:root {
  --site-ink: #142026;
  --site-muted: #66747c;
  --site-line: #dbe7e6;
  --site-bg: #f5f8f7;
  --site-panel: #ffffff;
  --site-teal: #0f766e;
  --site-mint: #dff5f0;
  --site-gold: #f3b64b;
  --site-font: ui-sans-serif, system-ui, -apple-system, Segoe UI, Roboto, Helvetica, Arial, "PingFang SC",
    "Hiragino Sans GB", "Microsoft YaHei", sans-serif;
}

* { box-sizing: border-box; }

body {
  margin: 0;
  font-family: var(--site-font);
  color: var(--site-ink);
  background: var(--site-bg);
}

.site-header {
  position: fixed;
  top: 0;
  left: 0;
  right: 0;
  z-index: 10;
  height: 68px;
  display: flex;
  align-items: center;
  justify-content: space-between;
  padding: 0 min(6vw, 76px);
  background: rgba(255, 255, 255, .92);
  border-bottom: 1px solid rgba(219, 231, 230, .9);
  backdrop-filter: blur(10px);
}

.site-brand {
  color: var(--site-ink);
  text-decoration: none;
  font-size: 20px;
  font-weight: 900;
}

.site-nav {
  display: flex;
  align-items: center;
  gap: 22px;
}

.site-nav a {
  color: var(--site-muted);
  text-decoration: none;
  font-size: 14px;
  font-weight: 700;
}

.site-account {
  display: flex;
  align-items: center;
  gap: 10px;
  min-height: 42px;
}

.account-link {
  border: 0;
  background: transparent;
  color: var(--site-teal);
  font: inherit;
  font-size: 14px;
  font-weight: 800;
  cursor: pointer;
}

.account-user {
  display: inline-flex;
  align-items: center;
  gap: 10px;
}

.account-user[hidden],
.site-account[data-auth-state="guest"] .account-user {
  display: none;
}

.account-avatar {
  width: 32px;
  height: 32px;
  display: inline-flex;
  align-items: center;
  justify-content: center;
  border-radius: 50%;
  background: var(--site-mint);
  color: var(--site-teal);
  font-size: 14px;
  font-weight: 900;
}

.account-name {
  max-width: 120px;
  overflow: hidden;
  color: var(--site-ink);
  font-size: 14px;
  font-weight: 800;
  text-overflow: ellipsis;
  white-space: nowrap;
}

.site-account[data-auth-state="user"] > .account-link,
.site-account[data-auth-state="user"] > .site-btn {
  display: none;
}

.site-account[data-auth-state="user"] .account-user {
  display: inline-flex;
}

.hero {
  min-height: 88vh;
  display: flex;
  align-items: center;
  background-size: cover;
  background-position: center;
  color: #fff;
  padding: 108px min(6vw, 76px) 80px;
}

.hero-inner {
  width: min(760px, 100%);
}

.eyebrow {
  margin: 0 0 12px;
  color: var(--site-gold);
  font-size: 13px;
  font-weight: 900;
  text-transform: uppercase;
  letter-spacing: 0;
}

.hero h1 {
  margin: 0;
  font-size: clamp(42px, 7vw, 86px);
  line-height: .98;
  letter-spacing: 0;
}

.hero-copy {
  width: min(620px, 100%);
  margin: 22px 0 0;
  color: rgba(255,255,255,.88);
  font-size: 18px;
  line-height: 1.8;
}

.hero-actions {
  display: flex;
  gap: 12px;
  flex-wrap: wrap;
  margin-top: 30px;
}

.site-btn {
  min-height: 42px;
  border: 0;
  display: inline-flex;
  align-items: center;
  justify-content: center;
  padding: 0 18px;
  border-radius: 8px;
  background: var(--site-teal);
  color: #fff;
  text-decoration: none;
  font-weight: 800;
  cursor: pointer;
}

.site-btn.ghost {
  background: rgba(255,255,255,.12);
  border: 1px solid rgba(255,255,255,.36);
}

.site-btn.small {
  min-height: 36px;
  padding: 0 14px;
  font-size: 14px;
}

.section {
  padding: 74px min(6vw, 76px);
}

.section-head {
  width: min(720px, 100%);
  margin-bottom: 30px;
}

.section h2,
.cta h2 {
  margin: 0;
  font-size: clamp(28px, 4vw, 48px);
  line-height: 1.15;
  letter-spacing: 0;
}

.section-copy {
  color: var(--site-muted);
  font-size: 16px;
  line-height: 1.8;
}

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

.feature,
.course,
.advantage {
  border: 1px solid var(--site-line);
  border-radius: 8px;
  background: var(--site-panel);
  padding: 22px;
}

.feature-icon {
  width: 36px;
  height: 36px;
  border-radius: 8px;
  background: var(--site-mint);
  border: 8px solid #fff;
  box-shadow: 0 0 0 1px var(--site-line);
  margin-bottom: 18px;
}

.feature h3,
.course h3 {
  margin: 0;
  font-size: 20px;
}

.feature p,
.course p,
.advantage p {
  color: var(--site-muted);
  line-height: 1.7;
}

.feature-sub,
.course span,
.advantage span {
  display: block;
  color: var(--site-teal);
  font-size: 13px;
  font-weight: 900;
  margin-top: 8px;
}

.split {
  display: grid;
  grid-template-columns: minmax(0, .8fr) minmax(0, 1.2fr);
  gap: 40px;
  background: #fff;
}

.course-list {
  display: grid;
  gap: 14px;
}

.advantage-row {
  display: grid;
  grid-template-columns: repeat(2, minmax(0, 1fr));
  gap: 16px;
}

.advantage strong {
  display: block;
  font-size: 20px;
}

.cta {
  margin: 0 min(6vw, 76px) 74px;
  padding: 46px;
  border-radius: 8px;
  background: var(--site-ink);
  color: #fff;
}

.cta p {
  width: min(780px, 100%);
  color: rgba(255,255,255,.78);
  line-height: 1.8;
}

.auth-modal[hidden] {
  display: none;
}

.auth-modal {
  position: fixed;
  inset: 0;
  z-index: 50;
  display: grid;
  place-items: center;
  padding: 24px;
}

.auth-backdrop {
  position: absolute;
  inset: 0;
  background: rgba(20, 32, 38, .62);
  backdrop-filter: blur(8px);
}

.auth-panel {
  position: relative;
  width: min(460px, 100%);
  max-height: calc(100vh - 48px);
  overflow: auto;
  border: 1px solid var(--site-line);
  border-radius: 8px;
  background: #fff;
  padding: 28px;
  box-shadow: 0 24px 70px rgba(20, 32, 38, .24);
}

.auth-close {
  position: absolute;
  top: 14px;
  right: 14px;
  width: 34px;
  height: 34px;
  border: 1px solid var(--site-line);
  border-radius: 8px;
  background: #fff;
  color: var(--site-muted);
  font-size: 24px;
  line-height: 1;
  cursor: pointer;
}

.auth-head h2 {
  margin: 0 0 18px;
  font-size: 28px;
  line-height: 1.2;
}

.auth-tabs {
  display: grid;
  grid-template-columns: repeat(3, 1fr);
  gap: 6px;
  padding: 4px;
  border: 1px solid var(--site-line);
  border-radius: 8px;
  background: var(--site-bg);
}

.auth-tab {
  min-height: 36px;
  border: 0;
  border-radius: 6px;
  background: transparent;
  color: var(--site-muted);
  font-weight: 800;
  cursor: pointer;
}

.auth-tab.active {
  background: #fff;
  color: var(--site-teal);
  box-shadow: 0 1px 8px rgba(20, 32, 38, .08);
}

.auth-form {
  display: none;
  margin-top: 18px;
}

.auth-form.active {
  display: grid;
  gap: 14px;
}

.auth-form label {
  display: grid;
  gap: 7px;
  color: var(--site-muted);
  font-size: 13px;
  font-weight: 800;
}

.auth-form input {
  width: 100%;
  min-height: 42px;
  border: 1px solid var(--site-line);
  border-radius: 8px;
  padding: 0 12px;
  color: var(--site-ink);
  font: inherit;
  outline: none;
}

.auth-form input:focus {
  border-color: var(--site-teal);
  box-shadow: 0 0 0 3px rgba(15, 118, 110, .12);
}

.auth-code-row {
  display: grid;
  grid-template-columns: minmax(0, 1fr) 118px;
  gap: 10px;
  align-items: end;
}

.account-code {
  min-height: 42px;
  border: 1px solid var(--site-teal);
  border-radius: 8px;
  background: #fff;
  color: var(--site-teal);
  font-weight: 800;
  cursor: pointer;
}

.account-code:disabled,
.auth-submit:disabled {
  opacity: .58;
  cursor: not-allowed;
}

.auth-submit {
  width: 100%;
  margin-top: 4px;
}

.auth-message {
  min-height: 20px;
  margin: 14px 0 0;
  color: var(--site-muted);
  font-size: 14px;
  line-height: 1.5;
}

.auth-message.error {
  color: #b42318;
}

.auth-message.success {
  color: var(--site-teal);
}

@media (max-width: 900px) {
  .site-header { position: static; height: auto; align-items: flex-start; flex-direction: column; gap: 10px; padding-top: 16px; padding-bottom: 16px; }
  .site-nav { flex-wrap: wrap; gap: 12px; }
  .site-account { width: 100%; justify-content: space-between; }
  .hero { min-height: 72vh; padding-top: 72px; }
  .feature-grid,
  .split,
  .advantage-row { grid-template-columns: 1fr; }
  .auth-code-row { grid-template-columns: 1fr; }
}