:root {
  color-scheme: dark;
  --bg: #050b16;
  --panel: rgba(9, 23, 43, 0.72);
  --panel-strong: rgba(10, 31, 58, 0.9);
  --line: rgba(93, 231, 255, 0.25);
  --text: #ecf9ff;
  --muted: #9ab3c8;
  --cyan: #22e7ff;
  --green: #8cffd4;
  --violet: #7787ff;
  --yellow: #ffe66d;
  --shadow: 0 24px 80px rgba(0, 0, 0, 0.42);
}

* {
  box-sizing: border-box;
}

html {
  scroll-behavior: smooth;
}

body {
  margin: 0;
  min-width: 320px;
  background:
    radial-gradient(circle at 18% 12%, rgba(34, 231, 255, 0.2), transparent 30%),
    radial-gradient(circle at 76% 8%, rgba(119, 135, 255, 0.18), transparent 34%),
    linear-gradient(180deg, #06111f 0%, var(--bg) 42%, #030710 100%);
  color: var(--text);
  font-family:
    Inter, "PingFang SC", "Microsoft YaHei", "Noto Sans SC", Arial, sans-serif;
  line-height: 1.65;
}

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

button,
a {
  -webkit-tap-highlight-color: transparent;
}

.starfield {
  position: fixed;
  inset: 0;
  z-index: -1;
  width: 100%;
  height: 100%;
  pointer-events: none;
}

.site-header {
  position: sticky;
  top: 0;
  z-index: 20;
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 24px;
  padding: 18px clamp(18px, 5vw, 72px);
  border-bottom: 1px solid rgba(117, 229, 255, 0.15);
  background: rgba(3, 9, 19, 0.78);
  backdrop-filter: blur(18px);
}

.brand {
  display: inline-flex;
  align-items: center;
  gap: 10px;
  font-weight: 800;
  letter-spacing: 0;
}

.brand-mark {
  display: grid;
  width: 38px;
  height: 38px;
  place-items: center;
  border: 1px solid rgba(140, 255, 212, 0.55);
  border-radius: 10px;
  background:
    radial-gradient(circle, rgba(140, 255, 212, 0.32), transparent 60%),
    rgba(10, 35, 58, 0.9);
  box-shadow: 0 0 30px rgba(34, 231, 255, 0.22);
  color: var(--green);
}

.nav {
  display: flex;
  gap: clamp(14px, 2vw, 30px);
  color: #ccecff;
  font-size: 0.95rem;
}

.nav a {
  position: relative;
  padding: 6px 0;
}

.nav a::after {
  position: absolute;
  right: 0;
  bottom: 0;
  left: 0;
  height: 2px;
  background: linear-gradient(90deg, var(--cyan), var(--green));
  content: "";
  opacity: 0;
  transform: scaleX(0.3);
  transition:
    opacity 180ms ease,
    transform 180ms ease;
}

.nav a:hover::after {
  opacity: 1;
  transform: scaleX(1);
}

.header-action,
.primary-button,
.secondary-button {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  min-height: 44px;
  border-radius: 8px;
  font-weight: 800;
  transition:
    transform 180ms ease,
    border-color 180ms ease,
    background 180ms ease;
}

.header-action,
.primary-button {
  border: 1px solid rgba(140, 255, 212, 0.55);
  background: linear-gradient(135deg, rgba(34, 231, 255, 0.95), rgba(140, 255, 212, 0.95));
  color: #03101b;
  box-shadow: 0 12px 35px rgba(34, 231, 255, 0.18);
}

.header-action {
  padding: 0 18px;
  white-space: nowrap;
}

.primary-button,
.secondary-button {
  padding: 0 22px;
}

.secondary-button {
  border: 1px solid rgba(115, 221, 255, 0.35);
  background: rgba(11, 30, 55, 0.82);
  color: #d9f6ff;
}

.header-action:hover,
.primary-button:hover,
.secondary-button:hover {
  transform: translateY(-2px);
}

.hero {
  display: grid;
  grid-template-columns: minmax(0, 0.92fr) minmax(420px, 1.08fr);
  align-items: center;
  gap: clamp(28px, 4vw, 64px);
  min-height: calc(100svh - 75px);
  padding: clamp(48px, 7vw, 94px) clamp(18px, 5vw, 72px) 48px;
}

.hero-copy {
  position: relative;
  z-index: 2;
  max-width: 710px;
}

.eyebrow {
  margin: 0 0 12px;
  color: var(--green);
  font-size: 0.82rem;
  font-weight: 900;
  letter-spacing: 0.12em;
  text-transform: uppercase;
}

h1,
h2,
h3,
p {
  margin-top: 0;
}

h1 {
  margin-bottom: 22px;
  font-size: clamp(4rem, 8vw, 7.8rem);
  line-height: 0.95;
  letter-spacing: 0;
  text-shadow:
    0 0 18px rgba(34, 231, 255, 0.34),
    0 0 55px rgba(119, 135, 255, 0.28);
}

h2 {
  margin-bottom: 16px;
  font-size: clamp(2rem, 4vw, 3.45rem);
  line-height: 1.08;
  letter-spacing: 0;
}

h3 {
  margin-bottom: 10px;
  font-size: 1.12rem;
  letter-spacing: 0;
}

.hero-subtitle {
  max-width: 640px;
  margin-bottom: 30px;
  color: #c1d9ea;
  font-size: clamp(1.06rem, 2vw, 1.28rem);
}

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

.signal-strip {
  display: flex;
  flex-wrap: wrap;
  gap: 10px;
}

.signal-strip span {
  border: 1px solid rgba(128, 230, 255, 0.22);
  border-radius: 999px;
  padding: 8px 13px;
  background: rgba(8, 29, 52, 0.72);
  color: #d6f6ff;
  font-size: 0.92rem;
}

.hero-visual {
  position: relative;
  overflow: hidden;
  border: 1px solid rgba(116, 235, 255, 0.24);
  border-radius: 8px;
  background: rgba(9, 28, 51, 0.72);
  box-shadow: var(--shadow);
}

.hero-visual::before {
  position: absolute;
  inset: -2px;
  background:
    linear-gradient(115deg, transparent 0%, rgba(34, 231, 255, 0.22) 40%, transparent 52%),
    radial-gradient(circle at 72% 22%, rgba(140, 255, 212, 0.26), transparent 36%);
  content: "";
  mix-blend-mode: screen;
  pointer-events: none;
}

.hero-visual img {
  display: block;
  width: 100%;
  aspect-ratio: 16 / 9;
  object-fit: cover;
}

.stats-band {
  display: grid;
  grid-template-columns: repeat(4, 1fr);
  gap: 1px;
  margin: 0 clamp(18px, 5vw, 72px);
  overflow: hidden;
  border: 1px solid rgba(116, 235, 255, 0.18);
  border-radius: 8px;
  background: rgba(87, 210, 255, 0.16);
}

.stats-band div {
  min-height: 118px;
  padding: 24px;
  background: rgba(7, 20, 38, 0.86);
}

.stats-band strong {
  display: block;
  color: var(--cyan);
  font-size: clamp(1.65rem, 3vw, 2.55rem);
  line-height: 1.05;
}

.stats-band span {
  color: var(--muted);
}

.section,
.teacher-section,
.site-footer {
  margin: 0 auto;
  padding: clamp(70px, 9vw, 118px) clamp(18px, 5vw, 72px);
}

.section-heading {
  max-width: 850px;
  margin-bottom: 34px;
}

.section-heading p:not(.eyebrow) {
  color: var(--muted);
  font-size: 1.06rem;
}

.course-grid {
  display: grid;
  grid-template-columns: repeat(3, minmax(0, 1fr));
  gap: 18px;
}

.course-card,
.timeline-item,
.teacher-card,
.teacher-points > div,
.audience-grid > div,
.contact-grid > a,
.contact-grid > button,
.contact-grid > div {
  border: 1px solid var(--line);
  border-radius: 8px;
  background:
    linear-gradient(180deg, rgba(13, 35, 63, 0.88), rgba(5, 17, 31, 0.78)),
    radial-gradient(circle at 80% 0%, rgba(34, 231, 255, 0.13), transparent 35%);
  box-shadow: 0 16px 54px rgba(0, 0, 0, 0.2);
}

.course-card {
  position: relative;
  overflow: hidden;
  min-height: 215px;
  padding: 25px;
}

.course-card::after {
  position: absolute;
  top: 0;
  right: 24px;
  width: 1px;
  height: 100%;
  background: linear-gradient(180deg, transparent, rgba(34, 231, 255, 0.35), transparent);
  content: "";
}

.course-icon {
  display: inline-grid;
  width: 42px;
  height: 42px;
  margin-bottom: 24px;
  place-items: center;
  border: 1px solid rgba(34, 231, 255, 0.36);
  border-radius: 8px;
  color: var(--green);
  font-weight: 900;
}

.course-card p,
.timeline-item p,
.teacher-card p,
.audience-grid div,
.footer-note {
  color: var(--muted);
}

.path-section {
  background:
    linear-gradient(180deg, rgba(7, 19, 36, 0), rgba(12, 32, 59, 0.48), rgba(7, 19, 36, 0)),
    repeating-linear-gradient(90deg, transparent, transparent 72px, rgba(34, 231, 255, 0.04) 73px);
}

.timeline {
  display: grid;
  grid-template-columns: repeat(4, minmax(0, 1fr));
  gap: 16px;
}

.timeline-item {
  min-height: 230px;
  padding: 24px;
}

.timeline-item span {
  display: inline-block;
  margin-bottom: 18px;
  color: var(--yellow);
  font-weight: 900;
}

.teacher-section {
  display: grid;
  grid-template-columns: minmax(0, 1.2fr) minmax(300px, 0.8fr);
  gap: 18px;
  align-items: stretch;
}

.teacher-card {
  display: grid;
  grid-template-columns: 150px 1fr;
  gap: 28px;
  align-items: center;
  padding: clamp(26px, 4vw, 40px);
  background:
    radial-gradient(circle at 16% 50%, rgba(34, 231, 255, 0.24), transparent 28%),
    linear-gradient(135deg, rgba(13, 37, 68, 0.92), rgba(5, 15, 29, 0.88));
}

.teacher-avatar {
  display: grid;
  width: 132px;
  height: 132px;
  place-items: center;
  border: 1px solid rgba(140, 255, 212, 0.44);
  border-radius: 50%;
  background:
    radial-gradient(circle, rgba(140, 255, 212, 0.22), transparent 63%),
    rgba(5, 17, 31, 0.9);
  box-shadow:
    inset 0 0 40px rgba(34, 231, 255, 0.18),
    0 0 58px rgba(34, 231, 255, 0.18);
}

.teacher-avatar span {
  position: relative;
  width: 64px;
  height: 82px;
  border-radius: 32px 32px 18px 18px;
  background: linear-gradient(180deg, #4eeaff, #112a43 42%, #071422);
}

.teacher-avatar span::before,
.teacher-avatar span::after {
  position: absolute;
  content: "";
}

.teacher-avatar span::before {
  top: -29px;
  left: 9px;
  width: 46px;
  height: 46px;
  border-radius: 50%;
  background: #263e5d;
  box-shadow: 0 0 0 2px rgba(34, 231, 255, 0.7);
}

.teacher-avatar span::after {
  top: -35px;
  left: 7px;
  width: 50px;
  height: 20px;
  border-radius: 22px 22px 4px 4px;
  background: #06101d;
}

.teacher-points {
  display: grid;
  gap: 16px;
}

.teacher-points > div {
  padding: 24px;
}

.teacher-points strong {
  display: block;
  color: var(--cyan);
  font-size: 1.45rem;
}

.teacher-points span {
  color: var(--muted);
}

.audience-grid {
  display: grid;
  grid-template-columns: repeat(4, minmax(0, 1fr));
  gap: 16px;
}

.audience-grid > div {
  min-height: 140px;
  padding: 24px;
}

.site-footer {
  border-top: 1px solid rgba(116, 235, 255, 0.18);
  background:
    radial-gradient(circle at 15% 0%, rgba(34, 231, 255, 0.16), transparent 35%),
    #030812;
}

.contact-grid {
  display: grid;
  grid-template-columns: repeat(3, minmax(0, 1fr));
  gap: 16px;
  margin: 30px 0;
}

.contact-grid > a,
.contact-grid > button,
.contact-grid > div {
  min-height: 126px;
  padding: 24px;
  text-align: left;
}

.contact-grid > button {
  color: inherit;
  font: inherit;
  cursor: pointer;
}

.contact-grid span {
  display: block;
  margin-bottom: 8px;
  color: var(--green);
  font-size: 0.95rem;
}

.contact-grid strong {
  font-size: clamp(1.22rem, 2vw, 1.68rem);
}

.footer-note {
  margin: 0;
}

.copy-toast {
  position: fixed;
  right: 22px;
  bottom: 22px;
  z-index: 40;
  border: 1px solid rgba(140, 255, 212, 0.45);
  border-radius: 8px;
  padding: 12px 16px;
  background: rgba(4, 17, 31, 0.94);
  box-shadow: var(--shadow);
  color: #dffff5;
  opacity: 0;
  transform: translateY(12px);
  transition:
    opacity 180ms ease,
    transform 180ms ease;
}

.copy-toast.is-visible {
  opacity: 1;
  transform: translateY(0);
}

@media (max-width: 980px) {
  .site-header {
    align-items: flex-start;
    flex-wrap: wrap;
  }

  .nav {
    order: 3;
    width: 100%;
    justify-content: space-between;
  }

  .hero {
    grid-template-columns: 1fr;
    min-height: auto;
  }

  .hero-visual {
    order: -1;
  }

  .stats-band,
  .course-grid,
  .timeline,
  .teacher-section,
  .audience-grid,
  .contact-grid {
    grid-template-columns: repeat(2, minmax(0, 1fr));
  }
}

@media (max-width: 640px) {
  .site-header {
    padding: 14px 16px;
  }

  .brand {
    font-size: 0.95rem;
  }

  .header-action {
    min-height: 38px;
    padding: 0 12px;
    font-size: 0.88rem;
  }

  .nav {
    gap: 10px;
    overflow-x: auto;
    padding-bottom: 4px;
    justify-content: flex-start;
  }

  .nav a {
    flex: 0 0 auto;
  }

  h1 {
    font-size: clamp(3.1rem, 18vw, 4.5rem);
  }

  .hero {
    padding-top: 28px;
  }

  .stats-band,
  .course-grid,
  .timeline,
  .teacher-section,
  .teacher-card,
  .audience-grid,
  .contact-grid {
    grid-template-columns: 1fr;
  }

  .teacher-card {
    gap: 20px;
  }

  .stats-band {
    margin: 0 16px;
  }

  .hero-actions a {
    width: 100%;
  }
}