/* ========================================
   QQ Browser - 重构样式
   配色：白底 + 深灰文字 + 紫色渐变点缀
   ======================================== */

/* Reset & Base */
*, *::before, *::after {
  margin: 0;
  padding: 0;
  box-sizing: border-box;
}

:root {
  --primary: #7c3aed;
  --primary-light: #8b5cf6;
  --primary-gradient: linear-gradient(135deg, #7c3aed, #6366f1);
  --bg-white: #ffffff;
  --bg-light: #f8f7fc;
  --bg-hero: linear-gradient(160deg, #f0ecff 0%, #e8eaff 40%, #f8f7fc 100%);
  --text-dark: #1a1a2e;
  --text-body: #4a4a5a;
  --text-light: #7c7c8a;
  --border-color: #e8e6f0;
  --shadow-sm: 0 2px 8px rgba(0, 0, 0, 0.06);
  --shadow-md: 0 8px 30px rgba(0, 0, 0, 0.08);
  --shadow-lg: 0 20px 50px rgba(0, 0, 0, 0.1);
  --section-padding: 100px 0;
  --max-width: 1120px;
}

html {
  scroll-behavior: smooth;
}

body {
  font-family: -apple-system, BlinkMacSystemFont, "Segoe UI", "PingFang SC",
    "Hiragino Sans GB", "Microsoft YaHei", sans-serif;
  background: var(--bg-white);
  color: var(--text-body);
  line-height: 1.6;
  overflow-x: hidden;
}

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

img {
  max-width: 100%;
  height: auto;
  display: block;
}

/* ========================================
   Header / Navigation
   ======================================== */
.header {
  position: fixed;
  top: 0;
  left: 0;
  width: 100%;
  z-index: 1000;
  padding: 14px 40px;
  transition: background 0.3s, box-shadow 0.3s;
}

.header.scrolled {
  background: rgba(255, 255, 255, 0.92);
  backdrop-filter: blur(16px);
  -webkit-backdrop-filter: blur(16px);
  box-shadow: 0 1px 3px rgba(0, 0, 0, 0.08);
}

.header-inner {
  max-width: var(--max-width);
  margin: 0 auto;
  display: flex;
  align-items: center;
  justify-content: space-between;
}

.logo {
  display: flex;
  align-items: center;
  gap: 10px;
}

.logo img {
  height: 32px;
  width: auto;
}

.logo span {
  font-size: 17px;
  font-weight: 600;
  color: var(--text-dark);
}

.nav-links {
  display: flex;
  align-items: center;
  gap: 32px;
  list-style: none;
}

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

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

/* Buttons */
.btn-download {
  display: inline-flex;
  align-items: center;
  gap: 8px;
  padding: 10px 24px;
  background: var(--primary-gradient);
  color: #fff;
  border: none;
  border-radius: 50px;
  font-size: 14px;
  font-weight: 500;
  cursor: pointer;
  transition: box-shadow 0.3s, transform 0.2s;
  text-decoration: none;
}

.btn-download:hover {
  box-shadow: 0 4px 20px rgba(124, 58, 237, 0.35);
  transform: translateY(-1px);
}

/* 导航栏中的下载按钮 - 描边样式，适配浅色背景 */
.nav-links .btn-download {
  background: transparent;
  color: var(--primary);
  border: 1.5px solid var(--primary);
}

.nav-links .btn-download:hover {
  background: var(--primary-gradient);
  color: #fff;
  border-color: transparent;
}

.btn-download svg {
  width: 16px;
  height: 16px;
  fill: currentColor;
}

.btn-download-lg {
  padding: 16px 40px;
  font-size: 17px;
  font-weight: 600;
}

.btn-download-lg svg {
  width: 20px;
  height: 20px;
}

/* ========================================
   Hero Section
   ======================================== */
.hero {
  min-height: 520px;
  display: flex;
  flex-direction: column;
  align-items: center;
  justify-content: center;
  text-align: center;
  padding: 140px 20px 80px;
  background: var(--bg-hero);
}

.hero-title {
  font-size: 48px;
  font-weight: 700;
  line-height: 1.25;
  margin-bottom: 20px;
  color: var(--text-dark);
}

.hero-subtitle {
  font-size: 17px;
  color: var(--text-body);
  max-width: 480px;
  margin: 0 auto 40px;
  line-height: 1.7;
}

/* ========================================
   Features Section (Alternating Layout)
   ======================================== */
.features {
  padding: 20px 0;
}

.feature-block {
  padding: var(--section-padding);
}

.feature-block:nth-child(even) {
  background: var(--bg-light);
}

.feature-inner {
  max-width: var(--max-width);
  margin: 0 auto;
  padding: 0 40px;
  display: flex;
  align-items: center;
  gap: 72px;
}

.feature-block:nth-child(even) .feature-inner {
  flex-direction: row-reverse;
}

.feature-text {
  flex: 1;
  min-width: 0;
}

.feature-tag {
  display: inline-block;
  font-size: 12px;
  font-weight: 600;
  letter-spacing: 1.5px;
  color: var(--primary);
  margin-bottom: 14px;
  padding: 4px 14px;
  background: rgba(124, 58, 237, 0.08);
  border-radius: 20px;
}

.feature-text h2 {
  font-size: 32px;
  font-weight: 700;
  margin-bottom: 14px;
  color: var(--text-dark);
  line-height: 1.3;
}

.feature-text p {
  font-size: 15px;
  color: var(--text-body);
  line-height: 1.8;
  max-width: 440px;
}

.feature-image {
  flex: 1;
  min-width: 0;
  border-radius: 14px;
  overflow: hidden;
  box-shadow: var(--shadow-md);
  border: 1px solid var(--border-color);
}

.feature-image img {
  width: 100%;
  display: block;
}

/* Scroll animation */
.fade-in {
  opacity: 0;
  transform: translateY(30px);
  transition: opacity 0.6s ease, transform 0.6s ease;
}

.fade-in.visible {
  opacity: 1;
  transform: translateY(0);
}

/* ========================================
   Testimonial Section
   ======================================== */
.testimonial {
  padding: var(--section-padding);
  background: var(--bg-white);
}

.testimonial-inner {
  max-width: 680px;
  margin: 0 auto;
  padding: 0 40px;
  text-align: center;
}

.testimonial-inner h2 {
  font-size: 30px;
  font-weight: 700;
  margin-bottom: 40px;
  color: var(--text-dark);
}

.testimonial-card {
  background: var(--bg-light);
  border: 1px solid var(--border-color);
  border-radius: 14px;
  padding: 36px;
  text-align: left;
}

.testimonial-quote {
  font-size: 15px;
  color: var(--text-body);
  line-height: 1.8;
  margin-bottom: 24px;
  font-style: italic;
  padding-left: 18px;
  border-left: 3px solid var(--primary);
}

.testimonial-author {
  display: flex;
  align-items: center;
  gap: 14px;
}

.testimonial-author img {
  width: 44px;
  height: 44px;
  border-radius: 50%;
  object-fit: cover;
}

.testimonial-author-info strong {
  display: block;
  font-size: 14px;
  font-weight: 600;
  color: var(--text-dark);
}

.testimonial-author-info span {
  font-size: 13px;
  color: var(--text-light);
}

/* ========================================
   CTA Section
   ======================================== */
.cta-section {
  padding: var(--section-padding);
  text-align: center;
  background: var(--bg-light);
}

.cta-section h2 {
  font-size: 32px;
  font-weight: 700;
  margin-bottom: 14px;
  color: var(--text-dark);
}

.cta-section p {
  font-size: 15px;
  color: var(--text-body);
  margin-bottom: 32px;
}

/* ========================================
   Footer
   ======================================== */
.footer {
  padding: 36px 40px;
  background: var(--bg-white);
  border-top: 1px solid var(--border-color);
}

.footer-inner {
  max-width: var(--max-width);
  margin: 0 auto;
  display: flex;
  justify-content: space-between;
  align-items: center;
  flex-wrap: wrap;
  gap: 16px;
}

.footer-copy {
  font-size: 13px;
  color: var(--text-light);
}

.footer-links {
  display: flex;
  gap: 24px;
  list-style: none;
}

.footer-links a {
  font-size: 13px;
  color: var(--text-light);
  transition: color 0.2s;
}

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

/* ========================================
   Responsive
   ======================================== */
@media (max-width: 768px) {
  .header {
    padding: 12px 20px;
  }

  .nav-links {
    display: none;
  }

  .hero {
    padding: 120px 20px 60px;
  }

  .hero-title {
    font-size: 30px;
  }

  .hero-subtitle {
    font-size: 15px;
  }

  .feature-inner {
    flex-direction: column !important;
    gap: 36px;
    padding: 0 20px;
  }

  .feature-block {
    padding: 60px 0;
  }

  .feature-text h2 {
    font-size: 24px;
  }

  .testimonial-inner {
    padding: 0 20px;
  }

  .footer-inner {
    flex-direction: column;
    text-align: center;
  }
}