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

:root {
  --bg: #0a0a0f;
  --bg-elevated: #14141c;
  --border: rgba(255, 255, 255, 0.08);
  --text: #e8e8ed;
  --text-secondary: #9a9aa8;
  --text-tertiary: #6a6a78;
  --accent: #4f8cff;
  --accent-hover: #6a9dff;
  --radius: 14px;
  --radius-sm: 8px;
}

body {
  font-family: -apple-system, BlinkMacSystemFont, "SF Pro Display", "PingFang SC", "Helvetica Neue", sans-serif;
  background: var(--bg);
  color: var(--text);
  line-height: 1.6;
  -webkit-font-smoothing: antialiased;
}

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

/* 导航 */
.nav {
  position: sticky;
  top: 0;
  z-index: 100;
  background: rgba(10, 10, 15, 0.8);
  backdrop-filter: blur(20px);
  -webkit-backdrop-filter: blur(20px);
  border-bottom: 1px solid var(--border);
}

.nav-inner {
  max-width: 1100px;
  margin: 0 auto;
  padding: 16px 24px;
  display: flex;
  align-items: center;
  justify-content: space-between;
}

.logo {
  display: flex;
  align-items: center;
  gap: 8px;
  font-size: 18px;
  font-weight: 600;
  color: var(--accent);
}

.nav-links {
  display: flex;
  gap: 28px;
}

.nav-links a {
  font-size: 14px;
  color: var(--text-secondary);
  transition: color 0.2s;
}

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

/* Hero */
.hero {
  padding: 100px 24px 80px;
  text-align: center;
  background: radial-gradient(ellipse at 50% 0%, rgba(79, 140, 255, 0.12) 0%, transparent 60%);
}

.hero-inner {
  max-width: 720px;
  margin: 0 auto;
}

.hero h1 {
  font-size: 48px;
  font-weight: 700;
  line-height: 1.2;
  letter-spacing: -0.02em;
  margin-bottom: 20px;
}

.hero-sub {
  font-size: 17px;
  color: var(--text-secondary);
  margin-bottom: 36px;
}

.hero-buttons {
  display: flex;
  gap: 12px;
  justify-content: center;
  flex-wrap: wrap;
  margin-bottom: 20px;
}

.hero-note {
  font-size: 13px;
  color: var(--text-tertiary);
}

/* 按钮 */
.btn {
  display: inline-flex;
  align-items: center;
  gap: 8px;
  padding: 12px 22px;
  border-radius: var(--radius-sm);
  font-size: 15px;
  font-weight: 500;
  transition: all 0.2s;
  cursor: pointer;
  border: none;
}

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

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

.btn-secondary {
  background: var(--bg-elevated);
  color: var(--text);
  border: 1px solid var(--border);
}

.btn-secondary:hover {
  background: rgba(255, 255, 255, 0.06);
}

.btn-block {
  width: 100%;
  justify-content: center;
}

/* 通用 section */
.section-inner {
  max-width: 1100px;
  margin: 0 auto;
  padding: 0 24px;
}

section h2 {
  font-size: 32px;
  font-weight: 700;
  text-align: center;
  margin-bottom: 48px;
  letter-spacing: -0.01em;
}

/* 功能 */
.features {
  padding: 80px 0;
}

.feature-grid {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(300px, 1fr));
  gap: 20px;
}

.feature-card {
  background: var(--bg-elevated);
  border: 1px solid var(--border);
  border-radius: var(--radius);
  padding: 28px;
  transition: border-color 0.2s;
}

.feature-card:hover {
  border-color: rgba(79, 140, 255, 0.3);
}

.feature-icon {
  font-size: 28px;
  margin-bottom: 14px;
}

.feature-card h3 {
  font-size: 18px;
  font-weight: 600;
  margin-bottom: 8px;
}

.feature-card p {
  font-size: 14px;
  color: var(--text-secondary);
}

/* 下载 */
.download {
  padding: 80px 0;
  background: var(--bg-elevated);
}

.download-cards {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(340px, 1fr));
  gap: 24px;
}

.download-card {
  background: var(--bg);
  border: 1px solid var(--border);
  border-radius: var(--radius);
  padding: 32px;
  display: flex;
  flex-direction: column;
}

.download-badge {
  display: inline-block;
  padding: 4px 12px;
  border-radius: 20px;
  font-size: 12px;
  font-weight: 600;
  background: rgba(79, 140, 255, 0.15);
  color: var(--accent);
  margin-bottom: 16px;
  align-self: flex-start;
}

.badge-mas {
  background: rgba(255, 255, 255, 0.08);
  color: var(--text-secondary);
}

.download-card h3 {
  font-size: 22px;
  font-weight: 600;
  margin-bottom: 10px;
}

.download-card > p {
  font-size: 14px;
  color: var(--text-secondary);
  margin-bottom: 20px;
}

.download-list {
  list-style: none;
  margin-bottom: 24px;
}

.download-list li {
  font-size: 14px;
  color: var(--text-secondary);
  padding: 6px 0;
}

.download-hint {
  text-align: center;
  font-size: 12px;
  color: var(--text-tertiary);
  margin-top: 12px;
}

/* FAQ */
.faq {
  padding: 80px 0;
}

.faq-list {
  max-width: 760px;
  margin: 0 auto;
}

.faq-item {
  border-bottom: 1px solid var(--border);
  padding: 20px 0;
}

.faq-item summary {
  font-size: 16px;
  font-weight: 600;
  cursor: pointer;
  list-style: none;
  display: flex;
  justify-content: space-between;
  align-items: center;
}

.faq-item summary::-webkit-details-marker {
  display: none;
}

.faq-item summary::after {
  content: "+";
  font-size: 20px;
  color: var(--text-tertiary);
  transition: transform 0.2s;
}

.faq-item[open] summary::after {
  content: "−";
}

.faq-item p {
  margin-top: 12px;
  font-size: 14px;
  color: var(--text-secondary);
  line-height: 1.7;
}

/* Footer */
.footer {
  padding: 40px 24px;
  text-align: center;
  border-top: 1px solid var(--border);
}

.footer-inner p {
  font-size: 13px;
  color: var(--text-tertiary);
  margin-top: 4px;
}

/* 响应式 */
@media (max-width: 640px) {
  .hero {
    padding: 60px 20px 50px;
  }
  .hero h1 {
    font-size: 32px;
  }
  .hero-sub {
    font-size: 15px;
  }
  section h2 {
    font-size: 26px;
  }
  .nav-links {
    gap: 16px;
  }
}