/* ==========================================================================
   CSS Variables & Tokens
   ========================================================================== */
:root {
  /* Light — minimal palette */
  --color-bg: #ffffff;
  --color-bg-alt: #fafafa;
  --color-surface: #ffffff;
  --color-surface-hover: #f5f5f5;

  --color-text: #0a0a0a;
  --color-text-muted: #4a4a4a;
  --color-primary: #262626;
  --color-primary-hover: #000000;

  --color-border: #e5e5e5;

  /* Typography */
  --font-sans: 'Inter', -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, Helvetica, Arial, sans-serif;

  /* Spacing */
  --space-xs: 0.5rem;
  --space-sm: 1rem;
  --space-md: 1.75rem;
  --space-lg: 3rem;
  --space-xl: 4rem;

  /* Transitions */
  --transition-fast: 0.15s ease-in-out;
  --transition-normal: 0.3s ease-in-out;

  /* Layout */
  --container-width: 1000px;
  --nav-height: 56px;
}

/* System dark when no explicit theme is stored */
@media (prefers-color-scheme: dark) {
  :root:not([data-theme]) {
    --color-bg: #0a0a0a;
    --color-bg-alt: #111111;
    --color-surface: #141414;
    --color-surface-hover: #1f1f1f;

    --color-text: #fafafa;
    --color-text-muted: #a3a3a3;
    --color-primary: #d4d4d4;
    --color-primary-hover: #ffffff;

    --color-border: #262626;
  }
}

/* Explicit light (e.g. OS dark but user chose light) */
[data-theme="light"] {
  --color-bg: #ffffff;
  --color-bg-alt: #fafafa;
  --color-surface: #ffffff;
  --color-surface-hover: #f5f5f5;

  --color-text: #0a0a0a;
  --color-text-muted: #4a4a4a;
  --color-primary: #262626;
  --color-primary-hover: #000000;

  --color-border: #e5e5e5;
}

[data-theme="dark"] {
  --color-bg: #0a0a0a;
  --color-bg-alt: #111111;
  --color-surface: #141414;
  --color-surface-hover: #1f1f1f;

  --color-text: #fafafa;
  --color-text-muted: #a3a3a3;
  --color-primary: #d4d4d4;
  --color-primary-hover: #ffffff;

  --color-border: #262626;
}

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

html {
  scroll-behavior: smooth;
  scroll-padding-top: var(--nav-height);
}

body {
  font-family: var(--font-sans);
  background-color: var(--color-bg);
  color: var(--color-text);
  line-height: 1.6;
  font-size: 1rem;
  -webkit-font-smoothing: antialiased;
}

/* Faded logo watermark (home + tools; paths relative to stylesheet at site root) */
body.page-home::before,
body.page-tools::before {
  content: '';
  position: fixed;
  inset: 0;
  z-index: 0;
  pointer-events: none;
  background-image: url('assets/logo.png');
  background-repeat: no-repeat;
  background-position: right center;
  background-size: min(92vmin, min(560px, 85vw));
  opacity: 0.3;
}

body.page-home>main,
body.page-home>footer,
body.page-tools>main,
body.page-tools>footer {
  position: relative;
  z-index: 1;
}

@media (prefers-reduced-motion: reduce) {

  body.page-home::before,
  body.page-tools::before {
    opacity: .22;
  }
}

/* Android-style snackbar (copy feedback, etc.) */
.app-toast {
  position: fixed;
  left: 50%;
  bottom: max(1.25rem, calc(env(safe-area-inset-bottom, 0px) + 0.75rem));
  z-index: 2500;
  max-width: min(calc(100vw - 2rem), 22rem);
  padding: 0.7rem 1.1rem;
  margin: 0;
  box-sizing: border-box;
  font-size: 0.875rem;
  font-weight: 400;
  line-height: 1.35;
  letter-spacing: 0.01em;
  text-align: center;
  color: #fafafa;
  background-color: #323232;
  border-radius: 4px;
  box-shadow:
    0 3px 5px -1px rgba(0, 0, 0, 0.22),
    0 6px 10px 0 rgba(0, 0, 0, 0.16),
    0 1px 18px 0 rgba(0, 0, 0, 0.12);
  pointer-events: none;
  opacity: 0;
  transform: translateX(-50%) translateY(calc(100% + 1.5rem));
  transition:
    transform 0.28s cubic-bezier(0.4, 0, 0.2, 1),
    opacity 0.22s ease-out;
}

.app-toast.app-toast--visible {
  opacity: 1;
  transform: translateX(-50%) translateY(0);
}

@media (prefers-reduced-motion: reduce) {
  .app-toast {
    transition-duration: 0.01ms;
  }
}

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

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

ul {
  list-style: none;
}

.container {
  max-width: var(--container-width);
  margin: 0 auto;
  padding: 0 var(--space-sm);
}

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

.bg-alt {
  /* Translucent so the page watermark shows through (striped sections) */
  background-color: color-mix(in srgb, var(--color-bg-alt) 42%, transparent);
}

.section-title {
  font-size: 1.25rem;
  font-weight: 600;
  letter-spacing: -0.02em;
  margin-bottom: var(--space-md);
  color: var(--color-text);
}

.section-title--inline {
  margin-top: var(--space-lg);
  margin-bottom: var(--space-md);
}

.section-inner {
  padding-top: 0;
}

.subsection-title {
  font-size: 1rem;
  font-weight: 600;
  margin-top: var(--space-md);
  margin-bottom: var(--space-xs);
  color: var(--color-text);
}

.content-list {
  list-style: disc;
  padding-left: 1.35rem;
  margin-bottom: var(--space-md);
  color: var(--color-text-muted);
}

.content-list li {
  margin-bottom: 0.5rem;
}

.content-list--tight li {
  margin-bottom: 0.35rem;
}

.activity-label {
  font-weight: 600;
  color: var(--color-text);
}

.edu-stack {
  display: flex;
  flex-direction: column;
  gap: var(--space-sm);
}

.edu-card .edu-institution {
  font-size: 1.05rem;
  font-weight: 600;
  margin-bottom: 0.25rem;
  color: var(--color-text);
}

.edu-meta {
  font-size: 0.875rem;
  color: var(--color-text-muted);
  margin-bottom: 0.5rem;
}

.edu-stack .edu-card.card:last-child,
.publications-list .publication-card.card:last-child {
  border-bottom: none;
}

.research-interests {
  max-width: 640px;
}

.teaching-lead {
  margin-bottom: var(--space-sm);
  color: var(--color-text);
}

.skills-line,
.other-job {
  margin-bottom: 0.5rem;
  color: var(--color-text-muted);
}

/* Tools directory (tools/index.html) — clear type scale + darker copy */
.page-tools #tools-directory {
  --tools-desc-color: var(--color-text-muted);
  --tools-note-color: var(--color-text-muted);
  --tools-badge-color: var(--color-text-muted);
  --tools-item-bg: var(--color-bg-alt);
  --tools-item-border: var(--color-border);
  /* Fixed header is taller than .section top padding alone — clear the bar + breathe */
  padding-top: calc(var(--nav-height) + var(--space-lg));
}

.page-tools .tools-page-h1 {
  font-size: clamp(1.875rem, 4.2vw, 2.35rem);
  font-weight: 700;
  line-height: 1.15;
  letter-spacing: -0.035em;
  margin: 0 0 0.65rem;
  color: var(--color-text);
}

.page-tools .tools-page-lead {
  max-width: 38rem;
  font-size: 1rem;
  font-weight: 400;
  line-height: 1.55;
  margin: 0 0 1.15rem;
  color: var(--tools-desc-color);
}

.page-tools .tools-block {
  margin-bottom: 1rem;
}

.page-tools .tools-block:last-of-type {
  margin-bottom: 0;
}

.page-tools .tools-block-title {
  font-size: 0.8rem;
  font-weight: 600;
  text-transform: uppercase;
  letter-spacing: 0.08em;
  line-height: 1.25;
  margin: 0 0 0.55rem;
  color: var(--tools-note-color);
}

.page-tools .tools-block-note {
  font-size: 0.75rem;
  font-weight: 500;
  text-transform: uppercase;
  letter-spacing: 0.055em;
  line-height: 1.45;
  margin: 0 0 var(--space-md);
  max-width: 38rem;
  color: var(--tools-note-color);
}

.page-tools .tools-list {
  list-style: none;
  margin: 0;
  padding: 0;
  display: grid;
  gap: 0.55rem;
}

.page-tools .tools-item {
  padding: 0.82rem 0.9rem;
  border: 1px solid var(--tools-item-border);
  border-radius: 0.6rem;
  background: var(--tools-item-bg);
  transition: border-color 0.2s ease, background-color 0.2s ease;
}

.page-tools .tools-item:hover {
  border-color: var(--color-border-strong);
  background: var(--color-bg);
}

.page-tools .tools-item-link {
  display: inline-block;
  font-size: 1rem;
  font-weight: 600;
  letter-spacing: -0.01em;
  color: var(--color-text);
  text-decoration: none;
}

.page-tools .tools-item-link--card {
  display: block;
}

.page-tools .tools-item-title {
  display: block;
}

.page-tools .tools-item-link:hover {
  color: var(--color-primary-hover);
}

.page-tools .tools-item-kind {
  display: inline-flex;
  align-items: center;
  font-size: 0.6875rem;
  font-weight: 600;
  text-transform: uppercase;
  letter-spacing: 0.07em;
  margin-top: 0.5rem;
  padding: 0.18rem 0.45rem;
  border-radius: 999px;
  border: 1px solid var(--color-border);
  background: transparent;
  color: var(--tools-badge-color);
}

.page-tools .tools-item-desc {
  font-size: 0.875rem;
  font-weight: 400;
  line-height: 1.45;
  margin: 0.28rem 0 0;
  max-width: 40rem;
  color: var(--tools-desc-color);
  display: block;
}

.page-tools .tools-empty {
  font-size: 0.9375rem;
  color: var(--tools-desc-color);
  margin: 0;
  padding: var(--space-sm) 0;
  border-bottom: 1px solid var(--color-border);
  max-width: 38rem;
}


/* Cards */
.card {
  background: transparent;
  border: none;
  border-bottom: 1px solid var(--color-border);
  border-radius: 0;
  padding: var(--space-sm) 0;
  transition: none;
}

.hover-scale:hover {
  transform: translateY(-4px);
  box-shadow: 0 10px 25px -5px rgba(0, 0, 0, 0.1), 0 8px 10px -6px rgba(0, 0, 0, 0.1);
}

@media (prefers-color-scheme: dark) {
  :root:not([data-theme]) .hover-scale:hover {
    box-shadow: 0 10px 25px -5px rgba(0, 0, 0, 0.5);
  }
}

[data-theme="dark"] .hover-scale:hover {
  box-shadow: 0 10px 25px -5px rgba(0, 0, 0, 0.5);
}

/* ==========================================================================
   Header & Navigation
   ========================================================================== */
.header {
  position: fixed;
  top: 0;
  left: 0;
  width: 100%;
  height: var(--nav-height);
  background-color: var(--color-bg);
  border-bottom: 1px solid var(--color-border);
  z-index: 1000;
}

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

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

.logo {
  display: inline-flex;
  align-items: center;
  gap: 0.5rem;
  font-weight: 600;
  font-size: 1rem;
  color: var(--color-text);
  letter-spacing: -0.02em;
  text-decoration: none;
}

.logo-mark {
  display: block;
  width: 2rem;
  height: 2rem;
  flex-shrink: 0;
  border-radius: 4px;
  object-fit: contain;
  object-position: center;
}

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

.nav-link {
  color: var(--color-text-muted);
  font-weight: 400;
  font-size: 0.875rem;
  padding: 0.35rem 0.55rem;
  border: 1px solid transparent;
  border-radius: 4px;
  box-sizing: border-box;
}

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

.nav-link.active {
  border-color: var(--color-border);
  background-color: var(--color-surface-hover);
}

.nav-theme-item {
  display: flex;
  align-items: center;
  margin: 0;
  padding: 0;
}

.theme-toggle {
  display: flex;
  align-items: center;
  justify-content: center;
  width: 2.5rem;
  height: 2.5rem;
  padding: 0;
  border: 1px solid var(--color-border);
  border-radius: 10px;
  background: var(--color-surface);
  color: var(--color-text);
  cursor: pointer;
}

.theme-toggle:hover {
  background: var(--color-surface-hover);
  color: var(--color-primary);
}

.theme-toggle:focus-visible {
  outline: 2px solid var(--color-primary);
  outline-offset: 2px;
}

.theme-toggle .icon-sun,
.theme-toggle .icon-moon {
  width: 1.15rem;
  height: 1.15rem;
}

.theme-toggle .icon-sun {
  display: none;
}

.theme-toggle .icon-moon {
  display: block;
}

@media (prefers-color-scheme: dark) {
  :root:not([data-theme]) .theme-toggle .icon-sun {
    display: block;
  }

  :root:not([data-theme]) .theme-toggle .icon-moon {
    display: none;
  }
}

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

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

[data-theme="light"] .theme-toggle .icon-moon {
  display: block;
}

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

.mobile-menu-btn {
  display: none;
  background: none;
  border: none;
  color: var(--color-text);
  cursor: pointer;
}

/* ==========================================================================
   In-page TOC (home only) — under profile photo, left column
   ========================================================================== */
.toc-list {
  list-style: none;
  margin: 0;
  padding: 0;
}

.toc-list li {
  margin: 0;
}

.toc-link {
  display: block;
  font-size: 0.8125rem;
  font-weight: 400;
  color: var(--color-text-muted);
  line-height: 1.35;
  text-decoration: none;
  border: none;
  transition: color var(--transition-fast);
}

.toc-link:hover {
  color: var(--color-text);
}

.toc-link.active {
  color: var(--color-text);
  font-weight: 500;
}

.page-home .toc-nav {
  text-align: left;
}

.page-home .toc-list {
  display: flex;
  flex-direction: column;
  gap: 0.35rem;
  align-items: flex-start;
}

.page-home .toc-link {
  padding: 0.1rem 0;
}

.page-home .home-layout {
  display: grid;
  grid-template-columns: minmax(160px, 240px) minmax(0, 1fr);
  gap: var(--space-md);
  align-items: start;
}

.page-home .home-sidebar {
  position: sticky;
  top: calc(var(--nav-height) + 1rem);
  align-self: start;
  display: flex;
  flex-direction: column;
  gap: 1rem;
  width: 100%;
  z-index: 2;
}

.page-home .home-sections {
  min-width: 0;
}

/* ==========================================================================
   Hero Section
   ========================================================================== */
.hero {
  padding-top: calc(var(--nav-height) + var(--space-lg));
  min-height: auto;
  display: flex;
  flex-direction: column;
  align-items: stretch;
}

.hero-image {
  flex: 0 0 auto;
}

.hero-image img {
  width: 100%;
  aspect-ratio: 4 / 5;
  height: auto;
  border-radius: 2px;
  object-fit: cover;
  border: 1px solid var(--color-border);
  box-shadow: none;
  display: block;
}

.hero-content {
  flex: 1;
}

.greeting {
  font-size: 0.8125rem;
  color: var(--color-text-muted);
  font-weight: 400;
  text-transform: uppercase;
  letter-spacing: 0.06em;
  margin-bottom: 0.35rem;
}

.name {
  font-size: clamp(1.75rem, 5vw, 2.25rem);
  font-weight: 600;
  line-height: 1.15;
  letter-spacing: -0.03em;
  margin-bottom: var(--space-xs);
  color: var(--color-text);
}

.title {
  font-size: 1rem;
  font-weight: 400;
  color: var(--color-text-muted);
  line-height: 1.5;
  margin-bottom: var(--space-md);
  max-width: 36rem;
}

.bio {
  font-size: 0.9375rem;
  color: var(--color-text-muted);
  max-width: 36rem;
  margin-bottom: var(--space-sm);
  line-height: 1.65;
}

.social-links {
  display: flex;
  flex-wrap: wrap;
  gap: 1rem 1.5rem;
  margin-top: 0.25rem;
}

.social-icon {
  display: inline-flex;
  align-items: center;
  gap: 0.4rem;
  color: var(--color-text);
  font-size: 0.875rem;
  padding: 0;
  border: none;
  background: none;
  cursor: pointer;
  font-family: inherit;
  text-align: left;
}

.social-icon:hover {
  color: var(--color-primary-hover);
}

.social-icon svg {
  opacity: 0.65;
}

.social-icon:hover svg {
  opacity: 1;
}

.social-icon:focus-visible {
  outline: 2px solid var(--color-primary);
  outline-offset: 3px;
  border-radius: 2px;
}

/* ==========================================================================
   Research Section
   ========================================================================== */
.publications-list {
  display: flex;
  flex-direction: column;
  gap: var(--space-sm);
}

.publication-card {
  display: flex;
  gap: var(--space-sm);
  align-items: flex-start;
}

.pub-year {
  font-size: 0.75rem;
  font-weight: 500;
  color: var(--color-text-muted);
  flex: 0 0 3.25rem;
  line-height: 1.5;
  letter-spacing: 0.02em;
}

.pub-details {
  flex: 1;
}

.pub-title {
  font-size: 1rem;
  font-weight: 600;
  margin-bottom: 0.2rem;
}

.pub-authors {
  color: var(--color-text-muted);
  font-size: 0.95rem;
  margin-bottom: 0.25rem;
}

.pub-venue {
  font-style: italic;
  font-size: 0.9rem;
  color: var(--color-text-muted);
  margin-bottom: var(--space-sm);
}

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

/* ==========================================================================
   Projects Section
   ========================================================================== */
.projects-grid {
  display: grid;
  grid-template-columns: repeat(auto-fill, minmax(300px, 1fr));
  gap: var(--space-md);
}

.project-card {
  display: block;
  color: inherit;
  height: 100%;
}

.project-content h3 {
  font-size: 1.2rem;
  margin-bottom: 0.5rem;
}

.project-content p {
  color: var(--color-text-muted);
  font-size: 0.95rem;
  margin-bottom: var(--space-sm);
  display: -webkit-box;
  -webkit-line-clamp: 3;
  -webkit-box-orient: vertical;
  overflow: hidden;
}

.tags {
  display: flex;
  flex-wrap: wrap;
  gap: 0.5rem;
  margin-top: auto;
}

.tag {
  font-size: 0.75rem;
  font-weight: 500;
  padding: 0.2rem 0.6rem;
  background-color: var(--color-surface-hover);
  color: var(--color-text-muted);
  border-radius: 4px;
}

/* Buttons */
.btn-sm {
  display: inline-block;
  padding: 0;
  font-size: 0.875rem;
  font-weight: 400;
  border-radius: 0;
  background: none;
  color: var(--color-text);
  border: none;
  text-decoration: underline;
  text-underline-offset: 3px;
}

.btn-sm:hover {
  color: var(--color-primary-hover);
}

/* ==========================================================================
   Footer
   ========================================================================== */
.footer {
  padding: var(--space-md) 0 var(--space-lg);
  text-align: left;
  border-top: 1px solid var(--color-border);
  color: var(--color-text-muted);
  font-size: 0.8125rem;
}

.footer-credit {
  margin-top: 0.65rem;
  max-width: 36rem;
  line-height: 1.5;
  font-size: 0.75rem;
}

.footer-credit a {
  color: inherit;
  text-decoration: underline;
  text-underline-offset: 2px;
}

.footer-credit a:hover {
  color: var(--color-text);
}

/* ==========================================================================
   Animations
   ========================================================================== */
.fade-in {
  opacity: 0;
  transition: opacity 0.35s ease-out;
}

.fade-in.visible {
  opacity: 1;
}

@media (prefers-reduced-motion: reduce) {
  .fade-in {
    opacity: 1;
    transition: none;
  }
}

/* ==========================================================================
   Responsive
   ========================================================================== */
@media (max-width: 768px) {
  .page-home .home-layout {
    grid-template-columns: 1fr;
  }

  .page-home .home-sidebar {
    position: static;
    flex-direction: row;
    flex-wrap: wrap;
    align-items: flex-start;
    column-gap: var(--space-md);
    row-gap: var(--space-sm);
  }

  .page-home .home-sidebar .hero-image {
    flex: 0 0 168px;
    width: 168px;
    max-width: 48vw;
  }

  .page-home .home-sidebar .toc-nav {
    display: none;
  }

  .social-links {
    justify-content: flex-start;
  }

  .publication-card {
    flex-direction: column;
    gap: var(--space-xs);
  }

  .pub-year {
    font-size: 1.2rem;
    flex: 0 0 auto;
  }

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

  .main-nav {
    display: none;
    position: absolute;
    top: var(--nav-height);
    left: 0;
    width: 100%;
    background-color: var(--color-surface);
    border-bottom: 1px solid var(--color-border);
    padding: var(--space-sm) 0;
    box-shadow: 0 10px 15px -3px rgba(0, 0, 0, 0.1);
  }

  .main-nav.show {
    display: block;
  }

  .nav-links {
    flex-direction: column;
    gap: var(--space-sm);
  }
}