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

:root { color-scheme: light; --ink: #213852; --muted: #50647d; --navy: #102d54; --line: #dce5f1; --paper: #f8faff; --cyan: #5dd0e3; }
* { box-sizing: border-box; }
[hidden] { display: none !important; }
html { scroll-behavior: smooth; scroll-padding-top: 24px; }
body { margin: 0; background: radial-gradient(ellipse at 95% 0%, #e2edff, transparent 30%), var(--paper); color: var(--ink); font: 16px/1.75 'DM Sans', sans-serif; }
a { color: #245d9d; text-underline-offset: 4px; }
a:hover { color: var(--navy); }
:focus-visible { outline: 3px solid #277cb4; outline-offset: 5px; }
button, input { font: inherit; }
button, a, input { -webkit-tap-highlight-color: transparent; }
.site-header, main, .site-footer { width: min(1120px, calc(100% - 48px)); margin-inline: auto; }
.site-header { display: flex; justify-content: space-between; align-items: center; gap: 24px; padding-block: 26px; border-bottom: 1px solid var(--line); }
.brand { display: flex; align-items: center; gap: 12px; color: var(--navy); text-decoration: none; font-weight: 700; flex-shrink: 0; }
.brand-mark { display: grid; place-items: center; width: 44px; height: 44px; border-radius: 12px; background: var(--navy); color: white; font: 700 27px 'Manrope', sans-serif; box-shadow: 0 5px 15px #102d5420; }
.brand small { display: block; color: var(--muted); font-size: 12px; font-weight: 400; }
nav { display: flex; flex-wrap: wrap; gap: 22px; font-size: 14px; font-weight: 600; }
nav a { position: relative; text-decoration: none; padding-block: 10px; }
nav a::after { content: ''; position: absolute; left: 0; bottom: 4px; width: 100%; height: 2px; background: #398ac4; transform: scaleX(0); transform-origin: left; transition: transform .2s ease; }
nav a:hover::after, nav a:focus-visible::after { transform: scaleX(1); }
h1, h2, h3 { font-family: 'Manrope', sans-serif; line-height: 1.2; letter-spacing: -.035em; color: var(--navy); }
h1 { font-size: clamp(38px, 5vw, 62px); font-weight: 800; margin: 14px 0 24px; }
h2 { font-size: clamp(28px, 3.4vw, 38px); margin: 10px 0 20px; }
h3 { font-size: 21px; }
p { color: var(--muted); margin: 0 0 18px; }
.eyebrow { color: #2b668c; text-transform: uppercase; font-size: 11px; font-weight: 700; letter-spacing: .15em; }
.hero { display: grid; grid-template-columns: 1.5fr 1fr; align-items: center; gap: 48px; padding-block: 78px; }
.hero-lead { font-size: 20px; line-height: 1.65; }
.hero-actions { display: flex; flex-wrap: wrap; gap: 12px; margin-block: 28px; }
.button { display: inline-flex; align-items: center; justify-content: center; gap: 14px; padding: 13px 22px; min-height: 48px; background: var(--navy); border: 1px solid var(--navy); color: white; border-radius: 9px; text-decoration: none; font-size: 14px; font-weight: 600; box-shadow: 0 5px 15px #102d5418; transition: transform .2s ease, box-shadow .2s ease, background .2s ease; }
.button:hover { color: white; background: #204f88; transform: translateY(-3px); box-shadow: 0 9px 20px #102d5428; }
.button-outline { background: transparent; color: var(--navy); box-shadow: none; border-color: #b9cce3; }
.hero-note { font-size: 12px; color: var(--muted); }
.hero-note span { color: #277cb4; margin-right: 6px; }
.chemistry-art { min-width: 0; text-align: center; }
.chemistry-art svg { width: 100%; max-width: 360px; height: auto; overflow: visible; }
.chemistry-art span { display: block; color: #526c8d; font-size: 11px; letter-spacing: .04em; }
.section { padding-block: 64px; border-top: 1px solid var(--line); }
.section > p { max-width: 720px; }
.catalog-tools { margin-top: 30px; }
.catalog-tools label { display: block; margin-bottom: 8px; font-size: 14px; font-weight: 600; }
input[type=search] { width: 100%; padding: 15px 18px; border: 1px solid #b9cce3; border-radius: 10px; color: var(--navy); background: white; appearance: none; }
input::placeholder { color: #657993; }
.filters { display: flex; flex-wrap: wrap; gap: 10px; margin-top: 18px; }
.filter { padding: 10px 17px; min-height: 44px; border: 1px solid var(--line); border-radius: 30px; color: var(--navy); background: white; cursor: pointer; font-size: 14px; transition: background .2s ease; }
.filter:hover { background: #e4efff; }
.filter.active { background: var(--navy); color: white; border-color: var(--navy); }
.result-count { font-size: 13px; margin-block: 16px 22px; }
.materials-grid { display: grid; grid-template-columns: repeat(3, minmax(0, 1fr)); gap: 20px; margin-top: 24px; }
.material-card { display: flex; flex-direction: column; padding: 25px; background: white; border: 1px solid var(--line); border-radius: 15px; box-shadow: 0 6px 24px #102d5406; transition: transform .2s ease, box-shadow .2s ease, border-color .2s ease; }
.material-card:hover { transform: translateY(-4px); box-shadow: 0 12px 28px #102d5410; border-color: #a9c5e6; }
.card-meta { display: flex; align-items: center; justify-content: space-between; flex-wrap: wrap; gap: 8px; font-size: 12px; font-weight: 700; }
.badge { padding: 3px 9px; border-radius: 30px; color: #5e6275; background: #f0f1f5; font-size: 11px; font-weight: 500; }
.badge.available { color: #185876; background: #e1f3f8; }
.card-area { font-size: 11px; text-transform: uppercase; letter-spacing: .06em; margin: 24px 0 10px; color: #396b97; }
.material-card h3 { margin: 0 0 15px; }
.card-topics { font-size: 14px; line-height: 1.7; margin-bottom: 24px; }
.card-link { display: flex; align-items: center; justify-content: space-between; margin-top: auto; padding: 12px 0 0; border-top: 1px solid var(--line); text-decoration: none; font-weight: 700; min-height: 44px; font-size: 14px; }
.card-pending { margin: auto 0 0; padding-top: 12px; border-top: 1px solid var(--line); font-size: 13px; }
.empty-state { padding: 30px; background: #eaf0fa; border-radius: 12px; }
.lessons { display: grid; grid-template-columns: 1fr 1fr; gap: 70px; }
.lesson-details { display: grid; gap: 20px; }
.lesson-details article { position: relative; padding-left: 54px; }
.lesson-details h3 { margin: 0 0 8px; font-size: 18px; }
.lesson-details p { font-size: 15px; }
.detail-number { position: absolute; left: 0; top: 0; display: grid; place-items: center; width: 36px; height: 36px; color: #245d9d; background: #e5effb; border-radius: 10px; font-size: 12px; }
.about { display: grid; grid-template-columns: 240px 1fr; gap: 64px; align-items: center; }
.profile-mark { aspect-ratio: 1; padding: 25px; display: flex; flex-direction: column; justify-content: space-between; background: linear-gradient(140deg, #102d54, #234f7d); color: #c4eaf5; border-radius: 24px; box-shadow: 0 16px 32px #102d5418; }
.profile-mark span { font-size: 12px; letter-spacing: .07em; }
.profile-mark strong { font: 600 88px/1 'Manrope', sans-serif; color: white; }
.credentials { display: flex; flex-wrap: wrap; gap: 10px; }
.credentials span { padding: 6px 12px; background: #eaf0fa; border-radius: 6px; font-size: 12px; }
.study-steps { display: grid; grid-template-columns: repeat(3, minmax(0, 1fr)); gap: 36px; padding: 0; list-style: none; counter-reset: step; margin: 30px 0 0; }
.study-steps li { counter-increment: step; }
.study-steps li::before { content: '0' counter(step); display: block; color: #3974a5; font: 600 26px 'Manrope', sans-serif; margin-bottom: 16px; }
.study-steps p { font-size: 14px; margin-top: 10px; }
.contact { display: grid; grid-template-columns: 1.5fr 1fr; gap: 48px; padding: 46px; margin-bottom: 48px; background: var(--navy); border-radius: 20px; border: 0; }
.contact h2 { color: white; font-size: 32px; }
.contact p { color: #c5d7eb; }
.contact .eyebrow { color: #80d4e6; }
.contact-actions { display: flex; flex-direction: column; align-items: flex-start; justify-content: center; gap: 14px; min-width: 0; }
.contact-actions a { color: white; overflow-wrap: anywhere; }
.contact .button { background: #c2f0fa; color: var(--navy); border-color: transparent; }
.contact .button:hover { background: white; }
.site-footer { padding-block: 10px 36px; color: var(--muted); font-size: 12px; }
.skip-link { position: absolute; top: -100px; left: 16px; padding: 10px; background: white; z-index: 10; }
.skip-link:focus { top: 10px; }
.atom-orbits { transform-origin: 180px 110px; animation: orbit 36s linear infinite; }
.flask { animation: float 6s ease-in-out infinite; }
.beaker { animation: float 6s ease-in-out -3s infinite; }
.bubble { animation: bubble 4s ease-in-out infinite; }
.bubble-two { animation-delay: -2s; }
@keyframes orbit { to { transform: rotate(360deg); } }
@keyframes float { 50% { transform: translateY(-7px); } }
@keyframes bubble { 0%, 100% { opacity: .3; transform: translateY(0); } 50% { opacity: 1; transform: translateY(-12px); } }

@media (max-width: 960px) {
  .site-header { align-items: flex-start; flex-direction: column; gap: 10px; }
  .materials-grid { grid-template-columns: repeat(2, minmax(0, 1fr)); }
  .hero { gap: 24px; }
  .lessons { gap: 32px; }
  .contact { grid-template-columns: 1fr; gap: 16px; }
}
@media (max-width: 600px) {
  .site-header, main, .site-footer { width: calc(100% - 32px); }
  nav { gap: 8px 18px; font-size: 13px; }
  .hero { grid-template-columns: 1fr; gap: 24px; padding-block: 42px; }
  .hero-lead { font-size: 18px; }
  .chemistry-art { width: 220px; margin-inline: auto; }
  .chemistry-art span { display: none; }
  .section { padding-block: 42px; }
  .materials-grid, .lessons, .about, .study-steps { grid-template-columns: 1fr; }
  .material-card { padding: 23px; }
  .card-topics { font-size: 15px; }
  .profile-mark { width: 170px; padding: 18px; border-radius: 18px; }
  .profile-mark strong { font-size: 58px; }
  .profile-mark span { font-size: 10px; }
  .about { gap: 28px; }
  .study-steps { gap: 20px; }
  .contact { padding: 28px 24px; }
  .contact h2 { font-size: 28px; }
  .contact .button { padding-inline: 14px; width: 100%; }
  .contact-actions { align-items: stretch; font-size: 14px; }
}
@media (prefers-reduced-motion: reduce) {
  html { scroll-behavior: auto; }
  *, *::before, *::after { animation: none !important; transition: none !important; }
}