/* ================================================================
   GLOBAL FONT CONFIGURATION
   ================================================================
   Change these variables to update fonts site-wide.
   Blog title and body fonts are separate from the main site fonts.
   ================================================================ */
:root {
  /* Main site fonts (About, Projects, navigation, etc.) */
  --font-heading: 'Inter', -apple-system, BlinkMacSystemFont, 'Segoe UI', sans-serif;
  --font-body: 'Inter', -apple-system, BlinkMacSystemFont, 'Segoe UI', sans-serif;

  /* Blog-specific fonts */
  --font-blog-title: 'Playfair Display', Georgia, 'Times New Roman', serif;
  --font-blog-body: 'Source Serif 4', Georgia, 'Times New Roman', serif;

  /* Code font */
  --font-code: 'JetBrains Mono', 'Fira Code', 'Consolas', monospace;

  /* Font weights */
  --fw-light: 300;
  --fw-regular: 400;
  --fw-medium: 500;
  --fw-semibold: 600;
  --fw-bold: 700;

  /* Font sizes */
  --fs-xs: 0.75rem;
  --fs-sm: 0.875rem;
  --fs-base: 1rem;
  --fs-lg: 1.125rem;
  --fs-xl: 1.25rem;
  --fs-2xl: 1.5rem;
  --fs-3xl: 1.875rem;
  --fs-4xl: 2.25rem;
  --fs-5xl: 3rem;

  /* Spacing */
  --spacing-xs: 0.25rem;
  --spacing-sm: 0.5rem;
  --spacing-md: 1rem;
  --spacing-lg: 1.5rem;
  --spacing-xl: 2rem;
  --spacing-2xl: 3rem;
  --spacing-3xl: 4rem;
  --spacing-4xl: 6rem;

  /* Border radius */
  --radius-sm: 0.375rem;
  --radius-md: 0.5rem;
  --radius-lg: 0.75rem;
  --radius-xl: 1rem;
  --radius-full: 9999px;

  /* Transitions */
  --transition-fast: 150ms ease;
  --transition-base: 250ms ease;
  --transition-slow: 350ms ease;

  /* Layout */
  --max-width: 1100px;
  --nav-height: 64px;
}

/* ================================================================
   LIGHT THEME (Default) — Academic / paper palette
   ================================================================ */
:root {
  --color-bg-primary: #fbfaf7;        /* warm ivory paper */
  --color-bg-secondary: #f4f2ec;
  --color-bg-tertiary: #ebe7dd;
  --color-bg-nav: rgba(251, 250, 247, 0.88);
  --color-text-primary: #14213d;       /* deep ink */
  --color-text-secondary: #4a5872;
  --color-text-tertiary: #7a8499;
  --color-accent: #14213d;             /* deep ink as primary accent */
  --color-accent-hover: #1d3557;
  --color-accent-light: #d9cfb8;
  --color-accent-subtle: #f1ece0;
  --color-accent-text: #14213d;
  --color-accent-secondary: #8a6a3a;   /* sepia / academic gold */
  --color-border: #e2dcce;
  --color-border-light: #ece7d8;
  --color-shadow: rgba(20, 33, 61, 0.06);
  --color-shadow-md: rgba(20, 33, 61, 0.10);
  --color-shadow-lg: rgba(20, 33, 61, 0.16);
  --color-code-bg: #f1ece0;
  --color-code-text: #14213d;
  --color-hero-start: #f4f2ec;
  --color-hero-end: #fbfaf7;
  --color-tag-bg: #ebe4d2;
  --color-tag-text: #14213d;
  --color-success: #2f6f4e;
  --color-warning: #8a6a3a;
  --color-pub-number: #14213d;
  --color-img-filter: none;
}

/* ================================================================
   DARK THEME — Midnight academic
   ================================================================ */
[data-theme="dark"] {
  --color-bg-primary: #0a0f1c;
  --color-bg-secondary: #111729;
  --color-bg-tertiary: #1a2238;
  --color-bg-nav: rgba(10, 15, 28, 0.78);
  --color-text-primary: #e8edf5;
  --color-text-secondary: #aab4cc;
  --color-text-tertiary: #6e7a96;
  --color-accent: #b8956a;             /* warm sepia / academic gold */
  --color-accent-hover: #d4b186;
  --color-accent-light: #2a2418;
  --color-accent-subtle: #18202f;
  --color-accent-text: #d4b186;
  --color-accent-secondary: #7aa7ff;
  --color-border: #1f2945;
  --color-border-light: #182238;
  --color-shadow: rgba(0, 0, 0, 0.35);
  --color-shadow-md: rgba(0, 0, 0, 0.45);
  --color-shadow-lg: rgba(0, 0, 0, 0.6);
  --color-code-bg: #0e1424;
  --color-code-text: #e8edf5;
  --color-hero-start: #0a0f1c;
  --color-hero-end: #111729;
  --color-tag-bg: #1f2945;
  --color-tag-text: #d4b186;
  --color-success: #34d399;
  --color-warning: #fbbf24;
  --color-pub-number: #d4b186;
  --color-img-filter: brightness(0.92);
}

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

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

body {
  font-family: var(--font-body);
  font-weight: var(--fw-regular);
  font-size: var(--fs-base);
  line-height: 1.7;
  color: var(--color-text-primary);
  background-color: var(--color-bg-primary);
  transition: background-color var(--transition-slow), color var(--transition-slow);
  -webkit-font-smoothing: antialiased;
  -moz-osx-font-smoothing: grayscale;
  min-height: 100vh;
  position: relative;
  overflow-x: hidden;
}

/* ================================================================
   LIVE BACKGROUND — Dark mode only
   Slow drifting gradient orbs + faint grid overlay.
   ================================================================ */
.bg-live {
  position: fixed;
  inset: 0;
  z-index: -1;
  pointer-events: none;
  overflow: hidden;
  opacity: 0;
  transition: opacity 600ms ease;
}

[data-theme="dark"] .bg-live { opacity: 1; }

.bg-live::before,
.bg-live::after {
  content: "";
  position: absolute;
  inset: -10%;
  background-image:
    linear-gradient(to right, rgba(180, 149, 106, 0.06) 1px, transparent 1px),
    linear-gradient(to bottom, rgba(180, 149, 106, 0.06) 1px, transparent 1px);
  background-size: 56px 56px;
  mask-image: radial-gradient(ellipse at center, #000 30%, transparent 75%);
  -webkit-mask-image: radial-gradient(ellipse at center, #000 30%, transparent 75%);
}

.bg-live::after {
  background-image: none;
  background:
    radial-gradient(38rem 38rem at 18% 22%, rgba(184, 149, 106, 0.18), transparent 60%),
    radial-gradient(34rem 34rem at 82% 78%, rgba(122, 167, 255, 0.14), transparent 60%),
    radial-gradient(28rem 28rem at 55% 50%, rgba(184, 149, 106, 0.08), transparent 65%);
  mask-image: none;
  -webkit-mask-image: none;
  animation: bgDrift 28s ease-in-out infinite alternate;
  filter: blur(20px);
}

@keyframes bgDrift {
  0%   { transform: translate3d(-2%, -1%, 0) scale(1); }
  50%  { transform: translate3d(2%, 3%, 0) scale(1.06); }
  100% { transform: translate3d(-1%, -2%, 0) scale(1.02); }
}

@media (prefers-reduced-motion: reduce) {
  .bg-live::after { animation: none; }
}

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

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

ul, ol {
  list-style: none;
}

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

button {
  cursor: pointer;
  border: none;
  background: none;
  font-family: inherit;
  font-size: inherit;
  color: inherit;
}

/* ================================================================
   TYPOGRAPHY
   ================================================================ */
h1, h2, h3, h4, h5, h6 {
  font-family: var(--font-heading);
  font-weight: var(--fw-bold);
  line-height: 1.3;
  color: var(--color-text-primary);
}

h1 { font-size: var(--fs-4xl); }
h2 { font-size: var(--fs-3xl); }
h3 { font-size: var(--fs-2xl); }
h4 { font-size: var(--fs-xl); }

p {
  color: var(--color-text-secondary);
  margin-bottom: var(--spacing-md);
}

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

.page-content {
  padding-top: calc(var(--nav-height) + var(--spacing-3xl));
  padding-bottom: var(--spacing-4xl);
  min-height: 100vh;
}

.section {
  margin-bottom: var(--spacing-4xl);
}

.section-title {
  font-family: var(--font-heading);
  font-size: var(--fs-2xl);
  font-weight: var(--fw-semibold);
  letter-spacing: -0.01em;
  margin-bottom: var(--spacing-xl);
  padding-bottom: var(--spacing-sm);
  border-bottom: 1px solid var(--color-border);
  display: block;
  position: relative;
}

.section-title::after {
  content: "";
  position: absolute;
  left: 0;
  bottom: -1px;
  width: 64px;
  height: 2px;
  background: var(--color-accent);
}

/* ================================================================
   NAVBAR
   ================================================================ */
.navbar {
  position: fixed;
  top: 0;
  left: 0;
  right: 0;
  height: var(--nav-height);
  background: var(--color-bg-nav);
  backdrop-filter: blur(12px);
  -webkit-backdrop-filter: blur(12px);
  border-bottom: 1px solid var(--color-border);
  z-index: 1000;
  transition: background-color var(--transition-slow), border-color var(--transition-slow);
}

.nav-inner {
  max-width: var(--max-width);
  margin: 0 auto;
  padding: 0 var(--spacing-xl);
  height: 100%;
  display: flex;
  align-items: center;
  justify-content: space-between;
}

.nav-logo {
  font-family: var(--font-heading);
  font-weight: var(--fw-bold);
  font-size: var(--fs-xl);
  color: var(--color-text-primary);
  text-decoration: none;
  letter-spacing: -0.02em;
}

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

.nav-links {
  display: flex;
  align-items: center;
  gap: var(--spacing-xs);
}

.nav-link {
  font-family: var(--font-body);
  font-weight: var(--fw-medium);
  font-size: var(--fs-sm);
  color: var(--color-text-secondary);
  text-decoration: none;
  padding: var(--spacing-sm) var(--spacing-md);
  border-radius: var(--radius-md);
  transition: all var(--transition-fast);
  position: relative;
}

.nav-link:hover {
  color: var(--color-text-primary);
  background: var(--color-bg-tertiary);
}

.nav-link.active {
  color: var(--color-accent);
  background: var(--color-accent-subtle);
}

.nav-right {
  display: flex;
  align-items: center;
  gap: var(--spacing-sm);
}

/* Theme Toggle */
.theme-toggle {
  width: 40px;
  height: 40px;
  display: flex;
  align-items: center;
  justify-content: center;
  border-radius: var(--radius-md);
  color: var(--color-text-secondary);
  transition: all var(--transition-fast);
}

.theme-toggle:hover {
  background: var(--color-bg-tertiary);
  color: var(--color-text-primary);
}

.theme-toggle svg {
  width: 20px;
  height: 20px;
}

.theme-toggle .icon-sun { display: none; }
.theme-toggle .icon-moon { display: block; }
[data-theme="dark"] .theme-toggle .icon-sun { display: block; }
[data-theme="dark"] .theme-toggle .icon-moon { display: none; }

/* Mobile Menu Button */
.mobile-menu-btn {
  display: none;
  width: 40px;
  height: 40px;
  align-items: center;
  justify-content: center;
  border-radius: var(--radius-md);
  color: var(--color-text-secondary);
  transition: all var(--transition-fast);
}

.mobile-menu-btn:hover {
  background: var(--color-bg-tertiary);
  color: var(--color-text-primary);
}

.mobile-menu-btn svg {
  width: 22px;
  height: 22px;
}

.mobile-menu-btn .icon-close { display: none; }
.mobile-menu-btn.active .icon-hamburger { display: none; }
.mobile-menu-btn.active .icon-close { display: block; }

/* ================================================================
   HERO SECTION
   ================================================================ */
.hero {
  text-align: center;
  padding: var(--spacing-3xl) var(--spacing-xl);
  background: linear-gradient(180deg, var(--color-hero-start) 0%, var(--color-hero-end) 100%);
  border: 1px solid var(--color-border);
  border-radius: var(--radius-xl);
  margin-bottom: var(--spacing-3xl);
}

[data-theme="dark"] .hero {
  background: linear-gradient(180deg, rgba(17, 23, 41, 0.65) 0%, rgba(10, 15, 28, 0.55) 100%);
  backdrop-filter: blur(6px);
  -webkit-backdrop-filter: blur(6px);
}

.hero-avatar {
  width: 160px;
  height: 160px;
  border-radius: var(--radius-full);
  object-fit: cover;
  border: 4px solid var(--color-accent);
  box-shadow: 0 0 0 6px var(--color-accent-light), 0 8px 32px var(--color-shadow-lg);
  margin-bottom: var(--spacing-xl);
  transition: transform var(--transition-base), box-shadow var(--transition-base);
}

.hero-avatar:hover {
  transform: scale(1.03);
  box-shadow: 0 0 0 8px var(--color-accent-light), 0 12px 40px var(--color-shadow-lg);
}

.hero-name {
  font-size: var(--fs-4xl);
  font-weight: var(--fw-bold);
  margin-bottom: var(--spacing-sm);
  letter-spacing: -0.02em;
}

.hero-motto {
  font-family: 'Great Vibes', cursive;
  font-weight: 400;
  font-size: 1.5rem;
  letter-spacing: 0.02em;
  margin-top: 0.5rem;
  color: var(--color-accent);
}

[data-theme="dark"] .hero-motto {
  background: linear-gradient(135deg, #2e6008, #000000);
  -webkit-background-clip: text;
  -webkit-text-fill-color: transparent;
  background-clip: text;
}

:root .hero-motto {
  background: linear-gradient(135deg, #bdc5d5, #c7d326);
  -webkit-background-clip: text;
  -webkit-text-fill-color: transparent;
  background-clip: text;
}

/* Publications jumper banner */
.hero-blog-jumper {
  display: inline-flex;
  align-items: center;
  gap: 0.6rem;
  margin-top: var(--spacing-xl);
  padding: 0.65rem 1.4rem;
  border-radius: var(--radius-full);
  background: var(--color-accent-subtle);
  border: 1px solid var(--color-border);
  color: var(--color-accent-text);
  font-family: var(--font-body);
  font-size: var(--fs-sm);
  font-weight: var(--fw-medium);
  text-decoration: none;
  transition: all var(--transition-base);
}

.hero-blog-jumper:hover {
  background: var(--color-accent-light);
  border-color: var(--color-accent);
  transform: translateY(-1px);
  box-shadow: 0 2px 12px var(--color-shadow-md);
}

.jumper-icon {
  font-size: 1.1rem;
}

.jumper-text {
  letter-spacing: 0.01em;
}

.jumper-arrow {
  width: 16px;
  height: 16px;
  transition: transform var(--transition-fast);
}

.hero-blog-jumper:hover .jumper-arrow {
  transform: translateX(3px);
}

@keyframes jumperPulse {
  0%, 100% { box-shadow: 0 0 0 0 transparent; }
  50% { box-shadow: 0 0 0 4px var(--color-border); }
}

.hero-tagline {
  font-size: var(--fs-lg);
  color: var(--color-text-secondary);
  max-width: 600px;
  margin: 0 auto var(--spacing-xl);
  line-height: 1.6;
}

.hero-social {
  display: flex;
  align-items: center;
  justify-content: center;
  gap: var(--spacing-md);
}

.social-link {
  display: flex;
  align-items: center;
  justify-content: center;
  width: 44px;
  height: 44px;
  border-radius: var(--radius-full);
  background: var(--color-bg-primary);
  color: var(--color-text-secondary);
  border: 1px solid var(--color-border);
  transition: all var(--transition-fast);
  box-shadow: 0 1px 3px var(--color-shadow);
}

.social-link:hover {
  color: var(--color-accent);
  border-color: var(--color-accent);
  background: var(--color-accent-subtle);
  transform: translateY(-2px);
  box-shadow: 0 4px 12px var(--color-shadow-md);
}

.social-link svg {
  width: 20px;
  height: 20px;
}

/* ================================================================
   SKILLS SECTION
   ================================================================ */
.skills-grid {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(280px, 1fr));
  gap: var(--spacing-lg);
}

.skill-category {
  background: var(--color-bg-secondary);
  border: 1px solid var(--color-border);
  border-radius: var(--radius-lg);
  padding: var(--spacing-xl);
  transition: all var(--transition-base);
}

[data-theme="dark"] .skill-category,
[data-theme="dark"] .education-card,
[data-theme="dark"] .project-card,
[data-theme="dark"] .publication-item {
  background: rgba(17, 23, 41, 0.72);
  backdrop-filter: blur(6px);
  -webkit-backdrop-filter: blur(6px);
}

.skill-category:hover {
  transform: translateY(-2px);
  box-shadow: 0 8px 24px var(--color-shadow-md);
  border-color: var(--color-accent);
}

.skill-category-title {
  font-size: var(--fs-sm);
  font-weight: var(--fw-semibold);
  text-transform: uppercase;
  letter-spacing: 0.05em;
  color: var(--color-accent);
  margin-bottom: var(--spacing-md);
}

.skill-tags {
  display: flex;
  flex-wrap: wrap;
  gap: var(--spacing-sm);
}

.skill-tag {
  display: inline-flex;
  align-items: center;
  gap: 0.35rem;
  font-size: var(--fs-sm);
  font-weight: var(--fw-medium);
  padding: var(--spacing-xs) var(--spacing-md);
  background: var(--color-tag-bg);
  color: var(--color-tag-text);
  border-radius: var(--radius-full);
  transition: all var(--transition-fast);
}

.skill-icon {
  width: 16px;
  height: 16px;
  flex-shrink: 0;
}

.skill-tag:hover {
  transform: scale(1.05);
}

/* ================================================================
   PUBLICATIONS SECTION
   ================================================================ */
.publication-list {
  display: flex;
  flex-direction: column;
  gap: var(--spacing-lg);
}

.publication-item {
  display: flex;
  gap: var(--spacing-lg);
  padding: var(--spacing-lg);
  background: var(--color-bg-secondary);
  border: 1px solid var(--color-border);
  border-radius: var(--radius-lg);
  transition: all var(--transition-base);
}

.publication-item:hover {
  border-color: var(--color-accent);
  box-shadow: 0 4px 16px var(--color-shadow);
}

.pub-number {
  flex-shrink: 0;
  width: 36px;
  height: 36px;
  display: flex;
  align-items: center;
  justify-content: center;
  background: var(--color-accent-light);
  color: var(--color-pub-number);
  font-weight: var(--fw-bold);
  font-size: var(--fs-sm);
  border-radius: var(--radius-full);
}

.pub-content {
  flex: 1;
}

.pub-title {
  font-size: var(--fs-base);
  font-weight: var(--fw-regular);
  line-height: 1.6;
  color: var(--color-text-primary);
  margin-bottom: var(--spacing-sm);
}

.pub-title strong {
  font-weight: var(--fw-semibold);
}

.pub-title em {
  color: var(--color-text-secondary);
}

.pub-link {
  display: inline-flex;
  align-items: center;
  gap: var(--spacing-xs);
  font-size: var(--fs-sm);
  font-weight: var(--fw-medium);
  color: var(--color-accent);
  padding: var(--spacing-xs) var(--spacing-sm);
  border-radius: var(--radius-sm);
  transition: all var(--transition-fast);
}

.pub-link:hover {
  background: var(--color-accent-subtle);
}

.pub-link svg {
  width: 14px;
  height: 14px;
}

/* ================================================================
   EDUCATION SECTION
   ================================================================ */
.education-list {
  display: flex;
  flex-direction: column;
  gap: var(--spacing-lg);
}

.education-card {
  display: flex;
  gap: var(--spacing-lg);
  padding: var(--spacing-xl);
  background: var(--color-bg-secondary);
  border: 1px solid var(--color-border);
  border-radius: var(--radius-lg);
  transition: all var(--transition-base);
  position: relative;
  overflow: hidden;
}

.education-card::before {
  content: '';
  position: absolute;
  left: 0;
  top: 0;
  bottom: 0;
  width: 4px;
  background: var(--color-accent);
}

.education-card:hover {
  transform: translateY(-2px);
  box-shadow: 0 8px 24px var(--color-shadow-md);
}

.education-icon {
  flex-shrink: 0;
  width: 56px;
  height: 56px;
  display: flex;
  align-items: center;
  justify-content: center;
  background: var(--color-bg-primary);
  border-radius: var(--radius-lg);
  overflow: hidden;
}

.education-logo {
  width: 100%;
  height: 100%;
  object-fit: contain;
  border-radius: var(--radius-lg);
}

.education-details {
  flex: 1;
}

.education-degree {
  font-size: var(--fs-lg);
  font-weight: var(--fw-semibold);
  color: var(--color-text-primary);
  margin-bottom: var(--spacing-xs);
}

.education-school {
  font-size: var(--fs-base);
  color: var(--color-accent-text);
  font-weight: var(--fw-medium);
  margin-bottom: var(--spacing-xs);
}

.education-meta {
  font-size: var(--fs-sm);
  color: var(--color-text-tertiary);
  display: flex;
  align-items: center;
  gap: var(--spacing-md);
}

.education-meta span {
  display: flex;
  align-items: center;
  gap: var(--spacing-xs);
}

/* ================================================================
   PROJECT CARDS
   ================================================================ */
.project-grid {
  display: grid;
  grid-template-columns: repeat(auto-fill, minmax(320px, 1fr));
  gap: var(--spacing-lg);
}

.project-card {
  background: var(--color-bg-secondary);
  border: 1px solid var(--color-border);
  border-radius: var(--radius-lg);
  padding: var(--spacing-xl);
  transition: all var(--transition-base);
  display: flex;
  flex-direction: column;
  position: relative;
}

.project-card:hover {
  transform: translateY(-3px);
  box-shadow: 0 12px 32px var(--color-shadow-md);
  border-color: var(--color-accent);
}

.project-card-header {
  display: flex;
  align-items: center;
  gap: var(--spacing-md);
  margin-bottom: var(--spacing-md);
}

.project-emoji {
  font-size: var(--fs-2xl);
}

.project-title {
  font-size: var(--fs-lg);
  font-weight: var(--fw-semibold);
}

.project-title a {
  color: var(--color-text-primary);
  text-decoration: none;
}

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

.project-description {
  font-size: var(--fs-sm);
  color: var(--color-text-secondary);
  flex: 1;
  line-height: 1.6;
  margin-bottom: var(--spacing-md);
}

.project-tags {
  display: flex;
  flex-wrap: wrap;
  gap: var(--spacing-xs);
}

.project-tag {
  font-size: var(--fs-xs);
  font-weight: var(--fw-medium);
  padding: 2px var(--spacing-sm);
  background: var(--color-accent-subtle);
  color: var(--color-accent);
  border-radius: var(--radius-full);
}

.project-status {
  position: absolute;
  top: var(--spacing-md);
  right: var(--spacing-md);
  font-size: var(--fs-xs);
  font-weight: var(--fw-semibold);
  padding: 2px var(--spacing-sm);
  border-radius: var(--radius-full);
}

.project-status.in-progress {
  background: #d1fae5;
  color: #065f46;
}

[data-theme="dark"] .project-status.in-progress {
  background: #064e3b;
  color: #6ee7b7;
}

.project-status.finished {
  background: #e2e8f0;
  color: #475569;
}

[data-theme="dark"] .project-status.finished {
  background: #1e293b;
  color: #94a3b8;
}

.project-link-btn {
  display: inline-flex;
  align-items: center;
  gap: var(--spacing-xs);
  font-size: var(--fs-sm);
  font-weight: var(--fw-medium);
  color: var(--color-accent);
  margin-top: auto;
  padding-top: var(--spacing-md);
  border-top: 1px solid var(--color-border-light);
}

.project-link-btn svg {
  width: 14px;
  height: 14px;
  transition: transform var(--transition-fast);
}

.project-link-btn:hover svg {
  transform: translateX(3px);
}

/* Project group sections (Currently Active / End of Life) */
.project-group {
  margin-bottom: var(--spacing-3xl);
}

.project-group-title {
  font-size: var(--fs-xl);
  font-weight: var(--fw-semibold);
  color: var(--color-text-primary);
  margin-bottom: var(--spacing-lg);
  padding-bottom: var(--spacing-sm);
  border-bottom: 1px solid var(--color-border);
  display: flex;
  align-items: center;
  gap: var(--spacing-sm);
}

.project-group-title::before {
  content: '';
  width: 6px;
  height: 22px;
  border-radius: 3px;
  background: var(--color-accent);
}

.project-group.end-of-life .project-group-title::before {
  background: var(--color-text-tertiary);
}

/* Full-width project cards inside groups */
.project-list {
  display: flex;
  flex-direction: column;
  gap: var(--spacing-lg);
}

.project-list .project-card {
  width: 100%;
}

.project-list .project-card .project-title {
  font-size: var(--fs-xl);
}

.project-list .project-card .project-description {
  font-size: var(--fs-base);
  max-width: 880px;
}

/* ================================================================
   BLOG LISTING
   ================================================================ */
.blog-filters {
  display: flex;
  flex-wrap: wrap;
  gap: var(--spacing-sm);
  margin-bottom: var(--spacing-2xl);
}

.filter-btn {
  font-family: var(--font-body);
  font-size: var(--fs-sm);
  font-weight: var(--fw-medium);
  padding: var(--spacing-sm) var(--spacing-lg);
  border-radius: var(--radius-full);
  background: var(--color-bg-secondary);
  color: var(--color-text-secondary);
  border: 1px solid var(--color-border);
  cursor: pointer;
  transition: all var(--transition-fast);
}

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

.filter-btn.active {
  background: var(--color-accent);
  color: #ffffff;
  border-color: var(--color-accent);
}

.filter-btn.active .filter-count {
  background: rgba(255, 255, 255, 0.25);
  color: #ffffff;
}

.filter-count {
  font-size: var(--fs-xs);
  font-weight: var(--fw-semibold);
  padding: 1px 6px;
  background: var(--color-accent-light);
  color: var(--color-accent);
  border-radius: var(--radius-full);
  margin-left: var(--spacing-xs);
}

.blog-cards {
  display: grid;
  grid-template-columns: repeat(auto-fill, minmax(320px, 1fr));
  gap: var(--spacing-lg);
}

.blog-card {
  background: var(--color-bg-secondary);
  border: 1px solid var(--color-border);
  border-radius: var(--radius-lg);
  padding: var(--spacing-xl);
  transition: all var(--transition-base);
  cursor: pointer;
  text-decoration: none;
  display: block;
}

.blog-card:hover {
  transform: translateY(-2px);
  box-shadow: 0 8px 24px var(--color-shadow-md);
  border-color: var(--color-accent);
}

.blog-card-date {
  font-size: var(--fs-xs);
  color: var(--color-text-tertiary);
  font-weight: var(--fw-medium);
  margin-bottom: var(--spacing-sm);
  text-transform: uppercase;
  letter-spacing: 0.05em;
}

.blog-card-title {
  font-family: var(--font-blog-title);
  font-size: var(--fs-xl);
  font-weight: var(--fw-semibold);
  color: var(--color-text-primary);
  margin-bottom: var(--spacing-sm);
  line-height: 1.4;
}

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

.blog-card-desc {
  font-size: var(--fs-sm);
  color: var(--color-text-secondary);
  line-height: 1.6;
  margin-bottom: var(--spacing-md);
}

.blog-card-context {
  font-size: var(--fs-xs);
  font-weight: var(--fw-semibold);
  padding: 2px var(--spacing-sm);
  background: var(--color-tag-bg);
  color: var(--color-tag-text);
  border-radius: var(--radius-full);
  display: inline-block;
}

.blog-card-keywords {
  display: flex;
  flex-wrap: wrap;
  gap: var(--spacing-xs);
}

/* Pinned posts */
.blog-section + .blog-section {
  margin-top: var(--spacing-2xl);
}

.blog-section-title {
  font-family: var(--font-blog-title);
  font-size: var(--fs-lg);
  font-weight: var(--fw-semibold);
  color: var(--color-text-primary);
  margin: 0 0 var(--spacing-lg);
  display: flex;
  align-items: center;
  gap: var(--spacing-sm);
}

.blog-section-icon {
  font-size: 1.1em;
}

.blog-card-pinned {
  position: relative;
  border-color: var(--color-accent);
  background: linear-gradient(135deg, var(--color-bg-secondary), var(--color-bg-tertiary, var(--color-bg-secondary)));
}

.blog-card-pin {
  position: absolute;
  top: var(--spacing-md);
  right: var(--spacing-md);
  font-size: 1rem;
  opacity: 0.7;
}

.blog-empty {
  text-align: center;
  padding: var(--spacing-4xl) var(--spacing-xl);
  color: var(--color-text-tertiary);
}

.blog-empty-icon {
  font-size: 3rem;
  margin-bottom: var(--spacing-md);
}

/* ================================================================
   BLOG POST VIEWER
   ================================================================ */
.post-header {
  text-align: center;
  margin-bottom: var(--spacing-3xl);
  padding-bottom: var(--spacing-2xl);
  border-bottom: 1px solid var(--color-border);
}

.post-back-link {
  display: inline-flex;
  align-items: center;
  gap: var(--spacing-sm);
  font-size: var(--fs-sm);
  font-weight: var(--fw-medium);
  color: var(--color-text-secondary);
  margin-bottom: var(--spacing-xl);
  transition: color var(--transition-fast);
}

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

.post-back-link svg {
  width: 16px;
  height: 16px;
}

.post-meta {
  display: flex;
  align-items: center;
  justify-content: center;
  gap: var(--spacing-md);
  margin-bottom: var(--spacing-lg);
  font-size: var(--fs-sm);
  color: var(--color-text-tertiary);
}

.post-meta-divider {
  width: 4px;
  height: 4px;
  border-radius: var(--radius-full);
  background: var(--color-text-tertiary);
}

.post-context-badge {
  font-size: var(--fs-xs);
  font-weight: var(--fw-semibold);
  padding: var(--spacing-xs) var(--spacing-md);
  background: var(--color-tag-bg);
  color: var(--color-tag-text);
  border-radius: var(--radius-full);
}

.post-title {
  font-family: var(--font-blog-title);
  font-size: var(--fs-5xl);
  font-weight: var(--fw-bold);
  line-height: 1.2;
  letter-spacing: -0.02em;
  margin-bottom: var(--spacing-md);
}

/* Post Content Typography */
.post-body {
  font-family: var(--font-blog-body);
  font-size: var(--fs-lg);
  line-height: 1.8;
  color: var(--color-text-primary);
  max-width: 740px;
  margin: 0 auto;
}

.post-body h1 {
  font-family: var(--font-blog-title);
  font-size: var(--fs-3xl);
  margin-top: var(--spacing-3xl);
  margin-bottom: var(--spacing-lg);
}

.post-body h2 {
  font-family: var(--font-blog-title);
  font-size: var(--fs-2xl);
  margin-top: var(--spacing-2xl);
  margin-bottom: var(--spacing-md);
}

.post-body h3 {
  font-family: var(--font-blog-title);
  font-size: var(--fs-xl);
  margin-top: var(--spacing-xl);
  margin-bottom: var(--spacing-md);
}

.post-body p {
  margin-bottom: var(--spacing-lg);
  color: var(--color-text-primary);
}

.post-body a {
  color: var(--color-accent);
  text-decoration: underline;
  text-underline-offset: 3px;
}

.post-body ul,
.post-body ol {
  margin-bottom: var(--spacing-lg);
  padding-left: var(--spacing-xl);
}

.post-body ul { list-style: disc; }
.post-body ol { list-style: decimal; }

.post-body li {
  margin-bottom: var(--spacing-sm);
  color: var(--color-text-primary);
}

.post-body blockquote {
  border-left: 4px solid var(--color-accent);
  padding: var(--spacing-md) var(--spacing-xl);
  margin: var(--spacing-xl) 0;
  background: var(--color-bg-secondary);
  border-radius: 0 var(--radius-md) var(--radius-md) 0;
  font-style: italic;
  color: var(--color-text-secondary);
}

.post-body img {
  max-width: 100%;
  border-radius: var(--radius-lg);
  margin: var(--spacing-xl) 0;
  box-shadow: 0 4px 16px var(--color-shadow);
}

.post-body pre {
  background: var(--color-code-bg);
  border: 1px solid var(--color-border);
  border-radius: var(--radius-lg);
  padding: var(--spacing-lg);
  overflow-x: auto;
  margin: var(--spacing-xl) 0;
  font-family: var(--font-code);
  font-size: var(--fs-sm);
  line-height: 1.6;
}

.post-body code {
  font-family: var(--font-code);
  font-size: 0.9em;
}

.post-body :not(pre) > code {
  background: var(--color-code-bg);
  padding: 2px var(--spacing-sm);
  border-radius: var(--radius-sm);
  color: var(--color-code-text);
  border: 1px solid var(--color-border);
}

.post-body .table-wrap {
  overflow-x: auto;
  margin: var(--spacing-xl) 0;
  -webkit-overflow-scrolling: touch;
}

.post-body table {
  width: 100%;
  border-collapse: collapse;
  margin: var(--spacing-xl) 0;
  font-size: 0.9em;
}

.post-body .table-wrap > table {
  margin: 0;
  min-width: max-content;
}

.post-body th,
.post-body td {
  padding: var(--spacing-sm) var(--spacing-md);
  border: 1px solid var(--color-border);
  text-align: left;
  white-space: nowrap;
}

.post-body th {
  background: var(--color-bg-tertiary);
  font-weight: var(--fw-semibold);
}

.post-body hr {
  border: none;
  height: 1px;
  background: var(--color-border);
  margin: var(--spacing-2xl) 0;
}

/* KaTeX overrides for blog */
.post-body .katex-display {
  margin: var(--spacing-xl) 0;
  overflow-x: auto;
  padding: var(--spacing-md) 0;
}

/* ================================================================
   FOOTER
   ================================================================ */
.footer {
  padding: var(--spacing-2xl) 0;
  border-top: 1px solid var(--color-border);
  text-align: center;
  color: var(--color-text-tertiary);
  font-size: var(--fs-sm);
  transition: border-color var(--transition-slow);
}

.footer-links {
  display: flex;
  align-items: center;
  justify-content: center;
  gap: var(--spacing-lg);
  margin-bottom: var(--spacing-md);
}

.footer-link {
  color: var(--color-text-tertiary);
  transition: color var(--transition-fast);
  display: inline-flex;
  align-items: center;
  gap: 0.4rem;
}

.footer-link svg {
  width: 16px;
  height: 16px;
  flex-shrink: 0;
}

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

/* ================================================================
   ANIMATIONS
   ================================================================ */
@keyframes fadeInUp {
  from {
    opacity: 0;
    transform: translateY(20px);
  }
  to {
    opacity: 1;
    transform: translateY(0);
  }
}

@keyframes fadeIn {
  from { opacity: 0; }
  to { opacity: 1; }
}

.animate-fade-in {
  animation: fadeIn 0.5s ease forwards;
}

.animate-fade-in-up {
  animation: fadeInUp 0.5s ease forwards;
}

.stagger-1 { animation-delay: 0.05s; }
.stagger-2 { animation-delay: 0.1s; }
.stagger-3 { animation-delay: 0.15s; }
.stagger-4 { animation-delay: 0.2s; }
.stagger-5 { animation-delay: 0.25s; }

/* ================================================================
   RESPONSIVE
   ================================================================ */
@media (max-width: 768px) {
  :root {
    --fs-4xl: 1.875rem;
    --fs-5xl: 2.25rem;
    --fs-3xl: 1.5rem;
  }

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

  .mobile-menu-btn {
    display: flex;
  }

  .nav-links {
    display: none;
    position: absolute;
    top: var(--nav-height);
    left: 0;
    right: 0;
    background: var(--color-bg-nav);
    backdrop-filter: blur(12px);
    -webkit-backdrop-filter: blur(12px);
    flex-direction: column;
    padding: var(--spacing-md);
    border-bottom: 1px solid var(--color-border);
    gap: var(--spacing-xs);
  }

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

  .nav-link {
    width: 100%;
    text-align: center;
    padding: var(--spacing-md);
  }

  .hero-avatar {
    width: 120px;
    height: 120px;
  }

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

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

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

  .publication-item {
    flex-direction: column;
    gap: var(--spacing-sm);
  }

  .pub-number {
    width: 30px;
    height: 30px;
  }

  .education-card {
    flex-direction: column;
    gap: var(--spacing-md);
  }

  .post-title {
    font-size: var(--fs-3xl);
  }
}

@media (max-width: 480px) {
  .hero-social {
    flex-direction: row;
    gap: var(--spacing-sm);
  }

  .blog-filters {
    gap: var(--spacing-xs);
  }

  .filter-btn {
    font-size: var(--fs-xs);
    padding: var(--spacing-xs) var(--spacing-md);
  }
}

/* ================================================================
   UTILITY CLASSES
   ================================================================ */
.sr-only {
  position: absolute;
  width: 1px;
  height: 1px;
  padding: 0;
  margin: -1px;
  overflow: hidden;
  clip: rect(0, 0, 0, 0);
  white-space: nowrap;
  border: 0;
}

.text-accent {
  color: var(--color-accent);
}

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

/* Loading state */
.loading {
  display: flex;
  align-items: center;
  justify-content: center;
  min-height: 200px;
}

.loading-spinner {
  width: 32px;
  height: 32px;
  border: 3px solid var(--color-border);
  border-top-color: var(--color-accent);
  border-radius: 50%;
  animation: spin 0.8s linear infinite;
}

@keyframes spin {
  to { transform: rotate(360deg); }
}

/* Highlight.js dark mode overrides */
[data-theme="dark"] .hljs {
  background: var(--color-code-bg) !important;
}