/* Alchemist · the curiosity studio. Shared across every learning route. */
@font-face {
  font-family: 'Plus Jakarta Sans';
  src: url('../assets/fonts/plus-jakarta-sans.ttf') format('truetype');
  font-style: normal;
  font-weight: 200 800;
  font-display: swap;
}
:root {
  --bg: #f7f9fd;
  --surface: #fff;
  --surface-2: #f0f4fb;
  --surface-3: #e4ebf7;
  --text: #192c4b;
  --muted: #586981;
  --border: #e0e7f1;
  --brand: #2563eb;
  --brand-strong: #194dc5;
  --brand-soft: #eaf1ff;
  --on-brand: #fff;
  --accent: #b47708;
  --link: #215bd0;
  --yellow: #ffda66;
  --yellow-soft: #fff7dc;
  --stage: radial-gradient(ellipse at 50% 35%, #fff 10%, #edf3ff 100%);
  --radius: 20px;
  --radius-sm: 12px;
  --shadow: 0 4px 18px #203f7810;
  --shadow-lg: 0 14px 40px #203f7820;
  --font: 'Plus Jakarta Sans', system-ui, sans-serif;
  --container: 1360px;
  --gutter: 28px;
  --sidebar: 240px;
  color-scheme: light;
}
body {
  font-size: 14px;
  line-height: 1.7;
}
h1,
h2,
h3,
h4 {
  font-weight: 800;
  letter-spacing: -0.025em;
  color: var(--text);
}
h1 {
  font-size: clamp(1.8rem, 2.8vw, 2.6rem);
}
h2 {
  font-size: clamp(1.15rem, 1.4vw, 1.5rem);
}
button,
a,
input,
select,
textarea {
  -webkit-tap-highlight-color: transparent;
}
:focus-visible {
  outline: 3px solid var(--focus);
  outline-offset: 4px;
}
[hidden] {
  display: none !important;
}
main {
  min-width: 0;
  padding-bottom: 48px;
}
main > .container {
  animation: page-arrive 0.35s ease-out both;
}
.container {
  width: 100%;
}
.btn {
  border-radius: 12px;
  min-height: 46px;
  font-size: 0.85rem;
  font-weight: 700;
  padding: 0.65rem 1rem;
  transition:
    background 0.18s,
    box-shadow 0.18s,
    transform 0.18s;
}
.btn-primary {
  box-shadow: 0 4px 10px #2563eb18;
}
.btn-yellow {
  background: var(--yellow);
  border-color: var(--yellow);
  color: #243453;
  box-shadow: 0 5px 0 #173f971f;
}
.btn-yellow:hover {
  background: #ffe388;
  border-color: #ffe388;
}
.btn:hover:not(:disabled) {
  transform: translateY(-2px);
}
.btn:active:not(:disabled) {
  transform: translateY(1px);
}
input,
select,
textarea {
  font-size: 0.875rem;
  border-color: #c6d2e4;
  min-height: 46px;
}
input::placeholder,
textarea::placeholder {
  color: #68788e;
  opacity: 1;
}
input:focus,
textarea:focus {
  box-shadow: 0 0 0 4px #2563eb0d;
}
.card {
  padding: 22px;
  box-shadow: none;
}
a.card:hover,
.mol-card:hover {
  border-color: #a9c3ff;
  box-shadow: var(--shadow-lg);
}
.card,
.quick-card {
  transition:
    transform 0.2s,
    box-shadow 0.2s,
    border-color 0.2s;
}
.grid {
  gap: 20px;
}
.card-title {
  font-size: 1rem;
  letter-spacing: -0.02em;
}
.card-text {
  font-size: 0.83rem;
  line-height: 1.75;
}
.chip {
  font-size: 0.8rem;
}
.chip-lg {
  min-height: 46px;
}
.badge {
  font-size: 0.72rem;
}
.section-head {
  align-items: center;
  margin-bottom: 12px;
}
.section-head h2 {
  margin: 0;
}
.link-more {
  font-size: 0.8rem;
  text-decoration: none;
}
.section-head + .muted {
  margin-top: -8px;
  margin-bottom: 20px;
  font-size: 0.84rem;
}
/* A quiet persistent sidebar gives every tool a predictable home. */
.site-header {
  background: #ffffffed;
  backdrop-filter: none;
  border-color: var(--border);
}
.header-bar {
  min-height: 78px;
  gap: 20px;
}
.brand {
  gap: 8px;
}
.brand img {
  width: 46px;
  height: 46px;
  object-fit: contain;
}
.brand-text strong {
  font-size: 1.22rem;
  letter-spacing: -0.05em;
  color: #193567;
}
.brand-dot {
  color: var(--brand);
}
.brand-text small {
  font-size: 8px;
  letter-spacing: 0.18em;
  margin-top: 8px;
  color: #566c8b;
}
.learning-sidebar {
  display: none;
}
.shell-location {
  display: none;
  align-items: center;
  gap: 10px;
  margin: 0;
  white-space: nowrap;
  font-size: 0.78rem;
}
.shell-location > span {
  color: var(--muted);
}
.header-tools {
  gap: 14px;
}
.header-search input {
  border: 1px solid var(--border);
  border-radius: 12px;
  background: #f7f9fd;
  width: 290px;
  min-height: 42px;
  font-size: 0.76rem;
}
.header-search .icon-btn {
  min-height: 42px;
  color: var(--muted);
}
.learner-select {
  display: flex;
  align-items: center;
  gap: 4px;
  color: var(--brand);
  border-left: 1px solid var(--border);
  padding-left: 14px;
}
.mode-select {
  border: 0;
  background: transparent;
  border-radius: 8px;
  font-size: 0.8rem;
  padding: 4px;
  color: var(--text);
  max-width: 95px;
}
.lang-btn {
  border: 1px solid var(--border);
  min-width: 38px;
  min-height: 38px;
  border-radius: 50%;
}
.lang-btn span {
  font-size: 0.7rem;
}
.mobile-dock {
  display: none;
}
.nav-link {
  font-size: 0.8rem;
  min-height: 44px;
  font-weight: 600;
  gap: 12px;
  padding: 10px 14px;
  border-radius: 10px;
  color: #536580;
}
.nav-link > svg {
  flex-shrink: 0;
}
.nav-link[aria-current='page'] {
  background: #eaf1ff;
  color: #2059d4;
  font-weight: 800;
}
.nav-link .count {
  margin-left: auto;
  font-size: 0.67rem;
  background: #e5edfb;
  color: #33568f;
}
.nav-link:hover {
  color: var(--brand);
  background: #f0f5ff;
}
.drawer {
  background: white;
  box-shadow: var(--shadow-lg);
  max-height: calc(100dvh - 150px);
  overflow-y: auto;
  padding: 16px 20px;
}
.drawer nav {
  display: grid;
  grid-template-columns: 1fr 1fr;
  gap: 4px;
}
@media (min-width: 1100px) {
  body {
    padding-left: var(--sidebar);
  }
  .learning-sidebar {
    display: flex;
    flex-direction: column;
    position: fixed;
    left: 0;
    top: 0;
    bottom: 0;
    width: var(--sidebar);
    padding: 26px 17px 16px;
    background: #fff;
    border-right: 1px solid var(--border);
    overflow-y: auto;
    overscroll-behavior: contain;
  }
  .learning-sidebar > .brand {
    margin: 0 6px 26px;
  }
  .learning-sidebar nav {
    display: grid;
    gap: 3px;
  }
  .nav-caption {
    margin: 22px 14px 7px;
    font-size: 9px;
    font-weight: 800;
    letter-spacing: 0.14em;
    color: #596d89;
  }
  .nav-caption:first-child {
    margin-top: 0;
  }
  .sidebar-teacher {
    display: flex;
    align-items: center;
    gap: 10px;
    margin-top: 28px;
    padding: 15px 11px;
    background: #f2f6ff;
    border-radius: 12px;
    text-decoration: none;
  }
  .sidebar-teacher strong {
    font-size: 11px;
  }
  .sidebar-teacher small {
    display: block;
    color: var(--muted);
    font-size: 9px;
  }
  .sidebar-teacher > svg {
    flex-shrink: 0;
  }
  .sidebar-about {
    display: flex;
    align-items: center;
    gap: 10px;
    margin: 16px 14px 0;
    font-size: 11px;
    color: var(--muted);
    text-decoration: none;
  }
  .shell-location {
    display: flex;
  }
  .mobile-brand,
  .menu-btn,
  .drawer {
    display: none !important;
  }
  .header-search {
    display: flex;
  }
}
/* Home: welcome, a science scene, four clear starting points, and an actual learning path. */
.home-welcome {
  display: flex;
  justify-content: space-between;
  gap: 20px;
  align-items: center;
  padding-top: 30px;
  padding-bottom: 24px;
}
.home-welcome .eyebrow {
  font-size: 9px;
  letter-spacing: 0.11em;
  color: #566b89;
}
.home-welcome h1 {
  font-size: clamp(1.5rem, 2.2vw, 2rem);
  margin: 8px 0;
}
.home-welcome p:last-child {
  color: var(--muted);
  margin: 0;
  font-size: 0.82rem;
}
.hello-star {
  display: inline-block;
  color: #bb7e00;
  font-size: 1.2em;
  vertical-align: -2px;
  margin-left: 6px;
}
.welcome-level {
  display: flex;
  align-items: center;
  gap: 7px;
  font-size: 11px;
  border: 1px solid var(--border);
  border-radius: 30px;
  padding: 8px 14px;
  background: white;
  color: var(--muted);
}
.discovery-hero {
  position: relative;
  display: grid;
  grid-template-columns: 1.35fr 1fr;
  min-height: 345px;
  border-radius: 24px;
  background: #245fdb;
  background-image: radial-gradient(circle at 1px 1px, #fff1 1px, transparent 0);
  background-size: 22px 22px;
  color: white;
  overflow: hidden;
}
.discovery-copy {
  position: relative;
  z-index: 2;
  padding: 36px 0 30px 36px;
}
.hero-label {
  display: inline-flex;
  align-items: center;
  gap: 7px;
  border: 1px solid #ffffff40;
  background: #ffffff13;
  color: white;
  border-radius: 30px;
  padding: 5px 11px;
  font-size: 9px;
  font-weight: 700;
  letter-spacing: 0.06em;
}
.discovery-copy h2 {
  color: white;
  font-size: clamp(1.9rem, 3.1vw, 3.2rem);
  line-height: 1.2;
  letter-spacing: -0.035em;
  margin: 8px 0 16px;
}
.discovery-copy h2 span {
  color: #ffe182;
}
.discovery-copy > p:not(.hero-label):not(.hero-footnote) {
  max-width: 350px;
  color: #edf3ff;
  font-size: 0.84rem;
  line-height: 1.85;
}
.hero-actions {
  display: flex;
  align-items: center;
  flex-wrap: wrap;
  gap: 18px;
  margin-top: 23px;
}
.hero-secondary {
  color: white;
  display: inline-flex;
  align-items: center;
  gap: 7px;
  font-size: 11px;
  text-decoration: none;
}
.hero-secondary:hover {
  text-decoration: underline;
}
.hero-footnote {
  display: flex;
  gap: 6px;
  align-items: center;
  font-size: 10px;
  margin: 18px 0 0;
  color: #edf3ff;
}
.molecule-scene {
  position: relative;
  min-height: 325px;
  align-self: stretch;
}
.scene-orbit {
  position: absolute;
  width: 310px;
  height: 310px;
  border: 1px solid #ffffff23;
  border-radius: 50%;
  top: 28px;
  left: 50%;
  transform: translateX(-50%);
}
.orbit-two {
  width: 240px;
  height: 240px;
  top: 63px;
  background: #ffffff07;
}
.water-model {
  position: absolute;
  width: 270px;
  height: 200px;
  left: 50%;
  top: 73px;
  transform: translateX(-50%) rotate(-12deg);
  animation: molecule-bob 4s ease-in-out;
}
.model-atom {
  position: absolute;
  z-index: 2;
  display: grid;
  place-items: center;
  border-radius: 50%;
  font-size: 24px;
  font-weight: 800;
  box-shadow:
    inset -10px -14px 18px #07266745,
    inset 4px 4px 10px #ffffff80,
    0 20px 24px #103b9d45;
}
.atom-o {
  width: 116px;
  height: 116px;
  top: 4px;
  left: 78px;
  color: #fff;
  background: radial-gradient(circle at 30% 25%, #b2d8ff, #5596ed 40%, #17459d);
  font-size: 38px;
}
.atom-h {
  width: 78px;
  height: 78px;
  top: 107px;
  color: #254577;
  background: radial-gradient(circle at 30% 25%, #fff, #e6effe 60%, #96b4df);
  box-shadow:
    inset -6px -8px 14px #456d9830,
    0 14px 20px #103b9d40;
}
.atom-h-left {
  left: 6px;
}
.atom-h-right {
  right: 0;
}
.model-bond {
  position: absolute;
  z-index: 1;
  top: 99px;
  width: 93px;
  height: 23px;
  border-radius: 12px;
  background: linear-gradient(#d5e6ff, #94b6ed 50%, #5178b6);
  box-shadow: 0 5px 8px #103b9d35;
}
.bond-left {
  left: 41px;
  transform: rotate(-47deg);
}
.bond-right {
  right: 31px;
  transform: rotate(47deg);
}
.floating-element {
  position: absolute;
  z-index: 3;
  right: 25px;
  top: 26px;
  display: flex;
  flex-direction: column;
  width: 67px;
  height: 79px;
  padding: 7px 12px;
  border-radius: 12px;
  background: #ffe182;
  color: #624811;
  transform: rotate(10deg);
  box-shadow: 0 8px 20px #102c7433;
}
.floating-element small {
  font-size: 10px;
  line-height: 1;
}
.floating-element strong {
  font-size: 27px;
  line-height: 1.35;
}
.floating-element > span {
  font-size: 8px;
}
.molecule-caption {
  position: absolute;
  bottom: 27px;
  left: 50%;
  transform: translateX(-50%) rotate(-4deg);
  white-space: nowrap;
  display: flex;
  align-items: center;
  gap: 12px;
  background: #fff;
  border-radius: 12px;
  padding: 10px 16px;
  box-shadow: 0 10px 25px #133b9730;
  color: #294775;
}
.molecule-caption strong {
  font-size: 22px;
}
.molecule-caption span {
  font-size: 10px;
}
.molecule-caption svg {
  color: #a76a00;
}
.scene-spark {
  position: absolute;
  color: #ffe182;
  font-size: 34px;
}
.spark-one {
  left: 6%;
  top: 58px;
}
.spark-two {
  right: 20px;
  bottom: 75px;
  font-size: 47px;
}
.scene-dot {
  position: absolute;
  border-radius: 50%;
  background: #89baff;
  width: 13px;
  height: 13px;
}
.dot-one {
  left: 18px;
  bottom: 62px;
}
.dot-two {
  right: 82px;
  top: 145px;
  width: 9px;
  height: 9px;
  background: #ffe182;
}
.quick-discover {
  display: grid;
  grid-template-columns: repeat(4, minmax(0, 1fr));
  gap: 14px;
  margin: 22px 0;
}
.quick-card {
  display: flex;
  flex-wrap: wrap;
  align-items: center;
  gap: 12px;
  position: relative;
  color: var(--text);
  text-decoration: none;
  padding: 18px;
  border: 1px solid var(--border);
  border-radius: 16px;
  background: white;
}
.quick-card:hover {
  transform: translateY(-4px);
  box-shadow: var(--shadow);
  border-color: #afc7f8;
}
.quick-icon {
  display: grid;
  place-items: center;
  width: 44px;
  height: 44px;
  border-radius: 12px;
  background: #eaf1ff;
  color: #2863da;
}
.quick-card > span:nth-child(2) {
  width: 100%;
}
.quick-card strong {
  display: block;
  font-size: 0.82rem;
  margin-bottom: 4px;
}
.quick-card small {
  display: block;
  font-size: 0.67rem;
  color: var(--muted);
}
.quick-card > svg {
  position: absolute;
  top: 28px;
  right: 17px;
  color: #8191a8;
}
.quick-yellow .quick-icon {
  background: #fff4ce;
  color: #956809;
}
.quick-purple .quick-icon {
  background: #f0eaff;
  color: #7b50bf;
}
.quick-peach .quick-icon {
  background: #fff0e6;
  color: #b56531;
}
.discovery-search {
  display: flex;
  align-items: center;
  gap: 12px;
  background: white;
  border: 1px solid var(--border);
  padding: 7px 8px 7px 20px;
  border-radius: 14px;
}
.discovery-search > svg {
  color: #7d8faa;
  flex-shrink: 0;
}
.discovery-search input {
  border: 0;
  background: transparent;
  padding-left: 0;
}
.discovery-search .btn {
  flex-shrink: 0;
  min-height: 42px;
}
.discovery-suggestions {
  display: flex;
  flex-wrap: wrap;
  gap: 13px;
  font-size: 11px;
  color: var(--muted);
  margin: 12px 2px 0;
}
.discovery-suggestions a {
  text-decoration: none;
  font-weight: 600;
}
.home-sections > section,
.learning-overview {
  margin-top: 32px;
}
.mode-line {
  font-size: 11px;
  color: var(--muted);
  margin-top: 18px;
}
.mode-line a {
  margin-left: auto;
}
.mode-choose {
  padding: 22px;
  box-shadow: none;
  background: white;
}
.mode-choose p {
  font-size: 0.82rem;
}
.mode-grid {
  grid-template-columns: repeat(5, minmax(0, 1fr));
}
.mode-card {
  border: 1px solid var(--border);
  background: #fff;
  padding: 14px;
  min-height: 80px;
  transition: 0.2s;
}
.mode-card strong {
  font-size: 0.9rem;
}
.mode-card span {
  font-size: 0.7rem;
}
.mode-card.is-active {
  box-shadow: inset 0 0 0 1px var(--brand);
}
.learning-overview {
  display: grid;
  grid-template-columns: minmax(0, 1.7fr) minmax(250px, 1fr);
  gap: 24px;
}
.learning-path {
  min-width: 0;
}
.path-steps {
  display: grid;
  gap: 10px;
}
.path-step {
  display: flex;
  align-items: center;
  gap: 15px;
  padding: 15px;
  background: white;
  border: 1px solid var(--border);
  border-radius: 14px;
  color: var(--text);
  text-decoration: none;
  transition: 0.2s;
}
.path-step:hover {
  transform: translateX(3px);
  border-color: #a9c3ff;
}
.step-number {
  flex-shrink: 0;
  width: 39px;
  height: 39px;
  display: grid;
  place-items: center;
  border-radius: 12px;
  background: #edf3ff;
  color: #245acc;
  font-weight: 800;
  font-size: 0.85rem;
}
.step-content {
  flex: 1;
  min-width: 0;
}
.step-content strong {
  display: block;
  font-size: 0.8rem;
}
.step-content small {
  display: block;
  white-space: nowrap;
  overflow: hidden;
  text-overflow: ellipsis;
  color: var(--muted);
  font-size: 0.7rem;
  margin-top: 4px;
}
.step-status {
  font-size: 10px;
  color: #5c718f;
}
.is-complete .step-number {
  background: var(--ok-soft);
  color: var(--ok);
}
.progress-card {
  text-align: center;
  background: #fff8e1;
  border: 1px solid #f1e2b3;
  border-radius: 20px;
  padding: 24px;
  align-self: stretch;
}
.progress-art {
  position: relative;
  display: inline-grid;
  place-items: center;
  background: #ffdd75;
  color: #775210;
  width: 66px;
  height: 66px;
  border: 5px solid #ffedb5;
  border-radius: 50%;
}
.progress-art > span {
  position: absolute;
  top: -4px;
  right: -16px;
  font-size: 23px;
  color: #9b6810;
}
.progress-card h2 {
  font-size: 1rem;
  margin-top: 16px;
}
.progress-card > p {
  font-size: 0.73rem;
  color: #726548;
  max-width: 32ch;
  margin: 0 auto 20px;
}
.progress-caption {
  display: flex;
  justify-content: space-between;
  font-size: 10px;
  color: #726548;
}
.progress-card progress {
  appearance: none;
  display: block;
  width: 100%;
  height: 7px;
  border: 0;
  background: #eddfb5;
  border-radius: 8px;
  margin: 9px 0 16px;
  overflow: hidden;
}
.progress-card progress::-webkit-progress-bar {
  background: #eddfb5;
}
.progress-card progress::-webkit-progress-value {
  background: #2563eb;
  border-radius: 8px;
}
.progress-card progress::-moz-progress-bar {
  background: #2563eb;
}
.progress-stats {
  display: grid;
  grid-template-columns: 1fr 1fr;
  margin: 16px 0;
}
.progress-stats span {
  display: flex;
  flex-direction: column;
  font-size: 10px;
  color: #726548;
}
.progress-stats span + span {
  border-left: 1px solid #e9dab3;
}
.progress-stats strong {
  font-size: 19px;
  color: #31436a;
}
.progress-card .btn {
  width: 100%;
  font-size: 12px;
}
.catalog-stats {
  display: grid;
  grid-template-columns: repeat(4, minmax(0, 1fr));
  gap: 20px;
  margin: 40px 0;
  padding: 26px 0;
  border-top: 1px solid var(--border);
  border-bottom: 1px solid var(--border);
  text-align: center;
}
.catalog-stats dt {
  font-size: 1.6rem;
  color: var(--brand);
  font-weight: 800;
}
.catalog-stats dd {
  font-size: 0.7rem;
  margin: 0;
  color: var(--muted);
}
/* Shared route headers and workspace controls. */
.page-head,
.mol-head,
.element-head {
  padding: 28px;
  margin: 26px 0 24px;
  border: 1px solid #dbe6f9;
  border-radius: 22px;
  background: linear-gradient(110deg, #edf3ff, #f6f9ff);
  position: relative;
}
.page-head h1 {
  margin: 8px 0 12px;
  max-width: 30ch;
}
.page-head .lead {
  font-size: 0.9rem;
  line-height: 1.85;
  max-width: 76ch;
}
.page-head .lead:last-child {
  margin-bottom: 0;
}
.page-head .eyebrow {
  font-size: 10px;
}
.page-head .crumbs ol {
  margin-top: 0;
}
.page-head::after {
  content: '';
  position: absolute;
  top: 24px;
  right: 26px;
  width: 32px;
  height: 8px;
  background: var(--yellow);
  border-radius: 5px;
  pointer-events: none;
}
.filters,
.table-tools {
  padding: 20px;
  background: white;
  border: 1px solid var(--border);
  border-radius: 18px;
  gap: 14px;
}
.filters .field {
  flex-basis: 140px;
}
.filters .field-grow {
  flex-basis: 260px;
}
.field > label,
.field > span,
legend {
  font-size: 0.8rem;
}
.filters .btn {
  align-self: flex-end;
}
.seg {
  background: #edf2fa;
  border-color: transparent;
  border-radius: 12px;
}
.seg-btn {
  font-size: 0.8rem;
}
.seg-btn[aria-pressed='true'] {
  box-shadow: 0 2px 6px #203f7812;
}
.tabs {
  border-bottom: 1px solid var(--border);
  margin-bottom: 24px;
}
.tab {
  font-size: 0.85rem;
  padding: 14px 18px;
}
.tab[aria-selected='true'] {
  color: var(--brand);
}
.notice {
  border-radius: 14px;
  font-size: 0.85rem;
}
.notice-info {
  background: #eef4ff;
}
.state-empty,
.state-error,
.page-state {
  border-radius: 20px;
  background: white;
  border: 1px dashed #bed0ed;
  padding: 40px 24px;
  margin-block: 24px;
}
.state-empty > svg {
  padding: 16px;
  box-sizing: content-box;
  background: #eff4ff;
  border-radius: 50%;
  color: var(--brand);
}
.crumbs {
  font-size: 0.8rem;
}
.crumbs a {
  text-decoration: none;
}
.crumbs ol {
  font-size: 0.75rem;
  margin-top: 22px;
}
/* Catalogue, family collections and molecule/element details. */
.mol-card {
  padding: 0;
  overflow: hidden;
}
.mol-card:hover {
  transform: translateY(-3px);
}
.mol-card .card-media {
  background: #f1f5fc;
  border-bottom: 1px solid #e9eef7;
  height: 170px;
  padding: 12px;
}
.card-media .depict {
  mix-blend-mode: multiply;
}
.mol-card .card-body {
  padding: 17px 18px 8px;
}
.mol-card .card-text {
  font-size: 0.76rem;
}
.mol-card .formula {
  font-size: 0.8rem;
  color: #245bd0;
  margin-bottom: 5px;
}
.mol-card .card-foot {
  padding: 10px 14px;
  gap: 5px;
}
.card-foot .chip {
  font-size: 0.66rem;
  padding: 3px 7px;
}
.card-foot .badge {
  font-size: 0.65rem;
}
.card-save {
  border-radius: 50%;
}
.class-card {
  position: relative;
  min-height: 156px;
  border-top: 1px solid var(--border);
}
.class-icon {
  width: 47px;
  height: 47px;
  border-radius: 14px;
  background: color-mix(in srgb, var(--accent) 10%, white);
}
.class-name {
  font-size: 0.93rem;
}
.class-count {
  font-size: 0.75rem;
}
.class-head {
  border-left: 5px solid var(--accent);
}
.tree > li {
  background: white;
  border: 1px solid var(--border);
  border-radius: 16px;
  padding: 16px;
}
.mol-head {
  align-items: center;
}
.mol-actions .btn {
  background: white;
}
.mol-stage,
.element-grid {
  gap: 24px;
}
.viewer-box {
  border-radius: 22px;
  padding: 16px;
  box-shadow: none;
}
.viewer {
  border-radius: 15px;
}
.viewer-toolbar .btn {
  font-size: 0.75rem;
}
.viewer-hint {
  font-size: 0.75rem;
}
.mol-side .card {
  padding: 20px;
}
.jump {
  top: 78px;
  border-bottom: 1px solid var(--border);
  padding: 10px 0;
  backdrop-filter: blur(12px);
}
.mol-section {
  margin-top: 32px;
}
.mol-section > h2 {
  margin-bottom: 15px;
}
.fun {
  background: #fff8e0;
  border-color: #efe0ad;
}
.element-day {
  border-top: 1px solid var(--border);
  background: #eef4ff;
}
.element-big {
  border-radius: 16px;
}
.split {
  gap: 24px;
}
.split > .card {
  padding: 26px;
}
.place-chips {
  gap: 10px;
}
.place-chips .chip {
  border-radius: 12px;
  background: #fff;
}
.pt-scroll {
  border: 1px solid var(--border);
  background: white;
  border-radius: 20px;
  padding: 18px;
}
.ptable {
  gap: 5px;
}
.el-tile {
  border-radius: 8px;
  transition:
    transform 0.16s,
    box-shadow 0.16s;
}
.el-tile:hover {
  transform: translateY(-3px) scale(1.07);
  box-shadow: 0 5px 12px #203f7830;
  z-index: 2;
}
.pt-legend {
  background: white;
  border-radius: 14px;
  padding: 16px;
  margin-block: 16px;
}
.table-wrap {
  border: 1px solid var(--border);
  border-radius: 14px;
}
.data-table th {
  background: #f0f5ff;
}
.data-table td,
.data-table th {
  padding: 12px;
  font-size: 0.83rem;
}
/* Lessons become a comfortable reading workspace; lab controls stay beside their simulation. */
.topic-card,
.lab-card {
  min-height: 195px;
  position: relative;
}
.topic-card .topic-icon,
.lab-card .topic-icon {
  display: grid;
  place-items: center;
  width: 50px;
  height: 50px;
  border-radius: 15px;
  background: #eaf1ff;
  color: #245bce;
  margin-bottom: 16px;
}
.lab-card .topic-icon {
  color: #7250a7;
  background: #f0eaff;
}
.topic-meta {
  font-size: 0.72rem;
  margin-top: 14px;
}
.lesson-body {
  max-width: 78ch;
  background: white;
  border: 1px solid var(--border);
  border-radius: 20px;
  padding: clamp(20px, 3vw, 42px);
  margin: 24px auto;
  font-size: 1rem;
  line-height: 1.95;
}
.lesson-body h2,
.lesson-body h3 {
  margin-top: 1.8em;
}
.lesson-body > :first-child {
  margin-top: 0;
}
.lesson-tools {
  gap: 10px;
  margin-top: 20px;
}
.lesson-nav {
  gap: 16px;
}
.lab-grid {
  gap: 24px;
}
.lab-grid > .card {
  padding: 24px;
}
.lab-canvas {
  background: #f0f5ff;
  border: 1px solid #e3ebfa;
  border-radius: 16px;
}
.lab-page .page-head {
  border-left: 5px solid #8e75d5;
}
.lab-host {
  margin-top: 24px;
}
.field input[type='range'] {
  min-height: 44px;
}
.ph-value {
  color: var(--brand);
}
.quiz-box {
  border-radius: 22px;
  padding: clamp(20px, 3vw, 36px);
  border-color: var(--border);
  box-shadow: var(--shadow);
}
.quiz-question {
  font-size: 1.2rem;
  line-height: 1.65;
}
.quiz-option {
  padding: 16px;
  border-radius: 14px;
  font-size: 0.9rem;
}
.quiz-option:hover {
  border-color: #a2bff6;
  background: #f7faff;
}
.quiz-progress {
  display: inline-flex;
  padding: 5px 10px;
  background: #edf3ff;
  border-radius: 8px;
  color: var(--brand-strong);
  font-size: 0.75rem;
}
.quiz-result {
  padding-block: 24px;
}
.feedback {
  border-radius: 14px;
}
.badge-card {
  border-radius: 16px;
}
.badge-card.is-earned {
  background: #fff7dc;
  border-color: #e8ce7b;
}
.badge-card.is-earned svg {
  color: #9b6900;
}
.term-card {
  border-radius: 16px;
}
.term-card h2 {
  font-size: 1rem;
}
.term-card.is-open {
  border-color: #8baffb;
  background: #f9fbff;
}
.note-text {
  border-radius: 14px;
}
.teacher-cta {
  padding: 28px;
  background: #edf3ff;
  border-color: #dbe5fa;
}
.teacher-cta p {
  font-size: 0.83rem;
}
.teacher-notes {
  background: #f9fbff;
  border-radius: 18px;
  padding: 24px;
}
.site-footer {
  padding-top: 32px;
  font-size: 0.76rem;
  background: white;
}
.footer-grid {
  gap: 32px;
}
.footer-brand img {
  width: 36px;
  height: 36px;
}
.footer-title {
  font-size: 0.8rem;
}
.footer-links a {
  text-decoration: none;
  color: var(--muted);
}
.footer-links a:hover {
  color: var(--brand);
}
.footer-bottom {
  font-size: 0.65rem;
  margin-top: 24px;
  padding-top: 18px;
}
.toast {
  border-radius: 14px;
  box-shadow: var(--shadow-lg);
  font-size: 0.85rem;
}
@keyframes page-arrive {
  from {
    opacity: 0.3;
    transform: translateY(7px);
  }
  to {
    opacity: 1;
    transform: translateY(0);
  }
}
@keyframes molecule-bob {
  0%,
  100% {
    transform: translateX(-50%) rotate(-12deg);
  }
  50% {
    transform: translateX(-50%) translateY(-10px) rotate(-6deg);
  }
}
@media (min-width: 1600px) {
  :root {
    --gutter: 42px;
    --sidebar: 256px;
  }
  .discovery-copy {
    padding: 44px;
  }
  .discovery-hero {
    min-height: 380px;
  }
  .molecule-scene {
    margin-top: 20px;
  }
  .quick-card {
    flex-wrap: nowrap;
  }
  .quick-card > span:nth-child(2) {
    width: auto;
  }
  .quick-card > svg {
    position: static;
    margin-left: auto;
  }
  .quick-icon {
    flex-shrink: 0;
  }
}
@media (min-width: 1100px) and (max-width: 1279px) {
  :root {
    --sidebar: 216px;
    --gutter: 24px;
  }
  .header-search input {
    width: 230px;
  }
  .shell-location > span {
    display: none;
  }
  .grid-4 {
    grid-template-columns: repeat(2, minmax(0, 1fr));
  }
  .discovery-copy {
    padding-left: 28px;
  }
  .hero-actions {
    gap: 12px;
  }
  .hero-secondary {
    font-size: 10px;
  }
}
@media (max-width: 1099px) {
  .menu-btn {
    display: inline-grid;
  }
  .header-search {
    display: none;
  }
  .drawer:not([hidden]) {
    display: block !important;
  }
  .discovery-copy h2 {
    font-size: clamp(2rem, 4.5vw, 3rem);
  }
  .discovery-hero {
    grid-template-columns: 1.3fr 1fr;
  }
  .header-bar {
    min-height: 70px;
  }
  .jump {
    top: 70px;
  }
}
@media (max-width: 760px) {
  :root {
    --gutter: 20px;
  }
  body {
    font-size: 14px;
  }
  .header-bar {
    gap: 8px;
  }
  .header-tools {
    gap: 8px;
  }
  .brand-text strong {
    font-size: 1.08rem;
  }
  .brand img {
    width: 38px;
    height: 38px;
  }
  .brand-text small {
    font-size: 7px;
  }
  .learner-select {
    padding-left: 8px;
  }
  .learner-select > svg {
    display: none;
  }
  .mode-select {
    max-width: 76px;
  }
  .lang-btn {
    min-height: 36px;
    min-width: 36px;
  }
  .home-welcome {
    padding-top: 24px;
    padding-bottom: 20px;
  }
  .home-welcome .eyebrow {
    font-size: 8px;
  }
  .welcome-level {
    display: none;
  }
  .discovery-hero {
    grid-template-columns: 1fr;
  }
  .discovery-copy {
    padding: 28px 26px 10px;
  }
  .discovery-copy h2 {
    font-size: clamp(1.85rem, 6.8vw, 2.8rem);
  }
  .discovery-copy > p:not(.hero-label):not(.hero-footnote) {
    max-width: 42ch;
  }
  .hero-actions {
    gap: 16px;
  }
  .hero-footnote {
    font-size: 9px;
  }
  .molecule-scene {
    min-height: 255px;
  }
  .scene-orbit {
    width: 240px;
    height: 240px;
    top: 5px;
  }
  .orbit-two {
    width: 190px;
    height: 190px;
    top: 30px;
  }
  .water-model {
    top: 10px;
    scale: 0.85;
    transform-origin: 0 center;
  }
  .floating-element {
    top: 10px;
    right: 15%;
    scale: 0.85;
  }
  .molecule-caption {
    bottom: 15px;
  }
  .spark-one {
    top: 30px;
    left: 15%;
  }
  .spark-two {
    right: 15%;
    bottom: 50px;
  }
  .dot-one {
    left: 20%;
    bottom: 65px;
  }
  .dot-two {
    right: 18%;
    top: 150px;
  }
  .quick-discover {
    grid-template-columns: repeat(2, minmax(0, 1fr));
    gap: 12px;
    margin: 18px 0;
  }
  .quick-card {
    padding: 16px;
  }
  .quick-card strong {
    font-size: 0.8rem;
  }
  .quick-card small {
    font-size: 0.64rem;
  }
  .discovery-search {
    gap: 8px;
    padding-left: 14px;
  }
  .discovery-search input {
    font-size: 0.75rem;
  }
  .discovery-search .btn {
    padding-inline: 12px;
  }
  .discovery-search .btn svg {
    display: none;
  }
  .discovery-suggestions {
    font-size: 10px;
    gap: 10px;
  }
  .learning-overview {
    grid-template-columns: 1fr;
  }
  .progress-card {
    padding: 24px;
  }
  .progress-card > p {
    max-width: none;
  }
  .progress-stats {
    margin-block: 18px;
  }
  .mode-grid {
    grid-template-columns: repeat(2, minmax(0, 1fr));
  }
  .mode-card:last-child {
    grid-column: 1 / -1;
  }
  .catalog-stats {
    grid-template-columns: repeat(2, minmax(0, 1fr));
  }
  .home-sections > section {
    margin-top: 28px;
  }
  .grid-cards {
    grid-template-columns: repeat(2, minmax(0, 1fr));
    gap: 12px;
  }
  .mol-card .card-media {
    height: 140px;
  }
  .mol-card .card-body {
    padding: 13px 12px 6px;
  }
  .mol-card .card-title {
    font-size: 0.85rem;
  }
  .mol-card .card-text {
    font-size: 0.7rem;
  }
  .mol-card .card-foot {
    padding: 6px 10px;
    flex-wrap: wrap;
  }
  .card-foot .chip {
    display: none;
  }
  .card-foot .card-save {
    margin-left: auto;
  }
  .card-foot .badge {
    font-size: 0.64rem;
  }
  .page-head,
  .mol-head,
  .element-head {
    padding: 22px;
    margin-top: 20px;
    border-radius: 18px;
  }
  .page-head h1 {
    font-size: 1.7rem;
  }
  .page-head .lead {
    font-size: 0.84rem;
  }
  .page-head::after {
    top: 15px;
    right: 18px;
    width: 22px;
    height: 5px;
  }
  .filters,
  .table-tools {
    padding: 16px;
  }
  .mol-stage,
  .element-grid,
  .lab-grid {
    grid-template-columns: 1fr;
  }
  .lesson-body {
    padding: 22px;
    font-size: 0.93rem;
  }
  .pt-scroll {
    padding: 10px;
  }
  .teacher-cta {
    padding: 22px;
  }
  .teacher-cta .btn {
    width: 100%;
  }
  .mobile-dock {
    position: fixed;
    z-index: 45;
    bottom: 0;
    left: 0;
    right: 0;
    display: grid;
    grid-template-columns: repeat(4, minmax(0, 1fr));
    padding: 7px 12px max(7px, env(safe-area-inset-bottom));
    background: #fffffff5;
    backdrop-filter: blur(16px);
    border-top: 1px solid var(--border);
    box-shadow: 0 -4px 20px #203f7808;
  }
  .mobile-dock .nav-link {
    display: flex;
    flex-direction: column;
    padding: 5px 2px;
    gap: 4px;
    font-size: 9px;
    min-width: 0;
  }
  .mobile-dock .nav-link .count {
    display: none;
  }
  .site-footer {
    padding-bottom: 100px;
  }
  .toast-region {
    bottom: 90px;
  }
  .section-head .link-more {
    font-size: 0.7rem;
  }
  .section-head h2 {
    font-size: 1.08rem;
  }
}
@media (max-width: 380px) {
  :root {
    --gutter: 14px;
  }
  .brand-text {
    display: flex;
  }
  .brand-text strong {
    font-size: 0.93rem;
  }
  .brand-text small {
    display: none;
  }
  .brand {
    gap: 3px;
  }
  .brand img {
    width: 30px;
    height: 30px;
  }
  .header-tools {
    gap: 4px;
  }
  .learner-select {
    padding-left: 4px;
  }
  .mode-select {
    max-width: 57px;
    font-size: 0.72rem;
  }
  .lang-btn {
    min-width: 30px;
    min-height: 34px;
  }
  .menu-btn {
    min-width: 36px;
  }
  .header-bar {
    min-height: 64px;
  }
  .discovery-copy {
    padding: 25px 20px 5px;
  }
  .hero-label {
    font-size: 8px;
  }
  .hero-actions {
    gap: 12px;
  }
  .hero-secondary {
    font-size: 10px;
  }
  .hero-footnote {
    font-size: 8px;
  }
  .quick-card small {
    font-size: 0.6rem;
  }
  .quick-card {
    padding: 13px;
  }
  .quick-card strong {
    font-size: 0.74rem;
  }
  .path-step {
    gap: 10px;
    padding: 12px;
  }
  .step-content strong {
    font-size: 0.75rem;
  }
  .step-status {
    font-size: 8px;
  }
  .drawer nav {
    grid-template-columns: 1fr;
  }
  .home-welcome h1 {
    font-size: 1.4rem;
  }
  .jump {
    top: 64px;
  }
}
@media (prefers-reduced-motion: reduce) {
  *,
  *::before,
  *::after {
    animation: none !important;
    transition: none !important;
    scroll-behavior: auto !important;
  }
}
@media print {
  body {
    padding-left: 0;
    background: white;
  }
  .learning-sidebar,
  .mobile-dock,
  .home-welcome,
  .discovery-hero,
  .quick-discover,
  .discovery-search,
  .discovery-suggestions {
    display: none !important;
  }
  .page-head,
  .mol-head,
  .element-head {
    background: white;
    padding: 0;
    border: 0;
  }
  .lesson-body {
    border: 0;
    padding: 0;
    max-width: none;
  }
  .site-footer {
    padding-bottom: 0;
  }
}
/* Keep long lesson summaries inside their grid track at every viewport. */
.path-steps {
  grid-template-columns: minmax(0, 1fr);
}
.path-step {
  min-width: 0;
}
/* Reading and experiment cards always show a clear next action. */
.card-next {
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 12px;
  padding-top: 15px;
  margin-top: auto;
  border-top: 1px solid var(--border);
  color: var(--brand-strong);
  font-size: 0.75rem;
  font-weight: 700;
}
.topic-card:has(.card-next),
.lab-card:has(.card-next) {
  display: flex;
  flex-direction: column;
  gap: 8px;
}
.topic-card .card-next,
.lab-card .card-next {
  margin-top: 16px;
}
.place-card {
  display: grid;
  gap: 10px;
}
.place-card .topic-icon {
  display: grid;
  place-items: center;
  width: 56px;
  height: 56px;
  border-radius: 16px;
  background: #fff2cf;
  color: #956809;
}
.place-card:nth-child(3n + 2) .topic-icon {
  background: #eaf1ff;
  color: #245bce;
}
.place-card:nth-child(3n) .topic-icon {
  background: #f0eaff;
  color: #7250a7;
}
.quiz-card {
  padding: clamp(22px, 4vw, 40px);
}
.quiz-q {
  font-size: 1.2rem;
  line-height: 1.6;
}
main h1[tabindex='-1']:focus {
  outline: none;
}
.sidebar-teacher[aria-current='page'],
.sidebar-about[aria-current='page'] {
  color: var(--brand-strong);
  font-weight: 800;
}
@media (max-width: 760px) {
  .hero-actions {
    gap: 12px;
  }
  .hero-actions .btn {
    font-size: 12px;
    padding-inline: 14px;
  }
  .molecule-scene {
    min-height: 220px;
  }
  .water-model {
    scale: 0.74;
    top: -3px;
  }
  .molecule-caption {
    bottom: 10px;
  }
  .scene-orbit {
    width: 205px;
    height: 205px;
  }
  .orbit-two {
    width: 160px;
    height: 160px;
  }
}

.quiz-bar {
  appearance: none;
  display: block;
  height: 8px;
  border: 0;
  border-radius: 8px;
  overflow: hidden;
  background: #e7efff;
}
.quiz-bar::-webkit-progress-bar {
  background: #e7efff;
  border-radius: 8px;
}
.quiz-bar::-webkit-progress-value {
  background: var(--brand);
  border-radius: 8px;
}
.quiz-bar::-moz-progress-bar {
  background: var(--brand);
  border-radius: 8px;
}