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

:root {
  --color-bg: #ffffff;
  --color-text: #111111;
  --color-text-secondary: #6b7280;
  --color-text-muted: #9ca3af;
  --color-border: #e5e7eb;
  --color-border-light: #f3f4f6;
  --color-accent: #111111;
  --color-accent-hover: #374151;
  --color-tag-bg: #f3f4f6;
  --color-tag-text: #4b5563;
  --color-code-bg: #f6f8fa;
  --color-code-border: #e9ecef;
  --color-pre-bg: #1c1c1e;
  --color-pre-text: #e2e8f0;
  --color-copy-btn: rgba(255,255,255,0.12);
  --color-copy-btn-hover: rgba(255,255,255,0.22);

  --font-sans: 'Inter', -apple-system, BlinkMacSystemFont, 'Segoe UI', sans-serif;
  --font-serif: 'Lora', Georgia, 'Times New Roman', serif;
  --font-mono: 'JetBrains Mono', 'Fira Code', Consolas, monospace;

  --max-width: 900px;
  --spacing-xs: 0.25rem;
  --spacing-sm: 0.5rem;
  --spacing-md: 1rem;
  --spacing-lg: 1.5rem;
  --spacing-xl: 2rem;
  --spacing-2xl: 3rem;
  --spacing-3xl: 5rem;

  --header-height: 64px;
}

/* Dark mode */
[data-theme="dark"] {
  --color-bg: #16181d;
  --color-text: #c9d1d9;
  --color-text-secondary: #8b949e;
  --color-text-muted: #6e7681;
  --color-border: #30363d;
  --color-border-light: #21262d;
  --color-accent: #c9d1d9;
  --color-accent-hover: #b1bac4;
  --color-tag-bg: #1e2533;
  --color-tag-text: #94a3b8;
  --color-code-bg: #1e2533;
  --color-code-border: #2d3748;
  --color-pre-bg: #161b27;
  --color-pre-text: #e2e8f0;
  --color-copy-btn: rgba(255,255,255,0.08);
  --color-copy-btn-hover: rgba(255,255,255,0.16);
}

[data-theme="dark"] .site-header {
  background: rgba(15, 17, 23, 0.92);
}

[data-theme="dark"] .lang-badge--en {
  background: #1e2d45;
  color: #60a5fa;
}

[data-theme="dark"] .lang-badge--zh {
  background: #14291f;
  color: #4ade80;
}

html {
  font-size: 17px;
  -webkit-text-size-adjust: 100%;
  scroll-behavior: smooth;
}

body {
  font-family: var(--font-sans);
  font-weight: 400;
  color: var(--color-text);
  background: var(--color-bg);
  line-height: 1.7;
  -webkit-font-smoothing: antialiased;
  -moz-osx-font-smoothing: grayscale;
  top: 0 !important;
}

a {
  color: inherit;
  text-decoration: none;
}

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

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

.site-main {
  min-height: calc(100vh - var(--header-height) - 80px);
  padding: var(--spacing-3xl) 0 var(--spacing-2xl);
}

/* ============================
   Header
   ============================ */
.site-header {
  position: sticky;
  top: 0;
  z-index: 100;
  background: rgba(255, 255, 255, 0.92);
  backdrop-filter: blur(12px);
  -webkit-backdrop-filter: blur(12px);
  border-bottom: 1px solid var(--color-border-light);
  height: var(--header-height);
  display: flex;
  align-items: center;
}

.site-header__inner {
  display: flex;
  align-items: center;
  justify-content: space-between;
  width: 100%;
}

.site-title {
  font-size: 1rem;
  font-weight: 600;
  letter-spacing: -0.01em;
  color: var(--color-text);
  transition: opacity 0.15s;
}

.site-title:hover {
  opacity: 0.7;
}

.site-nav {
  display: flex;
  align-items: center;
  gap: var(--spacing-lg);
  margin-left: var(--spacing-2xl);
}

.site-nav a {
  font-size: 0.875rem;
  font-weight: 400;
  color: var(--color-text-secondary);
  transition: color 0.15s;
}

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

/* ============================
   Translate Dropdown
   ============================ */

/* Suppress Google Translate default UI chrome */
.goog-te-banner-frame,
.skiptranslate { display: none !important; }

.translate-wrap {
  position: relative;
}

.translate-btn {
  display: flex;
  align-items: center;
  gap: 5px;
  padding: 0 10px;
  height: 32px;
  background: none;
  border: 1px solid var(--color-border);
  border-radius: 8px;
  cursor: pointer;
  color: var(--color-text-secondary);
  font-family: var(--font-sans);
  font-size: 0.8125rem;
  transition: color 0.15s, border-color 0.15s, background 0.15s;
  white-space: nowrap;
  user-select: none;
}

.translate-btn:hover,
.translate-btn[aria-expanded="true"] {
  color: var(--color-text);
  border-color: var(--color-text-secondary);
  background: var(--color-border-light);
}

.chevron {
  transition: transform 0.2s;
  flex-shrink: 0;
}

.translate-btn[aria-expanded="true"] .chevron {
  transform: rotate(180deg);
}

.translate-dropdown {
  display: none;
  position: absolute;
  top: calc(100% + 6px);
  right: 0;
  min-width: 150px;
  background: var(--color-bg);
  border: 1px solid var(--color-border);
  border-radius: 10px;
  padding: 4px;
  box-shadow: 0 4px 20px rgba(0,0,0,0.1);
  z-index: 200;
}

.translate-dropdown.open {
  display: block;
  animation: dropdownIn 0.15s ease;
}

@keyframes dropdownIn {
  from { opacity: 0; transform: translateY(-4px); }
  to   { opacity: 1; transform: translateY(0); }
}

.translate-option {
  display: flex;
  align-items: center;
  gap: 8px;
  width: 100%;
  padding: 7px 10px;
  background: none;
  border: none;
  border-radius: 6px;
  cursor: pointer;
  font-family: var(--font-sans);
  font-size: 0.8125rem;
  color: var(--color-text-secondary);
  text-align: left;
  transition: background 0.1s, color 0.1s;
  white-space: nowrap;
}

.translate-option:hover {
  background: var(--color-border-light);
  color: var(--color-text);
}

.translate-option.active {
  color: var(--color-text);
  font-weight: 500;
}


/* Google Translate unavailable (e.g. mainland China) */
.translate-blocked-overlay {
  position: fixed;
  inset: 0;
  background: rgba(15, 17, 23, 0.45);
  z-index: 1000;
  display: flex;
  align-items: center;
  justify-content: center;
  padding: var(--spacing-md);
  animation: dropdownIn 0.2s ease;
}

.translate-blocked-card {
  max-width: 400px;
  background: var(--color-bg);
  border: 1px solid var(--color-border);
  border-radius: 14px;
  padding: var(--spacing-xl);
  box-shadow: 0 12px 40px rgba(0,0,0,0.15);
  font-family: var(--font-sans);
  font-size: 0.9375rem;
  line-height: 1.65;
  color: var(--color-text);
}

.translate-blocked-card h3 {
  font-size: 1.0625rem;
  font-weight: 600;
  margin-bottom: var(--spacing-md);
}

.translate-blocked-card p {
  color: var(--color-text-secondary);
  margin-bottom: var(--spacing-sm);
}

.translate-blocked-card ul {
  margin: var(--spacing-md) 0 var(--spacing-md) 1.25rem;
  color: var(--color-text-secondary);
}

.translate-blocked-card li {
  margin-bottom: 0.35em;
}

.translate-blocked-close {
  margin-top: var(--spacing-lg);
  padding: 8px 18px;
  background: var(--color-text);
  color: var(--color-bg);
  border: none;
  border-radius: 8px;
  font-family: var(--font-sans);
  font-size: 0.875rem;
  cursor: pointer;
}

.translate-blocked-close:hover {
  opacity: 0.9;
}

.theme-toggle {
  display: flex;
  align-items: center;
  justify-content: center;
  width: 32px;
  height: 32px;
  background: none;
  border: 1px solid var(--color-border);
  border-radius: 8px;
  cursor: pointer;
  color: var(--color-text-secondary);
  transition: color 0.15s, border-color 0.15s, background 0.15s;
  flex-shrink: 0;
}

.theme-toggle:hover {
  color: var(--color-text);
  border-color: var(--color-text-secondary);
  background: var(--color-border-light);
}

/* Show sun in dark mode, moon in light mode */
.icon-moon { display: block; }
.icon-sun  { display: none; }
[data-theme="dark"] .icon-moon { display: none; }
[data-theme="dark"] .icon-sun  { display: block; }

/* ============================
   Home Page
   ============================ */
.page-home {
  display: flex;
  flex-direction: column;
  gap: var(--spacing-3xl);
}

.home-intro {
  border-bottom: 1px solid var(--color-border);
  padding-bottom: var(--spacing-2xl);
}

.home-title {
  font-size: 1.75rem;
  font-weight: 600;
  letter-spacing: -0.03em;
  line-height: 1.2;
  margin-bottom: var(--spacing-sm);
}

.home-desc {
  font-size: 1rem;
  color: var(--color-text-secondary);
  font-style: italic;
}

.post-year-group + .post-year-group {
  margin-top: var(--spacing-2xl);
}

.post-year {
  font-size: 0.8125rem;
  font-weight: 600;
  letter-spacing: 0.08em;
  text-transform: uppercase;
  color: var(--color-text-muted);
  margin-bottom: var(--spacing-md);
}

.posts {
  list-style: none;
}

.post-item {
  display: flex;
  align-items: baseline;
  gap: var(--spacing-md);
  padding: 0.6rem 0;
  border-bottom: 1px solid var(--color-border-light);
}

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

.post-date {
  font-size: 0.8125rem;
  color: var(--color-text-muted);
  font-variant-numeric: tabular-nums;
  flex-shrink: 0;
  width: 2.8rem;
  font-family: var(--font-mono);
}

.post-title-link {
  font-size: 0.9375rem;
  font-weight: 400;
  color: var(--color-text);
  transition: color 0.15s;
  flex: 1;
}

.post-title-link:hover {
  color: var(--color-accent-hover);
  text-decoration: underline;
  text-underline-offset: 3px;
}

.post-tags {
  display: flex;
  gap: var(--spacing-xs);
  flex-shrink: 0;
}

/* ============================
   Tag
   ============================ */
.tag {
  display: inline-block;
  padding: 2px 8px;
  background: var(--color-tag-bg);
  color: var(--color-tag-text);
  font-size: 0.75rem;
  border-radius: 4px;
  font-weight: 400;
}

/* ============================
   Post Page
   ============================ */
.post {
  max-width: 100%;
}

.post-header {
  margin-bottom: var(--spacing-2xl);
  padding-bottom: var(--spacing-xl);
  border-bottom: 1px solid var(--color-border);
}

.post-meta {
  font-size: 0.8125rem;
  color: var(--color-text-muted);
  margin-bottom: var(--spacing-md);
  display: flex;
  align-items: center;
  gap: var(--spacing-xs);
}

.post-meta .sep {
  color: var(--color-border);
}

.post-heading {
  font-family: var(--font-serif);
  font-size: 2rem;
  font-weight: 600;
  line-height: 1.3;
  letter-spacing: -0.02em;
  color: var(--color-text);
  margin-bottom: var(--spacing-md);
}

.post-subtitle {
  font-size: 1.0625rem;
  color: var(--color-text-secondary);
  line-height: 1.6;
  font-style: italic;
}

.post-header .post-tags {
  margin-top: var(--spacing-md);
  display: flex;
  gap: var(--spacing-sm);
}

/* ============================
   Post Content / Typography
   ============================ */
.post-content {
  font-family: var(--font-serif);
  font-size: 1.0625rem;
  line-height: 1.85;
  color: var(--color-text);
}

.post-content h1,
.post-content h2,
.post-content h3,
.post-content h4 {
  font-family: var(--font-sans);
  font-weight: 600;
  line-height: 1.3;
  letter-spacing: -0.02em;
  color: var(--color-text);
  margin-top: 2.5em;
  margin-bottom: 0.75em;
}

.post-content h1 { font-size: 1.75rem; }
.post-content h2 { font-size: 1.375rem; }
.post-content h3 { font-size: 1.125rem; }
.post-content h4 { font-size: 1rem; }

.post-content p {
  margin-bottom: 1.5em;
}

.post-content p:last-child {
  margin-bottom: 0;
}

.post-content a {
  color: var(--color-text);
  text-decoration: underline;
  text-underline-offset: 3px;
  text-decoration-color: var(--color-border);
  transition: text-decoration-color 0.15s;
}

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

.post-content strong {
  font-weight: 600;
  color: var(--color-text);
}

.post-content em {
  font-style: italic;
}

.post-content blockquote {
  border-left: 3px solid var(--color-text);
  margin: 2em 0;
  padding: 0.5em 0 0.5em 1.5em;
  color: var(--color-text-secondary);
}

.post-content blockquote p {
  margin-bottom: 0;
}

.post-content ul,
.post-content ol {
  margin: 1.5em 0;
  padding-left: 1.5em;
}

.post-content li {
  margin-bottom: 0.4em;
}

.post-content li + li {
  margin-top: 0.25em;
}

.post-content hr {
  border: none;
  border-top: 1px solid var(--color-border);
  margin: 2.5em 0;
}

.post-content img {
  max-width: 100%;
  border-radius: 8px;
  margin: 2em 0;
  border: 1px solid var(--color-border-light);
}

.post-content table {
  width: 100%;
  border-collapse: collapse;
  font-family: var(--font-sans);
  font-size: 0.9rem;
  margin: 2em 0;
}

.post-content th,
.post-content td {
  padding: 0.75em 1em;
  text-align: left;
  border-bottom: 1px solid var(--color-border);
}

.post-content th {
  font-weight: 600;
  background: var(--color-border-light);
}

/* ============================
   Code
   ============================ */
.post-content code {
  font-family: var(--font-mono);
  font-size: 0.85em;
  background: var(--color-code-bg);
  border: 1px solid var(--color-code-border);
  padding: 0.15em 0.4em;
  border-radius: 4px;
  font-style: normal;
}

/* Code block wrapper (injected by JS) */
.code-block-wrapper {
  position: relative;
  margin: 2em 0;
}

.code-lang {
  position: absolute;
  top: 0;
  left: 0;
  padding: 3px 10px;
  font-family: var(--font-mono);
  font-size: 0.7rem;
  font-weight: 600;
  letter-spacing: 0.06em;
  text-transform: uppercase;
  color: var(--color-text-muted);
  background: rgba(255,255,255,0.06);
  border-bottom-right-radius: 6px;
  user-select: none;
  z-index: 1;
}

.code-copy {
  position: absolute;
  top: 0.6rem;
  right: 0.6rem;
  padding: 3px 10px;
  background: var(--color-copy-btn);
  border: 1px solid rgba(255,255,255,0.1);
  border-radius: 5px;
  color: #94a3b8;
  font-family: var(--font-sans);
  font-size: 0.75rem;
  cursor: pointer;
  opacity: 0;
  transition: opacity 0.15s, background 0.15s;
  z-index: 1;
}

.code-block-wrapper:hover .code-copy {
  opacity: 1;
}

.code-copy:hover {
  background: var(--color-copy-btn-hover);
  color: #e2e8f0;
}

.code-copy.copied {
  color: #4ade80;
  border-color: rgba(74, 222, 128, 0.3);
}

.post-content pre {
  background: var(--color-pre-bg);
  color: var(--color-pre-text);
  border-radius: 10px;
  padding: 2.5rem 1.5rem 1.25rem;
  overflow-x: auto;
  margin: 0;
  font-size: 0.875rem;
  line-height: 1.75;
  border: 1px solid var(--color-border);
}

/* When no language label, reduce top padding */
.code-block-wrapper:not([data-lang]) .post-content pre,
.post-content pre:only-child {
  padding-top: 1.25rem;
}

.post-content pre code {
  background: none;
  border: none;
  padding: 0;
  color: inherit;
  font-size: inherit;
}

/* Rouge syntax highlight */
.highlight .c,  .highlight .c1, .highlight .cm { color: #6a9955 }
.highlight .k,  .highlight .kd, .highlight .kn { color: #569cd6 }
.highlight .s,  .highlight .s1, .highlight .s2 { color: #ce9178 }
.highlight .n,  .highlight .na, .highlight .nb { color: #9cdcfe }
.highlight .nf, .highlight .nx                  { color: #dcdcaa }
.highlight .o                                   { color: #d4d4d4 }
.highlight .m,  .highlight .mi, .highlight .mf  { color: #b5cea8 }
.highlight .nc, .highlight .nn                  { color: #4ec9b0 }
.highlight .nt                                  { color: #569cd6 }
.highlight .err                                 { color: #f44747; background: none }

/* ============================
   Post Footer / Navigation
   ============================ */
.post-footer {
  margin-top: var(--spacing-3xl);
  padding-top: var(--spacing-xl);
  border-top: 1px solid var(--color-border);
}

.post-nav {
  display: grid;
  grid-template-columns: 1fr 1fr;
  gap: var(--spacing-md);
  margin-bottom: var(--spacing-xl);
}

.post-nav__prev,
.post-nav__next {
  display: flex;
  flex-direction: column;
  gap: var(--spacing-xs);
  padding: var(--spacing-md);
  border: 1px solid var(--color-border);
  border-radius: 8px;
  transition: border-color 0.15s, background 0.15s;
}

.post-nav__next {
  text-align: right;
  grid-column: 2;
}

.post-nav__prev:only-child {
  grid-column: 1;
}

.post-nav__prev:hover,
.post-nav__next:hover {
  border-color: var(--color-text);
  background: var(--color-border-light);
}

.nav-label {
  font-size: 0.75rem;
  color: var(--color-text-muted);
  font-family: var(--font-sans);
  font-weight: 500;
  letter-spacing: 0.04em;
}

.nav-title {
  font-size: 0.875rem;
  color: var(--color-text);
  font-family: var(--font-sans);
  line-height: 1.4;
}

.back-home a {
  font-size: 0.875rem;
  color: var(--color-text-secondary);
  transition: color 0.15s;
}

.back-home a:hover {
  color: var(--color-text);
}

/* ============================
   About / Page
   ============================ */
.page-header {
  margin-bottom: var(--spacing-2xl);
  padding-bottom: var(--spacing-xl);
  border-bottom: 1px solid var(--color-border);
}

.page-title {
  font-size: 1.75rem;
  font-weight: 600;
  letter-spacing: -0.03em;
}

/* ============================
   Empty State
   ============================ */
.empty-state {
  color: var(--color-text-secondary);
  font-size: 0.9375rem;
}

.empty-state code {
  font-family: var(--font-mono);
  font-size: 0.85em;
  background: var(--color-code-bg);
  border: 1px solid var(--color-code-border);
  padding: 0.15em 0.4em;
  border-radius: 4px;
}

/* ============================
   Footer
   ============================ */
.site-footer {
  border-top: 1px solid var(--color-border-light);
  padding: var(--spacing-xl) 0;
}

.site-footer__inner p {
  font-size: 0.8125rem;
  color: var(--color-text-muted);
}

.site-footer__inner a {
  color: var(--color-text-secondary);
  text-decoration: underline;
  text-underline-offset: 3px;
  text-decoration-color: transparent;
  transition: text-decoration-color 0.15s;
}

.site-footer__inner a:hover {
  text-decoration-color: var(--color-text-secondary);
}

/* ============================
   Responsive — Tablet (≤1024px)
   ============================ */
@media (max-width: 1024px) {
  .container {
    padding: 0 var(--spacing-xl);
  }
}

/* ============================
   Responsive — Mobile (≤640px)
   ============================ */
@media (max-width: 640px) {
  html { font-size: 15px; }

  :root {
    --spacing-3xl: 3rem;
    --spacing-2xl: 2rem;
  }

  .container {
    padding: 0 var(--spacing-md);
  }

  .site-main {
    padding: var(--spacing-2xl) 0 var(--spacing-xl);
  }

  /* Header */
  .site-header__inner {
    gap: var(--spacing-sm);
  }

  .site-title {
    font-size: 0.9375rem;
  }

  /* Home */
  .home-title {
    font-size: 1.375rem;
  }

  .post-item {
    flex-wrap: wrap;
    gap: var(--spacing-xs);
  }

  .post-tags {
    display: none;
  }

  /* Post */
  .post-heading {
    font-size: 1.5rem;
  }

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

  .post-content h2 { font-size: 1.25rem; }
  .post-content h3 { font-size: 1.075rem; }

  /* Make tables scrollable on mobile */
  .post-content table {
    display: block;
    overflow-x: auto;
    -webkit-overflow-scrolling: touch;
    white-space: nowrap;
    font-size: 0.8125rem;
  }

  /* Make code blocks scrollable */
  .post-content pre {
    font-size: 0.8125rem;
    padding: 1rem;
    border-radius: 6px;
  }

  /* Post navigation */
  .post-nav {
    grid-template-columns: 1fr;
  }

  .post-nav__next {
    grid-column: 1;
    text-align: left;
  }
}

/* ============================
   Print
   ============================ */
@media print {
  .site-header,
  .site-footer,
  .post-footer {
    display: none;
  }
}