@import url('https://fonts.googleapis.com/css2?family=Inter:wght@300;400;500;600;700&family=Outfit:wght@500;700&display=swap');

:root {
  --font-sans: 'Inter', sans-serif;
  --font-display: 'Outfit', sans-serif;
  --transition: all 0.3s cubic-bezier(0.25, 0.8, 0.25, 1);
}

[data-theme="dark"] {
  --bg: #0b0f19;
  --surface: rgba(20, 26, 40, 0.6);
  --surface-hover: rgba(30, 38, 56, 0.8);
  --border: rgba(255, 255, 255, 0.08);
  --text: #f8fafc;
  --text-secondary: #94a3b8;
  --accent: #3b82f6;
  --accent-hover: #2563eb;
  --accent-secondary: #8b5cf6;
  --gradient-text: linear-gradient(to right, #60a5fa, #a78bfa);
  --gradient-bg: radial-gradient(circle at top right, rgba(59, 130, 246, 0.15), transparent 40%),
                 radial-gradient(circle at bottom left, rgba(139, 92, 246, 0.15), transparent 40%);
  --glass-shadow: 0 8px 32px 0 rgba(0, 0, 0, 0.37);
  --code-bg: rgba(255, 255, 255, 0.05);
  --table-border: rgba(255, 255, 255, 0.08);
  --progress-bg: rgba(255, 255, 255, 0.1);
}

[data-theme="light"] {
  --bg: #f8fafc;
  --surface: rgba(255, 255, 255, 0.8);
  --surface-hover: rgba(241, 245, 249, 0.9);
  --border: rgba(0, 0, 0, 0.1);
  --text: #0f172a;
  --text-secondary: #64748b;
  --accent: #2563eb;
  --accent-hover: #1d4ed8;
  --accent-secondary: #7c3aed;
  --gradient-text: linear-gradient(to right, #2563eb, #7c3aed);
  --gradient-bg: radial-gradient(circle at top right, rgba(37, 99, 235, 0.05), transparent 40%),
                 radial-gradient(circle at bottom left, rgba(124, 58, 237, 0.05), transparent 40%);
  --glass-shadow: 0 8px 32px 0 rgba(0, 0, 0, 0.08);
  --code-bg: rgba(0, 0, 0, 0.05);
  --table-border: rgba(0, 0, 0, 0.1);
  --progress-bg: rgba(0, 0, 0, 0.08);
}

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

body {
  font-family: var(--font-sans);
  background-color: var(--bg);
  background-image: var(--gradient-bg);
  color: var(--text);
  line-height: 1.6;
  overflow-x: hidden;
  scroll-behavior: smooth;
}

/* Reading progress bar */
#reading-progress {
  position: fixed;
  top: 0;
  left: 0;
  width: 0;
  height: 3px;
  background: var(--gradient-text);
  z-index: 1000;
  transition: width 0.1s linear;
}

.glass {
  background: var(--surface);
  backdrop-filter: blur(12px);
  -webkit-backdrop-filter: blur(12px);
  border: 1px solid var(--border);
  border-radius: 16px;
  box-shadow: var(--glass-shadow);
}

.container {
  max-width: 1280px;
  margin: 0 auto;
  padding: 0 24px;
}

/* Header */
header {
  position: fixed;
  top: 0;
  width: 100%;
  z-index: 100;
  padding: 20px 0;
  transition: var(--transition);
}

.header-content {
  display: flex;
  justify-content: space-between;
  align-items: center;
  padding: 12px 24px;
  border-radius: 999px;
}

.header-left {
  display: flex;
  align-items: center;
  gap: 8px;
}

.logo {
  display: flex;
  align-items: center;
  text-decoration: none;
}

.logo img {
  display: block;
  height: 36px;
  width: auto;
}

[data-theme="dark"] .logo-light {
  display: none;
}

[data-theme="light"] .logo-dark {
  display: none;
}

.nav-group {
  display: flex;
  align-items: center;
  gap: 4px;
}

nav a {
  color: var(--text-secondary);
  text-decoration: none;
  margin-left: 32px;
  font-weight: 500;
  font-size: 0.95rem;
  transition: var(--transition);
}

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

/* Theme Toggle */
.theme-toggle {
  background: none;
  border: none;
  cursor: pointer;
  padding: 8px;
  margin-left: 24px;
  border-radius: 50%;
  color: var(--text-secondary);
  transition: var(--transition);
  display: flex;
  align-items: center;
  justify-content: center;
  font-size: 1.2rem;
}

.theme-toggle:hover {
  color: var(--text);
  background: var(--surface);
}

/* Hero Section */
.hero {
  min-height: 100vh;
  display: flex;
  flex-direction: column;
  justify-content: center;
  align-items: center;
  text-align: center;
  padding-top: 80px;
}

.hero h1 {
  font-family: var(--font-display);
  font-size: clamp(3rem, 6vw, 5rem);
  line-height: 1.1;
  margin-bottom: 24px;
  max-width: 900px;
}

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

.hero p {
  font-size: clamp(1.1rem, 2vw, 1.3rem);
  color: var(--text-secondary);
  max-width: 700px;
  margin-bottom: 48px;
}

/* Buttons */
.btn-group {
  display: flex;
  gap: 16px;
  justify-content: center;
}

.btn {
  padding: 14px 32px;
  border-radius: 999px;
  font-weight: 600;
  font-size: 1rem;
  text-decoration: none;
  transition: var(--transition);
  cursor: pointer;
}

.btn-primary {
  background: var(--accent);
  color: #fff;
  border: none;
  box-shadow: 0 4px 14px 0 rgba(59, 130, 246, 0.39);
}

.btn-primary:hover {
  background: var(--accent-hover);
  transform: translateY(-2px);
  box-shadow: 0 6px 20px rgba(59, 130, 246, 0.23);
}

.btn-secondary {
  background: transparent;
  color: var(--text);
  border: 1px solid var(--border);
}

.btn-secondary:hover {
  background: var(--surface-hover);
  transform: translateY(-2px);
}

/* Sections */
section {
  padding: 100px 0;
}

.section-header {
  text-align: center;
  margin-bottom: 64px;
}

.section-header h2 {
  font-family: var(--font-display);
  font-size: 2.5rem;
  margin-bottom: 16px;
}

.section-header p {
  color: var(--text-secondary);
  font-size: 1.1rem;
}

/* Grid & Cards */
.grid {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(320px, 1fr));
  gap: 32px;
}

.card {
  padding: 40px;
  transition: var(--transition);
  position: relative;
  overflow: hidden;
}

.card::before {
  content: '';
  position: absolute;
  top: 0;
  left: 0;
  right: 0;
  height: 2px;
  background: var(--gradient-text);
  opacity: 0;
  transition: var(--transition);
}

.card:hover {
  transform: translateY(-5px);
  background: var(--surface-hover);
}

.card:hover::before {
  opacity: 1;
}

.card h3 {
  font-family: var(--font-display);
  font-size: 1.4rem;
  margin-bottom: 16px;
  color: var(--text);
}

.card p {
  color: var(--text-secondary);
}

/* Blog Card (listing) */
.blog-card {
  text-decoration: none;
  display: block;
}

.blog-card-category {
  display: inline-block;
  font-size: 0.7rem;
  font-weight: 600;
  text-transform: uppercase;
  letter-spacing: 1px;
  color: var(--accent);
  background: color-mix(in srgb, var(--accent) 10%, transparent);
  padding: 4px 12px;
  border-radius: 999px;
  margin-bottom: 12px;
}

.blog-card-date {
  color: var(--text-secondary);
  font-size: 0.8rem;
  margin-top: 16px;
  display: flex;
  align-items: center;
  gap: 6px;
}

/* Blog article page */
.blog-article-container {
  max-width: 720px;
  margin: 0 auto;
  line-height: 1.8;
  padding-top: 50px;
  padding-bottom: 80px;
}

.blog-article-container h1 {
  font-size: clamp(1.8rem, 3.5vw, 2.8rem);
  font-family: var(--font-display);
  line-height: 1.2;
}

.blog-article-container h2 {
  font-family: var(--font-display);
  font-size: 1.6rem;
  margin-top: 48px;
  margin-bottom: 16px;
}

.blog-article-container h3 {
  font-family: var(--font-display);
  font-size: 1.2rem;
  margin-top: 32px;
  margin-bottom: 12px;
  color: var(--text);
}

.blog-article-container p {
  color: var(--text-secondary);
  margin-bottom: 20px;
  font-size: 1.05rem;
}

.blog-article-container ul,
.blog-article-container ol {
  color: var(--text-secondary);
  margin-left: 24px;
  margin-bottom: 24px;
  line-height: 1.9;
}

.blog-article-container li {
  margin-bottom: 6px;
}

.blog-article-container a {
  color: var(--accent);
  text-decoration: none;
}

.blog-article-container a:hover {
  text-decoration: underline;
}

/* Source box */
.source-box {
  background: var(--surface);
  border: 1px solid var(--border);
  border-radius: 12px;
  padding: 16px 20px;
  margin-bottom: 32px;
  font-size: 0.85rem;
  color: var(--text-secondary);
  line-height: 1.6;
}

/* FAQ section */
.faq-section {
  margin-top: 48px;
}

.faq-section h2 {
  font-family: var(--font-display);
  font-size: 1.6rem;
  margin-bottom: 24px;
}

.faq-item {
  border-bottom: 1px solid var(--border);
  padding: 20px 0;
}

.faq-item h3 {
  font-family: var(--font-display);
  font-size: 1.05rem;
  margin-bottom: 8px;
  color: var(--text);
}

.faq-item p {
  color: var(--text-secondary);
  margin-bottom: 0;
  font-size: 0.95rem;
}

/* Highlight Box (blog) */
.highlight-box {
  background: var(--surface);
  border: 1px solid var(--border);
  border-radius: 12px;
  padding: 24px;
  margin: 32px 0;
  color: var(--text-secondary);
  line-height: 1.7;
}

/* Image Showcase */
.showcase-grid {
  display: grid;
  grid-template-columns: 1fr;
  gap: 60px;
}

.showcase-item {
  display: flex;
  flex-direction: column;
  gap: 32px;
}

@media (min-width: 1024px) {
  .showcase-item {
    flex-direction: row;
    align-items: center;
  }
  .showcase-item:nth-child(even) {
    flex-direction: row-reverse;
  }
}

.showcase-text {
  flex: 1;
}

.showcase-text h3 {
  font-family: var(--font-display);
  font-size: 2rem;
  margin-bottom: 16px;
}

.showcase-text p {
  color: var(--text-secondary);
  font-size: 1.1rem;
  margin-bottom: 24px;
}

.showcase-image {
  flex: 1;
  position: relative;
}

.showcase-image img {
  width: 100%;
  height: auto;
  border-radius: 12px;
  border: 1px solid var(--border);
  box-shadow: 0 20px 40px rgba(0,0,0,0.5);
  transition: var(--transition);
}

.showcase-image img:hover {
  transform: scale(1.02);
}

/* Footer */
footer {
  border-top: 1px solid var(--border);
  padding: 60px 0;
  margin-top: 100px;
}

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

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

/* Form elements */
.form-input,
.form-select,
.form-textarea {
  width: 100%;
  padding: 12px 16px;
  background: var(--bg);
  border: 1px solid var(--border);
  border-radius: 12px;
  color: var(--text);
  font-family: var(--font-sans);
  font-size: 0.95rem;
  transition: var(--transition);
}

.form-input:focus,
.form-select:focus,
.form-textarea:focus {
  outline: none;
  border-color: var(--accent);
  box-shadow: 0 0 0 3px color-mix(in srgb, var(--accent) 20%, transparent);
}

.form-label {
  display: block;
  margin-bottom: 6px;
  color: var(--text-secondary);
  font-size: 0.9rem;
}

.form-error-box {
  display: none;
  text-align: center;
  padding: 20px;
  background: rgba(239, 68, 68, 0.1);
  border: 1px solid #ef4444;
  border-radius: 12px;
  margin-bottom: 20px;
}

.form-error-box strong {
  color: #ef4444;
}

.form-ok-box {
  display: none;
  text-align: center;
  padding: 20px;
  background: rgba(34, 197, 94, 0.1);
  border: 1px solid #22c55e;
  border-radius: 12px;
  margin-bottom: 20px;
}

.form-ok-box strong {
  color: #22c55e;
}

/* Page header */
.page-header {
  text-align: center;
  padding-top: 50px;
}

.page-header h1 {
  font-size: clamp(2.2rem, 4vw, 3.5rem);
  font-family: var(--font-display);
  margin-bottom: 20px;
}

.page-header p {
  font-size: 1.2rem;
  color: var(--text-secondary);
  margin-bottom: 50px;
  max-width: 700px;
  margin-left: auto;
  margin-right: auto;
}

/* Blog listing header */
.blog-header {
  text-align: center;
  padding-top: 50px;
}

.blog-header h1 {
  font-size: clamp(2.2rem, 4vw, 3.5rem);
  font-family: var(--font-display);
  margin-bottom: 20px;
}

.blog-header p {
  font-size: 1.2rem;
  color: var(--text-secondary);
  margin-bottom: 20px;
  max-width: 700px;
  margin-left: auto;
  margin-right: auto;
}

/* Category filter */
.category-filter {
  display: flex;
  gap: 8px;
  flex-wrap: wrap;
  justify-content: center;
  margin-bottom: 50px;
}

.category-filter button {
  padding: 6px 16px;
  border-radius: 999px;
  border: 1px solid var(--border);
  background: transparent;
  color: var(--text-secondary);
  font-family: var(--font-sans);
  font-size: 0.85rem;
  cursor: pointer;
  transition: var(--transition);
}

.category-filter button:hover {
  border-color: var(--accent);
  color: var(--accent);
}

.category-filter button.active {
  background: var(--accent);
  color: #fff;
  border-color: var(--accent);
}

/* Blog count */
.blog-count {
  text-align: center;
  color: var(--text-secondary);
  font-size: 0.9rem;
  margin-bottom: 40px;
}

/* Blog empty state */
.blog-empty {
  text-align: center;
  padding: 60px 20px;
  color: var(--text-secondary);
}

/* Tables */
.table-wrapper {
  overflow-x: auto;
  margin: 24px 0;
}

table {
  width: 100%;
  border-collapse: collapse;
  min-width: 600px;
}

table th {
  padding: 16px;
  text-align: left;
  color: var(--text-secondary);
  border-bottom: 1px solid var(--table-border);
  font-weight: 600;
  font-size: 0.85rem;
  text-transform: uppercase;
  letter-spacing: 0.5px;
}

table td {
  padding: 16px;
  border-bottom: 1px solid var(--table-border);
  color: var(--text-secondary);
}

table tr:last-child td {
  border-bottom: none;
}

table th:not(:first-child),
table td:not(:first-child) {
  text-align: center;
}

/* Blog article meta */
.blog-meta {
  display: flex;
  gap: 16px;
  color: var(--text-secondary);
  font-size: 0.9rem;
  justify-content: center;
  flex-wrap: wrap;
  margin-bottom: 40px;
}

/* Responsive */
@media (max-width: 768px) {
  .header-content {
    flex-wrap: wrap;
    gap: 12px;
    justify-content: center;
  }

  nav a {
    margin-left: 16px;
    font-size: 0.85rem;
  }

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

  .blog-article-container {
    padding-left: 16px;
    padding-right: 16px;
  }

  .footer-content {
    flex-direction: column;
    gap: 16px;
    text-align: center;
  }
}

/* Transition for theme change */
body,
.glass,
.card,
.header-content,
.form-input,
.form-select,
.form-textarea,
.highlight-box,
.source-box,
.faq-item {
  transition: background-color 0.3s ease, color 0.3s ease, border-color 0.3s ease;
}

/* Print */
@media print {
  header { position: static; }
  .theme-toggle { display: none; }
  main { padding-top: 0 !important; }
}