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

:root {
  --bg: #ffffff;
  --bg2: #f5f5f7;
  --surface: #ffffff;
  --surface2: #f5f5f7;
  --border: transparent;
  --border2: transparent;
  --text: #1d1d1f;
  --text-dim: #6e6e73;
  --text-mute: #86868b;
  --accent: #0071e3;
  --accent-hover: #0066cc;
  --radius: 16px;
  --radius-lg: 22px;
  --shadow: 0 30px 80px rgba(0, 0, 0, 0.12);
  --shadow2: 0 14px 40px rgba(0, 0, 0, 0.08);
  --ring: 0 0 0 4px rgba(0, 113, 227, 0.18);
  --font-body: system-ui, -apple-system, BlinkMacSystemFont, "SF Pro Text", "SF Pro Display", "Helvetica Neue",
    "PingFang SC", "Hiragino Sans GB", "Microsoft YaHei", sans-serif;
  --font-display: system-ui, -apple-system, BlinkMacSystemFont, "SF Pro Display", "Helvetica Neue", sans-serif;
}

body {
  font-family: var(--font-body);
  background: var(--bg);
  color: var(--text);
  line-height: 1.6;
  -webkit-font-smoothing: antialiased;
  -moz-osx-font-smoothing: grayscale;
}

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

.container {
  max-width: 1040px;
  margin: 0 auto;
  padding: 0 24px;
}

.topbar {
  position: sticky;
  top: 0;
  z-index: 20;
  background: rgba(255, 255, 255, 0.78);
  border-bottom: 0;
  backdrop-filter: blur(10px);
  box-shadow: 0 1px 0 rgba(0, 0, 0, 0.06);
}

.topbar-inner {
  height: 64px;
  display: flex;
  align-items: center;
  justify-content: space-between;
}

.brand {
  display: inline-flex;
  align-items: center;
  gap: 10px;
  font-weight: 700;
  letter-spacing: -0.02em;
}

.brand-mark {
  width: 28px;
  height: 28px;
  border-radius: 10px;
  background: radial-gradient(120% 120% at 30% 10%, rgba(0, 113, 227, 1), rgba(0, 102, 204, 1));
  box-shadow: 0 14px 28px rgba(0, 113, 227, 0.18);
}

.nav {
  display: flex;
  gap: 14px;
  align-items: center;
  color: var(--text-dim);
  font-size: 13px;
}

.nav a {
  padding: 8px 10px;
  border-radius: 10px;
  transition: background 160ms ease, color 160ms ease;
}

.nav a:hover {
  background: rgba(0, 0, 0, 0.04);
  color: var(--text);
}

.nav-right {
  display: flex;
  gap: 12px;
  align-items: center;
}

.lang {
  padding: 8px 10px;
  border-radius: 10px;
  border: 0;
  background: rgba(0, 0, 0, 0.04);
  color: var(--text-dim);
  font-size: 13px;
  transition: background 160ms ease, color 160ms ease, transform 160ms ease;
}

.lang:hover {
  background: rgba(0, 0, 0, 0.06);
  color: var(--text);
  transform: translateY(-1px);
}

.button {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  gap: 8px;
  padding: 12px 18px;
  border-radius: 999px;
  border: 0;
  background: var(--accent);
  color: #fff;
  font-weight: 600;
  font-size: 14px;
  letter-spacing: -0.01em;
  transition: background 160ms ease, transform 160ms ease;
}

.button:hover {
  transform: translateY(-1px);
  background: var(--accent-hover);
}

.button:active {
  transform: translateY(0);
  filter: brightness(0.98);
}

.button.secondary {
  background: rgba(0, 0, 0, 0.04);
  color: var(--text);
}

.button.secondary:hover {
  background: rgba(0, 0, 0, 0.06);
  color: var(--text);
}

.link {
  color: var(--accent);
  font-weight: 600;
  font-size: 14px;
  letter-spacing: -0.01em;
  transition: color 160ms ease;
}

.link:hover {
  color: var(--accent-hover);
}

:focus-visible {
  outline: none;
  box-shadow: var(--ring);
  border-radius: 12px;
}