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

:root {
  --color-bg: #fafafa;
  --color-surface: #ffffff;
  --color-text: #2d2d2d;
  --color-text-light: #6b7280;
  --color-accent: #2563eb;
  --color-accent-light: #dbeafe;
  --color-border: #e5e7eb;
  --color-tag: #f3f4f6;
  --font-serif: 'Lora', 'Georgia', serif;
  --font-sans: 'Inter', 'Segoe UI', sans-serif;
  --max-width: 1100px;
  --radius: 8px;
}

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

body {
  font-family: var(--font-serif);
  color: var(--color-text);
  background: var(--color-bg);
  line-height: 1.7;
  -webkit-font-smoothing: antialiased;
}

a {
  color: var(--color-accent);
  text-decoration: none;
  transition: color 0.2s;
}

a:hover {
  color: #1d4ed8;
}

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

/* ===== Header ===== */
.site-header {
  background: var(--color-surface);
  border-bottom: 1px solid var(--color-border);
  position: sticky;
  top: 0;
  z-index: 100;
}

.header-inner {
  max-width: var(--max-width);
  margin: 0 auto;
  padding: 1rem 1.5rem;
  display: flex;
  justify-content: space-between;
  align-items: center;
}

.site-logo {
  font-family: var(--font-sans);
  font-size: 1.4rem;
  font-weight: 700;
  color: var(--color-text);
  letter-spacing: -0.5px;
}

.site-logo span {
  color: var(--color-accent);
}

.site-nav {
  display: flex;
  gap: 1.5rem;
  align-items: center;
}

.site-nav a {
  font-family: var(--font-sans);
  font-size: 0.9rem;
  color: var(--color-text-light);
  font-weight: 500;
  transition: color 0.2s;
}

.site-nav a:hover,
.site-nav a.active {
  color: var(--color-accent);
}

.menu-toggle {
  display: none;
  background: none;
  border: none;
  cursor: pointer;
  padding: 0.5rem;
}

.menu-toggle span {
  display: block;
  width: 22px;
  height: 2px;
  background: var(--color-text);
  margin: 5px 0;
  transition: 0.3s;
}

/* ===== Layout ===== */
.container {
  max-width: var(--max-width);
  margin: 0 auto;
  padding: 2rem 1.5rem;
}

.layout {
  display: grid;
  grid-template-columns: 1fr 300px;
  gap: 3rem;
  align-items: start;
}

.main-content {
  min-width: 0;
}

/* ===== Hero ===== */
.hero {
  background: linear-gradient(135deg, #1e3a5f 0%, #2563eb 100%);
  color: #fff;
  padding: 3rem 1.5rem;
  text-align: center;
  margin-bottom: 0;
}

.hero h1 {
  font-family: var(--font-sans);
  font-size: 2.2rem;
  font-weight: 800;
  margin-bottom: 0.5rem;
  letter-spacing: -1px;
}

.hero p {
  font-size: 1.05rem;
  opacity: 0.85;
  max-width: 500px;
  margin: 0 auto;
}

/* ===== Article Cards ===== */
.article-card {
  background: var(--color-surface);
  border: 1px solid var(--color-border);
  border-radius: var(--radius);
  padding: 1.75rem;
  margin-bottom: 1.5rem;
  transition: box-shadow 0.2s, transform 0.2s;
}

.article-card:hover {
  box-shadow: 0 4px 20px rgba(0,0,0,0.06);
  transform: translateY(-2px);
}

.article-meta {
  font-family: var(--font-sans);
  font-size: 0.8rem;
  color: var(--color-text-light);
  display: flex;
  gap: 1rem;
  margin-bottom: 0.75rem;
  flex-wrap: wrap;
}

.article-meta .category {
  color: var(--color-accent);
  font-weight: 600;
  text-transform: uppercase;
  letter-spacing: 0.5px;
}

.article-card h2 {
  font-family: var(--font-sans);
  font-size: 1.35rem;
  font-weight: 700;
  margin-bottom: 0.6rem;
  line-height: 1.3;
}

.article-card h2 a {
  color: var(--color-text);
}

.article-card h2 a:hover {
  color: var(--color-accent);
}

.article-card .excerpt {
  color: var(--color-text-light);
  font-size: 0.95rem;
  margin-bottom: 1rem;
  line-height: 1.6;
}

.article-card .tags {
  display: flex;
  gap: 0.5rem;
  flex-wrap: wrap;
}

.tag {
  font-family: var(--font-sans);
  font-size: 0.75rem;
  background: var(--color-tag);
  color: var(--color-text-light);
  padding: 0.25rem 0.65rem;
  border-radius: 50px;
  font-weight: 500;
}

.read-more {
  font-family: var(--font-sans);
  font-size: 0.85rem;
  font-weight: 600;
  display: inline-flex;
  align-items: center;
  gap: 0.3rem;
}

.read-more::after {
  content: '\2192';
  transition: transform 0.2s;
}

.read-more:hover::after {
  transform: translateX(3px);
}

/* ===== Sidebar ===== */
.sidebar {
  position: sticky;
  top: 5rem;
}

.sidebar-section {
  background: var(--color-surface);
  border: 1px solid var(--color-border);
  border-radius: var(--radius);
  padding: 1.5rem;
  margin-bottom: 1.5rem;
}

.sidebar-section h3 {
  font-family: var(--font-sans);
  font-size: 0.85rem;
  font-weight: 700;
  text-transform: uppercase;
  letter-spacing: 0.8px;
  color: var(--color-text);
  margin-bottom: 1rem;
  padding-bottom: 0.5rem;
  border-bottom: 2px solid var(--color-accent);
}

.category-list {
  list-style: none;
}

.category-list li {
  font-family: var(--font-sans);
  font-size: 0.9rem;
}

.category-list li a {
  display: flex;
  justify-content: space-between;
  padding: 0.5rem 0;
  color: var(--color-text);
  border-bottom: 1px solid var(--color-border);
}

.category-list li:last-child a {
  border-bottom: none;
}

.category-list li a:hover {
  color: var(--color-accent);
}

.category-list .count {
  font-size: 0.8rem;
  color: var(--color-text-light);
}

.sidebar-tags {
  display: flex;
  flex-wrap: wrap;
  gap: 0.5rem;
}

.sidebar-tags .tag {
  cursor: pointer;
  transition: background 0.2s, color 0.2s;
}

.sidebar-tags .tag:hover {
  background: var(--color-accent);
  color: #fff;
}

.about-widget p {
  font-size: 0.9rem;
  color: var(--color-text-light);
  margin-bottom: 0.75rem;
}

.about-widget .btn {
  font-family: var(--font-sans);
  font-size: 0.85rem;
  font-weight: 600;
  color: var(--color-accent);
}

/* ===== Article Page ===== */
.article-header {
  margin-bottom: 2rem;
}

.article-header h1 {
  font-family: var(--font-sans);
  font-size: 2rem;
  font-weight: 800;
  line-height: 1.25;
  margin-bottom: 1rem;
  letter-spacing: -0.5px;
}

.article-header .article-meta {
  font-size: 0.85rem;
}

.article-body {
  font-size: 1.05rem;
  line-height: 1.8;
}

.article-body h2 {
  font-family: var(--font-sans);
  font-size: 1.5rem;
  font-weight: 700;
  margin: 2rem 0 1rem;
  color: var(--color-text);
}

.article-body h3 {
  font-family: var(--font-sans);
  font-size: 1.2rem;
  font-weight: 600;
  margin: 1.5rem 0 0.75rem;
}

.article-body p {
  margin-bottom: 1.25rem;
}

.article-body ul, .article-body ol {
  margin: 1rem 0 1.25rem 1.5rem;
}

.article-body li {
  margin-bottom: 0.4rem;
}

.article-body code {
  font-family: 'Fira Code', 'Consolas', monospace;
  font-size: 0.88em;
  background: var(--color-tag);
  padding: 0.15rem 0.4rem;
  border-radius: 4px;
}

.article-body pre {
  background: #1e293b;
  color: #e2e8f0;
  padding: 1.25rem;
  border-radius: var(--radius);
  overflow-x: auto;
  margin: 1.25rem 0;
  line-height: 1.5;
}

.article-body pre code {
  background: none;
  padding: 0;
  color: inherit;
}

.article-body blockquote {
  border-left: 3px solid var(--color-accent);
  padding: 0.75rem 1.25rem;
  margin: 1.25rem 0;
  background: var(--color-accent-light);
  border-radius: 0 var(--radius) var(--radius) 0;
  font-style: italic;
}

.article-footer {
  margin-top: 2.5rem;
  padding-top: 1.5rem;
  border-top: 1px solid var(--color-border);
}

.article-footer .tags {
  display: flex;
  gap: 0.5rem;
  flex-wrap: wrap;
  margin-bottom: 1.5rem;
}

.back-link {
  font-family: var(--font-sans);
  font-size: 0.9rem;
  font-weight: 600;
  display: inline-flex;
  align-items: center;
  gap: 0.3rem;
}

.back-link::before {
  content: '\2190';
}

/* ===== About Page ===== */
.about-content {
  background: var(--color-surface);
  border: 1px solid var(--color-border);
  border-radius: var(--radius);
  padding: 2.5rem;
}

.about-content h1 {
  font-family: var(--font-sans);
  font-size: 2rem;
  font-weight: 800;
  margin-bottom: 1.5rem;
}

.about-content h2 {
  font-family: var(--font-sans);
  font-size: 1.3rem;
  font-weight: 700;
  margin: 2rem 0 0.75rem;
  color: var(--color-accent);
}

.about-content p {
  margin-bottom: 1rem;
  color: var(--color-text-light);
  font-size: 1rem;
}

.about-content ul {
  margin: 0.75rem 0 1.25rem 1.5rem;
  color: var(--color-text-light);
}

.about-content li {
  margin-bottom: 0.4rem;
}

/* ===== Footer ===== */
.site-footer {
  background: var(--color-surface);
  border-top: 1px solid var(--color-border);
  padding: 2rem 1.5rem;
  margin-top: 3rem;
  text-align: center;
  font-family: var(--font-sans);
  font-size: 0.85rem;
  color: var(--color-text-light);
}

/* ===== Responsive ===== */
@media (max-width: 768px) {
  .layout {
    grid-template-columns: 1fr;
  }

  .sidebar {
    position: static;
  }

  .hero h1 {
    font-size: 1.6rem;
  }

  .hero p {
    font-size: 0.95rem;
  }

  .article-header h1 {
    font-size: 1.6rem;
  }

  .menu-toggle {
    display: block;
  }

  .site-nav {
    display: none;
    position: absolute;
    top: 100%;
    left: 0;
    right: 0;
    background: var(--color-surface);
    flex-direction: column;
    padding: 1rem 1.5rem;
    border-bottom: 1px solid var(--color-border);
    gap: 0.75rem;
  }

  .site-nav.open {
    display: flex;
  }

  .about-content {
    padding: 1.5rem;
  }
}