:root {
  color-scheme: dark;
  --bg: #0b1020;
  --bg-soft: #10172b;
  --panel: rgba(17, 24, 42, 0.82);
  --panel-strong: rgba(19, 28, 49, 0.95);
  --text: #f3f7ff;
  --muted: #b8c4df;
  --border: rgba(140, 164, 214, 0.18);
  --accent: #7c9cff;
  --teal: #4ee1c1;
  --pink: #ff7ac6;
  --yellow: #ffd166;
  --purple: #b28cff;
  --danger: #ff8f97;
  --success: #78ecb2;
  --shadow: 0 24px 64px rgba(0, 0, 0, 0.35);
  --radius: 28px;
  --radius-sm: 18px;
  --content-width: min(100%, 560px);
  --safe-bottom: calc(92px + env(safe-area-inset-bottom, 0px));
}

* {
  box-sizing: border-box;
}

html {
  scroll-behavior: smooth;
}

body {
  margin: 0;
  min-height: 100vh;
  font-family: Inter, Aptos, system-ui, -apple-system, BlinkMacSystemFont, "Segoe UI", sans-serif;
  color: var(--text);
  background:
    radial-gradient(circle at top left, rgba(124, 156, 255, 0.22), transparent 28%),
    radial-gradient(circle at right, rgba(78, 225, 193, 0.16), transparent 20%),
    linear-gradient(180deg, #0b1020 0%, #09111b 100%);
  padding-bottom: var(--safe-bottom);
  overflow-x: hidden;
}

button {
  font: inherit;
  cursor: pointer;
}

a {
  color: inherit;
}

h1,
h2,
h3,
p,
ul,
ol,
blockquote {
  margin: 0;
}

.bg-orb,
.bg-grid {
  position: fixed;
  pointer-events: none;
  z-index: 0;
}

.bg-orb {
  border-radius: 999px;
  filter: blur(28px);
}

.orb-one {
  width: 180px;
  height: 180px;
  background: rgba(124, 156, 255, 0.22);
  top: -20px;
  left: -50px;
}

.orb-two {
  width: 160px;
  height: 160px;
  background: rgba(78, 225, 193, 0.15);
  top: 15%;
  right: -40px;
}

.orb-three {
  width: 180px;
  height: 180px;
  background: rgba(255, 122, 198, 0.12);
  bottom: 16%;
  right: -60px;
}

.bg-grid {
  inset: 0;
  background-image:
    linear-gradient(rgba(255, 255, 255, 0.025) 1px, transparent 1px),
    linear-gradient(90deg, rgba(255, 255, 255, 0.025) 1px, transparent 1px);
  background-size: 22px 22px;
  mask-image: linear-gradient(180deg, rgba(255,255,255,0.26), transparent 70%);
}

.scroll-progress {
  position: fixed;
  inset: 0 auto auto 0;
  height: 4px;
  width: 0;
  background: linear-gradient(90deg, var(--accent), var(--teal));
  z-index: 35;
  transition: width 0.12s linear;
}

.topbar {
  position: sticky;
  top: 0;
  z-index: 20;
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 12px;
  width: 100%;
  max-width: var(--content-width);
  margin: 0 auto;
  padding: calc(12px + env(safe-area-inset-top, 0px)) 16px 12px;
  backdrop-filter: blur(18px);
  background: linear-gradient(180deg, rgba(11, 16, 32, 0.96), rgba(11, 16, 32, 0.72));
}

.brand {
  display: grid;
  gap: 4px;
}

.brand p {
  font-size: 0.95rem;
  font-weight: 700;
}

.brand-badge,
.eyebrow,
.quiz-chip {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  width: fit-content;
  padding: 0.38rem 0.78rem;
  border-radius: 999px;
  border: 1px solid rgba(124, 156, 255, 0.25);
  background: rgba(124, 156, 255, 0.12);
  color: #ced9ff;
  font-size: 0.75rem;
  letter-spacing: 0.02em;
  font-weight: 700;
}

.eyebrow.accent {
  background: rgba(78, 225, 193, 0.12);
  border-color: rgba(78, 225, 193, 0.22);
  color: #bbfff1;
}

.quiz-chip.muted {
  background: rgba(17, 24, 42, 0.78);
  color: var(--muted);
}

.icon-btn {
  border: 1px solid var(--border);
  background: rgba(18, 27, 48, 0.9);
  color: var(--text);
  width: 42px;
  height: 42px;
  border-radius: 14px;
  display: inline-flex;
  align-items: center;
  justify-content: center;
  font-size: 1.1rem;
}

.icon-btn.ghost {
  background: rgba(15, 21, 38, 0.75);
}

.page-shell {
  position: relative;
  z-index: 1;
  width: var(--content-width);
  margin: 0 auto;
  padding: 0 16px 32px;
}

.section {
  padding: 22px 0 16px;
  scroll-margin-top: 92px;
}

.section-head {
  display: grid;
  gap: 10px;
  margin-bottom: 18px;
}

.section-head h2,
.hero h1 {
  font-size: clamp(1.82rem, 6vw, 2.7rem);
  line-height: 1.04;
}

.section-head p,
.hero-copy,
.info-card p,
.compare-panel li,
.compare-note,
.tab-panel p,
.experiment-copy p,
.myth-answer p,
.summary-card li,
.quiz-card h3,
.timeline-content p,
.timeline-points li,
.flip-card__face p,
.quote-card blockquote,
.memory-hook,
.experiment-result span,
.mini-feature-card p {
  color: var(--muted);
  line-height: 1.62;
}

.hero-card,
.glass-card {
  border: 1px solid var(--border);
  background: var(--panel);
  box-shadow: var(--shadow);
  backdrop-filter: blur(18px);
}

.reveal {
  opacity: 0;
  transform: translateY(16px);
  transition: opacity 0.5s ease, transform 0.5s ease;
}

.reveal.is-visible {
  opacity: 1;
  transform: translateY(0);
}

.hero-card {
  position: relative;
  overflow: hidden;
  border-radius: 34px;
  padding: 26px 20px 22px;
  display: grid;
  gap: 18px;
}

.hero-card::after {
  content: "";
  position: absolute;
  inset: auto -20% -18% auto;
  width: 190px;
  height: 190px;
  border-radius: 999px;
  background: radial-gradient(circle, rgba(124, 156, 255, 0.14), transparent 70%);
}

.hero h1 span {
  display: block;
  color: var(--accent);
}

.hero-pills {
  display: flex;
  flex-wrap: wrap;
  gap: 10px;
}

.hero-pills span {
  padding: 0.55rem 0.85rem;
  border-radius: 999px;
  background: rgba(18, 27, 48, 0.82);
  border: 1px solid var(--border);
  color: var(--text);
  font-size: 0.82rem;
  font-weight: 600;
}

.hero-showcase {
  display: grid;
  gap: 16px;
  align-items: center;
}

.atom-visual {
  position: relative;
  width: min(240px, 68vw);
  aspect-ratio: 1;
  margin: 4px auto 0;
}

.atom-core,
.electron {
  position: absolute;
  border-radius: 999px;
}

.atom-core {
  width: 26px;
  height: 26px;
  background: linear-gradient(135deg, var(--yellow), #ffef9b);
  top: 50%;
  left: 50%;
  transform: translate(-50%, -50%);
  box-shadow: 0 0 20px rgba(255, 209, 102, 0.45);
  animation: pulseGlow 3s ease-in-out infinite;
}

.orbit {
  position: absolute;
  inset: 16px;
  border: 2px solid rgba(124, 156, 255, 0.26);
  border-radius: 50%;
  animation: spin 9s linear infinite;
}

.orbit-b {
  transform: rotate(60deg);
  border-color: rgba(78, 225, 193, 0.24);
  animation-duration: 11s;
}

.orbit-c {
  transform: rotate(-60deg);
  border-color: rgba(255, 122, 198, 0.25);
  animation-duration: 13s;
}

.electron {
  width: 12px;
  height: 12px;
  animation: floaty 2.8s ease-in-out infinite;
}

.electron-a {
  background: var(--accent);
  top: 18%;
  left: 50%;
}

.electron-b {
  background: var(--teal);
  top: 68%;
  left: 18%;
  animation-delay: 0.8s;
}

.electron-c {
  background: var(--pink);
  top: 65%;
  left: 74%;
  animation-delay: 1.3s;
}

.mini-feature-card {
  border: 1px solid rgba(78, 225, 193, 0.16);
  background: rgba(10, 17, 31, 0.72);
  border-radius: 22px;
  padding: 16px;
  display: grid;
  gap: 8px;
}

.mini-feature-card__icon {
  width: 40px;
  height: 40px;
  display: inline-flex;
  align-items: center;
  justify-content: center;
  border-radius: 14px;
  background: rgba(78, 225, 193, 0.14);
  font-size: 1.1rem;
}

.mini-feature-card strong {
  font-size: 1rem;
}

.hero-actions,
.final-actions {
  display: grid;
  grid-template-columns: 1fr 1fr;
  gap: 12px;
}

.primary-btn,
.secondary-btn,
.quiz-option,
.bottom-nav__item,
.menu-links button,
.toggle-btn,
.tab-btn,
.exp-btn,
.timeline-year {
  border: none;
  transition: transform 0.18s ease, opacity 0.18s ease, background 0.18s ease, color 0.18s ease;
}

.primary-btn,
.secondary-btn {
  padding: 0.95rem 1rem;
  border-radius: 18px;
  font-weight: 700;
}

.primary-btn {
  background: linear-gradient(135deg, var(--accent), #96afff);
  color: #08101f;
}

.secondary-btn {
  border: 1px solid var(--border);
  background: rgba(21, 30, 52, 0.9);
  color: var(--text);
}

.hero-stats {
  display: grid;
  grid-template-columns: repeat(3, 1fr);
  gap: 10px;
}

.hero-stats article {
  padding: 14px 12px;
  border-radius: 18px;
  background: rgba(16, 24, 46, 0.78);
  border: 1px solid var(--border);
  text-align: center;
}

.hero-stats strong {
  display: block;
  font-size: 1.18rem;
}

.hero-stats span {
  color: var(--muted);
  font-size: 0.8rem;
}

.card-grid,
.myth-list,
.quiz-options,
.glossary-grid {
  display: grid;
  gap: 14px;
}

.info-card {
  border-radius: var(--radius);
  padding: 20px 18px;
}

.icon-chip {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  width: 42px;
  height: 42px;
  border-radius: 14px;
  background: rgba(124, 156, 255, 0.16);
  margin-bottom: 14px;
  font-size: 1.15rem;
}

.info-card h3,
.compare-panel h3,
.tab-panel h3,
.experiment-copy h3,
.quiz-card h3,
.timeline-content h3,
.flip-card__face h3 {
  font-size: 1.15rem;
  margin-bottom: 8px;
}

.wide {
  grid-column: 1 / -1;
}

.impact-strip {
  margin-top: 16px;
  border-radius: 22px;
  padding: 14px 16px;
  display: flex;
  flex-wrap: wrap;
  gap: 10px;
}

.impact-strip span {
  padding: 0.55rem 0.85rem;
  border-radius: 999px;
  background: rgba(255, 255, 255, 0.05);
  border: 1px solid var(--border);
  color: var(--text);
  font-size: 0.84rem;
  font-weight: 600;
}

.timeline-shell,
.compare-toggle,
.tab-panels,
.experiment-card,
.quiz-card,
.summary-card,
.quote-card {
  border-radius: 30px;
  padding: 18px;
}

.timeline-years,
.tab-list {
  display: flex;
  gap: 8px;
  overflow-x: auto;
  padding-bottom: 4px;
  scrollbar-width: none;
}

.timeline-years::-webkit-scrollbar,
.tab-list::-webkit-scrollbar {
  display: none;
}

.timeline-year,
.tab-btn {
  flex: 0 0 auto;
  padding: 0.82rem 1rem;
  border-radius: 999px;
  background: rgba(18, 27, 49, 0.88);
  color: var(--muted);
  border: 1px solid var(--border);
  font-weight: 700;
}

.timeline-year.active,
.toggle-btn.active,
.exp-btn.active,
.tab-btn.active,
.bottom-nav__item.active {
  background: var(--accent);
  color: #08101f;
}

.timeline-content {
  margin-top: 16px;
  padding: 16px;
  border-radius: 22px;
  background: rgba(10, 17, 31, 0.62);
  border: 1px solid var(--border);
  display: grid;
  gap: 10px;
}

.timeline-label {
  color: var(--teal) !important;
  font-size: 0.78rem;
  text-transform: uppercase;
  letter-spacing: 0.08em;
  font-weight: 700;
}

.timeline-points {
  padding-left: 18px;
  display: grid;
  gap: 8px;
}

.toggle-head,
.experiment-controls,
.quiz-head {
  display: grid;
  grid-template-columns: 1fr 1fr;
  gap: 10px;
  margin-bottom: 14px;
}

.toggle-btn,
.exp-btn {
  padding: 0.9rem 1rem;
  border-radius: 16px;
  background: rgba(18, 27, 49, 0.88);
  color: var(--muted);
  border: 1px solid var(--border);
  font-weight: 700;
}

.compare-panel,
.tab-panel {
  display: none;
}

.compare-panel.active,
.tab-panel.active {
  display: block;
}

.compare-panel ul {
  padding-left: 18px;
  display: grid;
  gap: 10px;
}

.compare-note {
  margin-top: 14px;
  padding: 14px 16px;
  border-radius: 18px;
  background: rgba(10, 17, 31, 0.64);
  border: 1px solid var(--border);
}

.concept-tabs {
  display: grid;
  gap: 12px;
}

.memory-hook {
  margin-top: 14px;
  padding: 12px 14px;
  border-radius: 16px;
  background: rgba(10, 17, 31, 0.64);
  border: 1px solid var(--border);
  font-size: 0.93rem;
}

.mini-visual {
  margin-top: 14px;
  min-height: 70px;
  display: flex;
  align-items: center;
  justify-content: center;
}

.levels {
  gap: 10px;
}

.levels span {
  width: 48px;
  height: 8px;
  border-radius: 999px;
  background: linear-gradient(90deg, var(--accent), transparent);
}

.wave-particle {
  gap: 18px;
}

.wave-particle .dot {
  width: 14px;
  height: 14px;
  border-radius: 999px;
  background: var(--yellow);
  box-shadow: 0 0 18px rgba(255, 209, 102, 0.5);
}

.wave-particle .wave {
  width: 120px;
  height: 30px;
  border-radius: 999px;
  border-top: 4px solid var(--teal);
  border-bottom: 4px solid transparent;
  border-left: 4px solid transparent;
  border-right: 4px solid transparent;
  position: relative;
}

.wave-particle .wave::before,
.wave-particle .wave::after {
  content: "";
  position: absolute;
  inset: -4px 18px auto;
  height: 30px;
  border-top: 4px solid var(--teal);
  border-radius: 999px;
}

.wave-particle .wave::after {
  inset: -4px 40px auto;
}

.overlap {
  position: relative;
  min-height: 90px;
}

.overlap span {
  position: absolute;
  width: 70px;
  height: 70px;
  border-radius: 999px;
  top: 8px;
}

.overlap span:first-child {
  left: calc(50% - 56px);
  background: rgba(124, 156, 255, 0.32);
}

.overlap span:last-child {
  left: calc(50% - 14px);
  background: rgba(255, 122, 198, 0.28);
}

.blur-bars {
  gap: 10px;
}

.blur-bars span {
  width: 14px;
  height: 70px;
  border-radius: 999px;
  background: linear-gradient(180deg, var(--accent), transparent);
}

.blur-bars span:nth-child(2) {
  height: 50px;
  background: linear-gradient(180deg, var(--yellow), transparent);
}

.blur-bars span:nth-child(3) {
  height: 38px;
  background: linear-gradient(180deg, var(--teal), transparent);
}

.experiment-card {
  display: grid;
  gap: 16px;
}

.double-slit-visual {
  position: relative;
  min-height: 220px;
  border-radius: 24px;
  background: rgba(9, 14, 28, 0.65);
  border: 1px solid var(--border);
  overflow: hidden;
}

.source-dot {
  position: absolute;
  left: 12%;
  top: 50%;
  transform: translateY(-50%);
  width: 14px;
  height: 14px;
  border-radius: 999px;
  background: var(--teal);
  box-shadow: 0 0 18px rgba(78, 225, 193, 0.5);
}

.slits {
  position: absolute;
  left: 42%;
  top: 50%;
  transform: translate(-50%, -50%);
  width: 16px;
  height: 120px;
  background: rgba(214, 223, 245, 0.82);
  border-radius: 999px;
}

.slits span {
  position: absolute;
  left: -1px;
  width: 18px;
  height: 18px;
  background: rgba(9, 14, 28, 0.9);
  border-radius: 999px;
}

.slits span:first-child {
  top: 30px;
}

.slits span:last-child {
  bottom: 30px;
}

.paths,
.screen {
  position: absolute;
  inset: 0;
  opacity: 0;
  transition: opacity 0.25s ease;
}

.paths.active,
.screen.active {
  opacity: 1;
}

.paths-wave i,
.paths-particle i {
  position: absolute;
  display: block;
  height: 2px;
  border-radius: 999px;
}

.paths-wave i:nth-child(1) {
  width: 34%;
  left: 45%;
  top: 38%;
  background: linear-gradient(90deg, rgba(124, 156, 255, 0.7), transparent);
  transform: rotate(-15deg);
}

.paths-wave i:nth-child(2) {
  width: 34%;
  left: 45%;
  top: 46%;
  background: linear-gradient(90deg, rgba(178, 140, 255, 0.7), transparent);
  transform: rotate(-5deg);
}

.paths-wave i:nth-child(3) {
  width: 34%;
  left: 45%;
  top: 55%;
  background: linear-gradient(90deg, rgba(78, 225, 193, 0.7), transparent);
  transform: rotate(6deg);
}

.paths-wave i:nth-child(4) {
  width: 34%;
  left: 45%;
  top: 63%;
  background: linear-gradient(90deg, rgba(255, 122, 198, 0.7), transparent);
  transform: rotate(15deg);
}

.paths-particle i:nth-child(1),
.paths-particle i:nth-child(2) {
  width: 34%;
  left: 45%;
  background: linear-gradient(90deg, rgba(255, 209, 102, 0.86), transparent);
}

.paths-particle i:nth-child(1) {
  top: 42%;
  transform: rotate(-10deg);
}

.paths-particle i:nth-child(2) {
  top: 58%;
  transform: rotate(10deg);
}

.screen {
  left: auto;
  right: 8%;
  width: 18%;
  top: 17%;
  bottom: 17%;
  border-left: 3px solid rgba(214, 223, 245, 0.82);
  display: flex;
  align-items: center;
  justify-content: center;
}

.screen-wave,
.screen-particle {
  flex-direction: column;
  gap: 7px;
}

.screen-wave span {
  width: 70%;
  height: 8px;
  border-radius: 999px;
  background: linear-gradient(90deg, var(--yellow), rgba(255, 209, 102, 0.1));
}

.screen-wave span:nth-child(2),
.screen-wave span:nth-child(6) {
  width: 38%;
}

.screen-wave span:nth-child(3),
.screen-wave span:nth-child(5) {
  width: 58%;
}

.screen-wave span:nth-child(4) {
  width: 82%;
}

.screen-particle span {
  width: 32%;
  height: 10px;
  border-radius: 999px;
  background: linear-gradient(90deg, var(--yellow), rgba(255, 209, 102, 0.1));
}

.screen-particle span:nth-child(2),
.screen-particle span:nth-child(3) {
  width: 48%;
}

.experiment-result {
  display: grid;
  gap: 4px;
  padding: 14px 16px;
  border-radius: 18px;
  background: rgba(10, 17, 31, 0.64);
  border: 1px solid var(--border);
}

.experiment-result strong {
  color: var(--teal);
  font-size: 0.85rem;
  text-transform: uppercase;
  letter-spacing: 0.08em;
}

.myth-card {
  border-radius: 24px;
  overflow: hidden;
}

.myth-toggle {
  width: 100%;
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 12px;
  padding: 18px;
  background: transparent;
  color: var(--text);
  text-align: left;
}

.myth-toggle strong {
  font-size: 1.25rem;
  color: var(--accent);
  transition: transform 0.2s ease;
}

.myth-answer {
  display: none;
  padding: 0 18px 18px;
}

.myth-card.open .myth-answer {
  display: block;
}

.myth-card.open .myth-toggle strong {
  transform: rotate(45deg);
}

.glossary-grid {
  grid-template-columns: repeat(2, minmax(0, 1fr));
}

.flip-card {
  perspective: 1000px;
  min-height: 180px;
  outline: none;
}

.flip-card__inner {
  position: relative;
  width: 100%;
  min-height: 180px;
  transform-style: preserve-3d;
  transition: transform 0.5s ease;
}

.flip-card.flipped .flip-card__inner,
.flip-card:focus-visible .flip-card__inner {
  transform: rotateY(180deg);
}

.flip-card__face {
  position: absolute;
  inset: 0;
  backface-visibility: hidden;
  border-radius: 24px;
  border: 1px solid var(--border);
  background: var(--panel);
  box-shadow: var(--shadow);
  padding: 18px;
  display: grid;
  align-content: center;
  justify-items: start;
  gap: 10px;
}

.flip-card__face--front span {
  width: 40px;
  height: 40px;
  display: inline-flex;
  align-items: center;
  justify-content: center;
  border-radius: 14px;
  background: rgba(124, 156, 255, 0.14);
  font-size: 1.12rem;
}

.flip-card__face--back {
  transform: rotateY(180deg);
  background: rgba(16, 24, 46, 0.96);
}

.quiz-card {
  display: grid;
  gap: 14px;
}

.quiz-option {
  width: 100%;
  padding: 1rem 1rem;
  border-radius: 18px;
  background: rgba(18, 27, 49, 0.88);
  color: var(--text);
  border: 1px solid var(--border);
  text-align: left;
  line-height: 1.55;
}

.quiz-option.correct {
  background: rgba(120, 236, 178, 0.18);
  border-color: rgba(120, 236, 178, 0.4);
}

.quiz-option.wrong {
  background: rgba(255, 143, 151, 0.14);
  border-color: rgba(255, 143, 151, 0.32);
}

.quiz-feedback {
  border-radius: 18px;
  padding: 16px;
  background: rgba(10, 17, 31, 0.72);
  border: 1px solid var(--border);
}

.quiz-feedback.correct {
  border-color: rgba(120, 236, 178, 0.45);
  background: rgba(120, 236, 178, 0.09);
}

.quiz-feedback.wrong {
  border-color: rgba(255, 143, 151, 0.34);
  background: rgba(255, 143, 151, 0.08);
}

.summary-card ol {
  padding-left: 20px;
  display: grid;
  gap: 12px;
}

.quote-card {
  margin-top: 16px;
  display: grid;
  gap: 10px;
}

.quote-card__label {
  color: var(--teal);
  text-transform: uppercase;
  font-size: 0.78rem;
  letter-spacing: 0.08em;
  font-weight: 700;
}

.quote-card blockquote {
  font-size: 1rem;
}

.side-menu {
  position: fixed;
  inset: 0;
  background: rgba(5, 9, 19, 0.62);
  backdrop-filter: blur(10px);
  z-index: 40;
  opacity: 0;
  pointer-events: none;
  transition: opacity 0.22s ease;
}

.side-menu.open {
  opacity: 1;
  pointer-events: auto;
}

.side-menu__panel {
  width: min(100%, 380px);
  height: 100%;
  margin-left: auto;
  background: rgba(11, 17, 32, 0.97);
  border-left: 1px solid var(--border);
  padding: calc(18px + env(safe-area-inset-top, 0px)) 18px 18px;
  display: grid;
  grid-template-rows: auto 1fr;
  gap: 20px;
}

.side-menu__head {
  display: flex;
  justify-content: space-between;
  align-items: flex-start;
  gap: 16px;
}

.side-menu__head h2 {
  margin-top: 8px;
  font-size: 1.35rem;
}

.menu-links {
  display: grid;
  gap: 10px;
  align-content: start;
}

.menu-links button {
  border-radius: 16px;
  padding: 0.95rem 1rem;
  background: rgba(18, 27, 49, 0.88);
  color: var(--text);
  border: 1px solid var(--border);
  text-align: left;
}

.bottom-nav {
  position: fixed;
  left: 50%;
  bottom: calc(12px + env(safe-area-inset-bottom, 0px));
  transform: translateX(-50%);
  z-index: 25;
  width: min(calc(100% - 24px), 560px);
  display: grid;
  grid-template-columns: repeat(5, 1fr);
  gap: 8px;
  padding: 10px;
  border-radius: 24px;
  background: rgba(11, 18, 33, 0.92);
  border: 1px solid var(--border);
  backdrop-filter: blur(18px);
  box-shadow: 0 20px 60px rgba(0, 0, 0, 0.35);
}

.bottom-nav__item {
  padding: 0.78rem 0.45rem;
  border-radius: 16px;
  background: transparent;
  color: var(--muted);
  font-size: 0.8rem;
  font-weight: 700;
}

.active-section .section-head h2,
.active-section.hero h1 {
  text-shadow: 0 0 16px rgba(124, 156, 255, 0.08);
}

@keyframes pulseGlow {
  0%, 100% { transform: translate(-50%, -50%) scale(1); }
  50% { transform: translate(-50%, -50%) scale(1.08); }
}

@keyframes floaty {
  0%, 100% { transform: translateY(0); }
  50% { transform: translateY(-6px); }
}

@keyframes spin {
  from { rotate: 0deg; }
  to { rotate: 360deg; }
}

@media (min-width: 700px) {
  :root {
    --content-width: min(100%, 920px);
  }

  .page-shell,
  .topbar {
    max-width: 920px;
  }

  .section {
    padding: 28px 0 20px;
  }

  .hero-card {
    padding: 34px 28px 28px;
  }

  .hero-showcase {
    grid-template-columns: 1.1fr 0.9fr;
  }

  .card-grid.two-up {
    grid-template-columns: repeat(2, minmax(0, 1fr));
  }

  .timeline-shell,
  .compare-toggle,
  .tab-panels,
  .experiment-card,
  .quiz-card,
  .summary-card,
  .quote-card {
    padding: 22px;
  }

  .glossary-grid {
    grid-template-columns: repeat(4, minmax(0, 1fr));
  }
}

@media (prefers-reduced-motion: reduce) {
  *, *::before, *::after {
    animation: none !important;
    transition: none !important;
    scroll-behavior: auto !important;
  }
}

@media (hover: hover) {
  .primary-btn:hover,
  .secondary-btn:hover,
  .menu-links button:hover,
  .quiz-option:hover,
  .bottom-nav__item:hover,
  .toggle-btn:hover,
  .tab-btn:hover,
  .exp-btn:hover,
  .icon-btn:hover,
  .timeline-year:hover {
    transform: translateY(-1px);
  }
}