/* ========================================
   SleepWell - Sleep Health Website
   Modern, calming dark theme
   ======================================== */

/* CSS Variables */
:root {
  --color-bg: #0b0d1a;
  --color-bg-secondary: #111327;
  --color-surface: #171935;
  --color-surface-hover: #1e2148;
  --color-primary: #7c6ff7;
  --color-primary-light: #a78bfa;
  --color-accent: #6ee7b7;
  --color-text: #e2e4f0;
  --color-text-secondary: #9a9cbf;
  --color-text-muted: #6b6d8a;
  --color-border: #2a2d4a;
  --color-card-bg: #13152b;
  --gradient-hero: linear-gradient(135deg, #0b0d1a 0%, #1a1040 50%, #0b0d1a 100%);
  --gradient-accent: linear-gradient(135deg, #7c6ff7, #6ee7b7);
  --shadow-card: 0 4px 24px rgba(0, 0, 0, 0.3);
  --shadow-card-hover: 0 8px 40px rgba(124, 111, 247, 0.15);
  --radius: 12px;
  --radius-lg: 20px;
  --max-width: 1200px;
  --header-height: 72px;
  --transition: 0.3s ease;
}

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

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

body {
  font-family: 'Inter', -apple-system, BlinkMacSystemFont, 'Segoe UI', Roboto, sans-serif;
  background-color: var(--color-bg);
  color: var(--color-text);
  line-height: 1.7;
  min-height: 100vh;
  overflow-x: hidden;
}

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

a:hover {
  color: var(--color-accent);
}

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

/* Typography */
h1, h2, h3, h4, h5, h6 {
  color: #fff;
  line-height: 1.3;
  font-weight: 700;
}

h1 { font-size: 2.75rem; }
h2 { font-size: 2rem; }
h3 { font-size: 1.5rem; }
h4 { font-size: 1.25rem; }

p {
  margin-bottom: 1rem;
  color: var(--color-text-secondary);
}

/* Container */
.container {
  max-width: var(--max-width);
  margin: 0 auto;
  padding: 0 24px;
}

/* ========================================
   Stars Background Animation
   ======================================== */
.stars-bg {
  position: fixed;
  top: 0;
  left: 0;
  width: 100%;
  height: 100%;
  pointer-events: none;
  z-index: 0;
  overflow: hidden;
}

.stars-bg .star {
  position: absolute;
  background: #fff;
  border-radius: 50%;
  animation: twinkle var(--duration, 3s) ease-in-out infinite;
  opacity: 0;
}

@keyframes twinkle {
  0%, 100% { opacity: 0; }
  50% { opacity: var(--max-opacity, 0.6); }
}

/* ========================================
   Header / Navigation
   ======================================== */
.site-header {
  position: fixed;
  top: 0;
  left: 0;
  right: 0;
  height: var(--header-height);
  background: rgba(11, 13, 26, 0.85);
  backdrop-filter: blur(20px);
  -webkit-backdrop-filter: blur(20px);
  border-bottom: 1px solid var(--color-border);
  z-index: 1000;
  transition: background var(--transition);
}

.header-inner {
  max-width: var(--max-width);
  margin: 0 auto;
  padding: 0 24px;
  height: 100%;
  display: flex;
  align-items: center;
  justify-content: space-between;
}

.site-logo {
  display: flex;
  align-items: center;
  gap: 10px;
  font-size: 1.4rem;
  font-weight: 800;
  color: #fff;
  text-decoration: none;
}

.site-logo .logo-icon {
  font-size: 1.8rem;
}

.site-logo span {
  background: var(--gradient-accent);
  -webkit-background-clip: text;
  -webkit-text-fill-color: transparent;
  background-clip: text;
}

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

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

.nav-links a:hover,
.nav-links a.active {
  color: #fff;
}

.nav-links a::after {
  content: '';
  position: absolute;
  bottom: -4px;
  left: 0;
  width: 0;
  height: 2px;
  background: var(--gradient-accent);
  transition: width var(--transition);
  border-radius: 1px;
}

.nav-links a:hover::after,
.nav-links a.active::after {
  width: 100%;
}

/* Mobile Menu Toggle */
.menu-toggle {
  display: none;
  flex-direction: column;
  gap: 5px;
  background: none;
  border: none;
  cursor: pointer;
  padding: 4px;
}

.menu-toggle span {
  display: block;
  width: 24px;
  height: 2px;
  background: var(--color-text);
  border-radius: 2px;
  transition: var(--transition);
}

/* ========================================
   Hero Section
   ======================================== */
.hero {
  position: relative;
  padding: 160px 0 100px;
  background: var(--gradient-hero);
  text-align: center;
  overflow: hidden;
}

.hero::before {
  content: '';
  position: absolute;
  top: 50%;
  left: 50%;
  transform: translate(-50%, -50%);
  width: 600px;
  height: 600px;
  background: radial-gradient(circle, rgba(124, 111, 247, 0.1) 0%, transparent 70%);
  pointer-events: none;
}

.hero h1 {
  font-size: 3.2rem;
  margin-bottom: 20px;
  letter-spacing: -0.02em;
}

.hero h1 .highlight {
  background: var(--gradient-accent);
  -webkit-background-clip: text;
  -webkit-text-fill-color: transparent;
  background-clip: text;
}

.hero p {
  font-size: 1.2rem;
  color: var(--color-text-secondary);
  max-width: 600px;
  margin: 0 auto 36px;
}

.hero-cta {
  display: inline-flex;
  align-items: center;
  gap: 8px;
  padding: 14px 32px;
  background: var(--color-primary);
  color: #fff;
  font-weight: 600;
  font-size: 1rem;
  border-radius: 50px;
  transition: all var(--transition);
  box-shadow: 0 4px 20px rgba(124, 111, 247, 0.3);
}

.hero-cta:hover {
  background: var(--color-primary-light);
  color: #fff;
  transform: translateY(-2px);
  box-shadow: 0 6px 30px rgba(124, 111, 247, 0.4);
}

/* ========================================
   Section Styles
   ======================================== */
.section {
  position: relative;
  padding: 80px 0;
  z-index: 1;
}

.section-header {
  text-align: center;
  margin-bottom: 48px;
}

.section-header h2 {
  margin-bottom: 12px;
}

.section-header p {
  font-size: 1.1rem;
  max-width: 560px;
  margin: 0 auto;
}

/* ========================================
   Article Cards Grid
   ======================================== */
.articles-grid {
  display: grid;
  grid-template-columns: repeat(auto-fill, minmax(340px, 1fr));
  gap: 28px;
}

.article-card {
  background: var(--color-card-bg);
  border: 1px solid var(--color-border);
  border-radius: var(--radius-lg);
  overflow: hidden;
  transition: all var(--transition);
  cursor: pointer;
  text-decoration: none;
  display: flex;
  flex-direction: column;
}

.article-card:hover {
  transform: translateY(-4px);
  box-shadow: var(--shadow-card-hover);
  border-color: rgba(124, 111, 247, 0.3);
}

.article-card .card-image {
  position: relative;
  width: 100%;
  height: 220px;
  overflow: hidden;
}

.article-card .card-image img {
  width: 100%;
  height: 100%;
  object-fit: cover;
  transition: transform 0.5s ease;
}

.article-card:hover .card-image img {
  transform: scale(1.05);
}

.article-card .card-image .card-category {
  position: absolute;
  top: 16px;
  left: 16px;
  padding: 4px 14px;
  background: rgba(124, 111, 247, 0.85);
  color: #fff;
  font-size: 0.78rem;
  font-weight: 600;
  border-radius: 50px;
  text-transform: uppercase;
  letter-spacing: 0.05em;
}

.article-card .card-body {
  padding: 24px;
  flex: 1;
  display: flex;
  flex-direction: column;
}

.article-card .card-meta {
  display: flex;
  align-items: center;
  gap: 16px;
  margin-bottom: 12px;
  font-size: 0.85rem;
  color: var(--color-text-muted);
}

.article-card .card-meta span {
  display: flex;
  align-items: center;
  gap: 4px;
}

.article-card .card-title {
  font-size: 1.25rem;
  font-weight: 700;
  color: #fff;
  margin-bottom: 10px;
  line-height: 1.4;
  transition: color var(--transition);
}

.article-card:hover .card-title {
  color: var(--color-primary-light);
}

.article-card .card-excerpt {
  font-size: 0.95rem;
  color: var(--color-text-secondary);
  line-height: 1.6;
  flex: 1;
  display: -webkit-box;
  -webkit-line-clamp: 3;
  -webkit-box-orient: vertical;
  overflow: hidden;
}

.article-card .card-footer {
  padding: 16px 24px;
  border-top: 1px solid var(--color-border);
  display: flex;
  align-items: center;
  justify-content: space-between;
}

.article-card .read-more {
  font-size: 0.9rem;
  font-weight: 600;
  color: var(--color-primary-light);
  display: flex;
  align-items: center;
  gap: 6px;
  transition: gap var(--transition);
}

.article-card:hover .read-more {
  gap: 10px;
}

/* ========================================
   Article Detail Page
   ======================================== */
.article-hero {
  position: relative;
  padding: 140px 0 60px;
  background: var(--gradient-hero);
}

.article-hero .article-meta {
  display: flex;
  align-items: center;
  gap: 20px;
  margin-bottom: 20px;
  flex-wrap: wrap;
}

.article-hero .article-category {
  display: inline-block;
  padding: 4px 16px;
  background: var(--color-primary);
  color: #fff;
  font-size: 0.8rem;
  font-weight: 600;
  border-radius: 50px;
  text-transform: uppercase;
  letter-spacing: 0.05em;
}

.article-hero .article-date,
.article-hero .article-read-time {
  font-size: 0.9rem;
  color: var(--color-text-muted);
}

.article-hero h1 {
  font-size: 2.8rem;
  max-width: 800px;
  margin-bottom: 20px;
}

.article-hero .article-excerpt {
  font-size: 1.15rem;
  color: var(--color-text-secondary);
  max-width: 700px;
  line-height: 1.7;
}

.article-featured-image {
  position: relative;
  max-width: 900px;
  margin: -40px auto 0;
  padding: 0 24px;
  z-index: 2;
}

.article-featured-image img {
  width: 100%;
  height: 480px;
  object-fit: cover;
  border-radius: var(--radius-lg);
  box-shadow: var(--shadow-card);
}

/* Article Content */
.article-content {
  max-width: 760px;
  margin: 0 auto;
  padding: 60px 24px 80px;
}

.article-content h2 {
  font-size: 1.75rem;
  margin-top: 48px;
  margin-bottom: 16px;
  padding-top: 24px;
  border-top: 1px solid var(--color-border);
}

.article-content h2:first-child {
  margin-top: 0;
  padding-top: 0;
  border-top: none;
}

.article-content h3 {
  font-size: 1.35rem;
  margin-top: 32px;
  margin-bottom: 12px;
}

.article-content p {
  font-size: 1.05rem;
  line-height: 1.8;
  margin-bottom: 1.25rem;
}

.article-content ul,
.article-content ol {
  margin-bottom: 1.25rem;
  padding-left: 24px;
}

.article-content li {
  margin-bottom: 8px;
  color: var(--color-text-secondary);
  font-size: 1.05rem;
  line-height: 1.7;
}

.article-content blockquote {
  margin: 24px 0;
  padding: 20px 24px;
  border-left: 4px solid var(--color-primary);
  background: var(--color-surface);
  border-radius: 0 var(--radius) var(--radius) 0;
}

.article-content blockquote p {
  font-style: italic;
  color: var(--color-text);
  margin-bottom: 0;
}

.article-content strong {
  color: #fff;
  font-weight: 600;
}

/* ========================================
   Ad Placeholders (Google AdSense)
   ======================================== */
.ad-container {
  margin: 32px 0;
  text-align: center;
}

.ad-container.ad-header {
  margin: 0 0 32px;
}

.ad-container.ad-sidebar {
  margin: 0 0 24px;
}

.ad-container.ad-in-article {
  margin: 40px 0;
}

/* ========================================
   Sidebar
   ======================================== */
.content-with-sidebar {
  display: grid;
  grid-template-columns: 1fr 300px;
  gap: 40px;
  max-width: var(--max-width);
  margin: 0 auto;
  padding: 0 24px;
}

.sidebar {
  position: sticky;
  top: calc(var(--header-height) + 24px);
  height: fit-content;
}

.sidebar-widget {
  background: var(--color-card-bg);
  border: 1px solid var(--color-border);
  border-radius: var(--radius);
  padding: 24px;
  margin-bottom: 24px;
}

.sidebar-widget h3 {
  font-size: 1.1rem;
  margin-bottom: 16px;
  padding-bottom: 12px;
  border-bottom: 1px solid var(--color-border);
}

.sidebar-widget .related-article {
  display: flex;
  gap: 12px;
  padding: 12px 0;
  border-bottom: 1px solid var(--color-border);
  text-decoration: none;
}

.sidebar-widget .related-article:last-child {
  border-bottom: none;
  padding-bottom: 0;
}

.sidebar-widget .related-article img {
  width: 72px;
  height: 54px;
  object-fit: cover;
  border-radius: 8px;
  flex-shrink: 0;
}

.sidebar-widget .related-article h4 {
  font-size: 0.9rem;
  font-weight: 600;
  color: var(--color-text);
  line-height: 1.4;
  transition: color var(--transition);
}

.sidebar-widget .related-article:hover h4 {
  color: var(--color-primary-light);
}

/* ========================================
   Newsletter Section
   ======================================== */
.newsletter {
  background: var(--color-surface);
  border: 1px solid var(--color-border);
  border-radius: var(--radius-lg);
  padding: 60px 40px;
  text-align: center;
  max-width: 700px;
  margin: 0 auto;
}

.newsletter h2 {
  margin-bottom: 12px;
}

.newsletter p {
  margin-bottom: 28px;
}

.newsletter-form {
  display: flex;
  gap: 12px;
  max-width: 440px;
  margin: 0 auto;
}

.newsletter-form input {
  flex: 1;
  padding: 14px 20px;
  background: var(--color-bg);
  border: 1px solid var(--color-border);
  border-radius: 50px;
  color: var(--color-text);
  font-size: 0.95rem;
  outline: none;
  transition: border-color var(--transition);
}

.newsletter-form input:focus {
  border-color: var(--color-primary);
}

.newsletter-form button {
  padding: 14px 28px;
  background: var(--color-primary);
  color: #fff;
  border: none;
  border-radius: 50px;
  font-weight: 600;
  font-size: 0.95rem;
  cursor: pointer;
  transition: all var(--transition);
  white-space: nowrap;
}

.newsletter-form button:hover {
  background: var(--color-primary-light);
  transform: translateY(-1px);
}

/* ========================================
   Footer
   ======================================== */
.site-footer {
  position: relative;
  background: var(--color-bg-secondary);
  border-top: 1px solid var(--color-border);
  padding: 60px 0 30px;
  z-index: 1;
}

.footer-grid {
  display: grid;
  grid-template-columns: 2fr 1fr 1fr 1fr;
  gap: 40px;
  margin-bottom: 48px;
}

.footer-brand .site-logo {
  margin-bottom: 16px;
}

.footer-brand p {
  font-size: 0.92rem;
  line-height: 1.6;
}

.footer-col h4 {
  font-size: 1rem;
  margin-bottom: 16px;
  color: #fff;
}

.footer-col ul {
  list-style: none;
}

.footer-col li {
  margin-bottom: 10px;
}

.footer-col a {
  color: var(--color-text-secondary);
  font-size: 0.92rem;
  transition: color var(--transition);
}

.footer-col a:hover {
  color: #fff;
}

.footer-bottom {
  padding-top: 24px;
  border-top: 1px solid var(--color-border);
  display: flex;
  align-items: center;
  justify-content: space-between;
  flex-wrap: wrap;
  gap: 16px;
}

.footer-bottom p {
  font-size: 0.85rem;
  color: var(--color-text-muted);
  margin: 0;
}

.footer-social {
  display: flex;
  gap: 12px;
}

.footer-social a {
  width: 40px;
  height: 40px;
  display: flex;
  align-items: center;
  justify-content: center;
  background: var(--color-surface);
  border: 1px solid var(--color-border);
  border-radius: 50%;
  color: var(--color-text-secondary);
  font-size: 1.1rem;
  transition: all var(--transition);
}

.footer-social a:hover {
  background: var(--color-primary);
  border-color: var(--color-primary);
  color: #fff;
}

/* ========================================
   Page Header (for non-home pages)
   ======================================== */
.page-header {
  padding: 140px 0 60px;
  background: var(--gradient-hero);
  text-align: center;
}

.page-header h1 {
  margin-bottom: 12px;
}

.page-header p {
  font-size: 1.1rem;
  max-width: 600px;
  margin: 0 auto;
}

/* Page Content */
.page-content {
  max-width: 800px;
  margin: 0 auto;
  padding: 60px 24px 80px;
}

.page-content h2 {
  font-size: 1.5rem;
  margin-top: 40px;
  margin-bottom: 16px;
}

.page-content h3 {
  font-size: 1.25rem;
  margin-top: 28px;
  margin-bottom: 12px;
}

.page-content p {
  font-size: 1rem;
  line-height: 1.8;
}

.page-content ul,
.page-content ol {
  margin-bottom: 1rem;
  padding-left: 24px;
}

.page-content li {
  margin-bottom: 6px;
  color: var(--color-text-secondary);
}

/* ========================================
   Back to Top Button
   ======================================== */
.back-to-top {
  position: fixed;
  bottom: 30px;
  right: 30px;
  width: 48px;
  height: 48px;
  background: var(--color-primary);
  color: #fff;
  border: none;
  border-radius: 50%;
  font-size: 1.2rem;
  cursor: pointer;
  opacity: 0;
  visibility: hidden;
  transition: all var(--transition);
  z-index: 999;
  box-shadow: 0 4px 16px rgba(124, 111, 247, 0.3);
}

.back-to-top.visible {
  opacity: 1;
  visibility: visible;
}

.back-to-top:hover {
  background: var(--color-primary-light);
  transform: translateY(-3px);
}

/* ========================================
   Loading State
   ======================================== */
.loading-skeleton {
  background: linear-gradient(90deg, var(--color-surface) 25%, var(--color-surface-hover) 50%, var(--color-surface) 75%);
  background-size: 200% 100%;
  animation: shimmer 1.5s infinite;
  border-radius: var(--radius);
}

@keyframes shimmer {
  0% { background-position: 200% 0; }
  100% { background-position: -200% 0; }
}

/* ========================================
   Breadcrumb
   ======================================== */
.breadcrumb {
  display: flex;
  align-items: center;
  gap: 8px;
  margin-bottom: 20px;
  font-size: 0.9rem;
}

.breadcrumb a {
  color: var(--color-text-muted);
}

.breadcrumb a:hover {
  color: var(--color-primary-light);
}

.breadcrumb .separator {
  color: var(--color-text-muted);
}

.breadcrumb .current {
  color: var(--color-text-secondary);
}

/* ========================================
   Responsive Design
   ======================================== */
@media (max-width: 1024px) {
  .content-with-sidebar {
    grid-template-columns: 1fr;
  }

  .sidebar {
    position: static;
    display: grid;
    grid-template-columns: 1fr 1fr;
    gap: 24px;
  }
}

@media (max-width: 768px) {
  h1 { font-size: 2rem; }
  h2 { font-size: 1.5rem; }

  .hero {
    padding: 120px 0 60px;
  }

  .hero h1 {
    font-size: 2.2rem;
  }

  .hero p {
    font-size: 1rem;
  }

  .articles-grid {
    grid-template-columns: 1fr;
  }

  .footer-grid {
    grid-template-columns: 1fr 1fr;
  }

  .menu-toggle {
    display: flex;
  }

  .nav-links {
    position: fixed;
    top: var(--header-height);
    left: 0;
    right: 0;
    background: rgba(11, 13, 26, 0.98);
    backdrop-filter: blur(20px);
    flex-direction: column;
    padding: 24px;
    gap: 20px;
    border-bottom: 1px solid var(--color-border);
    transform: translateY(-100%);
    opacity: 0;
    visibility: hidden;
    transition: all var(--transition);
  }

  .nav-links.active {
    transform: translateY(0);
    opacity: 1;
    visibility: visible;
  }

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

  .article-featured-image img {
    height: 280px;
  }

  .newsletter {
    padding: 40px 24px;
  }

  .newsletter-form {
    flex-direction: column;
  }

  .sidebar {
    grid-template-columns: 1fr;
  }
}

@media (max-width: 480px) {
  .footer-grid {
    grid-template-columns: 1fr;
  }

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

  .hero h1 {
    font-size: 1.8rem;
  }
}