { padding: 48px 28px; }
  .quiz-progress-bar { width: 120px; }
  .formula-math { font-size: 13px; }
  .hero { padding: 0 20px 50px; }
  .hero-title { letter-spacing: -1px; }
  .hero-sub { font-size: 15px; }
}

/* ── Mobile (up to 519px) ── */
@media (max-width: 519px) {
  :root { --nav-h: 58px; }
  #view-home { padding-top: calc(var(--nav-h) + 40px); }
  .view { padding-top: calc(var(--nav-h) + 28px); }
  .nav-title { font-size: 15px; }
  .nav-logo { width: 32px; height: 32px; font-size: 15px; }
  .hero { padding: 0 16px 40px; }
  .hero-title { letter-spacing: -0.5px; }
  .hero-badge { font-size: 10px; padding: 5px 14px; }
  .hero-sub { font-size: 14px; }
  .semesters-grid { grid-template-columns: 1fr; gap: 16px; padding: 0 16px 36px; }
  .semester-card-content { padding: 22px 18px; }
  .sem-icon-wrap { width: 52px; height: 52px; font-size: 22px; }
  .sem-title { font-size: 20px; }
  .sem-desc { font-size: 13px; }
  .sem-stats { gap: 14px; }
  .stats-bar { flex-wrap: wrap; padding: 8px 12px; margin: 0 16px; border-radius: 14px; }
  .stat-divider { display: none; }
  .stat-item { flex: 1 0 40%; padding: 14px 8px; }
  .stat-num { font-size: 22px; }
  .stat-label { font-size: 10px; }
  .view-header { padding: 0 16px 28px; }
  .view-title { font-size: 24px; letter-spacing: -1px; }
  .view-subtitle { font-size: 13px; }
  .lessons-grid { grid-template-columns: 1fr; padding: 0 16px; gap: 14px; }
  .lesson-card { padding: 20px 18px; }
  .lesson-card-title { font-size: 16px; }
  .lesson-card-icon { width: 44px; height: 44px; font-size: 18px; }
  .lesson-header { padding: 0 16px 24px; flex-direction: column; gap: 12px; }
  .lesson-icon-big { width: 52px; height: 52px; font-size: 22px; border-radius: 14px; }
  .lesson-title-big { letter-spacing: -1px; }
  .tabs-bar { overflow-x: auto; padding: 0 16px 20px; gap: 6px; }
  .tab-btn { padding: 8px 14px; font-size: 12px; white-space: nowrap; flex-shrink: 0; }
  .tab-panel { padding: 0 16px; }
  .learn-section { padding: 18px 16px; }
  .learn-intro { font-size: 14px; }
  .formula-box { padding: 14px 16px; }
  .formula-math { font-size: 12px; line-height: 1.8; }
  .example-content { font-size: 12px; }
  .video-note { padding: 12px 16px; font-size: 12px; }
  .quiz-start { padding: 36px 18px; }
  .quiz-start h2 { font-size: 20px; }
  .quiz-start-icon { width: 64px; height: 64px; font-size: 26px; }
  .quiz-body { padding: 18px 16px; }
  .question-card { font-size: 15px; padding: 18px 16px; }
  .option-btn { padding: 13px 14px; font-size: 13px; gap: 10px; }
  .quiz-progress-bar { width: 90px; }
  .quiz-result { padding: 36px 18px; }
  .result-circle { width: 100px; height: 100px; font-size: 30px; }
  .quiz-result h2 { font-size: 20px; }
  .back-btn { padding: 8px 14px; font-size: 12px; }
  .breadcrumb { font-size: 11px; }
  .breadcrumb .current { max-width: 120px; overflow: hidden; text-overflow: ellipsis; white-space: nowrap; }
}