/* 
  Kuku Cloud (酷酷云) - Core Design System
  Clean, Professional, Cloud-Themed
*/

:root {
  --primary: #0066FF;
  --primary-hover: #0052CC;
  --secondary: #00C2FF;
  --bg-main: #f8fafc;
  --bg-card: #ffffff;
  --text-main: #1e293b;
  --text-muted: #64748b;
  --accent: #eff6ff;
  --border: #e2e8f0;
  --shadow: 0 10px 15px -3px rgba(0, 0, 0, 0.1), 0 4px 6px -2px rgba(0, 0, 0, 0.05);
  --transition: all 0.3s cubic-bezier(0.4, 0, 0.2, 1);
}

@import url('https://fonts.googleapis.com/css2?family=Inter:wght@400;500;600;700&display=swap');

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

body {
  font-family: 'Inter', -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, sans-serif;
  background-color: var(--bg-main);
  color: var(--text-main);
  line-height: 1.6;
  overflow-x: hidden;
}

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

ul {
  list-style: none;
}

/* Layout Containers */
.container {
  max-width: 1200px;
  margin: 0 auto;
  padding: 0 20px;
}

section {
  padding: 80px 0;
}

/* Typography Extensions */
.text-center { text-align: center; }
.section-title {
  font-size: 2.5rem;
  font-weight: 700;
  margin-bottom: 20px;
  background: linear-gradient(135deg, var(--primary), var(--secondary));
  -webkit-background-clip: text;
  -webkit-text-fill-color: transparent;
}

.section-subtitle {
  color: var(--text-muted);
  font-size: 1.1rem;
  max-width: 600px;
  margin: 0 auto 50px;
}

/* Navigation */
nav {
  height: 80px;
  background: rgba(255, 255, 255, 0.8);
  backdrop-filter: blur(10px);
  position: sticky;
  top: 0;
  z-index: 1000;
  border-bottom: 1px solid var(--border);
}

nav .container {
  display: flex;
  justify-content: space-between;
  align-items: center;
  height: 100%;
}

.logo {
  font-size: 1.5rem;
  font-weight: 700;
  color: var(--primary);
  display: flex;
  align-items: center;
  gap: 10px;
}

.nav-links {
  display: flex;
  gap: 30px;
}

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

/* Hero Section */
.hero {
  background: radial-gradient(circle at top right, #e0f2fe, transparent),
              radial-gradient(circle at bottom left, #eff6ff, transparent);
  text-align: center;
  padding: 120px 0;
}

.hero h1 {
  font-size: 3.5rem;
  font-weight: 800;
  margin-bottom: 25px;
  line-height: 1.2;
}

.hero p {
  font-size: 1.25rem;
  color: var(--text-muted);
  max-width: 700px;
  margin: 0 auto 40px;
}

.btn {
  display: inline-block;
  padding: 15px 35px;
  border-radius: 50px;
  font-weight: 600;
  cursor: pointer;
  transition: var(--transition);
}

.btn-primary {
  background-color: var(--primary);
  color: white;
  box-shadow: 0 10px 20px rgba(0, 102, 255, 0.2);
}

.btn-primary:hover {
  background-color: var(--primary-hover);
  transform: translateY(-2px);
  box-shadow: 0 15px 25px rgba(0, 102, 255, 0.3);
}

/* Pricing Grid */
.pricing-grid {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(280px, 1fr));
  gap: 30px;
  margin-top: 50px;
}

.pricing-card {
  background: var(--bg-card);
  padding: 40px;
  border-radius: 24px;
  border: 1px solid var(--border);
  text-align: center;
  transition: var(--transition);
  position: relative;
  overflow: hidden;
}

.pricing-card:hover {
  transform: translateY(-10px);
  box-shadow: var(--shadow);
  border-color: var(--primary);
}

.pricing-card.featured {
  background: linear-gradient(to bottom, #ffffff, #f0f7ff);
  border: 2px solid var(--primary);
}

.pricing-card .badge {
  position: absolute;
  top: 20px;
  right: -30px;
  background: var(--primary);
  color: white;
  padding: 5px 40px;
  transform: rotate(45deg);
  font-size: 0.8rem;
  font-weight: 600;
}

.plan-name {
  font-size: 1.5rem;
  font-weight: 700;
  margin-bottom: 10px;
}

.plan-price {
  font-size: 2.5rem;
  font-weight: 800;
  margin: 20px 0;
}

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

.plan-features {
  margin: 30px 0;
  text-align: left;
}

.plan-features li {
  margin-bottom: 12px;
  display: flex;
  align-items: center;
  gap: 10px;
  font-size: 0.95rem;
}

.plan-features li i {
  color: #10b981;
}

/* Articles Section */
.articles-grid {
  display: grid;
  grid-template-columns: repeat(auto-fill, minmax(350px, 1fr));
  gap: 30px;
}

.article-card {
  background: var(--bg-card);
  border-radius: 16px;
  overflow: hidden;
  border: 1px solid var(--border);
  transition: var(--transition);
}

.article-card:hover {
  box-shadow: var(--shadow);
}

.article-img {
  height: 200px;
  background: #e2e8f0;
  display: flex;
  align-items: center;
  justify-content: center;
  font-size: 3rem;
  color: var(--primary);
}

.article-content {
  padding: 25px;
}

.article-title {
  font-size: 1.25rem;
  font-weight: 700;
  margin-bottom: 15px;
  display: block;
}

.article-excerpt {
  color: var(--text-muted);
  font-size: 0.9rem;
  margin-bottom: 20px;
}

/* Full Article Displays on Home */
.article-full-section {
  background: var(--bg-card);
  padding: 80px 0;
  border-bottom: 1px solid var(--border);
}

.article-full-section:nth-child(even) {
  background: var(--accent);
}

.article-full-section .container {
  max-width: 900px;
}

.article-full-section h2 {
  font-size: 2.2rem;
  margin-bottom: 30px;
  color: var(--text-main);
  font-weight: 800;
}

.article-full-section h3 {
  font-size: 1.5rem;
  margin: 40px 0 15px;
  color: var(--text-main);
}

.article-full-section p {
  margin-bottom: 25px;
  font-size: 1.1rem;
  color: #475569;
  line-height: 1.8;
}

.article-full-section .article-meta {
  color: var(--primary);
  font-weight: 600;
  margin-bottom: 15px;
  display: block;
}

.article-full-section table {
  width: 100%;
  border-collapse: collapse;
  margin: 30px 0;
  background: white;
}

.article-full-section th, .article-full-section td {
  border: 1px solid var(--border);
  padding: 15px;
  text-align: left;
}

.article-full-section th {
  background: #f8fafc;
  font-weight: 700;
}

/* Footer */
footer {
  background: #1e293b;
  color: white;
  padding: 80px 0 40px;
}

.footer-grid {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(300px, 1fr));
  gap: 60px;
  margin-bottom: 60px;
}

.footer-title {
  font-size: 1.1rem;
  font-weight: 600;
  margin-bottom: 25px;
}

.footer-links li {
  margin-bottom: 12px;
}

.footer-links a {
  color: #94a3b8;
  font-size: 0.9rem;
}

.footer-links a:hover {
  color: white;
}

.footer-bottom {
  border-top: 1px solid #334155;
  padding-top: 30px;
  display: flex;
  flex-direction: column;
  gap: 15px;
  text-align: center;
  align-items: center;
  font-size: 0.85rem;
  color: #64748b;
}

/* Responsive */
@media (max-width: 768px) {
  .hero h1 { font-size: 2.5rem; }
  .section-title { font-size: 2rem; }
  .nav-links { display: none; }
}