/* ========================================
   CSS Custom Properties
   ======================================== */

:root {
  /* Color palette */
  --color-bg: #fafaf8;
  --color-surface: #ffffff;
  --color-text: #2c2c2c;
  --color-text-secondary: #6b6b6b;
  --color-text-muted: #999999;
  --color-accent: #345;
  --color-accent-hover: #1a2a3a;
  --color-border: #e8e8e5;
  --color-link: #345;
  --color-link-hover: #1a2a3a;
  --color-code-bg: #f5f5f2;

  /* Typography */
  --font-sans: "PingFang SC", "Hiragino Sans GB", "Microsoft YaHei",
    "Noto Sans SC", "Source Han Sans SC", sans-serif;
  --font-mono: "JetBrains Mono", "Fira Code", "SF Mono", Menlo, Consolas,
    monospace;
  --font-size-base: 16px;
  --line-height-base: 1.8;
  --line-height-heading: 1.4;

  /* Spacing */
  --space-xs: 0.25rem;
  --space-sm: 0.5rem;
  --space-md: 1rem;
  --space-lg: 1.5rem;
  --space-xl: 2rem;
  --space-2xl: 3rem;
  --space-3xl: 4rem;

  /* Layout */
  --content-width: 720px;
  --site-width: 960px;

  /* Transitions */
  --transition-fast: 0.15s ease;
}

/* ========================================
   Reset & Base
   ======================================== */

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

html {
  font-size: var(--font-size-base);
  -webkit-font-smoothing: antialiased;
  -moz-osx-font-smoothing: grayscale;
  text-rendering: optimizeLegibility;
}

body {
  font-family: var(--font-sans);
  line-height: var(--line-height-base);
  color: var(--color-text);
  background-color: var(--color-bg);
  min-height: 100vh;
  display: flex;
  flex-direction: column;
}

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

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

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

/* ========================================
   Header & Navigation
   ======================================== */

.site-header {
  border-bottom: 1px solid var(--color-border);
  background-color: var(--color-surface);
}

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

.site-title {
  font-size: 1.25rem;
  font-weight: 600;
  color: var(--color-text);
  text-decoration: none;
  letter-spacing: 0.02em;
}

.site-title:hover {
  color: var(--color-accent);
}

.nav-links {
  display: flex;
  gap: var(--space-lg);
  list-style: none;
}

.nav-links a {
  color: var(--color-text-secondary);
  text-decoration: none;
  font-size: 0.95rem;
  transition: color var(--transition-fast);
}

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

.menu-toggle {
  display: none;
  background: none;
  border: none;
  cursor: pointer;
  padding: var(--space-sm);
  color: var(--color-text);
}

/* ========================================
   Main Content
   ======================================== */

.main-content {
  flex: 1;
  max-width: var(--site-width);
  margin: 0 auto;
  padding: var(--space-3xl) var(--space-xl);
  width: 100%;
}

/* ========================================
   Post List (Homepage)
   ======================================== */

.post-list {
  display: flex;
  flex-direction: column;
  gap: var(--space-2xl);
}

.post-item {
  padding-bottom: var(--space-2xl);
  border-bottom: 1px solid var(--color-border);
}

.post-item:last-child {
  border-bottom: none;
  padding-bottom: 0;
}

.post-date {
  font-size: 0.875rem;
  color: var(--color-text-muted);
  font-variant-numeric: tabular-nums;
}

.post-title {
  font-size: 1.5rem;
  font-weight: 600;
  line-height: var(--line-height-heading);
  margin: var(--space-sm) 0 var(--space-md);
}

.post-title a {
  color: var(--color-text);
  text-decoration: none;
  transition: color var(--transition-fast);
}

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

.post-excerpt {
  color: var(--color-text-secondary);
  font-size: 0.95rem;
  line-height: 1.7;
}

.read-more {
  display: inline-block;
  margin-top: var(--space-md);
  color: var(--color-accent);
  text-decoration: none;
  font-size: 0.9rem;
}

.read-more:hover {
  color: var(--color-accent-hover);
}

/* ========================================
   Post Article Content
   ======================================== */

.post-header {
  margin-bottom: var(--space-2xl);
}

.post-header .post-title {
  font-size: 2rem;
  margin-bottom: var(--space-md);
}

.post-meta {
  color: var(--color-text-muted);
  font-size: 0.875rem;
}

.post-content {
  max-width: var(--content-width);
  font-size: 1.05rem;
  line-height: 2;
}

.post-content p {
  margin-bottom: var(--space-lg);
  text-align: justify;
}

.post-content h2 {
  font-size: 1.4rem;
  font-weight: 600;
  margin: var(--space-3xl) 0 var(--space-lg);
  line-height: var(--line-height-heading);
}

.post-content h3 {
  font-size: 1.2rem;
  font-weight: 600;
  margin: var(--space-2xl) 0 var(--space-md);
  line-height: var(--line-height-heading);
}

.post-content a {
  color: var(--color-link);
  text-decoration: underline;
  text-underline-offset: 0.15em;
}

.post-content a:hover {
  color: var(--color-link-hover);
}

.post-content blockquote {
  border-left: 3px solid var(--color-border);
  padding-left: var(--space-lg);
  color: var(--color-text-secondary);
  margin: var(--space-xl) 0;
  font-style: normal;
}

.post-content code {
  font-family: var(--font-mono);
  font-size: 0.9em;
  background: var(--color-code-bg);
  padding: 0.15em 0.4em;
  border-radius: 3px;
}

.post-content pre {
  background: var(--color-code-bg);
  padding: var(--space-lg);
  border-radius: 6px;
  overflow-x: auto;
  margin: var(--space-xl) 0;
}

.post-content pre code {
  background: none;
  padding: 0;
  font-size: 0.875rem;
  line-height: 1.6;
}

.post-content img {
  border-radius: 4px;
  margin: var(--space-xl) 0;
}

.post-content ul,
.post-content ol {
  padding-left: var(--space-xl);
  margin: var(--space-lg) 0;
}

.post-content li {
  margin-bottom: var(--space-sm);
}

.post-content hr {
  border: none;
  border-top: 1px solid var(--color-border);
  margin: var(--space-2xl) 0;
}

/* ========================================
   Post Navigation
   ======================================== */

.post-nav {
  margin-top: var(--space-3xl);
  padding-top: var(--space-xl);
  border-top: 1px solid var(--color-border);
}

.post-nav-link {
  color: var(--color-accent);
  text-decoration: none;
  font-size: 0.95rem;
}

.post-nav-link:hover {
  color: var(--color-accent-hover);
}

/* ========================================
   Page Title (About, etc.)
   ======================================== */

.page-title {
  font-size: 1.8rem;
  font-weight: 600;
  margin-bottom: var(--space-2xl);
  line-height: var(--line-height-heading);
}

/* ========================================
   About Page
   ======================================== */

.about-content {
  max-width: var(--content-width);
}

.about-content p {
  margin-bottom: var(--space-lg);
  line-height: 2;
}

.about-content h2 {
  font-size: 1.3rem;
  font-weight: 600;
  margin: var(--space-2xl) 0 var(--space-lg);
}

.about-content ul {
  list-style: none;
  padding: 0;
}

.about-content li {
  margin-bottom: var(--space-sm);
  color: var(--color-text-secondary);
}

.about-content li a {
  color: var(--color-link);
}

/* ========================================
   Footer
   ======================================== */

.site-footer {
  border-top: 1px solid var(--color-border);
  padding: var(--space-xl);
  text-align: center;
  font-size: 0.85rem;
  color: var(--color-text-muted);
  margin-top: auto;
}

.site-footer a {
  color: var(--color-text-secondary);
  text-decoration: none;
}

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

/* ========================================
   Responsive
   ======================================== */

@media (max-width: 768px) {
  :root {
    --font-size-base: 15px;
  }

  .main-content {
    padding: var(--space-2xl) var(--space-lg);
  }

  .post-header .post-title {
    font-size: 1.6rem;
  }

  .post-title {
    font-size: 1.3rem;
  }
}

@media (max-width: 640px) {
  .menu-toggle {
    display: block;
  }

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

  .nav-links.is-open {
    display: flex;
  }

  .site-header {
    position: relative;
  }

  .main-content {
    padding: var(--space-xl) var(--space-md);
  }

  .header-inner {
    padding: var(--space-md);
  }

  .post-content {
    font-size: 1rem;
  }
}