:root {
  --bg: #0d0e12;
  --bg-soft: #14161d;
  --surface: #1a1d27;
  --text: #eceef4;
  --muted: #9aa1b2;
  --accent: #ff7a59;
  --accent2: #5b8cff;
  --line: rgba(255, 255, 255, 0.08);
  --radius: 16px;
  --maxw: 1120px;
}

* { box-sizing: border-box; }

html { scroll-behavior: smooth; }

body {
  margin: 0;
  background: var(--bg);
  color: var(--text);
  font-family: -apple-system, BlinkMacSystemFont, "Segoe UI", "PingFang SC",
    "Hiragino Sans GB", "Microsoft YaHei", Roboto, Helvetica, Arial, sans-serif;
  line-height: 1.7;
  -webkit-font-smoothing: antialiased;
}

a { color: inherit; text-decoration: none; }

/* ---------- 导航 ---------- */
.nav {
  position: fixed;
  inset: 0 0 auto 0;
  z-index: 50;
  display: flex;
  align-items: center;
  justify-content: space-between;
  padding: 14px clamp(16px, 4vw, 40px);
  background: rgba(13, 14, 18, 0.6);
  backdrop-filter: blur(12px);
  border-bottom: 1px solid var(--line);
}
.nav__brand { font-weight: 800; letter-spacing: 0.5px; font-size: 18px; }
.nav__brand span { color: var(--accent); }
.nav__links {
  display: flex;
  gap: 26px;
  list-style: none;
  margin: 0;
  padding: 0;
}
.nav__links a {
  color: var(--muted);
  font-size: 15px;
  transition: color 0.2s;
  position: relative;
}
.nav__links a:hover,
.nav__links a.active { color: var(--text); }
.nav__links a.active::after {
  content: "";
  position: absolute;
  left: 0; bottom: -6px;
  width: 100%; height: 2px;
  background: var(--accent);
  border-radius: 2px;
}
.nav__toggle {
  display: none;
  background: none;
  border: 0;
  color: var(--text);
  font-size: 22px;
  cursor: pointer;
}

/* ---------- Hero ---------- */
.hero {
  position: relative;
  min-height: 100vh;
  display: flex;
  align-items: center;
  overflow: hidden;
}
.hero__bg {
  position: absolute;
  inset: 0;
  background:
    radial-gradient(60% 60% at 20% 20%, rgba(255, 122, 89, 0.18), transparent 60%),
    radial-gradient(50% 50% at 85% 30%, rgba(91, 140, 255, 0.18), transparent 60%),
    linear-gradient(180deg, #0d0e12, #11131a);
}
.hero__bg::after {
  content: "";
  position: absolute;
  inset: 0;
  background-image:
    linear-gradient(var(--line) 1px, transparent 1px),
    linear-gradient(90deg, var(--line) 1px, transparent 1px);
  background-size: 48px 48px;
  mask-image: radial-gradient(circle at 50% 40%, #000 30%, transparent 75%);
  opacity: 0.5;
}
.hero__inner {
  position: relative;
  z-index: 1;
  max-width: var(--maxw);
  margin: 0 auto;
  padding: 0 clamp(16px, 4vw, 40px);
}
.hero__kicker {
  color: var(--accent);
  letter-spacing: 3px;
  text-transform: uppercase;
  font-size: 13px;
  margin: 0 0 12px;
}
.hero__title {
  font-size: clamp(48px, 10vw, 104px);
  line-height: 0.98;
  margin: 0;
  font-weight: 900;
}
.hero__title span {
  background: linear-gradient(90deg, var(--accent), var(--accent2));
  -webkit-background-clip: text;
  background-clip: text;
  color: transparent;
}
.hero__lead {
  margin: 22px 0 32px;
  font-size: clamp(16px, 2.4vw, 20px);
  color: var(--muted);
  max-width: 620px;
}
.hero__cta { display: flex; gap: 14px; flex-wrap: wrap; }
.hero__scroll {
  position: absolute;
  bottom: 26px; left: 50%;
  transform: translateX(-50%);
  font-size: 22px;
  color: var(--muted);
  animation: bob 1.8s ease-in-out infinite;
  z-index: 1;
}
@keyframes bob { 0%,100% { transform: translate(-50%, 0); } 50% { transform: translate(-50%, 8px); } }

/* ---------- 按钮 ---------- */
.btn {
  display: inline-block;
  padding: 12px 22px;
  border-radius: 999px;
  font-weight: 600;
  font-size: 15px;
  transition: transform 0.15s, box-shadow 0.2s, background 0.2s;
}
.btn--primary {
  background: linear-gradient(90deg, var(--accent), var(--accent2));
  color: #0d0e12;
}
.btn--primary:hover { transform: translateY(-2px); box-shadow: 0 10px 30px rgba(255, 122, 89, 0.3); }
.btn--ghost {
  border: 1px solid var(--line);
  color: var(--text);
}
.btn--ghost:hover { border-color: var(--accent); color: var(--accent); }

/* ---------- 区块 ---------- */
.section {
  max-width: var(--maxw);
  margin: 0 auto;
  padding: clamp(64px, 10vw, 120px) clamp(16px, 4vw, 40px);
}
.section__head { display: flex; align-items: baseline; gap: 16px; margin-bottom: 40px; }
.section__no {
  font-size: 14px;
  font-weight: 700;
  color: var(--accent);
  border: 1px solid var(--line);
  padding: 4px 10px;
  border-radius: 999px;
}
.section__title { font-size: clamp(28px, 5vw, 44px); margin: 0; font-weight: 800; }

/* 关于 / 作业三 通用 */
.about { display: grid; grid-template-columns: 1.1fr 1fr; gap: 40px; align-items: start; }
.about__text p { color: var(--muted); font-size: 16px; }
.about__text strong { color: var(--text); }
.about__cards { list-style: none; margin: 0; padding: 0; display: grid; gap: 16px; }
.card {
  background: var(--surface);
  border: 1px solid var(--line);
  border-radius: var(--radius);
  padding: 22px 24px;
  transition: transform 0.2s, border-color 0.2s;
}
.card:hover { transform: translateY(-4px); border-color: rgba(255, 122, 89, 0.4); }
.card__tag {
  display: inline-block;
  font-size: 12px;
  color: var(--accent);
  background: rgba(255, 122, 89, 0.12);
  padding: 3px 10px;
  border-radius: 999px;
  margin-bottom: 10px;
}
.card h3 { margin: 0 0 6px; font-size: 19px; }
.card p { margin: 0; color: var(--muted); font-size: 14px; }

/* 作品 */
.work { display: grid; grid-template-columns: 0.9fr 1.1fr; gap: 40px; align-items: center; }
.work--reverse .work__intro { order: 2; }
.work__intro p { color: var(--muted); font-size: 16px; }
.work__intro strong { color: var(--text); }
.work__points { list-style: none; padding: 0; margin: 18px 0; }
.work__points li {
  position: relative;
  padding-left: 22px;
  margin-bottom: 12px;
  color: var(--muted);
  font-size: 15px;
}
.work__points li::before {
  content: "▸";
  position: absolute; left: 0;
  color: var(--accent);
}
.work__tech {
  font-size: 13px;
  color: var(--accent2);
  background: rgba(91, 140, 255, 0.1);
  padding: 8px 12px;
  border-radius: 10px;
  display: inline-block;
  margin: 6px 0 18px;
}
code {
  font-family: "SFMono-Regular", Consolas, monospace;
  background: rgba(255, 255, 255, 0.07);
  padding: 1px 6px;
  border-radius: 5px;
  font-size: 0.9em;
  color: var(--accent);
}

.work__frames { display: grid; gap: 18px; }
.frame {
  margin: 0;
  background: #fff;
  border-radius: var(--radius);
  overflow: hidden;
  border: 1px solid var(--line);
  box-shadow: 0 18px 50px rgba(0, 0, 0, 0.35);
}
.frame figcaption {
  background: #fff;
  color: #333;
  font-size: 13px;
  font-weight: 600;
  padding: 10px 16px;
  border-bottom: 1px solid #eee;
}
.frame iframe {
  display: block;
  width: 100%;
  height: 600px;
  border: 0;
  background: #fff;
}
.frame--wide iframe { height: 620px; }

/* ---------- 页脚 ---------- */
.footer {
  border-top: 1px solid var(--line);
  padding: 28px clamp(16px, 4vw, 40px);
  background: var(--bg-soft);
}
.footer__inner {
  max-width: var(--maxw);
  margin: 0 auto;
  display: flex;
  justify-content: space-between;
  align-items: center;
  flex-wrap: wrap;
  gap: 12px;
  color: var(--muted);
  font-size: 14px;
}
.footer__links { display: flex; gap: 18px; }
.footer__links a:hover { color: var(--accent); }

/* ---------- 滚动揭示动画 ---------- */
.reveal {
  opacity: 0;
  transform: translateY(24px);
  transition: opacity 0.7s ease, transform 0.7s ease;
}
.reveal.is-visible { opacity: 1; transform: none; }

/* ---------- 响应式 ---------- */
@media (max-width: 860px) {
  .nav__toggle { display: block; }
  .nav__links {
    position: absolute;
    top: 100%; right: 0;
    flex-direction: column;
    gap: 0;
    background: rgba(20, 22, 29, 0.98);
    border: 1px solid var(--line);
    border-radius: 0 0 14px 14px;
    width: 200px;
    padding: 8px 0;
    transform: translateY(-10px);
    opacity: 0;
    pointer-events: none;
    transition: opacity 0.2s, transform 0.2s;
  }
  .nav__links.open { opacity: 1; transform: none; pointer-events: auto; }
  .nav__links li { padding: 10px 20px; }
  .about, .work { grid-template-columns: 1fr; }
  .work--reverse .work__intro { order: 0; }
  .frame iframe, .frame--wide iframe { height: 520px; }
}