:root {
  color-scheme: light;
  --paper: #f5f3eb;
  --white: #fffdf7;
  --ink: #182b24;
  --muted: #52625a;
  --green: #153f34;
  --line: #d8ded2;
  --yellow: #efc665;
  font-family: "Source Sans 3", "Microsoft YaHei", "PingFang SC", system-ui, sans-serif;
  scroll-behavior: smooth;
}
* { box-sizing: border-box; }
body { margin: 0; background: var(--paper); color: var(--ink); }
a { color: inherit; text-decoration: none; }
button { font: inherit; cursor: pointer; }
:focus-visible { outline: 3px solid #9c5519; outline-offset: 4px; }
.skip { position: absolute; top: 0; left: 1rem; background: var(--white); padding: .7rem; transform: translateY(-120%); z-index: 2; }
.skip:focus { transform: translateY(0); }
.shell { width: min(1200px, calc(100% - 80px)); margin-inline: auto; }
.top { border-bottom: 1px solid var(--line); }
.bar { min-height: 72px; display: flex; align-items: center; justify-content: space-between; gap: 20px; }
.brand { display: inline-flex; gap: 10px; align-items: center; font-weight: 800; letter-spacing: .08em; white-space: nowrap; }
.mark { display: grid; place-items: center; color: var(--yellow); background: var(--green); border-radius: 50%; width: 33px; height: 33px; font-size: 23px; letter-spacing: 0; }
nav { display: flex; gap: clamp(18px, 4vw, 44px); font-size: .93rem; font-weight: 650; }
nav a:hover, footer a:hover { text-decoration: underline; text-underline-offset: 5px; }
.hero { display: grid; grid-template-columns: 1fr 1fr; align-items: center; gap: 36px; min-height: 460px; margin-top: 28px; padding: 44px 50px; color: var(--white); background-color: var(--green); background-image: linear-gradient(#ffffff0c 1px, transparent 1px), linear-gradient(90deg, #ffffff0c 1px, transparent 1px); background-size: 26px 26px; border-radius: 25px; overflow: hidden; }
.eyebrow { color: #f5d685; font-weight: 700; letter-spacing: .19em; margin: 0 0 14px; font-size: .85rem; }
h1 { font-size: clamp(3rem, 6.4vw, 6rem); line-height: 1.09; letter-spacing: -.075em; margin: 0; }
h1 span { color: var(--yellow); }
.intro { color: #e0ece3; font-size: 1.03rem; line-height: 1.8; margin: 23px 0; max-width: 32ch; }
.button { display: inline-flex; align-items: center; justify-content: space-between; gap: 20px; min-height: 45px; padding: 10px 17px; border-radius: 8px; font-weight: 750; white-space: nowrap; font-size: .91rem; }
.primary { background: var(--yellow); color: #223026; }
.primary:hover { background: #ffdc87; }
.hero-photo { margin: 0; min-width: 0; background: #fdf9eb; color: var(--green); padding: 9px; border-radius: 15px; box-shadow: 0 16px 32px #081d175e; }
.hero-photo img { display: block; width: 100%; height: auto; aspect-ratio: 1.48; object-fit: cover; border-radius: 8px; }
figcaption { font-size: .82rem; padding: 12px 6px 6px; letter-spacing: .06em; }
.dot { display: inline-block; width: 7px; height: 7px; margin-right: 5px; background: #3d806b; border-radius: 50%; }
.section { margin: 58px 0 0; scroll-margin-top: 20px; }
.section-head { display: flex; justify-content: space-between; align-items: end; gap: 20px; margin-bottom: 22px; }
h2 { font-size: clamp(1.75rem, 3.2vw, 2.5rem); margin: 0 0 8px; letter-spacing: -.04em; }
.section-head p { margin: 0; color: var(--muted); font-size: .94rem; line-height: 1.6; }
.filters { display: flex; gap: 4px; padding: 4px; border: 1px solid var(--line); border-radius: 10px; background: #eaece2; flex-wrap: wrap; }
.filters button { border: 0; border-radius: 7px; background: transparent; color: var(--green); padding: 7px 12px; white-space: nowrap; font-size: .86rem; }
.filters button[aria-pressed="true"] { background: var(--green); color: var(--white); }
.grid { display: grid; grid-template-columns: repeat(4, minmax(0, 1fr)); gap: 18px; align-items: start; }
.lesson, .resource { border: 1px solid var(--line); background: var(--white); border-radius: 13px; overflow: hidden; }
.lesson:hover { border-color: #99b0a0; }
.cover { overflow: hidden; background: #dce5d8; }
.cover img { display: block; width: 100%; height: auto; aspect-ratio: 1.62; object-fit: cover; }
.card-body { padding: 16px; }
.meta { margin: 0 0 7px; font-size: .76rem; color: #42705e; font-weight: 750; }
.meta span { color: #7a8d7b; margin: 0 2px; }
h3 { margin: 0; font-size: 1.12rem; line-height: 1.4; }
.project { margin: 5px 0 0; font-size: .85rem; color: #415d4f; font-weight: 700; }
.description, details p, .resource p { color: var(--muted); font-size: .88rem; line-height: 1.65; margin: 9px 0; }
.description { min-height: 4.35em; }
details { border-top: 1px solid var(--line); padding: 11px 0; }
summary { cursor: pointer; color: var(--green); font-size: .85rem; font-weight: 700; }
details p.reference { font-size: .78rem; }
.download { display: flex; align-items: center; justify-content: space-between; gap: 8px; border-radius: 7px; background: #e8eee5; color: var(--green); font-weight: 750; font-size: .84rem; padding: 8px 10px; white-space: nowrap; }
.download:hover { background: #dce9dc; }
.resources { border-top: 1px solid var(--line); padding: 35px 0 56px; }
.resource-grid { display: grid; grid-template-columns: repeat(2, minmax(0, 1fr)); gap: 12px; }
.resource { display: grid; grid-template-columns: auto 1fr auto; gap: 13px; align-items: center; padding: 13px; }
.file-type { display: grid; place-items: center; min-width: 49px; height: 42px; color: #38584c; border-radius: 7px; background: #e9eee4; font-size: .72rem; font-weight: 800; }
.resource h3 { font-size: .99rem; }
.resource p { margin: 2px 0 0; font-size: .8rem; }
footer { border-top: 1px solid var(--line); color: var(--muted); font-size: .87rem; }
@media (max-width: 1020px) {
  .grid { grid-template-columns: repeat(3, minmax(0, 1fr)); }
  .hero { padding: 34px; min-height: 380px; }
}
@media (max-width: 780px) {
  .shell { width: calc(100% - 38px); }
  .hero { grid-template-columns: 1fr; gap: 26px; padding: 28px; }
  .hero-photo img { aspect-ratio: 1.78; }
  .grid { grid-template-columns: repeat(2, minmax(0, 1fr)); gap: 12px; }
  .section-head { align-items: start; flex-direction: column; gap: 14px; }
  .resource-grid { grid-template-columns: 1fr; }
  footer .bar > span { display: none; }
}
@media (max-width: 420px) {
  .grid { grid-template-columns: 1fr; }
  .description { min-height: 0; }
  .hero { padding: 23px; }
  .bar { gap: 8px; }
  .brand { letter-spacing: 0; }
  nav { gap: 14px; }
}
@media (prefers-reduced-motion: reduce) { :root { scroll-behavior: auto; } }