/* ========================================
   CSS Custom Properties — Light Theme (Default)
   ======================================== */
:root {
  --font-primary: 'Inter', -apple-system, BlinkMacSystemFont, 'Segoe UI', sans-serif;
  --font-mono: 'SF Mono', 'Fira Code', 'Consolas', monospace;

  --space-xs: 0.25rem;
  --space-sm: 0.5rem;
  --space-md: 1rem;
  --space-lg: 1.5rem;
  --space-xl: 2rem;
  --space-25xl: 2.5rem;
  --space-2xl: 3rem;
  --space-3xl: 4rem;

  --max-width: 960px;
  --header-height: 56px;

  --radius-sm: 4px;
  --radius-md: 8px;
  --radius-lg: 12px;
  --radius-4lg: 25pt;

  --transition-fast: 150ms ease;
  --transition-base: 250ms ease;

  /* Colors — Light */
  --color-bg: #ffffff;
  --color-bg-secondary: #f8f9fa;
  --color-bg-card: #ffffff;
  --color-text: #111111;
  --color-text-secondary: #555555;
  --color-text-tertiary: #666666;
  --color-border: #d9d9d9;
  --color-border-hover: #b3b3b3;
  --color-accent: #111111;
  --color-link: #111111;
  --color-link-hover: #555555;
  --color-tag-bg: #f0f0f0;
  --color-tag-text: #333333;
  --color-shadow: rgba(0, 0, 0, 0.06);
  --color-shadow-hover: rgba(0, 0, 0, 0.12);
  --color-header-bg: var(--color-bg-secondary);
  --color-header-border: rgba(0, 0, 0, 0.08);
  --color-popup-bg: #f5f5f5;
  --color-clock-bg: var(--color-bg-card);
  --color-clock-border: rgba(0, 0, 0, 0.08);

  /* Quick Nav — Refined Glass (Header Tone) */
  --color-quicknav-bg: rgba(248, 249, 250, 0.8);
  --color-quicknav-text: var(--color-text-secondary);
  --color-quicknav-border: rgba(0, 0, 0, 0.1);
  --color-quicknav-active-bg: rgba(0, 0, 0, 0.05);
}

/* ========================================
   Dark Theme
   ======================================== */
[data-theme="dark"] {
  --color-bg: #0a0a0a;
  --color-bg-secondary: #111111;
  --color-bg-card: #141414;
  --color-text: #e8e8e8;
  --color-text-secondary: #c8c8c8;
  --color-text-tertiary: #a0a0a0;
  --color-border: #272727;
  --color-border-hover: #3a3a3a;
  --color-accent: #e8e8e8;
  --color-link: #e8e8e8;
  --color-link-hover: #c0c0c0;
  --color-tag-bg: #1e1e1e;
  --color-tag-text: #d0d0d0;
  --color-shadow: rgba(0, 0, 0, 0.3);
  --color-shadow-hover: rgba(0, 0, 0, 0.5);
  --color-header-bg: var(--color-bg-secondary);
  --color-header-border: rgba(255, 255, 255, 0.08);
  --color-popup-bg: #1a1a1a;
  --color-clock-bg: var(--color-bg-card);
  --color-clock-border: rgba(255, 255, 255, 0.06);

  /* Quick Nav — Refined Dark Glass (Header Tone) */
  --color-quicknav-bg: rgba(17, 17, 17, 0.85);
  --color-quicknav-text: var(--color-text-secondary);
  --color-quicknav-border: rgba(255, 255, 255, 0.1);
  --color-quicknav-active-bg: rgba(255, 255, 255, 0.08);
}

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

html {
  scroll-behavior: smooth;
  scroll-padding-top: calc(var(--header-height) + var(--space-xl));
}

body {
  font-family: var(--font-primary);
  font-size: 15px;
  line-height: 1.7;
  color: var(--color-text);
  background: var(--color-bg);
  transition: background-color var(--transition-base), color var(--transition-base);
  -webkit-font-smoothing: antialiased;
  -moz-osx-font-smoothing: grayscale;
}

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

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

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

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

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

/* Section padding */
.section {
  padding-top: var(--space-xl);
  padding-bottom: var(--space-25xl);
  position: relative;
  scroll-margin-top: calc(var(--header-height) + 20px);
}

/* Section divider line (stays within margins using pseudo-element) */
.section::after {
  content: '';
  position: absolute;
  bottom: 0;
  left: 0;
  right: 0;
  margin: 0 auto;
  max-width: calc(var(--max-width) - var(--space-xl) * 2);
  height: 1.5px;
  background: var(--color-border);
  will-change: transform;
  transform: translateZ(0);
}

/* Home section and page title sections need more top padding */
#home.section,
section:has(.page-title) {
  padding-top: var(--space-3xl);
}

/* Remove bottom margin on last publication card */
body:has(#publications-list) .pub-card:last-child {
  margin-bottom: 0;
}

/* Last section needs more bottom padding */
#skills.section,
body:has(#projects-list) section:has(.page-title):last-of-type,
body:has(#publications-list) section:has(.page-title):last-of-type {
  padding-bottom: var(--space-3xl);
}

/* Remove divider on last section */
.section:last-of-type::after {
  display: none;
}

/* Section title styling */
.section-title {
  font-size: 1.25rem;
  font-weight: 600;
  letter-spacing: -0.01em;
  margin-bottom: var(--space-lg);
  color: var(--color-text);
}

/* ========================================
   Header / Nav
   ======================================== */
#site-header {
  position: fixed;
  top: 0;
  left: 0;
  right: 0;
  height: var(--header-height);
  background: var(--color-header-bg);
  backdrop-filter: blur(12px);
  -webkit-backdrop-filter: blur(12px);
  border-bottom: 1px solid var(--color-header-border);
  z-index: 100;
  transition: background-color var(--transition-base), border-color var(--transition-base);
}

.nav {
  display: flex;
  align-items: center;
  justify-content: space-between;
  height: 100%;
}

.nav-name {
  font-size: 1rem;
  font-weight: 600;
  color: var(--color-text);
  text-decoration: none;
  letter-spacing: -0.01em;
  opacity: 0;
  pointer-events: none;
  transition: opacity var(--transition-base);
}

.nav-name.visible {
  opacity: 1;
  pointer-events: auto;
}

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

.nav-links a {
  font-size: 0.85rem;
  font-weight: 400;
  color: var(--color-text-secondary);
  text-decoration: none;
  transition: color var(--transition-fast);
  position: relative;
}

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

.nav-links a.active::after {
  content: '';
  position: absolute;
  bottom: -4px;
  left: 0;
  right: 0;
  height: 1.5px;
  background: var(--color-text);
}

/* Theme toggle */
.theme-toggle-btn {
  display: flex;
  align-items: center;
  justify-content: center;
  width: 32px;
  height: 32px;
  border-radius: var(--radius-md);
  color: var(--color-text-secondary);
  transition: color var(--transition-fast), background-color var(--transition-fast);
}

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

.theme-toggle-btn svg {
  width: 18px;
  height: 18px;
}

.icon-moon {
  display: block;
}

.icon-sun {
  display: none;
}

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

[data-theme="dark"] .icon-sun {
  display: block;
}

/* Mobile menu button */
.mobile-menu-btn {
  display: none;
  flex-direction: column;
  justify-content: center;
  gap: 4px;
  width: 32px;
  height: 32px;
  padding: 6px;
}

.mobile-menu-btn span {
  display: block;
  height: 1.5px;
  background: var(--color-text);
  border-radius: 1px;
  transition: transform var(--transition-base), opacity var(--transition-fast);
}

.mobile-menu-btn.active span:nth-child(1) {
  transform: translateY(5.5px) rotate(45deg);
}

.mobile-menu-btn.active span:nth-child(2) {
  opacity: 0;
}

.mobile-menu-btn.active span:nth-child(3) {
  transform: translateY(-5.5px) rotate(-45deg);
}

/* ========================================
   Digital Clock (fixed, hanging from header)
   ======================================== */
/* Digital clock (centered on page) */
#digital-clock {
  position: fixed;
  top: var(--header-height);
  left: 50%;
  transform: translateX(-50%);
  display: flex;
  align-items: center;
  gap: var(--space-sm);
  padding: var(--space-xs) var(--space-md);
  background: var(--color-clock-bg);
  backdrop-filter: blur(8px);
  -webkit-backdrop-filter: blur(8px);
  border: 1px solid var(--color-clock-border);
  border-top: none;
  border-radius: 0 0 var(--radius-md) var(--radius-md);
  font-family: var(--font-mono);
  font-size: 0.7rem;
  color: var(--color-text);
  z-index: 50;
  transition: opacity 0.4s ease, background-color var(--transition-base), border-color var(--transition-base), color var(--transition-base);
  pointer-events: none;
  user-select: none;
  white-space: nowrap;
}

#clock-time {
  font-weight: 600;
  font-size: 0.75rem;
  color: var(--color-text);
}

#clock-separator {
  color: var(--color-text-tertiary);
}

/* ========================================
   About Section
   ======================================== */
.about-grid {
  display: flex;
  flex-direction: column;
  align-items: center;
  gap: var(--space-xl);
}

.about-text h1 {
  font-size: 1.75rem;
  font-weight: 700;
  letter-spacing: -0.02em;
  margin-bottom: var(--space-xs);
}

.affiliation {
  font-size: 0.85rem;
  color: var(--color-text-secondary);
  margin-bottom: var(--space-lg);
}

.about-text p,
.bio p {
  font-size: 0.9rem;
  color: var(--color-text-secondary);
  margin-bottom: var(--space-md);
  line-height: 1.75;
  text-align: justify;
  text-justify: inter-word;
}

/* Remove margin on last paragraph in bio/about */
.about-text p:last-child,
.bio p:last-child {
  margin-bottom: 0;
}

.bio a {
  text-decoration: underline;
  text-underline-offset: 2px;
}

.about-profile {
  display: flex;
  flex-direction: column;
  align-items: center;
  gap: var(--space-md);
  flex-shrink: 0;
}

.profile-img {
  width: 180px;
  height: 180px;
  border-radius: var(--radius-4lg);
  object-fit: cover;
  border: 3px solid var(--color-border);
  transition: border-color var(--transition-base);
}

.social-links {
  display: flex;
  gap: var(--space-sm);
}

.social-links a {
  display: flex;
  align-items: center;
  justify-content: center;
  width: 36px;
  height: 36px;
  border-radius: var(--radius-md);
  color: var(--color-text-secondary);
  background: var(--color-tag-bg);
  transition: color var(--transition-fast), background-color var(--transition-fast);
}

.social-links a:hover {
  background: var(--color-border);
}

/* Pastel hover colors for each social icon */
.social-links a[aria-label="Email"]:hover {
  color: #e57373;
  background: rgba(229, 115, 115, 0.12);
}

.social-links a[aria-label="LinkedIn"]:hover {
  color: #3a7bbf;
  background: rgba(58, 123, 191, 0.12);
}

.social-links a[aria-label="GitHub"]:hover {
  color: #9e9e9e;
  background: rgba(158, 158, 158, 0.12);
}

.social-links a[aria-label="Google Scholar"]:hover {
  color: #4da8da;
  background: rgba(77, 168, 218, 0.12);
}

[data-theme="dark"] .social-links a[aria-label="Email"]:hover {
  background: rgba(229, 115, 115, 0.15);
}

[data-theme="dark"] .social-links a[aria-label="LinkedIn"]:hover {
  background: rgba(58, 123, 191, 0.15);
}

[data-theme="dark"] .social-links a[aria-label="GitHub"]:hover {
  background: rgba(158, 158, 158, 0.15);
}

[data-theme="dark"] .social-links a[aria-label="Google Scholar"]:hover {
  background: rgba(77, 168, 218, 0.15);
}

.social-links svg {
  width: 18px;
  height: 18px;
}

/* ========================================
   News
   ======================================== */
.news-list {
  display: flex;
  flex-direction: column;
  gap: 0;
}

.news-item {
  display: flex;
  gap: var(--space-lg);
  padding: var(--space-sm) 0;
  font-size: 0.875rem;
  border-bottom: 1px solid var(--color-border);
}

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

.news-date {
  flex-shrink: 0;
  width: 80px;
  font-weight: 500;
  color: var(--color-text-tertiary);
  font-size: 0.8rem;
}

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

.news-text a {
  text-decoration: underline;
  text-underline-offset: 2px;
}

.news-more-container {
  max-height: 0;
  overflow: hidden;
  transition: max-height 0.4s ease;
}

.news-more-container.open {
  max-height: 200px;
  overflow-y: auto;
  border-top: 1px solid var(--color-border);
}

.news-toggle-btn {
  display: inline-block;
  margin-top: var(--space-md);
  font-size: 0.8rem;
  font-weight: 500;
  color: var(--color-text-secondary);
  padding: 4px 14px;
  border-radius: var(--radius-sm);
  border: 1px solid var(--color-border);
  background: transparent;
  cursor: pointer;
  transition: all var(--transition-fast);
}

.news-toggle-btn:hover {
  color: var(--color-text);
  border-color: var(--color-border-hover);
  background: var(--color-tag-bg);
}

/* ========================================
   Publications
   ======================================== */
.pub-year-group {
  margin-bottom: var(--space-md);
  border: 1px solid var(--color-border);
  border-radius: var(--radius-lg);
  overflow: hidden;
  transition: border-color var(--transition-base);
}

.pub-year-group:last-child {
  margin-bottom: 0;
}

.pub-year-group[open] {
  border-color: var(--color-border-hover);
}

.pub-year-label {
  display: flex;
  align-items: center;
  justify-content: space-between;
  font-size: 1rem;
  font-weight: 600;
  color: var(--color-text);
  padding: var(--space-md) var(--space-lg);
  cursor: pointer;
  user-select: none;
  list-style: none;
  background: var(--color-bg-card);
  transition: background-color var(--transition-fast), color var(--transition-base);
}

.pub-year-label::-webkit-details-marker {
  display: none;
}

.pub-year-label::after {
  content: '';
  width: 8px;
  height: 8px;
  border-right: 2px solid var(--color-text-tertiary);
  border-bottom: 2px solid var(--color-text-tertiary);
  transform: rotate(-45deg);
  transition: transform var(--transition-base);
  flex-shrink: 0;
}

.pub-year-group[open]>.pub-year-label::after {
  transform: rotate(45deg);
}

.pub-year-label:hover {
  background: var(--color-bg-secondary);
}

.pub-year-label .pub-year-count {
  font-size: 0.75rem;
  font-weight: 400;
  color: var(--color-text-tertiary);
  margin-left: var(--space-sm);
}

.pub-year-content {
  padding: var(--space-md) var(--space-lg) var(--space-lg);
  max-height: 400px;
  overflow-y: auto;
}

.pub-card {
  display: flex;
  gap: var(--space-lg);
  padding: var(--space-md);
  margin-bottom: var(--space-md);
  background: var(--color-bg-card);
  border: 1px solid var(--color-border);
  border-radius: var(--radius-lg);
  transition: box-shadow var(--transition-base), border-color var(--transition-base), background-color var(--transition-base);
}

.pub-card:hover {
  box-shadow: 0 2px 16px var(--color-shadow-hover);
  border-color: var(--color-border-hover);
}

.pub-image {
  width: 220px;
  min-width: 220px;
  height: 120px;
  border-radius: var(--radius-md);
  object-fit: fill;
  align-self: flex-start;
}

.pub-content {
  flex: 1;
  min-width: 0;
}

.pub-title-row {
  display: flex;
  align-items: flex-start;
  gap: var(--space-sm);
  margin-bottom: var(--space-xs);
  flex-wrap: wrap;
}

.pub-title {
  font-size: 0.95rem;
  font-weight: 600;
  line-height: 1.4;
  color: var(--color-text);
}

.badge {
  display: inline-block;
  font-size: 0.65rem;
  font-weight: 600;
  letter-spacing: 0.03em;
  padding: 2px 8px;
  border-radius: var(--radius-sm);
  white-space: nowrap;
  flex-shrink: 0;
  text-transform: uppercase;
}

.badge-arxiv {
  background: #b31b1b;
  color: #fff;
}

.badge-eccvw {
  background: #7c3aed;
  color: #fff;
}

.badge-cvpr {
  background: #e74c3c;
  color: #fff;
}

.badge-iccv {
  background: #3b82f6;
  color: #fff;
}

.badge-neurips {
  background: #059669;
  color: #fff;
}

.pub-authors {
  font-size: 0.8rem;
  color: var(--color-text-secondary);
  margin-bottom: 2px;
}

.pub-venue {
  font-size: 0.78rem;
  color: var(--color-text-tertiary);
  margin-bottom: var(--space-sm);
}

.pub-links {
  display: flex;
  flex-wrap: wrap;
  gap: var(--space-sm);
}

.pub-link,
.pub-link-btn {
  display: inline-block;
  font-size: 0.75rem;
  font-weight: 500;
  padding: 3px 10px;
  border-radius: var(--radius-sm);
  border: 1px solid var(--color-border);
  color: var(--color-text-secondary);
  background: transparent;
  transition: all var(--transition-fast);
  cursor: pointer;
  text-decoration: none;
}

.pub-link:hover,
.pub-link-btn:hover {
  color: var(--color-text);
  border-color: var(--color-border-hover);
  background: var(--color-tag-bg);
}

.pub-abstract,
.pub-bibtex {
  margin-top: var(--space-md);
  padding: var(--space-md);
  background: var(--color-popup-bg);
  border-radius: var(--radius-md);
  font-size: 0.8rem;
  line-height: 1.65;
  color: var(--color-text-secondary);
  transition: background-color var(--transition-base), color var(--transition-base);
}

.pub-bibtex {
  position: relative;
}

.pub-bibtex pre {
  font-family: var(--font-mono);
  font-size: 0.72rem;
  white-space: pre-wrap;
  word-break: break-word;
  margin: 0;
  color: var(--color-text-secondary);
}

.copy-btn {
  position: absolute;
  top: var(--space-sm);
  right: var(--space-sm);
  font-size: 0.7rem;
  font-weight: 500;
  padding: 3px 10px;
  border-radius: var(--radius-sm);
  border: 1px solid var(--color-border);
  color: var(--color-text-secondary);
  background: var(--color-bg-card);
  transition: all var(--transition-fast);
}

.copy-btn:hover {
  color: var(--color-text);
  border-color: var(--color-border-hover);
}

/* ========================================
   Projects
   ======================================== */
.project-category {
  margin-bottom: var(--space-2xl);
}

.project-category:last-child {
  margin-bottom: 0;
}

.project-category-title {
  font-size: 1rem;
  font-weight: 600;
  color: var(--color-text);
  margin-bottom: var(--space-lg);
  padding-bottom: var(--space-xs);
  border-bottom: 1px solid var(--color-border);
}

/* Project card as details/summary expandable */
.project-card {
  margin-bottom: var(--space-md);
  background: var(--color-bg-card);
  border: 1px solid var(--color-border);
  border-radius: var(--radius-lg);
  overflow: hidden;
  transition: border-color var(--transition-base), background-color var(--transition-base);
}

.project-card[open] {
  border-color: var(--color-border-hover);
}

.project-summary {
  display: flex;
  align-items: center;
  gap: var(--space-lg);
  padding: var(--space-md) var(--space-lg);
  cursor: pointer;
  user-select: none;
  list-style: none;
  transition: background-color var(--transition-fast);
}

.project-summary::-webkit-details-marker {
  display: none;
}

.project-summary:hover {
  background: var(--color-bg-secondary);
}

.project-thumb {
  width: 200px;
  min-width: 200px;
  height: auto;
  border-radius: var(--radius-md);
  object-fit: contain;
  align-self: center;
  flex-shrink: 0;
}

.project-summary-text {
  flex: 1;
  min-width: 0;
}

.project-title {
  font-size: 0.95rem;
  font-weight: 600;
  color: var(--color-text);
  margin-bottom: var(--space-xs);
}

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

.project-expand-icon {
  width: 8px;
  height: 8px;
  border-right: 2px solid var(--color-text-tertiary);
  border-bottom: 2px solid var(--color-text-tertiary);
  transform: rotate(-45deg);
  transition: transform var(--transition-base);
  flex-shrink: 0;
  margin-left: var(--space-sm);
}

.project-card[open]>.project-summary .project-expand-icon {
  transform: rotate(45deg);
}

.project-details-content {
  padding: 0 var(--space-lg) var(--space-lg);
  border-top: 1px solid var(--color-border);
}

.project-details-body {
  display: flex;
  gap: var(--space-lg);
  margin-top: var(--space-md);
  margin-bottom: var(--space-md);
}

.project-details-text {
  flex: 1;
  min-width: 0;
}

.project-desc {
  font-size: 0.82rem;
  color: var(--color-text-secondary);
  line-height: 1.7;
  margin-bottom: var(--space-md);
}

.project-embedded-img {
  width: 280px;
  min-width: 280px;
  height: auto;
  border-radius: var(--radius-md);
  border: 1px solid var(--color-border);
  object-fit: contain;
  align-self: flex-start;
}

.project-tags {
  display: flex;
  flex-wrap: wrap;
  gap: var(--space-xs);
  margin-bottom: var(--space-sm);
}

.tag {
  display: inline-block;
  font-size: 0.7rem;
  font-weight: 500;
  padding: 2px 10px;
  border-radius: var(--radius-sm);
  background: var(--color-tag-bg);
  color: var(--color-tag-text);
  transition: background-color var(--transition-base), color var(--transition-base);
}

.project-links {
  display: flex;
  gap: var(--space-sm);
}

.project-links a {
  font-size: 0.75rem;
  font-weight: 500;
  padding: 3px 10px;
  border-radius: var(--radius-sm);
  border: 1px solid var(--color-border);
  color: var(--color-text-secondary);
  transition: all var(--transition-fast);
}

.project-links a:hover {
  color: var(--color-text);
  border-color: var(--color-border-hover);
  background: var(--color-tag-bg);
}

/* Color-coded project link buttons */
.project-link-github {
  color: #6e40c9 !important;
  border-color: rgba(110, 64, 201, 0.3) !important;
}

.project-link-github:hover {
  background: rgba(110, 64, 201, 0.08) !important;
  border-color: rgba(110, 64, 201, 0.5) !important;
}

.project-link-thesis {
  color: #d97706 !important;
  border-color: rgba(217, 119, 6, 0.3) !important;
}

.project-link-thesis:hover {
  background: rgba(217, 119, 6, 0.08) !important;
  border-color: rgba(217, 119, 6, 0.5) !important;
}

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

.education-item {
  padding: var(--space-lg);
  background: var(--color-bg-card);
  border: 1px solid var(--color-border);
  border-radius: var(--radius-lg);
  transition: background-color var(--transition-base), border-color var(--transition-base);
}

.education-header {
  display: flex;
  justify-content: space-between;
  align-items: baseline;
  flex-wrap: wrap;
  gap: var(--space-sm);
  margin-bottom: var(--space-xs);
}

.education-header h3 {
  font-size: 0.95rem;
  font-weight: 600;
}

.education-location {
  font-size: 0.78rem;
  color: var(--color-text-tertiary);
}

.degree-line {
  display: flex;
  justify-content: space-between;
  align-items: baseline;
  flex-wrap: wrap;
  gap: var(--space-sm);
  margin-bottom: var(--space-xs);
}

.degree {
  font-size: 0.85rem;
  color: var(--color-text-secondary);
}

.dates {
  font-size: 0.78rem;
  color: var(--color-text-tertiary);
  white-space: nowrap;
}


.supervisor {
  font-size: 0.8rem;
  color: var(--color-text-secondary);
}

.supervisor a {
  color: var(--color-text-secondary);
  text-decoration: underline;
  text-underline-offset: 2px;
}

.classification {
  font-size: 0.8rem;
  color: var(--color-text-secondary);
  font-style: italic;
}

/* ========================================
   Skills
   ======================================== */
.skills-grid {
  display: grid;
  grid-template-columns: 1fr;
  gap: var(--space-lg);
  justify-items: center;
  text-align: center;
}

.skill-category h3 {
  font-size: 0.85rem;
  font-weight: 600;
  margin-bottom: var(--space-sm);
  color: var(--color-text);
}

.skill-tags {
  display: flex;
  flex-wrap: wrap;
  gap: var(--space-xs);
  justify-content: center;
}

/* ========================================
   Page Title (Publications / Projects pages)
   ======================================== */
/* Page title styling */
.page-title {
  font-size: 1.5rem;
  font-weight: 700;
  letter-spacing: -0.02em;
  margin-bottom: var(--space-lg);
  color: var(--color-text);
}

/* Year heading on publications page (flat, not collapsible) */
.pub-year-section {
  margin-bottom: var(--space-2xl);
}

.pub-year-section:last-child {
  margin-bottom: 0;
}

.pub-year-heading {
  font-size: 1.1rem;
  font-weight: 600;
  color: var(--color-text);
  margin-bottom: var(--space-lg);
  padding-bottom: var(--space-xs);
  border-bottom: 1px solid var(--color-border);
}

/* ========================================
   Full Project Cards (Projects page)
   ======================================== */

/* Grid layout for categories without embedded images (e.g. Academic) */
.project-cards-grid {
  display: grid;
  grid-template-columns: 1fr 1fr;
  gap: var(--space-lg);
  align-items: start;
}

/* List layout for categories with embedded images (e.g. Libraries) */
.project-cards-list {
  display: flex;
  flex-direction: column;
  gap: var(--space-lg);
}

.project-card-full {
  display: flex;
  flex-direction: column;
  background: var(--color-bg-card);
  border: 1px solid var(--color-border);
  border-radius: var(--radius-lg);
  overflow: hidden;
  transition: border-color var(--transition-base), background-color var(--transition-base);
}

.project-card-full[open] {
  border-color: var(--color-border-hover);
}

.project-full-summary {
  display: block;
  cursor: pointer;
  list-style: none;
  user-select: none;
}

.project-full-summary::-webkit-details-marker {
  display: none;
}

.project-full-summary:hover {
  background: var(--color-bg-secondary);
}

.project-full-image {
  width: 100%;
  height: 200px;
  object-fit: fill;
  display: block;
}

.project-full-image-cover {
  object-fit: cover;
}

.project-full-header {
  display: flex;
  align-items: center;
  justify-content: space-between;
  padding: var(--space-md) var(--space-lg);
  border-top: 1px solid var(--color-border);
}

.project-full-title {
  font-size: 0.95rem;
  font-weight: 600;
  color: var(--color-text);
  margin: 0;
}

.project-full-hint {
  font-size: 0.72rem;
  color: var(--color-text-tertiary);
  white-space: nowrap;
  flex-shrink: 0;
  margin-left: var(--space-md);
  align-self: flex-end;
}


.project-full-content {
  padding: var(--space-lg);
  border-top: 1px solid var(--color-border);
  display: flex;
  flex-direction: column;
  flex: 1;
}

.project-full-content .project-tags {
  margin-top: auto;
  padding-top: var(--space-md);
}

.project-full-content .project-links {
  padding-top: var(--space-sm);
}

/* Split layout: description left, embedded plot right */
.project-full-split {
  display: flex;
  gap: var(--space-lg);
}

.project-full-desc {
  flex: 1;
  min-width: 0;
}

.project-full-embedded {
  width: 380px;
  min-width: 380px;
  height: auto;
  border-radius: var(--radius-md);
  border: 1px solid var(--color-border);
  object-fit: contain;
  align-self: flex-start;
}

/* ========================================
   Footer
   ======================================== */
.footer {
  padding: var(--space-md) 0;
  background: var(--color-header-bg);
  border-top: 1px solid var(--color-header-border);
  text-align: center;
  font-size: 0.78rem;
  color: var(--color-text-tertiary);
  transition: background-color var(--transition-base), border-color var(--transition-base), color var(--transition-base);
}

/* ========================================
   Scroll Animation
   ======================================== */
.fade-in {
  opacity: 0;
  transform: translateY(16px);
  transition: opacity 0.5s ease, transform 0.5s ease;
}

.fade-in.visible {
  opacity: 1;
  transform: translateY(0);
}

/* ========================================
   Main offset for fixed header
   ======================================== */
main {
  padding-top: var(--header-height);
}

/* ========================================
   Quick Navigation
   ======================================== */
.quick-nav {
  position: fixed;
  /* Pixel-perfect centering in right margin (compensated for visual balance) */
  left: calc(50% + (var(--max-width) / 2) + ((100vw - var(--max-width)) / 4) - 16px);
  top: 50%;
  transform: translate(-50%, -50%);
  width: auto;
  max-width: calc((100vw - var(--max-width)) / 2 - var(--space-xl));
  display: none;
  /* Shown on wider screens */
  z-index: 1000;
  text-align: center;
  pointer-events: none;
}

.quick-nav-inner {
  display: inline-block;
  background: var(--color-quicknav-bg);
  backdrop-filter: blur(12px);
  -webkit-backdrop-filter: blur(12px);
  border: 1px solid var(--color-quicknav-border);
  border-radius: var(--radius-lg);
  padding: var(--space-md);
  pointer-events: auto;
  min-width: 140px;
  box-shadow: none;
  /* Shadow removed per request */
}

.quick-nav-title {
  font-size: 0.7rem;
  font-weight: 700;
  text-transform: uppercase;
  letter-spacing: 0.08em;
  color: var(--color-quicknav-text);
  margin-bottom: var(--space-sm);
  opacity: 0.5;
}

.quick-nav-list {
  list-style: none;
  display: flex;
  flex-direction: column;
  gap: var(--space-xs);
}

.quick-nav-link {
  font-size: 0.75rem;
  color: var(--color-quicknav-text);
  opacity: 0.7;
  text-decoration: none;
  transition: opacity var(--transition-fast), transform var(--transition-fast);
  display: block;
  padding: 4px 8px;
  border-radius: var(--radius-sm);
}

.quick-nav-link:hover {
  opacity: 1;
  background: var(--color-quicknav-active-bg);
  transform: translateY(-1px);
}

.quick-nav-link.active {
  opacity: 1;
  font-weight: 600;
  color: var(--color-accent);
  background: var(--color-quicknav-active-bg);
}

/* Back to Top Button */
.back-to-top {
  position: fixed;
  bottom: var(--space-xl);
  right: var(--space-xl);
  width: 44px;
  height: 44px;
  background: var(--color-quicknav-bg);
  backdrop-filter: blur(12px);
  -webkit-backdrop-filter: blur(12px);
  border: 1px solid var(--color-quicknav-border);
  border-radius: 50%;
  color: var(--color-text);
  display: flex;
  align-items: center;
  justify-content: center;
  cursor: pointer;
  z-index: 1000;
  opacity: 0;
  visibility: hidden;
  transition: all var(--transition-base);
  box-shadow: 0 4px 12px rgba(0, 0, 0, 0.1);
}

.back-to-top.visible {
  opacity: 1;
  visibility: visible;
}

.back-to-top:hover {
  transform: translateY(-4px);
  background: var(--color-bg-card);
  box-shadow: 0 6px 16px rgba(0, 0, 0, 0.15);
}

.back-to-top svg {
  width: 20px;
  height: 20px;
  stroke: currentColor;
  stroke-width: 2.5;
  fill: none;
}

@media (max-width: 768px) {
  .back-to-top {
    bottom: var(--space-lg);
    right: var(--space-lg);
    width: 40px;
    height: 40px;
  }
}



/* ========================================
   Responsive — Tablet (>= 640px)
   ======================================== */
@media (min-width: 640px) {
  .container {
    padding: 0 var(--space-xl);
  }

  .about-grid {
    flex-direction: row;
    align-items: flex-start;
    gap: var(--space-2xl);
  }

  .about-text h1 {
    font-size: 2rem;
  }

  .profile-img {
    width: 220px;
    height: 220px;
  }

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

/* ========================================
   Responsive — Desktop (>= 768px)
   ======================================== */
@media (min-width: 768px) {
  .profile-img {
    width: 250px;
    height: 250px;
  }

  .skills-grid {
    grid-template-columns: repeat(4, 1fr);
  }
}

/* ========================================
   Responsive — Large (>= 1024px)
   ======================================== */
@media (min-width: 1024px) {
  :root {
    --max-width: 1020px;
  }

  .container {
    padding: 0 var(--space-2xl);
  }
}

/* ========================================
   Responsive — Wide (>= 1280px)
   ======================================== */
@media (min-width: 1280px) {
  :root {
    --max-width: 1140px;
  }

  .container {
    padding: 0 var(--space-xl);
  }

  .pub-image {
    width: 260px;
    min-width: 260px;
    height: 120px;
  }

  .project-thumb {
    width: 240px;
    min-width: 240px;
  }

  .project-embedded-img {
    width: 340px;
    min-width: 340px;
  }

}

/* ========================================
   Responsive — Mobile (< 640px)
   ======================================== */
@media (max-width: 639px) {
  .mobile-menu-btn {
    display: flex;
  }

  .nav-links {
    position: fixed;
    top: var(--header-height);
    left: 0;
    right: 0;
    flex-direction: column;
    background: var(--color-header-bg);
    backdrop-filter: blur(12px);
    -webkit-backdrop-filter: blur(12px);
    border-bottom: 1px solid var(--color-header-border);
    padding: var(--space-md);
    gap: var(--space-sm);
    transform: translateY(-100%);
    opacity: 0;
    pointer-events: none;
    transition: transform var(--transition-base), opacity var(--transition-base);
  }

  .nav-links.open {
    transform: translateY(0);
    opacity: 1;
    pointer-events: auto;
  }

  .nav-links a.active::after {
    display: none;
  }

  .pub-card {
    flex-direction: column;
  }

  .pub-image {
    width: 100%;
    min-width: unset;
    height: 140px;
    object-fit: fill;
  }

  .project-thumb {
    width: 100%;
    min-width: unset;
    max-height: 160px;
  }

  .project-summary {
    gap: var(--space-md);
    padding: var(--space-sm) var(--space-md);
  }

  .project-details-body {
    flex-direction: column;
  }

  .project-embedded-img {
    width: 100%;
    min-width: unset;
  }

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

  .project-full-image {
    height: 130px;
  }

  .project-full-header {
    padding: var(--space-sm) var(--space-md);
  }

  .project-full-content {
    padding: var(--space-md);
  }

  .project-full-split {
    flex-direction: column;
  }

  .project-full-embedded {
    width: 100%;
    min-width: unset;
  }

  #digital-clock {
    font-size: 0.6rem;
    padding: var(--space-xs) var(--space-sm);
  }

  #clock-time {
    font-size: 0.65rem;
  }

  .education-header,
  .degree-line {
    flex-direction: column;
    gap: 2px;
  }

  .section {
    padding: var(--space-2xl) 0;
  }
}