:root {
  --primary-color: #0f766e;
  --primary-hover: #115e59;
  --bg-color: #f8fafc;
  --text-color: #0f172a;
  --text-muted: #64748b;
  --card-bg: #ffffff;
  --border-color: #e2e8f0;
  --max-width: 1100px;
}

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

body {
  font-family: -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, Helvetica, Arial, sans-serif;
  background-color: var(--bg-color);
  color: var(--text-color);
  line-height: 1.7;
}

.container {
  max-width: var(--max-width);
  margin: 0 auto;
  padding: 0 1.5rem;
}

/* Header Navbar */
header {
  background: #ffffff;
  border-bottom: 1px solid var(--border-color);
  position: sticky;
  top: 0;
  z-index: 100;
}

.navbar {
  display: flex;
  justify-content: space-between;
  align-items: center;
  height: 70px;
}

.nav-left {
  display: flex;
  align-items: center;
  gap: 2rem;
}

.logo-container {
  display: flex;
  align-items: center;
  gap: 0.75rem;
  text-decoration: none;
  font-weight: 700;
  font-size: 1.25rem;
  color: var(--text-color);
}

.logo-img {
  width: 36px;
  height: 36px;
  background: var(--primary-color);
  border-radius: 8px;
  display: flex;
  align-items: center;
  justify-content: center;
  color: #fff;
  font-weight: bold;
}

.nav-menu {
  display: flex;
  gap: 1.5rem;
  list-style: none;
}

.nav-menu a {
  text-decoration: none;
  color: var(--text-muted);
  font-weight: 500;
  transition: color 0.2s;
}

.nav-menu a:hover,
.nav-menu a.active {
  color: var(--primary-color);
}

.btn-download {
  background-color: var(--primary-color);
  color: #ffffff;
  padding: 0.6rem 1.2rem;
  border-radius: 6px;
  text-decoration: none;
  font-weight: 600;
  transition: background-color 0.2s;
  white-space: nowrap;
  display: inline-block;
}

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

/* Hero Section */
.hero {
  padding: 5rem 0 4rem;
  text-align: center;
  background: #ffffff;
  border-bottom: 1px solid var(--border-color);
}

.hero h1 {
  font-size: 2.8rem;
  margin-bottom: 1.2rem;
  letter-spacing: -0.02em;
}

.hero p {
  font-size: 1.25rem;
  color: var(--text-muted);
  max-width: 680px;
  margin: 0 auto 2.5rem;
}

/* Features Grid (核心卖点) */
.features-section {
  padding: 4rem 0;
}

.section-title {
  text-align: center;
  font-size: 2rem;
  margin-bottom: 3rem;
}

.features-grid {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(280px, 1fr));
  gap: 2rem;
}

.feature-card {
  background: var(--card-bg);
  padding: 2rem;
  border-radius: 12px;
  border: 1px solid var(--border-color);
}

.feature-card h3 {
  font-size: 1.3rem;
  margin-bottom: 0.75rem;
  color: var(--primary-color);
}

.feature-card p {
  color: var(--text-muted);
  font-size: 0.98rem;
}

/* How it works */
.how-it-works {
  background: #ffffff;
  padding: 4rem 0;
  border-top: 1px solid var(--border-color);
  border-bottom: 1px solid var(--border-color);
}

.steps-grid {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(250px, 1fr));
  gap: 2rem;
  margin-top: 2rem;
}

.step-item {
  text-align: center;
}

.step-num {
  width: 45px;
  height: 45px;
  background: var(--bg-color);
  color: var(--primary-color);
  border: 2px solid var(--primary-color);
  border-radius: 50%;
  display: flex;
  align-items: center;
  justify-content: center;
  font-weight: 700;
  margin: 0 auto 1rem;
}

/* Pure Text Article List */
.text-list {
  display: flex;
  flex-direction: column;
  gap: 1.5rem;
  margin: 3rem 0;
}

.text-card {
  background: var(--card-bg);
  border: 1px solid var(--border-color);
  border-radius: 10px;
  padding: 1.8rem;
  transition: border-color 0.2s;
}

.text-card:hover {
  border-color: var(--primary-color);
}

.text-card h2 {
  font-size: 1.35rem;
  margin-bottom: 0.6rem;
}

.text-card h2 a {
  color: var(--text-color);
  text-decoration: none;
}

.text-card h2 a:hover {
  color: var(--primary-color);
}

.text-card p {
  color: var(--text-muted);
  font-size: 1rem;
  margin-bottom: 1rem;
}

.link-more {
  color: var(--primary-color);
  font-weight: 600;
  text-decoration: none;
}

/* Content Box (Article Detail & Privacy) */
.content-box {
  background: var(--card-bg);
  padding: 3rem;
  margin: 3rem auto;
  border-radius: 12px;
  border: 1px solid var(--border-color);
  max-width: 850px;
}

.content-box h1 {
  font-size: 2.2rem;
  margin-bottom: 1.5rem;
  line-height: 1.3;
}

.content-box h2 {
  font-size: 1.4rem;
  margin: 2rem 0 0.8rem;
  color: var(--text-color);
}

.content-box h3 {
  font-size: 1.15rem;
  margin: 1.5rem 0 0.5rem;
}

.content-box p {
  margin-bottom: 1.2rem;
  color: #334155;
  font-size: 1.05rem;
}

.content-box ul, .content-box ol {
  margin: 0 0 1.5rem 1.5rem;
  color: #334155;
}

.content-box li {
  margin-bottom: 0.5rem;
}

.content-box blockquote {
  border-left: 4px solid var(--primary-color);
  padding-left: 1rem;
  margin: 1.5rem 0;
  color: var(--text-muted);
  font-style: italic;
  background: var(--bg-color);
  padding: 1rem;
  border-radius: 0 8px 8px 0;
}

/* Footer */
footer {
  text-align: center;
  padding: 2.5rem 0;
  border-top: 1px solid var(--border-color);
  color: var(--text-muted);
  font-size: 0.9rem;
  background: #ffffff;
}

/* Mobile Responsive */
@media (max-width: 768px) {
  .navbar {
    flex-direction: column;
    height: auto;
    padding: 1rem 0;
    gap: 1rem;
  }
  
  .nav-left {
    flex-direction: column;
    gap: 1rem;
  }
  
  .nav-menu {
    gap: 1rem;
  }

  .hero h1 {
    font-size: 2rem;
  }

  .content-box {
    padding: 1.5rem;
  }
}
/* App Screenshot Mockups */
.phone-mockup {
  width: 100%;
  max-width: 220px; /* 从 280px 缩小 */
  aspect-ratio: 9/19;
  background: #cbd5e1;
  border-radius: 28px; /* 适配缩小的尺寸 */
  border: 8px solid #1e293b; /* 边框等比缩小 */
  margin: 0 auto 1.2rem;
  display: flex;
  align-items: center;
  justify-content: center;
  text-align: center;
  color: #475569;
  font-size: 0.85rem;
  font-weight: 600;
  box-shadow: 0 15px 30px rgba(0,0,0,0.1);
  overflow: hidden;
  position: relative;
}

.phone-mockup span {
  padding: 0.8rem;
}