:root {
  --bg: #f4f6f8;
  --bg-elev: #ffffff;
  --text: #1a1d21;
  --text-muted: #5c6570;
  --border: rgba(26, 29, 33, 0.1);
  --nav-bg: rgba(255, 255, 255, 0.86);
  --accent: #2f8f46;
  --accent-hover: #26753a;
  --chip-bg: rgba(255, 255, 255, 0.8);
  --overlay: #ffffff;
  --shadow: 0 8px 24px rgba(20, 24, 28, 0.08);
  --btn-primary-bg: #2f8f46;
  --btn-primary-text: #ffffff;
  --btn-secondary-bg: #ffffff;
  --btn-secondary-text: #1a1d21;
}

[data-theme="dark"] {
  --bg: #121416;
  --bg-elev: #1b1e22;
  --text: #e8eaed;
  --text-muted: #9aa3ad;
  --border: rgba(232, 234, 237, 0.12);
  --nav-bg: rgba(18, 20, 22, 0.86);
  --accent: #5cbc70;
  --accent-hover: #74cc86;
  --chip-bg: rgba(255, 255, 255, 0.06);
  --overlay: #1b1e22;
  --shadow: 0 8px 24px rgba(0, 0, 0, 0.32);
  --btn-primary-bg: #3aa054;
  --btn-primary-text: #ffffff;
  --btn-secondary-bg: #24282d;
  --btn-secondary-text: #e8eaed;
}

* {
  box-sizing: border-box;
  margin: 0;
  padding: 0;
}

html, body {
  min-height: 100%;
}

body {
  font-family: "Segoe UI", "PingFang SC", "Noto Sans SC", "Microsoft YaHei", sans-serif;
  background: var(--bg);
  color: var(--text);
  line-height: 1.6;
}

button, a {
  font-family: inherit;
}

.topbar {
  position: sticky;
  top: 0;
  z-index: 50;
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 16px;
  padding: 12px 28px;
  background: var(--nav-bg);
  backdrop-filter: blur(16px);
  border-bottom: 1px solid var(--border);
}

.brand {
  flex-shrink: 0;
  text-decoration: none;
  color: var(--text);
  font-weight: 700;
  font-size: 18px;
  letter-spacing: 0.6px;
}

.nav-links {
  display: flex;
  align-items: center;
  gap: 4px;
  list-style: none;
}

.nav-links a {
  text-decoration: none;
  color: var(--text-muted);
  font-size: 14px;
  font-weight: 600;
  padding: 8px 14px;
  border-radius: 8px;
}

.nav-links a:hover {
  color: var(--text);
  background: color-mix(in srgb, var(--text) 6%, transparent);
}

.nav-links a.active {
  color: var(--accent);
  background: color-mix(in srgb, var(--accent) 12%, transparent);
}

.nav-right {
  display: flex;
  align-items: center;
  gap: 10px;
  flex-shrink: 0;
}

.lang-switch {
  position: relative;
}

.lang-btn {
  display: flex;
  align-items: center;
  gap: 8px;
  background: var(--chip-bg);
  border: 1px solid var(--border);
  color: var(--text);
  padding: 7px 10px 7px 12px;
  border-radius: 999px;
  cursor: pointer;
  font-size: 13px;
  font-weight: 600;
}

.lang-btn svg {
  width: 16px;
  height: 16px;
}

.caret {
  width: 10px;
  height: 10px;
  opacity: 0.6;
}

.lang-menu {
  position: absolute;
  right: 0;
  top: calc(100% + 8px);
  min-width: 150px;
  background: var(--overlay);
  border: 1px solid var(--border);
  border-radius: 12px;
  box-shadow: var(--shadow);
  padding: 6px;
  display: none;
}

.lang-menu.open {
  display: block;
}

.lang-menu button {
  width: 100%;
  text-align: left;
  background: none;
  border: 0;
  color: var(--text);
  padding: 8px 10px;
  border-radius: 8px;
  cursor: pointer;
  font-size: 13px;
  font-weight: 600;
}

.lang-menu button:hover {
  background: color-mix(in srgb, var(--text) 6%, transparent);
}

.lang-menu button[aria-current="true"] {
  color: var(--accent);
}

.theme-switch {
  width: 52px;
  height: 30px;
  border-radius: 999px;
  border: 1px solid var(--border);
  background: var(--chip-bg);
  position: relative;
  cursor: pointer;
  padding: 0;
}

.theme-switch .knob {
  position: absolute;
  top: 3px;
  left: 3px;
  width: 22px;
  height: 22px;
  border-radius: 50%;
  background: #fff;
  box-shadow: 0 2px 6px rgba(0, 0, 0, 0.18);
  transition: transform 0.25s ease;
  display: grid;
  place-items: center;
}

[data-theme="dark"] .theme-switch .knob {
  transform: translateX(22px);
  background: #2a2f34;
}

.theme-switch .icon {
  width: 13px;
  height: 13px;
}

.menu-toggle {
  display: none;
  width: 40px;
  height: 40px;
  border-radius: 10px;
  border: 1px solid var(--border);
  background: var(--chip-bg);
  color: var(--text);
  cursor: pointer;
}

.page {
  display: none;
}

.page.active {
  display: block;
}

.hero {
  min-height: calc(100vh - 61px);
  display: flex;
  flex-direction: column;
  align-items: center;
  justify-content: center;
  text-align: center;
  padding: 48px 24px;
}

.logo-hero {
  font-size: clamp(56px, 12vw, 120px);
  font-weight: 800;
  letter-spacing: 2px;
  line-height: 1;
}

.tagline {
  margin-top: 18px;
  font-size: 15px;
  color: var(--text-muted);
}

.hero-actions {
  margin-top: 32px;
  display: flex;
  gap: 14px;
  flex-wrap: wrap;
  justify-content: center;
}

.btn {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  min-width: 168px;
  height: 48px;
  padding: 0 28px;
  border-radius: 12px;
  font-size: 15px;
  font-weight: 700;
  text-decoration: none;
  border: 1px solid transparent;
}

.btn-primary {
  background: var(--btn-primary-bg);
  color: var(--btn-primary-text);
}

.btn-primary:hover {
  background: var(--accent-hover);
}

.btn-secondary {
  background: var(--btn-secondary-bg);
  color: var(--btn-secondary-text);
  border-color: var(--border);
}

.wrap {
  width: min(960px, calc(100% - 40px));
  margin: 0 auto;
  padding: 48px 0 80px;
}

.wrap h1 {
  font-size: 28px;
  font-weight: 700;
}

@media (max-width: 860px) {
  .menu-toggle {
    display: grid;
    place-items: center;
    margin-left: auto;
  }

  .nav-right {
    margin-left: 0;
  }

  .nav-links {
    position: absolute;
    top: 61px;
    left: 0;
    right: 0;
    display: none;
    flex-direction: column;
    align-items: stretch;
    padding: 10px;
    background: var(--overlay);
    border-bottom: 1px solid var(--border);
  }

  .nav-links.open {
    display: flex;
  }

  .topbar {
    padding: 10px 16px;
  }
}