/* ===== 基础与变量 ===== */
:root {
  --bg: #0f1419;
  --bg-card: #1a2332;
  --bg-card-hover: #243044;
  --text: #e6edf3;
  --text-muted: #8b949e;
  --accent: #58a6ff;
  --accent-hover: #79b8ff;
  --border: #30363d;
  --gradient-start: #1f6feb;
  --gradient-end: #58a6ff;
  --font: 'Noto Sans SC', -apple-system, BlinkMacSystemFont, 'Segoe UI', sans-serif;
  --radius: 12px;
  --shadow: 0 8px 24px rgba(0, 0, 0, 0.35);
}

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

html {
  scroll-behavior: smooth;
}

body {
  margin: 0;
  font-family: var(--font);
  font-size: 16px;
  line-height: 1.6;
  color: var(--text);
  background: var(--bg);
  -webkit-font-smoothing: antialiased;
}

a {
  color: var(--accent);
  text-decoration: none;
}

a:hover {
  color: var(--accent-hover);
}

/* ===== 页头 ===== */
.header {
  position: sticky;
  top: 0;
  z-index: 100;
  background: rgba(15, 20, 25, 0.85);
  backdrop-filter: saturate(180%) blur(12px);
  border-bottom: 1px solid var(--border);
}

.nav {
  max-width: 1100px;
  margin: 0 auto;
  padding: 0.75rem 1.5rem;
  display: flex;
  align-items: center;
  justify-content: space-between;
}

.logo {
  display: flex;
  align-items: center;
  gap: 0.5rem;
  color: var(--text);
  font-weight: 600;
  font-size: 1.25rem;
}

.logo:hover {
  color: var(--text);
  opacity: 0.9;
}

.logo-img {
  width: 36px;
  height: 36px;
  object-fit: contain;
}

.nav-links {
  list-style: none;
  margin: 0;
  padding: 0;
  display: flex;
  gap: 1.5rem;
}

.nav-links a {
  color: var(--text-muted);
  font-weight: 500;
}

.nav-links a:hover {
  color: var(--text);
}

/* ===== 主视觉区 ===== */
.hero {
  padding: 4rem 1.5rem 5rem;
  text-align: center;
}

.hero-content {
  max-width: 640px;
  margin: 0 auto;
}

.hero-icon {
  width: 80px;
  height: 80px;
  object-fit: contain;
  margin-bottom: 1rem;
  filter: drop-shadow(0 4px 12px rgba(88, 166, 255, 0.25));
}

.hero-title {
  margin: 0 0 0.5rem;
  font-size: 2.5rem;
  font-weight: 700;
  letter-spacing: -0.02em;
  background: linear-gradient(135deg, var(--gradient-start), var(--gradient-end));
  -webkit-background-clip: text;
  -webkit-text-fill-color: transparent;
  background-clip: text;
}

.hero-subtitle {
  margin: 0 0 1rem;
  font-size: 1.25rem;
  color: var(--text-muted);
  font-weight: 500;
}

.hero-desc {
  margin: 0 0 2rem;
  color: var(--text-muted);
  font-size: 1rem;
  line-height: 1.7;
}

.cta-button {
  display: inline-block;
  padding: 0.875rem 2rem;
  font-size: 1rem;
  font-weight: 600;
  color: #fff;
  background: linear-gradient(135deg, var(--gradient-start), var(--gradient-end));
  border: none;
  border-radius: var(--radius);
  box-shadow: var(--shadow);
  cursor: pointer;
  transition: transform 0.15s ease, box-shadow 0.15s ease;
}

.cta-button:hover {
  color: #fff;
  transform: translateY(-2px);
  box-shadow: 0 12px 28px rgba(31, 111, 235, 0.4);
}

/* ===== 功能区块 ===== */
.features {
  max-width: 1100px;
  margin: 0 auto;
  padding: 4rem 1.5rem;
}

.section-title {
  margin: 0 0 2.5rem;
  font-size: 1.75rem;
  font-weight: 600;
  text-align: center;
  color: var(--text);
}

.features-grid {
  display: grid;
  grid-template-columns: repeat(auto-fill, minmax(300px, 1fr));
  gap: 1.5rem;
}

.feature-card {
  padding: 1.5rem;
  background: var(--bg-card);
  border: 1px solid var(--border);
  border-radius: var(--radius);
  transition: background 0.2s ease, border-color 0.2s ease, transform 0.2s ease;
}

.feature-card:hover {
  background: var(--bg-card-hover);
  border-color: var(--accent);
  transform: translateY(-2px);
}

.feature-icon {
  font-size: 2rem;
  margin-bottom: 0.75rem;
  line-height: 1;
}

.feature-card h3 {
  margin: 0 0 0.5rem;
  font-size: 1.1rem;
  font-weight: 600;
  color: var(--text);
}

.feature-card p {
  margin: 0;
  font-size: 0.95rem;
  color: var(--text-muted);
  line-height: 1.6;
}

/* ===== 下载区块 ===== */
.download {
  max-width: 600px;
  margin: 0 auto;
  padding: 4rem 1.5rem 5rem;
  text-align: center;
}

.download-desc {
  margin: 0 0 1.5rem;
  color: var(--text-muted);
  font-size: 0.95rem;
}

.download-card {
  display: flex;
  align-items: center;
  justify-content: space-between;
  flex-wrap: wrap;
  gap: 1rem;
  padding: 1.25rem 1.5rem;
  background: var(--bg-card);
  border: 1px solid var(--border);
  border-radius: var(--radius);
  margin-bottom: 1rem;
}

.download-info {
  display: flex;
  flex-direction: column;
  align-items: flex-start;
  gap: 0.25rem;
}

.download-label {
  font-weight: 600;
  color: var(--text);
}

.download-version {
  font-size: 0.875rem;
  color: var(--text-muted);
}

.download-button {
  padding: 0.75rem 1.5rem;
  font-weight: 600;
  color: #fff;
  background: linear-gradient(135deg, var(--gradient-start), var(--gradient-end));
  border-radius: var(--radius);
  white-space: nowrap;
  transition: transform 0.15s ease, box-shadow 0.15s ease;
}

.download-button:hover {
  color: #fff;
  transform: translateY(-1px);
  box-shadow: 0 8px 20px rgba(31, 111, 235, 0.35);
}

.download-button--disabled {
  cursor: default;
  opacity: 0.7;
  background: var(--bg-card-hover);
  color: var(--text-muted);
}

.download-button--disabled:hover {
  transform: none;
  box-shadow: none;
}

.download-note {
  margin: 0;
  font-size: 0.8rem;
  color: var(--text-muted);
}

/* ===== 页脚 ===== */
.footer {
  padding: 2rem 1.5rem;
  text-align: center;
  border-top: 1px solid var(--border);
}

.footer p {
  margin: 0;
  font-size: 0.875rem;
  color: var(--text-muted);
}

/* ===== 响应式 ===== */
@media (max-width: 640px) {
  .hero-title {
    font-size: 2rem;
  }

  .hero-subtitle {
    font-size: 1.1rem;
  }

  .download-card {
    flex-direction: column;
    align-items: stretch;
    text-align: center;
  }

  .download-info {
    align-items: center;
  }
}