/* =========================================================
   EfficientScience – Premium Science IAC Practice Platform
   ========================================================= */

@import url('https://fonts.googleapis.com/css2?family=Inter:wght@300;400;500;600;700&family=Space+Grotesk:wght@400;500;600;700;800&display=swap');

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

:root {
  --bg:          #030712;
  --bg-1:        #0a0f1e;
  --bg-2:        #0d1530;
  --surface:     rgba(255,255,255,0.04);
  --surface-2:   rgba(255,255,255,0.08);
  --border:      rgba(255,255,255,0.09);
  --border-2:    rgba(255,255,255,0.15);

  --blue:        #3b82f6;
  --blue-light:  #60a5fa;
  --purple:      #a855f7;
  --purple-light:#c084fc;
  --teal:        #2dd4bf;
  --rose:        #f43f5e;
  --amber:       #f59e0b;
  --green:       #22c55e;

  --grad-primary: linear-gradient(135deg, #3b82f6 0%, #a855f7 100%);
  --grad-hero:    radial-gradient(ellipse 80% 60% at 50% 0%, rgba(59,130,246,0.25) 0%, transparent 70%),
                  radial-gradient(ellipse 60% 40% at 80% 50%, rgba(168,85,247,0.15) 0%, transparent 70%),
                  #030712;

  --text:        #f1f5f9;
  --text-2:      #94a3b8;
  --text-3:      #475569;

  --radius-sm:   8px;
  --radius:      14px;
  --radius-lg:   20px;
  --radius-xl:   28px;

  --shadow-blue: 0 0 40px rgba(59,130,246,0.25);
  --shadow-card: 0 4px 24px rgba(0,0,0,0.4);

  --transition: 0.25s cubic-bezier(0.4,0,0.2,1);
  --transition-slow: 0.5s cubic-bezier(0.4,0,0.2,1);
}

html { scroll-behavior: smooth; }

body {
  font-family: 'Inter', sans-serif;
  background: var(--bg);
  color: var(--text);
  line-height: 1.6;
  min-height: 100vh;
  overflow-x: hidden;
}

h1,h2,h3,h4,h5 {
  font-family: 'Space Grotesk', sans-serif;
  font-weight: 700;
  line-height: 1.2;
}

a { color: inherit; text-decoration: none; }
img { max-width: 100%; }

/* ── Scrollbar ─────────────────────────────────────────── */
::-webkit-scrollbar { width: 6px; }
::-webkit-scrollbar-track { background: var(--bg-1); }
::-webkit-scrollbar-thumb { background: rgba(59,130,246,0.4); border-radius: 99px; }

/* ── Utility ───────────────────────────────────────────── */
.container { max-width: 1200px; margin: 0 auto; padding: 0 24px; }
.grad-text {
  background: var(--grad-primary);
  -webkit-background-clip: text;
  -webkit-text-fill-color: transparent;
  background-clip: text;
}
.badge {
  display: inline-flex; align-items: center; gap: 6px;
  padding: 6px 14px; border-radius: 99px;
  background: rgba(59,130,246,0.12);
  border: 1px solid rgba(59,130,246,0.25);
  font-size: 12px; font-weight: 600;
  color: var(--blue-light); letter-spacing: 0.5px;
  text-transform: uppercase;
}
.badge::before { content: ''; width: 6px; height: 6px; border-radius: 50%; background: var(--blue); animation: pulse 2s infinite; }

@keyframes pulse {
  0%,100% { opacity: 1; transform: scale(1); }
  50%      { opacity: 0.5; transform: scale(1.4); }
}

/* ── Navigation ────────────────────────────────────────── */
.nav {
  position: fixed; top: 0; left: 0; right: 0; z-index: 100;
  padding: 16px 0;
  transition: var(--transition);
}
.nav.scrolled {
  background: rgba(3,7,18,0.85);
  backdrop-filter: blur(20px);
  border-bottom: 1px solid var(--border);
  padding: 12px 0;
}
.nav-inner {
  display: flex; align-items: center; gap: 32px;
}
.nav-logo {
  display: flex; align-items: center; gap: 10px;
  font-family: 'Space Grotesk', sans-serif;
  font-size: 20px; font-weight: 800;
  flex-shrink: 0;
}
.nav-logo .logo-icon {
  width: 36px; height: 36px; border-radius: 10px;
  background: var(--grad-primary);
  display: flex; align-items: center; justify-content: center;
  font-size: 18px;
}
.nav-links {
  display: flex; align-items: center; gap: 4px;
  list-style: none; flex: 1;
}
.nav-links a {
  padding: 8px 14px; border-radius: var(--radius-sm);
  font-size: 14px; font-weight: 500;
  color: var(--text-2);
  transition: var(--transition);
}
.nav-links a:hover, .nav-links a.active { color: var(--text); background: var(--surface-2); }
.nav-actions { display: flex; align-items: center; gap: 10px; margin-left: auto; }
.btn {
  display: inline-flex; align-items: center; gap: 8px;
  padding: 10px 22px; border-radius: var(--radius-sm);
  font-size: 14px; font-weight: 600;
  border: none; cursor: pointer;
  transition: var(--transition);
  white-space: nowrap;
}
.btn-ghost {
  background: transparent;
  color: var(--text-2);
  border: 1px solid var(--border);
}
.btn-ghost:hover { color: var(--text); border-color: var(--border-2); background: var(--surface); }
.btn-primary {
  background: var(--grad-primary);
  color: #fff;
  box-shadow: 0 0 20px rgba(59,130,246,0.3);
}
.btn-primary:hover { opacity: 0.9; transform: translateY(-1px); box-shadow: 0 4px 30px rgba(59,130,246,0.4); }
.btn-outline {
  background: transparent; color: var(--blue-light);
  border: 1px solid rgba(59,130,246,0.4);
}
.btn-outline:hover { background: rgba(59,130,246,0.1); border-color: var(--blue); }
.btn-lg { padding: 14px 32px; font-size: 16px; border-radius: var(--radius); }
.btn-sm { padding: 7px 16px; font-size: 13px; }

/* ── Canvas Background ─────────────────────────────────── */
#star-canvas {
  position: fixed; top: 0; left: 0;
  width: 100%; height: 100%;
  pointer-events: none; z-index: 0;
}

/* ── Hero ──────────────────────────────────────────────── */
.hero {
  position: relative; z-index: 1;
  padding: 180px 0 120px;
  background: var(--grad-hero);
  overflow: hidden;
}
.hero-glow {
  position: absolute;
  width: 600px; height: 600px;
  background: radial-gradient(circle, rgba(59,130,246,0.15) 0%, transparent 70%);
  border-radius: 50%;
  top: -100px; left: 50%; transform: translateX(-50%);
  pointer-events: none;
}
.hero-glow-2 {
  position: absolute;
  width: 400px; height: 400px;
  background: radial-gradient(circle, rgba(168,85,247,0.12) 0%, transparent 70%);
  border-radius: 50%;
  bottom: -100px; right: 10%;
  pointer-events: none;
}
.hero-content { text-align: center; max-width: 860px; margin: 0 auto; }
.hero-eyebrow { margin-bottom: 28px; }
.hero h1 {
  font-size: clamp(44px, 7vw, 82px);
  font-weight: 800;
  line-height: 1.08;
  margin-bottom: 24px;
  letter-spacing: -2px;
}
.hero p {
  font-size: clamp(16px, 2vw, 20px);
  color: var(--text-2);
  max-width: 580px; margin: 0 auto 44px;
  line-height: 1.7;
}
.hero-cta { display: flex; gap: 14px; justify-content: center; flex-wrap: wrap; }
.hero-stats {
  display: flex; justify-content: center; gap: 60px;
  margin-top: 72px;
  padding-top: 48px;
  border-top: 1px solid var(--border);
}
.stat-item { text-align: center; }
.stat-num {
  font-family: 'Space Grotesk', sans-serif;
  font-size: 36px; font-weight: 800;
  background: var(--grad-primary);
  -webkit-background-clip: text;
  -webkit-text-fill-color: transparent;
  background-clip: text;
}
.stat-label { font-size: 13px; color: var(--text-2); margin-top: 4px; font-weight: 500; }

/* ── Section ───────────────────────────────────────────── */
section { position: relative; z-index: 1; }
.section { padding: 96px 0; }
.section-header { text-align: center; margin-bottom: 64px; }
.section-header h2 { font-size: clamp(28px, 4vw, 44px); margin-bottom: 16px; letter-spacing: -1px; }
.section-header p { font-size: 17px; color: var(--text-2); max-width: 520px; margin: 0 auto; }

/* ── Features ──────────────────────────────────────────── */
.features-grid {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(300px, 1fr));
  gap: 20px;
}
.feature-card {
  background: var(--surface);
  border: 1px solid var(--border);
  border-radius: var(--radius-lg);
  padding: 36px 32px;
  transition: var(--transition);
  position: relative; overflow: hidden;
}
.feature-card::before {
  content: '';
  position: absolute; inset: 0;
  background: linear-gradient(135deg, rgba(59,130,246,0.05) 0%, transparent 60%);
  opacity: 0; transition: var(--transition);
}
.feature-card:hover { border-color: var(--border-2); transform: translateY(-4px); box-shadow: var(--shadow-card); }
.feature-card:hover::before { opacity: 1; }
.feature-icon {
  width: 52px; height: 52px; border-radius: 14px;
  display: flex; align-items: center; justify-content: center;
  font-size: 24px; margin-bottom: 20px;
  background: var(--surface-2);
  border: 1px solid var(--border);
}
.feature-card h3 { font-size: 19px; margin-bottom: 10px; }
.feature-card p { font-size: 14px; color: var(--text-2); line-height: 1.7; }

/* ── Subjects ──────────────────────────────────────────── */
.subjects { background: linear-gradient(to bottom, transparent, var(--bg-1) 20%, var(--bg-1) 80%, transparent); }
.subjects-grid {
  display: grid;
  grid-template-columns: repeat(3, 1fr);
  gap: 20px;
}
@media (max-width: 900px) { .subjects-grid { grid-template-columns: repeat(2,1fr); } }
@media (max-width: 560px) { .subjects-grid { grid-template-columns: 1fr; } }

.subject-card {
  position: relative;
  background: var(--surface);
  border: 1px solid var(--border);
  border-radius: var(--radius-xl);
  padding: 36px 28px;
  cursor: pointer;
  transition: var(--transition);
  overflow: hidden;
  text-decoration: none;
  display: block;
}
.subject-card::after {
  content: '';
  position: absolute; top: 0; left: 0; right: 0;
  height: 2px;
  background: var(--card-grad);
  transform: scaleX(0);
  transform-origin: left;
  transition: var(--transition);
}
.subject-card:hover { border-color: var(--border-2); transform: translateY(-6px); box-shadow: var(--shadow-card); }
.subject-card:hover::after { transform: scaleX(1); }
.subject-card .icon {
  font-size: 40px; margin-bottom: 20px;
  display: block;
}
.subject-card h3 { font-size: 20px; margin-bottom: 8px; }
.subject-card .desc { font-size: 13px; color: var(--text-2); margin-bottom: 20px; line-height: 1.6; }
.subject-meta {
  display: flex; align-items: center; gap: 12px;
  font-size: 12px; color: var(--text-3);
}
.subject-meta .pill {
  padding: 3px 10px; border-radius: 99px;
  background: var(--surface-2);
  color: var(--text-2); font-weight: 500;
}
.subject-arrow {
  position: absolute; top: 28px; right: 28px;
  width: 32px; height: 32px;
  background: var(--surface-2);
  border-radius: 50%; display: flex; align-items: center; justify-content: center;
  font-size: 14px; opacity: 0;
  transition: var(--transition);
}
.subject-card:hover .subject-arrow { opacity: 1; transform: translate(2px, -2px); }

/* ── Practice Preview ──────────────────────────────────── */
.preview-section { background: var(--bg-1); }
.preview-inner {
  display: grid; grid-template-columns: 1fr 1fr; gap: 64px; align-items: center;
}
@media (max-width: 800px) { .preview-inner { grid-template-columns: 1fr; } }
.preview-text h2 { font-size: clamp(26px,4vw,40px); margin-bottom: 16px; letter-spacing: -1px; }
.preview-text p { color: var(--text-2); margin-bottom: 28px; font-size: 16px; line-height: 1.75; }
.preview-points { list-style: none; display: flex; flex-direction: column; gap: 14px; margin-bottom: 36px; }
.preview-points li {
  display: flex; align-items: flex-start; gap: 12px;
  font-size: 14px; color: var(--text-2);
}
.preview-points li::before {
  content: '✓';
  min-width: 22px; height: 22px;
  background: rgba(34,197,94,0.12);
  color: var(--green);
  border-radius: 50%;
  display: flex; align-items: center; justify-content: center;
  font-size: 12px; font-weight: 700;
}

/* ── Question Mock Card ─────────────────────────────────── */
.question-mock {
  background: var(--surface);
  border: 1px solid var(--border);
  border-radius: var(--radius-xl);
  padding: 32px;
  box-shadow: var(--shadow-card), 0 0 80px rgba(59,130,246,0.08);
}
.qm-header {
  display: flex; align-items: center; justify-content: space-between;
  margin-bottom: 24px;
}
.qm-tag {
  padding: 4px 12px; border-radius: 99px;
  font-size: 11px; font-weight: 700;
  background: rgba(59,130,246,0.15); color: var(--blue-light);
  text-transform: uppercase; letter-spacing: 0.5px;
}
.qm-diff {
  font-size: 12px; color: var(--amber);
  background: rgba(245,158,11,0.1);
  padding: 4px 10px; border-radius: 99px;
}
.qm-q { font-size: 16px; font-weight: 600; margin-bottom: 24px; line-height: 1.55; }
.qm-options { display: flex; flex-direction: column; gap: 10px; }
.qm-opt {
  padding: 12px 16px;
  border: 1px solid var(--border);
  border-radius: var(--radius-sm);
  font-size: 14px; cursor: pointer;
  transition: var(--transition);
  display: flex; align-items: center; gap: 12px;
}
.qm-opt:hover { border-color: var(--blue); background: rgba(59,130,246,0.05); }
.qm-opt.correct { border-color: var(--green); background: rgba(34,197,94,0.08); color: var(--green); }
.qm-opt.wrong   { border-color: var(--rose);  background: rgba(244,63,94,0.08);  color: var(--rose); }
.qm-opt .opt-letter {
  width: 26px; height: 26px; border-radius: 7px;
  background: var(--surface-2);
  display: flex; align-items: center; justify-content: center;
  font-size: 12px; font-weight: 700; flex-shrink: 0;
}
.qm-opt.correct .opt-letter { background: rgba(34,197,94,0.2); }
.qm-opt.wrong   .opt-letter { background: rgba(244,63,94,0.2); }
.qm-explanation {
  margin-top: 20px; padding: 16px;
  background: rgba(59,130,246,0.06);
  border: 1px solid rgba(59,130,246,0.15);
  border-radius: var(--radius-sm);
  font-size: 13px; color: var(--text-2);
  line-height: 1.65; display: none;
}
.qm-explanation.show { display: block; animation: fadeIn 0.3s ease; }
.qm-footer { display: flex; align-items: center; justify-content: space-between; margin-top: 20px; }
.qm-progress { font-size: 12px; color: var(--text-3); }
.progress-bar-wrap {
  height: 4px; background: var(--surface-2);
  border-radius: 99px; margin-top: 6px; width: 120px;
}
.progress-bar {
  height: 100%; border-radius: 99px;
  background: var(--grad-primary); width: 40%;
  transition: width 0.5s ease;
}

/* ── Leaderboard Section ───────────────────────────────── */
.leaderboard-section { background: linear-gradient(to bottom, transparent, var(--bg-2) 30%, var(--bg-2) 70%, transparent); }
.leaderboard-wrap { max-width: 680px; margin: 0 auto; }
.lb-card {
  background: var(--surface);
  border: 1px solid var(--border);
  border-radius: var(--radius-xl);
  overflow: hidden;
}
.lb-header {
  padding: 24px 28px;
  border-bottom: 1px solid var(--border);
  display: flex; align-items: center; justify-content: space-between;
}
.lb-header h3 { font-size: 18px; }
.lb-header .view-all { font-size: 13px; color: var(--blue-light); }
.lb-row {
  display: flex; align-items: center; gap: 16px;
  padding: 16px 28px;
  border-bottom: 1px solid var(--border);
  transition: var(--transition);
}
.lb-row:last-child { border-bottom: none; }
.lb-row:hover { background: var(--surface-2); }
.lb-rank {
  font-family: 'Space Grotesk', sans-serif;
  font-size: 13px; font-weight: 700;
  width: 28px; text-align: center; color: var(--text-3);
}
.lb-rank.gold   { color: #f59e0b; }
.lb-rank.silver { color: #94a3b8; }
.lb-rank.bronze { color: #cd7c4a; }
.lb-avatar {
  width: 40px; height: 40px; border-radius: 50%;
  display: flex; align-items: center; justify-content: center;
  font-size: 18px; background: var(--surface-2);
}
.lb-name { flex: 1; font-size: 15px; font-weight: 600; }
.lb-sub  { font-size: 12px; color: var(--text-2); }
.lb-score {
  font-family: 'Space Grotesk', sans-serif;
  font-size: 16px; font-weight: 700;
  background: var(--grad-primary);
  -webkit-background-clip: text;
  -webkit-text-fill-color: transparent;
  background-clip: text;
}

/* ── CTA Section ───────────────────────────────────────── */
.cta-section {
  padding: 96px 0;
  text-align: center;
}
.cta-inner {
  background: linear-gradient(135deg, rgba(59,130,246,0.12) 0%, rgba(168,85,247,0.12) 100%);
  border: 1px solid rgba(59,130,246,0.2);
  border-radius: 32px;
  padding: 80px 40px;
  position: relative; overflow: hidden;
}
.cta-inner::before {
  content: '';
  position: absolute;
  width: 500px; height: 500px;
  background: radial-gradient(circle, rgba(59,130,246,0.12) 0%, transparent 70%);
  top: -200px; left: 50%; transform: translateX(-50%);
  border-radius: 50%;
}
.cta-inner h2 { font-size: clamp(28px,4vw,48px); margin-bottom: 16px; letter-spacing: -1px; }
.cta-inner p { font-size: 18px; color: var(--text-2); max-width: 480px; margin: 0 auto 40px; }
.cta-buttons { display: flex; gap: 14px; justify-content: center; flex-wrap: wrap; }

/* ── Footer ────────────────────────────────────────────── */
.footer {
  border-top: 1px solid var(--border);
  padding: 60px 0 32px;
}
.footer-top {
  display: grid; grid-template-columns: 2fr 1fr 1fr 1fr;
  gap: 48px; margin-bottom: 48px;
}
@media (max-width: 800px) { .footer-top { grid-template-columns: 1fr 1fr; } }
@media (max-width: 500px) { .footer-top { grid-template-columns: 1fr; } }
.footer-brand p { font-size: 13px; color: var(--text-2); margin-top: 14px; max-width: 260px; line-height: 1.7; }
.footer-col h4 { font-size: 13px; font-weight: 700; margin-bottom: 16px; color: var(--text); text-transform: uppercase; letter-spacing: 0.5px; }
.footer-col ul { list-style: none; display: flex; flex-direction: column; gap: 10px; }
.footer-col ul li a { font-size: 13px; color: var(--text-2); transition: var(--transition); }
.footer-col ul li a:hover { color: var(--text); }
.footer-bottom {
  border-top: 1px solid var(--border);
  padding-top: 28px;
  display: flex; align-items: center; justify-content: space-between;
  font-size: 12px; color: var(--text-3);
}
@media (max-width: 560px) { .footer-bottom { flex-direction: column; gap: 10px; } }

/* ── Practice Page ─────────────────────────────────────── */
.practice-page {
  display: flex; min-height: 100vh; padding-top: 70px;
}
.practice-sidebar {
  width: 280px; flex-shrink: 0;
  background: var(--bg-1);
  border-right: 1px solid var(--border);
  padding: 32px 20px;
  position: sticky; top: 70px;
  height: calc(100vh - 70px);
  overflow-y: auto;
}
.practice-main {
  flex: 1; padding: 40px 48px;
  max-width: 860px;
}
@media (max-width: 900px) {
  .practice-page { flex-direction: column; }
  .practice-sidebar { width: 100%; height: auto; position: relative; top: 0; }
  .practice-main { padding: 32px 20px; }
}

.sidebar-section { margin-bottom: 32px; }
.sidebar-label {
  font-size: 11px; font-weight: 700;
  text-transform: uppercase; letter-spacing: 1px;
  color: var(--text-3); margin-bottom: 12px;
}
.filter-pills { display: flex; flex-wrap: wrap; gap: 6px; }
.filter-pill {
  display: inline-flex; align-items: center;
  padding: 6px 12px; border-radius: 99px;
  border: 1px solid var(--border);
  background: transparent;
  font-size: 12px; font-weight: 500;
  color: var(--text-2); cursor: pointer;
  transition: var(--transition);
}
.filter-pill:hover { border-color: var(--blue); color: var(--blue-light); }
.filter-pill.active { background: var(--blue); border-color: var(--blue); color: #fff; }
.filter-pill.active .pill-count { background: rgba(255,255,255,0.2); color: rgba(255,255,255,0.8); }

.diff-pills { display: flex; flex-direction: column; gap: 6px; }
.diff-pill {
  display: flex; align-items: center; justify-content: space-between;
  padding: 8px 12px; border-radius: var(--radius-sm);
  border: 1px solid var(--border); background: transparent;
  font-size: 13px; font-weight: 500;
  color: var(--text-2); cursor: pointer; transition: var(--transition);
}
.diff-pill:hover { border-color: var(--border-2); color: var(--text); }
.diff-pill.active { border-color: var(--blue); background: rgba(59,130,246,0.08); color: var(--blue-light); }
.diff-dot { width: 8px; height: 8px; border-radius: 50%; }

.practice-header {
  display: flex; align-items: flex-start; justify-content: space-between;
  margin-bottom: 36px; gap: 16px; flex-wrap: wrap;
}
.practice-header h1 { font-size: 28px; letter-spacing: -0.5px; }
.practice-header p { font-size: 14px; color: var(--text-2); margin-top: 4px; }

.quiz-card {
  background: var(--surface);
  border: 1px solid var(--border);
  border-radius: var(--radius-xl);
  padding: 40px;
  margin-bottom: 24px;
  position: relative;
}
.quiz-meta {
  display: flex; align-items: center; gap: 10px;
  margin-bottom: 24px; flex-wrap: wrap;
}
.tag {
  padding: 4px 12px; border-radius: 99px;
  font-size: 11px; font-weight: 700;
  text-transform: uppercase; letter-spacing: 0.5px;
}
.tag-physics   { background: rgba(59,130,246,0.15);  color: #60a5fa; }
.tag-chemistry { background: rgba(168,85,247,0.15);  color: #c084fc; }
.tag-biology   { background: rgba(34,197,94,0.15);   color: #4ade80; }
.tag-earth     { background: rgba(245,158,11,0.15);  color: #fbbf24; }
.tag-astronomy { background: rgba(45,212,191,0.15);  color: #5eead4; }
.tag-env       { background: rgba(244,63,94,0.15);   color: #fb7185; }
.tag-easy      { background: rgba(34,197,94,0.12);   color: #22c55e; }
.tag-medium    { background: rgba(245,158,11,0.12);  color: #f59e0b; }
.tag-hard      { background: rgba(244,63,94,0.12);   color: #f43f5e; }
.tag-olympiad  { background: rgba(168,85,247,0.12);  color: #a855f7; }

.quiz-num { font-size: 12px; color: var(--text-3); font-weight: 500; }
.timer-display {
  margin-left: auto; display: flex; align-items: center; gap: 6px;
  font-family: 'Space Grotesk', sans-serif;
  font-size: 14px; font-weight: 700;
  color: var(--blue-light);
}
.timer-display.warning { color: var(--amber); }
.timer-display.danger  { color: var(--rose); }

.quiz-question {
  font-size: 18px; font-weight: 600;
  margin-bottom: 32px; line-height: 1.6;
}
.quiz-options { display: flex; flex-direction: column; gap: 12px; margin-bottom: 28px; }
.quiz-opt {
  display: flex; align-items: flex-start; gap: 14px;
  padding: 16px 20px; border-radius: var(--radius);
  border: 1px solid var(--border); background: transparent;
  cursor: pointer; transition: var(--transition);
  text-align: left; width: 100%;
  color: var(--text); font-size: 15px;
}
.quiz-opt:hover:not(:disabled) { border-color: var(--blue); background: rgba(59,130,246,0.05); }
.quiz-opt.selected { border-color: var(--blue); background: rgba(59,130,246,0.08); }
.quiz-opt.correct  { border-color: var(--green)!important; background: rgba(34,197,94,0.08)!important; }
.quiz-opt.wrong    { border-color: var(--rose)!important;  background: rgba(244,63,94,0.08)!important; }
.quiz-opt:disabled { cursor: not-allowed; }
.opt-badge {
  min-width: 30px; height: 30px; border-radius: 8px;
  background: var(--surface-2); color: var(--text-2);
  display: flex; align-items: center; justify-content: center;
  font-size: 13px; font-weight: 700; flex-shrink: 0;
}
.quiz-opt.selected .opt-badge { background: rgba(59,130,246,0.2); color: var(--blue-light); }
.quiz-opt.correct  .opt-badge { background: rgba(34,197,94,0.2);  color: var(--green); }
.quiz-opt.wrong    .opt-badge { background: rgba(244,63,94,0.2);   color: var(--rose); }

.explanation-box {
  background: rgba(59,130,246,0.06);
  border: 1px solid rgba(59,130,246,0.2);
  border-radius: var(--radius);
  padding: 20px 24px;
  margin-bottom: 28px;
  display: none;
}
.explanation-box.show { display: block; animation: fadeIn 0.3s ease; }
.explanation-box .exp-label {
  font-size: 11px; font-weight: 700;
  color: var(--blue-light); text-transform: uppercase;
  letter-spacing: 0.5px; margin-bottom: 8px;
}
.explanation-box p { font-size: 14px; color: var(--text-2); line-height: 1.7; }

.quiz-footer {
  display: flex; align-items: center; justify-content: space-between; gap: 12px;
  flex-wrap: wrap;
}
.quiz-progress-info { font-size: 13px; color: var(--text-3); }
.quiz-progress-bar-wrap {
  height: 4px; background: var(--surface-2);
  border-radius: 99px; margin-bottom: 20px;
}
.quiz-progress-bar {
  height: 100%; border-radius: 99px;
  background: var(--grad-primary); transition: width 0.5s ease;
}

/* ── Score Summary Modal ────────────────────────────────── */
.modal-overlay {
  position: fixed; inset: 0; z-index: 200;
  background: rgba(0,0,0,0.75);
  backdrop-filter: blur(10px);
  display: none; align-items: center; justify-content: center;
  padding: 20px;
}
.modal-overlay.show { display: flex; animation: fadeIn 0.3s ease; }
.modal-box {
  background: var(--bg-1);
  border: 1px solid var(--border-2);
  border-radius: 28px;
  padding: 48px 40px;
  max-width: 480px; width: 100%;
  text-align: center;
  box-shadow: 0 24px 80px rgba(0,0,0,0.5);
}
.modal-emoji { font-size: 64px; margin-bottom: 24px; display: block; }
.modal-box h2 { font-size: 28px; margin-bottom: 8px; }
.modal-box p  { color: var(--text-2); margin-bottom: 32px; }
.score-ring {
  width: 120px; height: 120px;
  margin: 0 auto 28px;
  position: relative;
}
.score-ring svg { transform: rotate(-90deg); }
.score-ring .ring-bg { fill: none; stroke: var(--surface-2); stroke-width: 8; }
.score-ring .ring-val { fill: none; stroke: url(#scoreGrad); stroke-width: 8; stroke-linecap: round; transition: stroke-dashoffset 1s ease; }
.score-text {
  position: absolute; inset: 0;
  display: flex; align-items: center; justify-content: center;
  font-family: 'Space Grotesk', sans-serif;
  font-size: 24px; font-weight: 800;
}
.modal-stats {
  display: grid; grid-template-columns: 1fr 1fr 1fr;
  gap: 16px; margin-bottom: 32px;
}
.modal-stat { background: var(--surface); border: 1px solid var(--border); border-radius: 14px; padding: 16px; }
.modal-stat .val { font-size: 22px; font-weight: 800; font-family: 'Space Grotesk',sans-serif; }
.modal-stat .lbl { font-size: 11px; color: var(--text-2); margin-top: 4px; text-transform: uppercase; letter-spacing: 0.5px; }
.modal-buttons { display: flex; gap: 12px; justify-content: center; }

/* ── Grade Level Pills ───────────────────────────────────── */
.grade-pills { display: flex; flex-direction: column; gap: 8px; }
.grade-pill {
  display: flex; align-items: center; gap: 10px;
  padding: 11px 14px; border-radius: var(--radius);
  border: 1px solid var(--border);
  background: transparent; cursor: pointer;
  transition: var(--transition); text-align: left; width: 100%;
  color: var(--text-2);
}
.grade-pill:hover { border-color: var(--border-2); color: var(--text); background: var(--surface); }
.grade-pill.active { color: var(--text); background: var(--surface-2); border-color: var(--border-2); }
.gp-icon { font-size: 18px; flex-shrink: 0; }
.gp-label { font-size: 13px; font-weight: 600; line-height: 1.3; }
.gp-label small { display: block; font-size: 11px; font-weight: 400; color: var(--text-3); margin-top: 1px; }

/* Active tints per grade */
.grade-pill.grade-elem.active  { border-color: rgba(34,197,94,0.4);  background: rgba(34,197,94,0.08); }
.grade-pill.grade-elem:hover   { border-color: rgba(34,197,94,0.3);  background: rgba(34,197,94,0.05); }
.grade-pill.grade-mid.active   { border-color: rgba(45,212,191,0.4); background: rgba(45,212,191,0.08); }
.grade-pill.grade-mid:hover    { border-color: rgba(45,212,191,0.3); background: rgba(45,212,191,0.05); }
.grade-pill.grade-hs.active    { border-color: rgba(168,85,247,0.4); background: rgba(168,85,247,0.08); }
.grade-pill.grade-hs:hover     { border-color: rgba(168,85,247,0.3); background: rgba(168,85,247,0.05); }

/* ── Disabled pill state ─────────────────────────────────── */
.filter-pill.pill-disabled,
.diff-pill.pill-disabled,
.grade-pill.pill-disabled {
  opacity: 0.28;
  cursor: not-allowed;
  pointer-events: none;
}

/* ── Count badges on pills ───────────────────────────────── */
.pill-count {
  font-size: 10px; font-weight: 700;
  background: rgba(255,255,255,0.08);
  border-radius: 99px;
  padding: 1px 6px;
  color: var(--text-3);
  margin-left: 4px;
  flex-shrink: 0;
}
.filter-pill .pill-count { margin-left: auto; }

/* count on diff pills sits between label and colored dot */
.pill-count-inline {
  font-size: 10px; font-weight: 700;
  background: rgba(255,255,255,0.08);
  border-radius: 99px;
  padding: 1px 6px;
  color: var(--text-3);
  margin: 0 6px 0 auto;
  flex-shrink: 0;
}

/* count on grade pills */
.grade-pill .pill-count {
  margin-left: auto;
  font-size: 11px;
}

/* ── Grade Level Cards (landing page) ────────────────────── */
.levels-grid {
  display: grid; grid-template-columns: repeat(3, 1fr);
  gap: 20px;
}
@media (max-width: 768px) { .levels-grid { grid-template-columns: 1fr; } }

.level-card {
  position: relative;
  border-radius: var(--radius-xl);
  padding: 40px 32px;
  border: 1px solid var(--border);
  background: var(--surface);
  text-decoration: none; display: block;
  transition: var(--transition);
  overflow: hidden;
}
.level-card::before {
  content: ''; position: absolute; inset: 0;
  opacity: 0; transition: var(--transition);
}
.level-card:hover { transform: translateY(-6px); box-shadow: var(--shadow-card); }
.level-card:hover::before { opacity: 1; }

.level-card.elem::before  { background: linear-gradient(135deg, rgba(34,197,94,0.08) 0%, transparent 60%); }
.level-card.mid::before   { background: linear-gradient(135deg, rgba(45,212,191,0.08) 0%, transparent 60%); }
.level-card.hs::before    { background: linear-gradient(135deg, rgba(168,85,247,0.08) 0%, transparent 60%); }
.level-card.elem:hover  { border-color: rgba(34,197,94,0.3); }
.level-card.mid:hover   { border-color: rgba(45,212,191,0.3); }
.level-card.hs:hover    { border-color: rgba(168,85,247,0.3); }

.level-badge {
  display: inline-flex; align-items: center; gap: 6px;
  padding: 5px 12px; border-radius: 99px;
  font-size: 11px; font-weight: 700;
  text-transform: uppercase; letter-spacing: 0.5px;
  margin-bottom: 20px;
}
.elem .level-badge { background: rgba(34,197,94,0.12);  color: #4ade80;  border: 1px solid rgba(34,197,94,0.2); }
.mid  .level-badge { background: rgba(45,212,191,0.12); color: #5eead4;  border: 1px solid rgba(45,212,191,0.2); }
.hs   .level-badge { background: rgba(168,85,247,0.12); color: #c084fc;  border: 1px solid rgba(168,85,247,0.2); }

.level-icon { font-size: 48px; display: block; margin-bottom: 18px; }
.level-card h3 { font-size: 22px; margin-bottom: 6px; }
.level-card .grades { font-size: 13px; color: var(--text-3); margin-bottom: 14px; font-weight: 500; }
.level-card p { font-size: 14px; color: var(--text-2); line-height: 1.65; margin-bottom: 24px; }
.level-topics { display: flex; flex-wrap: wrap; gap: 6px; margin-bottom: 24px; }
.level-topics span {
  padding: 3px 10px; border-radius: 99px;
  background: var(--surface-2); border: 1px solid var(--border);
  font-size: 11px; color: var(--text-2); font-weight: 500;
}
.level-cta {
  display: flex; align-items: center; gap: 6px;
  font-size: 13px; font-weight: 700;
}
.elem .level-cta { color: #4ade80; }
.mid  .level-cta { color: #5eead4; }
.hs   .level-cta { color: #c084fc; }

/* ── Stats Grid (practice sidebar) ──────────────────────── */
.sidebar-stats {
  background: var(--surface);
  border: 1px solid var(--border);
  border-radius: var(--radius);
  padding: 16px; margin-top: 8px;
}
.sidebar-stat { display: flex; justify-content: space-between; align-items: center; padding: 8px 0; }
.sidebar-stat:not(:last-child) { border-bottom: 1px solid var(--border); }
.ss-label { font-size: 12px; color: var(--text-2); }
.ss-val   { font-size: 14px; font-weight: 700; font-family: 'Space Grotesk',sans-serif; }

/* ── Animations ────────────────────────────────────────── */
@keyframes fadeIn { from { opacity:0; transform:translateY(10px);} to { opacity:1; transform:translateY(0);} }
@keyframes floatUp { from { opacity:0; transform:translateY(30px);} to { opacity:1; transform:translateY(0);} }
@keyframes shimmer {
  0%   { background-position: -200% center; }
  100% { background-position:  200% center; }
}

.reveal { opacity: 0; transform: translateY(24px); transition: opacity 0.6s ease, transform 0.6s ease; }
.reveal.visible { opacity: 1; transform: translateY(0); }
.reveal-delay-1 { transition-delay: 0.1s; }
.reveal-delay-2 { transition-delay: 0.2s; }
.reveal-delay-3 { transition-delay: 0.3s; }
.reveal-delay-4 { transition-delay: 0.4s; }

/* ── Responsive ─────────────────────────────────────────── */
@media (max-width: 768px) {
  .hero { padding: 130px 0 80px; }
  .hero-stats { gap: 32px; flex-wrap: wrap; }
  .nav-links { display: none; }
  .features-grid { grid-template-columns: 1fr; }
  .quiz-card { padding: 24px 20px; }
  .modal-stats { grid-template-columns: 1fr 1fr; }
}

/* ── Auth Modal ──────────────────────────────────────────── */
.auth-modal-overlay { z-index: 300; }

.auth-box {
  max-width: 420px; width: 100%;
  padding: 40px 36px;
  position: relative;
}

.auth-close-btn {
  position: absolute; top: 16px; right: 16px;
  background: var(--surface-2); border: 1px solid var(--border);
  color: var(--text-2); border-radius: 8px;
  width: 32px; height: 32px;
  display: flex; align-items: center; justify-content: center;
  cursor: pointer; font-size: 13px;
  transition: var(--transition);
}
.auth-close-btn:hover { color: var(--text); border-color: var(--border-2); }

.auth-brand {
  display: flex; align-items: center; gap: 14px;
  margin-bottom: 28px;
}
.logo-icon {
  display: flex; align-items: center; justify-content: center;
  background: var(--grad-primary);
  flex-shrink: 0;
}
.auth-brand-name {
  font-family: 'Space Grotesk', sans-serif;
  font-size: 17px; font-weight: 800;
}
.auth-brand-sub { font-size: 12px; color: var(--text-2); margin-top: 2px; }

.auth-tabs {
  display: flex; gap: 4px;
  background: var(--surface);
  border: 1px solid var(--border);
  border-radius: var(--radius);
  padding: 4px;
  margin-bottom: 24px;
  position: relative;
}
.auth-tab {
  flex: 1; padding: 9px; border-radius: var(--radius-sm);
  background: transparent; border: none;
  font-size: 14px; font-weight: 600;
  color: var(--text-2); cursor: pointer;
  transition: var(--transition); position: relative; z-index: 1;
}
.auth-tab.active {
  background: var(--bg-2); color: var(--text);
  box-shadow: 0 1px 4px rgba(0,0,0,0.3);
}

.auth-error {
  background: rgba(244,63,94,0.1);
  border: 1px solid rgba(244,63,94,0.25);
  border-radius: var(--radius-sm);
  padding: 10px 14px;
  font-size: 13px; color: #fb7185;
  margin-bottom: 16px;
}

.auth-form {
  display: flex; flex-direction: column; gap: 16px;
}

.auth-field { display: flex; flex-direction: column; gap: 7px; }
.auth-field label {
  font-size: 12px; font-weight: 700;
  color: var(--text-2); text-transform: uppercase; letter-spacing: 0.5px;
}
.auth-field input {
  background: var(--surface);
  border: 1px solid var(--border);
  border-radius: var(--radius-sm);
  padding: 12px 14px;
  color: var(--text); font-size: 14px;
  outline: none; transition: var(--transition);
  width: 100%;
}
.auth-field input:focus { border-color: var(--blue); box-shadow: 0 0 0 3px rgba(59,130,246,0.12); }
.auth-field input::placeholder { color: var(--text-3); }

.auth-pw-wrap { position: relative; }
.auth-pw-wrap input { padding-right: 44px; }
.pw-toggle {
  position: absolute; right: 12px; top: 50%; transform: translateY(-50%);
  background: none; border: none; cursor: pointer;
  font-size: 16px; color: var(--text-3); padding: 0; line-height: 1;
}

.auth-submit {
  width: 100%; justify-content: center;
  padding: 13px; font-size: 15px;
  margin-top: 4px;
}

.auth-switch {
  text-align: center; font-size: 13px;
  color: var(--text-2); margin-top: 4px;
}
.auth-switch a { color: var(--blue-light); font-weight: 600; }
.auth-switch a:hover { color: var(--text); }

/* ── Nav User State ──────────────────────────────────────── */
.nav-user {
  display: flex; align-items: center; gap: 8px;
}
.nav-avatar {
  width: 34px; height: 34px; border-radius: 50%;
  background: var(--grad-primary);
  display: flex; align-items: center; justify-content: center;
  font-size: 12px; font-weight: 800; color: #fff;
  flex-shrink: 0;
}
.nav-username {
  font-size: 14px; font-weight: 600;
  color: var(--text); max-width: 120px;
  overflow: hidden; text-overflow: ellipsis; white-space: nowrap;
}

/* ── Live Leaderboard ────────────────────────────────────── */
#lb-rows { min-height: 80px; }
.lb-loading, .lb-empty {
  text-align: center; padding: 40px 20px;
  color: var(--text-2); font-size: 14px;
}
.lb-row-me {
  background: rgba(59,130,246,0.06);
  border-left: 2px solid var(--blue);
}
.lb-you {
  display: inline-block;
  background: rgba(59,130,246,0.15); color: var(--blue-light);
  font-size: 10px; font-weight: 700; padding: 1px 7px;
  border-radius: 99px; margin-left: 6px;
  vertical-align: middle; text-transform: uppercase; letter-spacing: 0.5px;
}

/* ── Score Modal — save status ───────────────────────────── */
.modal-save-status {
  margin-top: 4px; margin-bottom: 4px;
  padding: 10px 16px; border-radius: var(--radius-sm);
  font-size: 13px; text-align: center;
}
.modal-save-status.saving  { background: var(--surface); color: var(--text-2); }
.modal-save-status.saved   { background: rgba(34,197,94,0.1); color: var(--green); border: 1px solid rgba(34,197,94,0.2); }
.modal-save-status.unsaved { background: var(--surface); color: var(--text-2); }
.modal-save-status.unsaved a { color: var(--blue-light); cursor: pointer; font-weight: 600; }