/* ==========================================================================
   biubiu云官网落地页 - 主样式表 (css/style.css)
   ========================================================================== */

:root {
  --bg-primary: #0a0f1d;
  --bg-secondary: #121a2d;
  --bg-card: rgba(22, 32, 54, 0.7);
  --bg-card-hover: rgba(30, 44, 74, 0.85);
  
  --primary-color: #00e5ff;
  --primary-glow: rgba(0, 229, 255, 0.4);
  --secondary-color: #00ff88;
  --accent-color: #7000ff;
  
  --text-main: #f0f6fc;
  --text-muted: #8b949e;
  --text-sub: #c9d1d9;
  
  --border-color: rgba(255, 255, 255, 0.1);
  --border-glow: rgba(0, 229, 255, 0.3);
  
  --font-family: -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, "Helvetica Neue", Arial, "Noto Sans", sans-serif;
  --max-width: 1200px;
  --radius-sm: 8px;
  --radius-md: 14px;
  --radius-lg: 20px;
  --transition: all 0.3s cubic-bezier(0.4, 0, 0.2, 1);
}

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

html {
  scroll-behavior: smooth;
  font-size: 16px;
}

body {
  background-color: var(--bg-primary);
  color: var(--text-main);
  font-family: var(--font-family);
  line-height: 1.6;
  overflow-x: hidden;
  background-image: 
    radial-gradient(circle at 15% 20%, rgba(0, 229, 255, 0.08) 0%, transparent 45%),
    radial-gradient(circle at 85% 70%, rgba(112, 0, 255, 0.08) 0%, transparent 45%);
  background-attachment: fixed;
}

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

a:hover {
  color: #66efff;
}

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

/* Container */
.container {
  width: 100%;
  max-width: var(--max-width);
  margin: 0 auto;
  padding: 0 20px;
}

/* Header & Nav */
.site-header {
  position: fixed;
  top: 0;
  left: 0;
  width: 100%;
  z-index: 1000;
  background: rgba(10, 15, 29, 0.85);
  backdrop-filter: blur(12px);
  border-bottom: 1px solid var(--border-color);
  padding: 15px 0;
  transition: var(--transition);
}

.nav-container {
  display: flex;
  justify-content: space-between;
  align-items: center;
}

.brand-logo {
  display: flex;
  align-items: center;
  gap: 12px;
  font-size: 1.4rem;
  font-weight: 700;
  color: #fff;
}

.brand-logo img {
  width: 38px;
  height: 38px;
  border-radius: var(--radius-sm);
  box-shadow: 0 0 12px var(--primary-glow);
}

.brand-logo .tag {
  font-size: 0.75rem;
  background: linear-gradient(135deg, #00c6ff, #0072ff);
  padding: 2px 8px;
  border-radius: 20px;
  margin-left: 6px;
  font-weight: 500;
}

.nav-links {
  display: flex;
  align-items: center;
  gap: 25px;
  list-style: none;
}

.nav-links a {
  color: var(--text-sub);
  font-size: 0.95rem;
  font-weight: 500;
}

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

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

/* Buttons */
.btn {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  gap: 8px;
  padding: 10px 22px;
  border-radius: var(--radius-sm);
  font-size: 0.95rem;
  font-weight: 600;
  cursor: pointer;
  border: none;
  transition: var(--transition);
}

.btn-primary {
  background: linear-gradient(135deg, var(--primary-color), #00a8ff);
  color: #040914;
  box-shadow: 0 4px 15px var(--primary-glow);
}

.btn-primary:hover {
  transform: translateY(-2px);
  box-shadow: 0 6px 20px rgba(0, 229, 255, 0.6);
  color: #000;
}

.btn-outline {
  background: rgba(255, 255, 255, 0.05);
  color: var(--primary-color);
  border: 1px solid var(--border-glow);
}

.btn-outline:hover {
  background: rgba(0, 229, 255, 0.15);
  border-color: var(--primary-color);
  color: #fff;
}

.btn-recommend {
  background: linear-gradient(135deg, #00ff88, #00b359);
  color: #002b13;
  box-shadow: 0 4px 15px rgba(0, 255, 136, 0.3);
}

.btn-recommend:hover {
  transform: translateY(-2px);
  box-shadow: 0 6px 20px rgba(0, 255, 136, 0.5);
  color: #000;
}

/* Hero Section */
.hero-section {
  padding: 160px 0 90px;
  text-align: center;
  position: relative;
}

.badge-tag {
  display: inline-flex;
  align-items: center;
  gap: 8px;
  padding: 6px 16px;
  background: rgba(0, 229, 255, 0.1);
  border: 1px solid var(--border-glow);
  border-radius: 30px;
  color: var(--primary-color);
  font-size: 0.88rem;
  margin-bottom: 25px;
}

.hero-title {
  font-size: 3.2rem;
  font-weight: 800;
  line-height: 1.25;
  margin-bottom: 20px;
  background: linear-gradient(135deg, #ffffff 30%, var(--primary-color) 70%, var(--secondary-color) 100%);
  -webkit-background-clip: text;
  -webkit-text-fill-color: transparent;
}

.hero-subtitle {
  font-size: 1.25rem;
  color: var(--text-sub);
  max-width: 780px;
  margin: 0 auto 35px;
}

.hero-actions {
  display: flex;
  justify-content: center;
  align-items: center;
  gap: 16px;
  flex-wrap: wrap;
}

.hero-stats {
  display: flex;
  justify-content: center;
  gap: 40px;
  margin-top: 60px;
  padding-top: 40px;
  border-top: 1px solid var(--border-color);
}

.stat-item h3 {
  font-size: 2.2rem;
  color: var(--primary-color);
  font-weight: 700;
}

.stat-item p {
  color: var(--text-muted);
  font-size: 0.9rem;
}

/* Features Grid */
.section-title {
  text-align: center;
  margin-bottom: 50px;
}

.section-title h2 {
  font-size: 2.2rem;
  margin-bottom: 12px;
  color: #fff;
}

.section-title p {
  color: var(--text-muted);
  font-size: 1.05rem;
}

.features-grid {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(280px, 1fr));
  gap: 25px;
  margin-bottom: 90px;
}

.feature-card {
  background: var(--bg-card);
  border: 1px solid var(--border-color);
  border-radius: var(--radius-md);
  padding: 30px;
  transition: var(--transition);
}

.feature-card:hover {
  background: var(--bg-card-hover);
  border-color: var(--border-glow);
  transform: translateY(-5px);
  box-shadow: 0 10px 30px rgba(0, 0, 0, 0.4);
}

.feature-icon {
  width: 50px;
  height: 50px;
  border-radius: var(--radius-sm);
  background: rgba(0, 229, 255, 0.1);
  display: flex;
  align-items: center;
  justify-content: center;
  font-size: 1.6rem;
  color: var(--primary-color);
  margin-bottom: 20px;
}

.feature-card h3 {
  font-size: 1.25rem;
  margin-bottom: 10px;
  color: #fff;
}

.feature-card p {
  color: var(--text-muted);
  font-size: 0.95rem;
}

/* Pricing Section */
.pricing-section {
  padding: 80px 0;
  background: rgba(18, 26, 45, 0.5);
}

.pricing-grid {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(260px, 1fr));
  gap: 25px;
}

.price-card {
  background: var(--bg-card);
  border: 1px solid var(--border-color);
  border-radius: var(--radius-lg);
  padding: 35px 25px;
  text-align: center;
  position: relative;
  transition: var(--transition);
}

.price-card.popular {
  border-color: var(--primary-color);
  box-shadow: 0 0 25px rgba(0, 229, 255, 0.2);
  background: rgba(22, 35, 62, 0.85);
}

.popular-badge {
  position: absolute;
  top: -14px;
  left: 50%;
  transform: translateX(-50%);
  background: linear-gradient(135deg, var(--primary-color), var(--accent-color));
  color: #fff;
  font-size: 0.75rem;
  font-weight: 700;
  padding: 4px 16px;
  border-radius: 20px;
  letter-spacing: 1px;
}

.price-card h3 {
  font-size: 1.4rem;
  color: #fff;
  margin-bottom: 15px;
}

.price-amount {
  font-size: 2.8rem;
  font-weight: 800;
  color: var(--primary-color);
  margin-bottom: 5px;
}

.price-amount span {
  font-size: 1rem;
  color: var(--text-muted);
  font-weight: 400;
}

.price-desc {
  color: var(--text-muted);
  font-size: 0.88rem;
  margin-bottom: 25px;
}

.price-features {
  list-style: none;
  margin-bottom: 30px;
  text-align: left;
}

.price-features li {
  padding: 8px 0;
  color: var(--text-sub);
  font-size: 0.92rem;
  display: flex;
  align-items: center;
  gap: 8px;
}

.price-features li::before {
  content: "✓";
  color: var(--secondary-color);
  font-weight: bold;
}

/* Articles Section */
.articles-section {
  padding: 90px 0;
}

.articles-grid {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(320px, 1fr));
  gap: 25px;
}

.article-card {
  background: var(--bg-card);
  border: 1px solid var(--border-color);
  border-radius: var(--radius-md);
  padding: 25px;
  transition: var(--transition);
  display: flex;
  flex-direction: column;
}

.article-card:hover {
  border-color: var(--border-glow);
  transform: translateY(-4px);
}

.article-tag {
  font-size: 0.75rem;
  color: var(--primary-color);
  text-transform: uppercase;
  letter-spacing: 1px;
  margin-bottom: 10px;
}

.article-card h3 {
  font-size: 1.2rem;
  margin-bottom: 12px;
  color: #fff;
  line-height: 1.4;
}

.article-card p {
  color: var(--text-muted);
  font-size: 0.92rem;
  margin-bottom: 20px;
  flex-grow: 1;
}

.article-link {
  font-size: 0.9rem;
  font-weight: 600;
  display: inline-flex;
  align-items: center;
  gap: 6px;
}

/* Testimonials Section */
.testimonials-section {
  padding: 90px 0;
  background: rgba(18, 26, 45, 0.4);
}

.testimonials-grid {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(280px, 1fr));
  gap: 25px;
}

.testimonial-card {
  background: var(--bg-card);
  border: 1px solid var(--border-color);
  border-radius: var(--radius-md);
  padding: 25px;
}

.user-info {
  display: flex;
  align-items: center;
  gap: 15px;
  margin-bottom: 15px;
}

.user-avatar {
  width: 48px;
  height: 48px;
  border-radius: 50%;
  background: linear-gradient(135deg, var(--primary-color), var(--accent-color));
  display: flex;
  align-items: center;
  justify-content: center;
  font-weight: bold;
  color: #fff;
  font-size: 1.1rem;
}

.user-name h4 {
  color: #fff;
  font-size: 1rem;
}

.user-name p {
  color: var(--text-muted);
  font-size: 0.8rem;
}

.rating {
  color: #ffb703;
  margin-bottom: 12px;
  font-size: 0.9rem;
}

.testimonial-card p {
  color: var(--text-sub);
  font-size: 0.92rem;
}

/* FAQ Section */
.faq-section {
  padding: 90px 0;
}

.faq-list {
  max-width: 850px;
  margin: 0 auto;
}

.faq-item {
  background: var(--bg-card);
  border: 1px solid var(--border-color);
  border-radius: var(--radius-sm);
  margin-bottom: 15px;
  overflow: hidden;
}

.faq-question {
  padding: 20px 25px;
  cursor: pointer;
  display: flex;
  justify-content: space-between;
  align-items: center;
  font-size: 1.1rem;
  font-weight: 600;
  color: #fff;
}

.faq-answer {
  padding: 0 25px 20px;
  color: var(--text-muted);
  font-size: 0.95rem;
  display: none;
  line-height: 1.7;
}

.faq-item.active .faq-answer {
  display: block;
}

.faq-item.active .faq-toggle {
  transform: rotate(180deg);
  color: var(--primary-color);
}

/* Article Detail Layout */
.article-page {
  padding: 140px 0 80px;
}

.article-header {
  margin-bottom: 40px;
  text-align: center;
}

.article-header h1 {
  font-size: 2.4rem;
  color: #fff;
  margin-bottom: 15px;
  line-height: 1.3;
}

.article-meta {
  color: var(--text-muted);
  font-size: 0.9rem;
  display: flex;
  justify-content: center;
  gap: 20px;
}

.article-body {
  max-width: 860px;
  margin: 0 auto;
  background: var(--bg-card);
  border: 1px solid var(--border-color);
  border-radius: var(--radius-lg);
  padding: 45px;
  color: var(--text-sub);
  font-size: 1.05rem;
  line-height: 1.85;
}

.article-body h2 {
  font-size: 1.6rem;
  color: #fff;
  margin: 35px 0 15px;
  border-left: 4px solid var(--primary-color);
  padding-left: 12px;
}

.article-body h3 {
  font-size: 1.3rem;
  color: #fff;
  margin: 25px 0 12px;
}

.article-body p {
  margin-bottom: 20px;
}

.article-body ul, .article-body ol {
  margin-bottom: 20px;
  padding-left: 25px;
}

.article-body li {
  margin-bottom: 8px;
}

.article-cta {
  background: linear-gradient(135deg, rgba(0, 229, 255, 0.1), rgba(112, 0, 255, 0.1));
  border: 1px solid var(--border-glow);
  border-radius: var(--radius-md);
  padding: 30px;
  text-align: center;
  margin: 40px 0;
}

.article-cta h3 {
  color: #fff;
  font-size: 1.4rem;
  margin-bottom: 10px;
}

.internal-links-box {
  margin-top: 50px;
  padding-top: 30px;
  border-top: 1px solid var(--border-color);
}

.internal-links-box h4 {
  color: #fff;
  margin-bottom: 15px;
}

.internal-links-grid {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(250px, 1fr));
  gap: 12px;
  list-style: none;
}

.internal-links-grid a {
  display: block;
  padding: 10px 14px;
  background: rgba(255, 255, 255, 0.03);
  border: 1px solid var(--border-color);
  border-radius: var(--radius-sm);
  font-size: 0.9rem;
}

.internal-links-grid a:hover {
  background: rgba(0, 229, 255, 0.1);
  border-color: var(--primary-color);
}

/* Footer Section */
footer {
  background: #060912;
  border-top: 1px solid var(--border-color);
  padding: 50px 0 30px;
  text-align: center;
}

.footer-content {
  display: flex;
  flex-direction: column;
  align-items: center;
  gap: 25px;
  max-width: var(--max-width);
  margin: 0 auto;
  padding: 0 20px;
}

.footer-links {
  display: flex;
  gap: 20px;
  list-style: none;
  flex-wrap: wrap;
  justify-content: center;
}

.footer-links a {
  color: var(--text-muted);
  font-size: 0.9rem;
}

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

/* PBN Friendly Links Section */
.friendly-links-section {
  display: flex;
  align-items: center;
  justify-content: center;
  gap: 15px;
  padding: 12px 25px;
  background: rgba(255, 255, 255, 0.02);
  border: 1px solid rgba(255, 255, 255, 0.05);
  border-radius: 30px;
  margin-top: 10px;
}

.friendly-links-title {
  font-size: 0.8rem;
  color: var(--text-muted);
}

.friendly-links-list {
  display: flex;
  align-items: center;
  gap: 15px;
}

.friendly-link-item {
  font-size: 0.82rem;
  color: #7a8599;
  transition: var(--transition);
}

.friendly-link-item:hover {
  color: var(--primary-color);
  text-decoration: underline;
}

.copyright {
  color: var(--text-muted);
  font-size: 0.85rem;
}

/* Responsive */
@media (max-width: 768px) {
  .hero-title {
    font-size: 2.2rem;
  }
  
  .nav-links {
    display: none;
  }
  
  .hero-stats {
    flex-wrap: wrap;
    gap: 20px;
  }
  
  .article-body {
    padding: 25px 20px;
  }
}