:root {
  --ink: #0f172a;
  --muted: #5f6f86;
  --line: #dbe3ee;
  --soft: #f6f8fb;
  --white: #ffffff;
  --orange: #f97316;
  --blue: #2563eb;
  --green: #16a34a;
  --shadow: 0 18px 45px rgba(15, 23, 42, 0.08);
}

* {
  box-sizing: border-box;
}

html {
  scroll-behavior: smooth;
}

body {
  margin: 0;
  color: var(--ink);
  background: var(--white);
  font-family: -apple-system, BlinkMacSystemFont, "Segoe UI", "PingFang SC", "Microsoft YaHei", Arial, sans-serif;
  line-height: 1.7;
}

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

button {
  font: inherit;
}

.site-header {
  position: sticky;
  top: 0;
  z-index: 20;
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 24px;
  min-height: 72px;
  padding: 12px clamp(18px, 5vw, 64px);
  border-bottom: 1px solid rgba(219, 227, 238, 0.86);
  background: rgba(255, 255, 255, 0.94);
  backdrop-filter: blur(12px);
}

.brand img {
  display: block;
  width: 148px;
  height: auto;
}

.nav {
  display: flex;
  align-items: center;
  gap: 8px;
  flex-wrap: wrap;
  justify-content: flex-end;
}

.nav-link {
  display: inline-flex;
  align-items: center;
  min-height: 40px;
  padding: 8px 13px;
  border: 0;
  color: #334155;
  background: transparent;
  font-size: 15px;
  font-weight: 700;
  border-radius: 999px;
  cursor: pointer;
}

.nav-link:hover,
.nav-link:focus-visible,
.platform-dropdown:focus-within .platform-toggle {
  outline: none;
  background: #fff7ed;
  color: #ea580c;
}

.platform-dropdown {
  position: relative;
}

.platform-toggle::after {
  content: "";
  width: 7px;
  height: 7px;
  margin-left: 7px;
  border-right: 2px solid currentColor;
  border-bottom: 2px solid currentColor;
  transform: translateY(-2px) rotate(45deg);
}

.platform-toggle[aria-expanded="true"]::after {
  transform: translateY(2px) rotate(225deg);
}

.platform-menu {
  position: absolute;
  top: calc(100% + 10px);
  left: 50%;
  z-index: 40;
  display: grid;
  grid-template-columns: repeat(2, minmax(118px, 1fr));
  gap: 8px;
  width: min(360px, calc(100vw - 32px));
  padding: 12px;
  background: #fff;
  border: 1px solid var(--line);
  border-radius: 8px;
  box-shadow: 0 20px 45px rgba(15, 23, 42, 0.16);
  transform: translateX(-50%);
}

.platform-menu[hidden] {
  display: none;
}

.platform-menu::before {
  content: "";
  position: absolute;
  top: -7px;
  left: 50%;
  width: 12px;
  height: 12px;
  background: #fff;
  border-left: 1px solid var(--line);
  border-top: 1px solid var(--line);
  transform: translateX(-50%) rotate(45deg);
}

.platform-menu a {
  position: relative;
  display: flex;
  align-items: center;
  min-height: 42px;
  padding: 9px 12px;
  color: #1e293b;
  background: #f8fafc;
  border: 1px solid #e7edf5;
  border-radius: 8px;
  font-size: 14px;
  font-weight: 800;
}

.platform-menu a:hover,
.platform-menu a:focus-visible {
  outline: none;
  color: #ea580c;
  background: #fff7ed;
  border-color: #fed7aa;
}

.hero {
  display: grid;
  grid-template-columns: minmax(0, 1.25fr) minmax(300px, 0.75fr);
  gap: 34px;
  align-items: center;
  padding: clamp(56px, 8vw, 96px) clamp(18px, 5vw, 64px);
  background:
    radial-gradient(circle at 12% 10%, rgba(249, 115, 22, 0.16), transparent 30%),
    radial-gradient(circle at 92% 0%, rgba(37, 99, 235, 0.13), transparent 28%),
    linear-gradient(180deg, #ffffff 0%, #f8fafc 100%);
  border-bottom: 1px solid var(--line);
}

.hero-inner {
  max-width: 880px;
}

.eyebrow {
  margin: 0 0 12px;
  color: var(--orange);
  font-size: 14px;
  font-weight: 900;
  letter-spacing: 0.08em;
  text-transform: uppercase;
}

h1,
h2,
h3,
h4,
p {
  overflow-wrap: anywhere;
}

h1 {
  max-width: 820px;
  margin: 0;
  font-size: clamp(42px, 6vw, 72px);
  line-height: 1.08;
  letter-spacing: 0;
}

.hero-copy {
  max-width: 820px;
  margin: 24px 0 0;
  color: #43536a;
  font-size: clamp(17px, 2vw, 20px);
}

.hero-actions {
  display: flex;
  gap: 14px;
  flex-wrap: wrap;
  margin-top: 34px;
}

.button {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  min-height: 46px;
  padding: 11px 20px;
  border-radius: 8px;
  font-weight: 800;
  border: 1px solid transparent;
}

.button.primary {
  color: #fff;
  background: var(--orange);
}

.button.secondary {
  color: #1e293b;
  background: #fff;
  border-color: var(--line);
}

.hero-panel {
  display: grid;
  gap: 16px;
  padding: 24px;
  background: rgba(255, 255, 255, 0.9);
  border: 1px solid var(--line);
  border-radius: 8px;
  box-shadow: var(--shadow);
}

.hero-panel div {
  padding: 24px;
  border-radius: 8px;
  background: #f8fafc;
  border: 1px solid #e7edf5;
}

.hero-panel strong {
  display: block;
  font-size: 44px;
  line-height: 1;
  color: var(--blue);
}

.hero-panel span {
  display: block;
  margin-top: 10px;
  color: var(--muted);
  font-weight: 800;
}

.section {
  padding: clamp(58px, 8vw, 92px) clamp(18px, 5vw, 64px);
}

.soft {
  background: var(--soft);
  border-top: 1px solid var(--line);
  border-bottom: 1px solid var(--line);
}

.section-heading {
  width: min(850px, 100%);
  margin: 0 auto 38px;
  text-align: center;
}

.section-heading h2 {
  margin: 0;
  font-size: clamp(30px, 4vw, 44px);
  line-height: 1.18;
}

.section-heading p:not(.eyebrow) {
  margin: 18px auto 0;
  color: var(--muted);
  font-size: 17px;
}

.section-heading.compact {
  margin-top: 56px;
}

.feature-grid,
.course-grid,
.campus-grid {
  display: grid;
  grid-template-columns: repeat(4, minmax(0, 1fr));
  gap: 18px;
  width: min(1180px, 100%);
  margin: 0 auto;
}

.course-grid {
  grid-template-columns: repeat(3, minmax(0, 1fr));
}

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

.campus-grid {
  grid-template-columns: repeat(3, minmax(0, 1fr));
}

.feature-grid article,
.course-card,
.campus-grid article {
  min-width: 0;
  padding: 24px;
  background: var(--white);
  border: 1px solid var(--line);
  border-radius: 8px;
  box-shadow: 0 10px 24px rgba(15, 23, 42, 0.05);
}

.feature-grid span {
  display: inline-flex;
  width: 42px;
  height: 42px;
  align-items: center;
  justify-content: center;
  color: #fff;
  background: var(--blue);
  border-radius: 8px;
  font-weight: 900;
}

.feature-grid h3,
.course-card h3,
.campus-grid h3 {
  margin: 18px 0 8px;
  font-size: 24px;
  line-height: 1.25;
}

.feature-grid p,
.course-card p,
.campus-grid p {
  margin: 0;
  color: var(--muted);
}

.course-card h4 {
  margin: 0 0 14px;
  color: #334155;
  font-size: 16px;
}

.course-tag {
  color: #ea580c !important;
  font-size: 13px;
  font-weight: 900;
}

.course-card.accent {
  border-top: 4px solid var(--orange);
}

.platform-picker {
  width: min(1040px, 100%);
  margin: 0 auto;
  display: grid;
  grid-template-columns: minmax(160px, 220px) minmax(260px, 1fr);
  align-items: center;
  gap: 16px;
  padding: 22px;
  background: #fff;
  border: 1px solid var(--line);
  border-radius: 8px;
  box-shadow: 0 10px 24px rgba(15, 23, 42, 0.05);
}

.platform-picker label {
  color: #1e293b;
  font-size: 18px;
  font-weight: 900;
}

.select-wrap {
  position: relative;
}

.select-wrap::after {
  content: "";
  position: absolute;
  right: 18px;
  top: 50%;
  width: 10px;
  height: 10px;
  border-right: 2px solid #64748b;
  border-bottom: 2px solid #64748b;
  transform: translateY(-65%) rotate(45deg);
  pointer-events: none;
}

.select-wrap select {
  width: 100%;
  min-height: 52px;
  appearance: none;
  padding: 0 48px 0 16px;
  border: 1px solid var(--line);
  border-radius: 8px;
  background: #f8fafc;
  color: #1e293b;
  font: inherit;
  font-weight: 800;
  cursor: pointer;
}

.select-wrap select:hover,
.select-wrap select:focus {
  outline: none;
  border-color: #93c5fd;
  background: #eff6ff;
}

.faculty-list {
  display: flex;
  flex-wrap: wrap;
  gap: 12px;
  width: min(980px, 100%);
  margin: 0 auto;
  justify-content: center;
}

.faculty-list span {
  padding: 10px 16px;
  background: #fff;
  border: 1px solid var(--line);
  border-radius: 8px;
  color: #334155;
  font-weight: 800;
}

.contact {
  background:
    linear-gradient(rgba(15, 23, 42, 0.88), rgba(15, 23, 42, 0.88)),
    radial-gradient(circle at 20% 10%, rgba(249, 115, 22, 0.45), transparent 26%),
    #0f172a;
  color: #fff;
}

.contact .section-heading p:not(.eyebrow),
.contact .campus-grid p {
  color: #cbd5e1;
}

.contact .campus-grid article {
  background: rgba(255, 255, 255, 0.08);
  border-color: rgba(255, 255, 255, 0.18);
}

.footer {
  display: flex;
  align-items: center;
  justify-content: center;
  gap: 14px;
  flex-wrap: wrap;
  padding: 24px 18px;
  color: #64748b;
  border-top: 1px solid var(--line);
  background: #fff;
}

.footer p {
  margin: 0;
}

.footer a {
  color: #475569;
}

@media (max-width: 1000px) {
  .hero,
  .feature-grid,
  .course-grid,
  .course-grid.four,
  .campus-grid,
  .platform-picker {
    grid-template-columns: repeat(2, minmax(0, 1fr));
  }
}

@media (max-width: 720px) {
  .site-header {
    position: static;
    align-items: flex-start;
    flex-direction: column;
  }

  .nav {
    justify-content: flex-start;
  }

  .platform-dropdown {
    width: 100%;
  }

  .platform-menu {
    left: 0;
    grid-template-columns: 1fr;
    width: min(320px, calc(100vw - 36px));
    transform: none;
  }

  .platform-menu::before {
    left: 28px;
  }

  .hero,
  .feature-grid,
  .course-grid,
  .course-grid.four,
  .campus-grid,
  .platform-picker {
    grid-template-columns: 1fr;
  }

  .hero {
    padding-top: 46px;
  }

  .hero-panel {
    padding: 16px;
  }

  .feature-grid article,
  .course-card,
  .campus-grid article {
    padding: 20px;
  }
}