/* ==========================================================================
   Modern Design System for hfly2019.github.io
   Adhering to Modern Web Guidance: Design Tokens, Dark Mode, light-dark()
   ========================================================================== */

:root {
  /* Typography Stack */
  --font-sans: -apple-system, BlinkMacSystemFont, "SF Pro Display", "Segoe UI", Roboto, "PingFang SC", "Hiragino Sans GB", "Microsoft YaHei", sans-serif;
  --font-mono: ui-monospace, SFMono-Regular, "SF Mono", Menlo, Consolas, "Liberation Mono", monospace;

  /* Base Spacing & Radius */
  --radius-sm: 6px;
  --radius-md: 10px;
  --radius-lg: 16px;
  --radius-full: 9999px;

  /* Light Theme Tokens */
  --bg-light: #f8fafc;
  --bg-surface-light: #ffffff;
  --bg-card-light: #ffffff;
  --bg-card-hover-light: #f1f5f9;
  --text-primary-light: #0f172a;
  --text-secondary-light: #334155;
  --text-muted-light: #64748b;
  --border-light: #e2e8f0;
  --border-subtle-light: #edf2f7;
  --accent-light: #2563eb;
  --accent-hover-light: #1d4ed8;
  --accent-soft-light: rgba(37, 99, 235, 0.08);
  --card-shadow-light: 0 4px 20px -2px rgba(15, 23, 42, 0.05), 0 2px 6px -1px rgba(15, 23, 42, 0.02);
  --card-shadow-hover-light: 0 10px 25px -3px rgba(15, 23, 42, 0.08), 0 4px 8px -2px rgba(15, 23, 42, 0.03);
  --code-bg-light: #f1f5f9;
  --scrollbar-track-light: #f1f5f9;
  --scrollbar-thumb-light: #cbd5e1;

  /* Dark Theme Tokens */
  --bg-dark: #0b0f17;
  --bg-surface-dark: #111827;
  --bg-card-dark: #151d2e;
  --bg-card-hover-dark: #1c263c;
  --text-primary-dark: #f8fafc;
  --text-secondary-dark: #cbd5e1;
  --text-muted-dark: #818cf8;
  --border-dark: #1f293d;
  --border-subtle-dark: #182234;
  --accent-dark: #38bdf8;
  --accent-hover-dark: #7dd3fc;
  --accent-soft-dark: rgba(56, 189, 248, 0.12);
  --card-shadow-dark: 0 4px 20px -2px rgba(0, 0, 0, 0.5), 0 2px 6px -1px rgba(0, 0, 0, 0.3);
  --card-shadow-hover-dark: 0 12px 30px -4px rgba(0, 0, 0, 0.6), 0 6px 10px -2px rgba(0, 0, 0, 0.4);
  --code-bg-dark: #1e293b;
  --scrollbar-track-dark: #111827;
  --scrollbar-thumb-dark: #334155;

  /* Default Active Variables (Fallback: Light) */
  --bg: var(--bg-light);
  --bg-surface: var(--bg-surface-light);
  --bg-card: var(--bg-card-light);
  --bg-card-hover: var(--bg-card-hover-light);
  --text-primary: var(--text-primary-light);
  --text-secondary: var(--text-secondary-light);
  --text-muted: var(--text-muted-light);
  --border: var(--border-light);
  --border-subtle: var(--border-subtle-light);
  --accent: var(--accent-light);
  --accent-hover: var(--accent-hover-light);
  --accent-soft: var(--accent-soft-light);
  --card-shadow: var(--card-shadow-light);
  --card-shadow-hover: var(--card-shadow-hover-light);
  --code-bg: var(--code-bg-light);
  --scrollbar-track: var(--scrollbar-track-light);
  --scrollbar-thumb: var(--scrollbar-thumb-light);

  /* Browser level controls */
  color-scheme: light dark;
  accent-color: var(--accent);
}

/* MANDATORY: Fallback for browsers without light-dark support */
@media (prefers-color-scheme: dark) {
  :root {
    --bg: var(--bg-dark);
    --bg-surface: var(--bg-surface-dark);
    --bg-card: var(--bg-card-dark);
    --bg-card-hover: var(--bg-card-hover-dark);
    --text-primary: var(--text-primary-dark);
    --text-secondary: var(--text-secondary-dark);
    --text-muted: var(--text-muted-dark);
    --border: var(--border-dark);
    --border-subtle: var(--border-subtle-dark);
    --accent: var(--accent-dark);
    --accent-hover: var(--accent-hover-dark);
    --accent-soft: var(--accent-soft-dark);
    --card-shadow: var(--card-shadow-dark);
    --card-shadow-hover: var(--card-shadow-hover-dark);
    --code-bg: var(--code-bg-dark);
    --scrollbar-track: var(--scrollbar-track-dark);
    --scrollbar-thumb: var(--scrollbar-thumb-dark);
  }
}

/* Modern light-dark() CSS Standard implementation */
@supports (color: light-dark(white, black)) {
  :root {
    --bg: light-dark(var(--bg-light), var(--bg-dark));
    --bg-surface: light-dark(var(--bg-surface-light), var(--bg-surface-dark));
    --bg-card: light-dark(var(--bg-card-light), var(--bg-card-dark));
    --bg-card-hover: light-dark(var(--bg-card-hover-light), var(--bg-card-hover-dark));
    --text-primary: light-dark(var(--text-primary-light), var(--text-primary-dark));
    --text-secondary: light-dark(var(--text-secondary-light), var(--text-secondary-dark));
    --text-muted: light-dark(var(--text-muted-light), var(--text-muted-dark));
    --border: light-dark(var(--border-light), var(--border-dark));
    --border-subtle: light-dark(var(--border-subtle-light), var(--border-subtle-dark));
    --accent: light-dark(var(--accent-light), var(--accent-dark));
    --accent-hover: light-dark(var(--accent-hover-light), var(--accent-hover-dark));
    --accent-soft: light-dark(var(--accent-soft-light), var(--accent-soft-dark));
    --card-shadow: light-dark(var(--card-shadow-light), var(--card-shadow-dark));
    --card-shadow-hover: light-dark(var(--card-shadow-hover-light), var(--card-shadow-hover-dark));
    --code-bg: light-dark(var(--code-bg-light), var(--code-bg-dark));
    --scrollbar-track: light-dark(var(--scrollbar-track-light), var(--scrollbar-track-dark));
    --scrollbar-thumb: light-dark(var(--scrollbar-thumb-light), var(--scrollbar-thumb-dark));
  }
}

/* ==========================================================================
   Global Resets & Poole Overrides
   ========================================================================== */

html, body {
  font-family: var(--font-sans) !important;
  background-color: var(--bg) !important;
  color: var(--text-secondary) !important;
  line-height: 1.7 !important;
  -webkit-font-smoothing: antialiased;
  -moz-osx-font-smoothing: grayscale;
  scroll-behavior: smooth;
  scrollbar-color: var(--scrollbar-thumb) var(--scrollbar-track);
}

/* Container width expansion for modern displays */
.container {
  max-width: 840px !important;
  padding-left: 1.5rem !important;
  padding-right: 1.5rem !important;
}

.wrap {
  background-color: var(--bg) !important;
  min-height: 100vh;
  display: flex;
  flex-direction: column;
}

#main-content {
  flex: 1 0 auto;
  padding-top: 2rem;
  padding-bottom: 3.5rem;
}

/* Headings */
h1, h2, h3, h4, h5, h6 {
  font-family: var(--font-sans) !important;
  color: var(--text-primary) !important;
  font-weight: 700 !important;
  letter-spacing: -0.02em;
}

h1 { font-size: 2rem; margin-top: 1.8rem; margin-bottom: 1rem; }
h2 { font-size: 1.5rem; margin-top: 2.2rem; margin-bottom: 0.9rem; }
h3 { font-size: 1.25rem; margin-top: 1.6rem; margin-bottom: 0.75rem; }

a {
  color: var(--accent);
  text-decoration: none;
  transition: color 0.15s ease;
}

a:hover {
  color: var(--accent-hover);
  text-decoration: none;
}

/* ==========================================================================
   Masthead (Top Navigation)
   ========================================================================== */

.masthead {
  border-bottom: 1px solid var(--border);
  background-color: var(--bg-surface);
  position: sticky;
  top: 0;
  z-index: 20;
  backdrop-filter: blur(12px);
  -webkit-backdrop-filter: blur(12px);
  padding: 0.85rem 0;
  margin-bottom: 0 !important;
}

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

.masthead-brand {
  display: flex;
  align-items: center;
  gap: 0.75rem;
}

.masthead-brand .site-title {
  font-size: 1.25rem;
  font-weight: 800;
  color: var(--text-primary);
  letter-spacing: -0.03em;
}

.site-status {
  display: inline-flex;
  align-items: center;
  gap: 0.35rem;
  font-size: 0.75rem;
  font-weight: 600;
  color: var(--text-muted);
  background: var(--border-subtle);
  border: 1px solid var(--border);
  padding: 0.2rem 0.55rem;
  border-radius: var(--radius-full);
}

.status-dot {
  width: 6px;
  height: 6px;
  border-radius: 50%;
  background-color: #10b981;
  box-shadow: 0 0 6px rgba(16, 185, 129, 0.6);
}

.masthead-nav {
  display: flex;
  align-items: center;
  gap: 1.25rem;
}

.masthead-nav a {
  font-size: 0.9rem;
  font-weight: 500;
  color: var(--text-secondary);
}

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

.masthead-nav .nav-gh {
  background-color: var(--text-primary);
  color: var(--bg-surface) !important;
  padding: 0.35rem 0.85rem;
  border-radius: var(--radius-full);
  font-size: 0.82rem;
  font-weight: 600;
  transition: opacity 0.15s ease;
}

.masthead-nav .nav-gh:hover {
  opacity: 0.85;
}

/* ==========================================================================
   Hero Section
   ========================================================================== */

.hero-box {
  background: var(--bg-surface);
  border: 1px solid var(--border);
  border-radius: var(--radius-lg);
  padding: 2.25rem 2rem;
  margin-bottom: 2.5rem;
  box-shadow: var(--card-shadow);
  position: relative;
  overflow: hidden;
}

.hero-box::before {
  content: "";
  position: absolute;
  top: 0;
  left: 0;
  right: 0;
  height: 4px;
  background: linear-gradient(90deg, #3b82f6, #8b5cf6, #ec4899);
}

.hero-badge-row {
  display: flex;
  flex-wrap: wrap;
  align-items: center;
  gap: 0.5rem;
  margin-bottom: 1rem;
}

.hero-badge {
  display: inline-flex;
  align-items: center;
  gap: 0.35rem;
  font-size: 0.8rem;
  font-weight: 600;
  background-color: var(--accent-soft);
  color: var(--accent);
  border: 1px solid rgba(59, 130, 246, 0.2);
  padding: 0.25rem 0.65rem;
  border-radius: var(--radius-full);
}

.hero-title {
  font-size: 2.25rem;
  font-weight: 800;
  color: var(--text-primary);
  line-height: 1.25;
  margin-top: 0;
  margin-bottom: 0.85rem;
  letter-spacing: -0.03em;
}

.hero-lead {
  font-size: 1.1rem;
  color: var(--text-secondary);
  line-height: 1.65;
  margin-bottom: 1.5rem;
}

.hero-actions {
  display: flex;
  flex-wrap: wrap;
  gap: 0.75rem;
}

.btn-primary {
  display: inline-flex;
  align-items: center;
  gap: 0.4rem;
  background-color: var(--accent);
  color: #ffffff !important;
  font-size: 0.9rem;
  font-weight: 600;
  padding: 0.6rem 1.2rem;
  border-radius: var(--radius-md);
  transition: transform 0.15s ease, background-color 0.15s ease;
}

.btn-primary:hover {
  background-color: var(--accent-hover);
  transform: translateY(-1px);
}

.btn-secondary {
  display: inline-flex;
  align-items: center;
  gap: 0.4rem;
  background-color: var(--border-subtle);
  color: var(--text-primary) !important;
  border: 1px solid var(--border);
  font-size: 0.9rem;
  font-weight: 600;
  padding: 0.6rem 1.2rem;
  border-radius: var(--radius-md);
  transition: transform 0.15s ease, background-color 0.15s ease;
}

.btn-secondary:hover {
  background-color: var(--border);
  transform: translateY(-1px);
}

/* ==========================================================================
   Section Headers
   ========================================================================== */

.section-head {
  display: flex;
  align-items: baseline;
  justify-content: space-between;
  border-bottom: 1px solid var(--border);
  padding-bottom: 0.6rem;
  margin-top: 2.5rem;
  margin-bottom: 1.25rem;
}

.section-title {
  font-size: 1.35rem;
  font-weight: 700;
  color: var(--text-primary);
  margin: 0;
  display: flex;
  align-items: center;
  gap: 0.5rem;
}

.section-sub {
  font-size: 0.85rem;
  color: var(--text-muted);
}

/* ==========================================================================
   Project Cards Grid
   ========================================================================== */

.project-grid {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(280px, 1fr));
  gap: 1.25rem;
  margin-bottom: 2rem;
}

.project-card {
  background: var(--bg-surface);
  border: 1px solid var(--border);
  border-radius: var(--radius-md);
  padding: 1.25rem;
  display: flex;
  flex-direction: column;
  justify-content: space-between;
  box-shadow: var(--card-shadow);
  transition: transform 0.2s ease, box-shadow 0.2s ease, border-color 0.2s ease;
}

.project-card:hover {
  transform: translateY(-3px);
  box-shadow: var(--card-shadow-hover);
  border-color: var(--accent);
}

.project-top {
  display: flex;
  align-items: flex-start;
  justify-content: space-between;
  gap: 0.5rem;
  margin-bottom: 0.6rem;
}

.project-name {
  font-size: 1.05rem;
  font-weight: 700;
  color: var(--text-primary);
  margin: 0;
}

.project-tag {
  font-size: 0.72rem;
  font-weight: 600;
  padding: 0.15rem 0.5rem;
  border-radius: var(--radius-full);
  background: var(--accent-soft);
  color: var(--accent);
  white-space: nowrap;
}

.project-desc {
  font-size: 0.88rem;
  color: var(--text-secondary);
  line-height: 1.55;
  margin-bottom: 1rem;
  flex-grow: 1;
}

.project-meta {
  display: flex;
  align-items: center;
  justify-content: space-between;
  border-top: 1px solid var(--border-subtle);
  padding-top: 0.75rem;
  font-size: 0.8rem;
  color: var(--text-muted);
}

.project-link {
  font-weight: 600;
  color: var(--accent);
  display: inline-flex;
  align-items: center;
  gap: 0.25rem;
}

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

/* ==========================================================================
   Article Feed Cards
   ========================================================================== */

.post-list {
  display: flex;
  flex-direction: column;
  gap: 1rem;
  margin-bottom: 2rem;
}

.post-card {
  background: var(--bg-surface);
  border: 1px solid var(--border);
  border-radius: var(--radius-md);
  padding: 1.25rem 1.5rem;
  box-shadow: var(--card-shadow);
  transition: transform 0.15s ease, border-color 0.15s ease;
  display: block;
}

.post-card:hover {
  transform: translateX(4px);
  border-color: var(--accent);
}

.post-card-header {
  display: flex;
  align-items: center;
  gap: 0.75rem;
  margin-bottom: 0.4rem;
  font-size: 0.82rem;
}

.post-card-date {
  color: var(--text-muted);
  font-weight: 500;
}

.post-card-title {
  font-size: 1.15rem;
  font-weight: 700;
  color: var(--text-primary);
  margin-top: 0;
  margin-bottom: 0.4rem;
}

.post-card-desc {
  font-size: 0.9rem;
  color: var(--text-secondary);
  line-height: 1.55;
  margin: 0;
}

.post-card-tags {
  display: flex;
  gap: 0.4rem;
  margin-top: 0.75rem;
}

.tag-badge {
  font-size: 0.72rem;
  color: var(--accent);
  background: var(--accent-soft);
  padding: 0.15rem 0.5rem;
  border-radius: var(--radius-full);
  font-weight: 500;
}

/* ==========================================================================
   About & Pillars
   ========================================================================== */

.about-box {
  background: var(--bg-surface);
  border: 1px solid var(--border);
  border-radius: var(--radius-md);
  padding: 1.5rem;
  box-shadow: var(--card-shadow);
  margin-bottom: 2rem;
}

.about-features {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(220px, 1fr));
  gap: 1rem;
  margin-top: 1rem;
}

.about-item {
  background: var(--bg);
  border: 1px solid var(--border);
  padding: 1rem;
  border-radius: var(--radius-sm);
}

.about-item-title {
  font-size: 0.95rem;
  font-weight: 700;
  color: var(--text-primary);
  margin-bottom: 0.35rem;
  display: flex;
  align-items: center;
  gap: 0.4rem;
}

.about-item-desc {
  font-size: 0.84rem;
  color: var(--text-secondary);
  line-height: 1.5;
  margin: 0;
}

/* ==========================================================================
   Post Detail Page Typography
   ========================================================================== */

.post-header {
  margin-bottom: 2rem;
  border-bottom: 1px solid var(--border);
  padding-bottom: 1.5rem;
}

.post-meta {
  display: flex;
  align-items: center;
  gap: 0.75rem;
  margin-bottom: 0.75rem;
  font-size: 0.85rem;
  color: var(--text-muted);
}

.post-lead {
  font-size: 1.05rem;
  color: var(--text-secondary);
  margin-top: 0.5rem;
  line-height: 1.6;
}

.post-content {
  color: var(--text-primary);
  line-height: 1.8;
  font-size: 1.02rem;
}

.post-content pre,
.post-content code {
  font-family: var(--font-mono);
  font-size: 0.9em;
}

.post-content code {
  background: var(--code-bg);
  color: var(--accent);
  padding: 0.2em 0.4em;
  border-radius: var(--radius-sm);
  border: 1px solid var(--border);
}

.post-content pre {
  background: var(--code-bg);
  padding: 1.25rem;
  border-radius: var(--radius-md);
  border: 1px solid var(--border);
  overflow-x: auto;
  line-height: 1.5;
}

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

.post-content blockquote {
  border-left: 4px solid var(--accent);
  background: var(--bg-surface);
  margin: 1.5rem 0;
  padding: 1rem 1.25rem;
  border-radius: 0 var(--radius-sm) var(--radius-sm) 0;
  color: var(--text-secondary);
  font-style: normal;
}

.post-content table {
  width: 100%;
  border-collapse: collapse;
  margin: 1.5rem 0;
  font-size: 0.92rem;
}

.post-content th,
.post-content td {
  padding: 0.75rem 1rem;
  border: 1px solid var(--border);
}

.post-content th {
  background-color: var(--border-subtle);
  font-weight: 700;
  color: var(--text-primary);
}

.post-footer {
  margin-top: 3rem;
  padding-top: 1.5rem;
  border-top: 1px solid var(--border);
}

.post-nav-back {
  display: flex;
  justify-content: space-between;
  align-items: center;
}

.btn-back {
  font-weight: 600;
  color: var(--accent);
}

.btn-gh {
  background: var(--border-subtle);
  border: 1px solid var(--border);
  padding: 0.4rem 0.9rem;
  border-radius: var(--radius-full);
  font-size: 0.82rem;
  font-weight: 600;
  color: var(--text-primary);
}

/* ==========================================================================
   Sidebar & Toggle
   ========================================================================== */

.sidebar {
  background-color: var(--bg-surface) !important;
  border-right: 1px solid var(--border);
  padding: 2rem 1.5rem !important;
  color: var(--text-secondary) !important;
}

.sidebar-header {
  margin-bottom: 2rem;
}

.sidebar-avatar {
  width: 52px;
  height: 52px;
  border-radius: 50%;
  background: linear-gradient(135deg, #3b82f6, #8b5cf6);
  color: #ffffff;
  display: flex;
  align-items: center;
  justify-content: center;
  font-size: 1.25rem;
  font-weight: 800;
  margin-bottom: 0.75rem;
  box-shadow: 0 4px 12px rgba(59, 130, 246, 0.4);
}

.sidebar-title {
  font-size: 1.25rem;
  font-weight: 800;
  color: var(--text-primary);
}

.sidebar-bio {
  font-size: 0.85rem;
  color: var(--text-muted);
  margin-top: 0.25rem;
}

.sidebar-nav-item {
  color: var(--text-secondary) !important;
  padding: 0.65rem 0.85rem !important;
  border-radius: var(--radius-sm);
  display: flex !important;
  align-items: center;
  gap: 0.6rem;
  font-weight: 500;
  transition: all 0.15s ease;
}

.sidebar-nav-item:hover,
.sidebar-nav-item.active {
  background-color: var(--border-subtle) !important;
  color: var(--accent) !important;
}

.sidebar-divider {
  height: 1px;
  background-color: var(--border);
  margin: 1rem 0;
}

.sidebar-footer {
  margin-top: 2.5rem;
  font-size: 0.78rem;
  color: var(--text-muted);
  line-height: 1.5;
}

.toggle {
  background-color: var(--bg-surface) !important;
  border: 1px solid var(--border);
  border-radius: var(--radius-md);
  box-shadow: var(--card-shadow);
  top: 0.85rem !important;
  left: 0.85rem !important;
}

.toggle:after {
  content: "☰" !important;
  font-size: 1.15rem;
  color: var(--text-primary);
  line-height: 1;
  display: flex;
  align-items: center;
  justify-content: center;
}

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

.site-footer {
  border-top: 1px solid var(--border);
  background-color: var(--bg-surface);
  padding: 2rem 0;
  margin-top: auto;
}

.footer-content {
  display: flex;
  flex-direction: column;
  align-items: center;
  justify-content: center;
  gap: 0.5rem;
  text-align: center;
  font-size: 0.85rem;
  color: var(--text-muted);
}

.footer-links {
  display: flex;
  gap: 0.75rem;
  align-items: center;
}

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

@media (max-width: 768px) {
  .hero-box {
    padding: 1.5rem 1.25rem;
  }
  .hero-title {
    font-size: 1.75rem;
  }
  .masthead-nav {
    display: none;
  }
}