/* ============================================================
   DESIGN TOKENS
   ============================================================ */

:root {
  /* Colors — light mode */
  --bg: #faf7f2;
  --bg-subtle: #f3efe8;
  --text: #2a2520;
  --text-secondary: #6a6050;
  --text-muted: #a09888;
  --border: #e0d8cc;
  --accent: #8b5e3c;
  --accent-hover: #6d4a2e;

  /* Typography */
  --font-heading: 'Newsreader', Georgia, serif;
  --font-body: 'DM Sans', -apple-system, sans-serif;
  --font-mono: 'JetBrains Mono', monospace;

  /* Type scale */
  --text-xs: 0.75rem;
  --text-sm: 0.875rem;
  --text-base: 1rem;
  --text-lg: 1.125rem;
  --text-xl: clamp(1.375rem, 2.5vw, 1.625rem);
  --text-2xl: clamp(1.625rem, 3vw, 2rem);
  --text-3xl: clamp(2rem, 4vw, 2.75rem);

  /* Spacing */
  --space-xs: 0.5rem;
  --space-sm: 0.75rem;
  --space-md: 1.25rem;
  --space-lg: 2rem;
  --space-xl: 3.5rem;
  --space-2xl: 8rem;

  /* Layout */
  --max-width: 1100px;
  --nav-height: 64px;
  --radius: 6px;
  --radius-lg: 10px;
  --transition: 0.2s ease;
}

/* Dark mode — respects system preference unless overridden */
@media (prefers-color-scheme: dark) {
  :root:not([data-theme="light"]) {
    --bg: #151518;
    --bg-subtle: #1c1a1e;
    --text: #e0dcd4;
    --text-secondary: #8a8880;
    --text-muted: #5a5856;
    --border: #2a282c;
    --accent: #c4956c;
    --accent-hover: #d4a87c;
  }
}

/* Manual theme overrides */
[data-theme="dark"] {
  --bg: #151518;
  --bg-subtle: #1c1a1e;
  --text: #e0dcd4;
  --text-secondary: #8a8880;
  --text-muted: #5a5856;
  --border: #2a282c;
  --accent: #c4956c;
  --accent-hover: #d4a87c;
}

[data-theme="light"] {
  --bg: #faf7f2;
  --bg-subtle: #f3efe8;
  --text: #2a2520;
  --text-secondary: #6a6050;
  --text-muted: #a09888;
  --border: #e0d8cc;
  --accent: #8b5e3c;
  --accent-hover: #6d4a2e;
}

/* ============================================================
   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);
  background: var(--bg);
  color: var(--text);
  line-height: 1.6;
  min-height: 100vh;
  overflow-x: hidden;
  -webkit-font-smoothing: antialiased;
}

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

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

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

ul, ol {
  list-style: none;
}

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

/* ============================================================
   ACCESSIBILITY
   ============================================================ */

.skip-link {
  position: absolute;
  top: -100%;
  left: 0;
  padding: 0.5rem 1rem;
  background: var(--accent);
  color: var(--bg);
  font-family: var(--font-body);
  font-size: var(--text-sm);
  z-index: 9999;
  transition: top var(--transition);
}

.skip-link:focus {
  top: 0;
}

.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;
}

:focus-visible {
  box-shadow: 0 0 0 2px var(--accent);
  outline: 2px solid transparent;
  border-radius: 2px;
}

/* ============================================================
   TYPOGRAPHY
   ============================================================ */

h1, h2, h3, h4 {
  font-family: var(--font-heading);
  font-weight: 600;
  line-height: 1.25;
  letter-spacing: -0.02em;
  color: var(--text);
}

h1 { font-size: var(--text-2xl); }
h2 { font-size: var(--text-xl); }
h3 { font-size: 1.15rem; }
h4 { font-size: var(--text-base); }

.section-label {
  font-family: var(--font-body);
  font-size: var(--text-xs);
  font-weight: 600;
  font-variant: small-caps;
  color: var(--text-muted);
  margin-bottom: 0.5rem;
  letter-spacing: 0.04em;
}

/* ============================================================
   LAYOUT
   ============================================================ */

.container {
  width: 100%;
  max-width: var(--max-width);
  margin: 0 auto;
  padding: 0 1.5rem;
}

/* ============================================================
   NAV
   ============================================================ */

.nav {
  position: fixed;
  top: 0;
  left: 0;
  right: 0;
  height: var(--nav-height);
  background: var(--bg);
  border-bottom: 1px solid var(--border);
  z-index: 1000;
  display: flex;
  align-items: center;
}

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

.nav-name {
  font-family: var(--font-body);
  font-size: 1.05rem;
  font-weight: 600;
  color: var(--text);
  letter-spacing: -0.01em;
}

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

.nav-links {
  display: flex;
  gap: 1.5rem;
  align-items: center;
}

.nav-links a {
  font-size: var(--text-sm);
  color: var(--text-secondary);
  transition: color var(--transition);
}

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

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

.theme-toggle {
  width: 36px;
  height: 36px;
  display: flex;
  align-items: center;
  justify-content: center;
  color: var(--text-muted);
  border-radius: var(--radius);
  transition: color var(--transition);
  flex-shrink: 0;
}

.theme-toggle:hover {
  color: var(--text);
}

.theme-icon-sun,
.theme-icon-moon {
  width: 18px;
  height: 18px;
  display: block;
}

.nav-toggle {
  display: none;
  flex-direction: column;
  gap: 5px;
  width: 44px;
  height: 44px;
  align-items: center;
  justify-content: center;
  flex-shrink: 0;
}

.nav-toggle span {
  display: block;
  width: 22px;
  height: 2px;
  background: var(--text);
  border-radius: 1px;
  transition: transform var(--transition), opacity var(--transition);
}

.nav-toggle.open span:nth-child(1) {
  transform: rotate(45deg) translate(5px, 5px);
}

.nav-toggle.open span:nth-child(2) {
  opacity: 0;
}

.nav-toggle.open span:nth-child(3) {
  transform: rotate(-45deg) translate(5px, -5px);
}

/* ============================================================
   FOOTER
   ============================================================ */

.footer {
  border-top: 1px solid var(--border);
  padding: var(--space-lg) 0;
  margin-top: var(--space-xl);
}

.footer .container {
  display: flex;
  justify-content: space-between;
  align-items: center;
}

.footer-text {
  font-size: var(--text-sm);
  color: var(--text-muted);
}

.footer-links {
  display: flex;
  gap: 1.5rem;
}

.footer-links a {
  font-size: var(--text-sm);
  color: var(--text-secondary);
}

/* ============================================================
   BUTTONS
   ============================================================ */

.btn {
  display: inline-flex;
  align-items: center;
  gap: 0.5rem;
  padding: 0.65rem 1.25rem;
  border-radius: var(--radius);
  font-family: var(--font-body);
  font-size: var(--text-sm);
  font-weight: 500;
  transition: all var(--transition);
  min-height: 44px;
}

.btn-primary {
  background: var(--accent);
  color: var(--bg);
}

.btn-primary:hover {
  background: var(--accent-hover);
  color: var(--bg);
}

.btn-outline {
  border: 1px solid var(--border);
  color: var(--text-secondary);
}

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

.btn-sm {
  padding: 0.4rem 0.875rem;
  font-size: var(--text-xs);
  min-height: 32px;
}

/* ============================================================
   PAGE HEADER
   ============================================================ */

.page-header {
  padding: calc(var(--nav-height) + var(--space-xl)) 0 var(--space-lg);
}

/* ============================================================
   HERO (LANDING PAGE)
   ============================================================ */

.hero {
  padding-top: calc(var(--nav-height) + var(--space-xl));
  padding-bottom: var(--space-xl);
}

.hero-grid {
  display: grid;
  grid-template-columns: 1fr 1fr;
  gap: var(--space-lg);
  align-items: center;
}

.hero-eyebrow {
  font-family: var(--font-body);
  font-size: var(--text-lg);
  font-weight: 600;
  color: var(--text);
  letter-spacing: -0.01em;
  margin-bottom: 0.35rem;
}

.hero-text h1 {
  font-size: clamp(2.25rem, 4.5vw, 3.25rem);
  font-weight: 400;
  margin-bottom: var(--space-sm);
}

.hero-role {
  font-size: var(--text-sm);
  color: var(--text-muted);
  margin-bottom: var(--space-md);
}

.hero-bio {
  font-size: var(--text-base);
  color: var(--text-secondary);
  line-height: 1.7;
  margin-bottom: var(--space-lg);
}

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

.hero-viz {
  background: var(--bg-subtle);
  border: 1px solid var(--border);
  border-radius: var(--radius-lg);
  aspect-ratio: 4 / 3;
  cursor: pointer;
  position: relative;
  overflow: hidden;
}

.hero-viz canvas {
  display: block;
  width: 100%;
  height: 100%;
}

.hero-viz-caption {
  position: absolute;
  bottom: 0;
  left: 0;
  right: 0;
  padding: 0.5rem 0.75rem;
  font-size: var(--text-xs);
  color: var(--text-muted);
  background: linear-gradient(transparent, var(--bg-subtle));
}

/* ============================================================
   TWO-COLUMN SECTION
   ============================================================ */

.two-col {
  display: grid;
  grid-template-columns: 1fr 1fr;
  border-top: 1px solid var(--border);
}

.two-col-left {
  padding: var(--space-lg) var(--space-lg) var(--space-lg) 0;
  border-right: 1px solid var(--border);
}

.two-col-right {
  padding: var(--space-lg) 0 var(--space-lg) var(--space-lg);
}

/* ============================================================
   PUBLICATION ENTRIES
   ============================================================ */

.pub-list {
  display: flex;
  flex-direction: column;
  gap: var(--space-md);
}

.pub-entry {
  padding-bottom: var(--space-md);
  border-bottom: 1px solid var(--border);
}

.pub-entry:last-child {
  border-bottom: none;
}

.pub-title {
  font-family: var(--font-heading);
  font-weight: 600;
  font-size: var(--text-base);
  color: var(--text);
  margin-bottom: 0.25rem;
}

.pub-meta {
  font-size: var(--text-sm);
  color: var(--text-muted);
  margin-bottom: 0.35rem;
}

.pub-desc {
  font-size: var(--text-sm);
  color: var(--text-secondary);
  line-height: 1.6;
}

.pub-link {
  color: var(--accent);
  text-decoration: underline;
  text-decoration-color: transparent;
  transition: text-decoration-color var(--transition), color var(--transition);
}

.pub-link:hover {
  text-decoration-color: currentColor;
  color: var(--accent-hover);
}

/* ============================================================
   EXPERIENCE ENTRIES
   ============================================================ */

.exp-list {
  display: flex;
  flex-direction: column;
  gap: var(--space-md);
}

.exp-entry {
  padding-bottom: var(--space-md);
  border-bottom: 1px solid var(--border);
}

.exp-entry:last-child {
  border-bottom: none;
}

.exp-entry-title {
  font-family: var(--font-body);
  font-weight: 600;
  font-size: var(--text-base);
  color: var(--text);
  margin-bottom: 0.2rem;
}

.exp-entry-meta {
  font-size: var(--text-sm);
  color: var(--text-muted);
}

/* ============================================================
   INTERESTS SECTION
   ============================================================ */

.interests-section {
  border-top: 1px solid var(--border);
  padding: var(--space-lg) 0;
}

.interests-text {
  font-size: var(--text-base);
  color: var(--text-secondary);
  line-height: 1.8;
}

.interests-list {
  display: flex;
  flex-wrap: wrap;
  gap: 0.5rem 1.5rem;
  list-style: none;
}

.interests-list li {
  font-size: var(--text-sm);
  color: var(--text-secondary);
  position: relative;
  padding-left: 0.85rem;
}

.interests-list li::before {
  content: '';
  position: absolute;
  left: 0;
  top: 0.6em;
  width: 4px;
  height: 4px;
  border-radius: 50%;
  background: var(--accent);
  opacity: 0.6;
}

/* ============================================================
   RESEARCH PAGE
   ============================================================ */

.research-section {
  max-width: 760px;
}

.research-section + .research-section {
  margin-top: var(--space-xl);
  padding-top: var(--space-xl);
  border-top: 1px solid var(--border);
}

.research-section-head {
  margin-bottom: var(--space-md);
}

.research-list {
  display: flex;
  flex-direction: column;
  gap: var(--space-lg);
  max-width: 760px;
}

.research-entry {
  padding-bottom: var(--space-lg);
  border-bottom: 1px solid var(--border);
}

.research-entry:last-child {
  border-bottom: none;
}

.research-entry.featured {
  padding: 1.25rem 1.35rem;
  border: 1px solid var(--border);
  border-radius: var(--radius);
  background: color-mix(in srgb, var(--bg-subtle) 45%, transparent);
}

.research-entry.featured h3 {
  font-size: clamp(1.15rem, 2vw, 1.35rem);
}

.research-entry.featured .pub-meta {
  color: var(--accent);
  opacity: 0.8;
}

.research-tech {
  display: flex;
  flex-wrap: wrap;
  gap: 0.4rem;
  margin-top: 0.75rem;
}

.tech-tag {
  font-family: var(--font-body);
  font-size: var(--text-xs);
  font-variant: small-caps;
  padding: 0.2rem 0.6rem;
  border-radius: 999px;
  border: 1px solid var(--border);
  color: var(--text-muted);
}

/* ============================================================
   CV PAGE
   ============================================================ */

.cv-section {
  max-width: 760px;
  margin: 0 auto;
}

.timeline {
  position: relative;
  padding-left: 2rem;
}

.timeline::before {
  content: '';
  position: absolute;
  left: 0;
  top: 0;
  bottom: 0;
  width: 1px;
  background: var(--border);
}

.timeline-item {
  position: relative;
  padding-bottom: var(--space-lg);
}

.timeline-item:last-child {
  padding-bottom: 0;
}

.timeline-dot {
  position: absolute;
  left: -2rem;
  top: 0.3rem;
  width: 8px;
  height: 8px;
  border-radius: 50%;
  background: var(--text-muted);
  transform: translateX(-3px);
}

.timeline-dot.current {
  background: var(--accent);
}

.timeline-date {
  font-family: var(--font-body);
  font-size: var(--text-xs);
  color: var(--text-muted);
  margin-bottom: 0.4rem;
}

.timeline-entry h3 {
  font-family: var(--font-body);
  font-weight: 600;
  font-size: var(--text-base);
  color: var(--text);
  letter-spacing: 0;
  margin-bottom: 0.2rem;
}

.timeline-role {
  font-size: var(--text-sm);
  color: var(--text-secondary);
  margin-bottom: 0.15rem;
}

.timeline-location {
  font-size: var(--text-xs);
  color: var(--text-muted);
  margin-bottom: 0.6rem;
}

.timeline-entry ul {
  padding-left: 1rem;
}

.timeline-entry li {
  position: relative;
  padding-left: 0.75rem;
  margin-bottom: 0.35rem;
  font-size: var(--text-sm);
  color: var(--text-secondary);
  line-height: 1.6;
}

.timeline-entry li::before {
  content: '';
  position: absolute;
  left: 0;
  top: 0.6em;
  width: 4px;
  height: 4px;
  border-radius: 50%;
  background: var(--text-muted);
}

.education-section {
  margin-top: var(--space-lg);
}

.education-tags {
  display: flex;
  flex-wrap: wrap;
  gap: 0.4rem;
  margin-top: 0.5rem;
}

.education-tag {
  font-family: var(--font-body);
  font-size: var(--text-xs);
  font-variant: small-caps;
  padding: 0.2rem 0.6rem;
  border-radius: 999px;
  border: 1px solid var(--border);
  color: var(--text-muted);
}

.skills-grid {
  display: grid;
  grid-template-columns: 1fr 1fr;
  gap: var(--space-md) var(--space-lg);
  margin-top: var(--space-md);
}

.skills-group {
  display: flex;
  flex-direction: column;
  gap: 0.3rem;
}

.skills-label {
  font-family: var(--font-body);
  font-size: var(--text-xs);
  font-weight: 600;
  font-variant: small-caps;
  letter-spacing: 0.04em;
  color: var(--text-muted);
}

.skills-items {
  font-size: var(--text-sm);
  color: var(--text-secondary);
  line-height: 1.6;
}

.cv-contact {
  margin-top: var(--space-lg);
}

.cv-contact-links {
  display: flex;
  gap: var(--space-md);
  flex-wrap: wrap;
  margin-top: 0.5rem;
}

/* ============================================================
   DEMO HUB
   ============================================================ */

.demo-list {
  display: flex;
  flex-direction: column;
}

.demo-entry {
  padding: var(--space-md) 0;
  border-bottom: 1px solid var(--border);
}

.demo-entry:first-child {
  border-top: 1px solid var(--border);
}

.demo-entry h3 {
  font-size: var(--text-base);
  margin-bottom: 0.35rem;
}

.demo-entry h3 a {
  color: var(--text);
  font-family: var(--font-heading);
  font-weight: 600;
  transition: color var(--transition);
}

.demo-entry h3 a:hover {
  color: var(--accent);
}

.demo-entry p {
  font-size: var(--text-sm);
  color: var(--text-secondary);
  line-height: 1.6;
}

.demo-section {
  padding-bottom: var(--space-xl);
}

.pg-back-link {
  display: inline-block;
  font-family: var(--font-body);
  font-size: var(--text-sm);
  color: var(--text-muted);
  margin-bottom: var(--space-md);
  transition: color var(--transition);
}

.pg-back-link::before {
  content: '\2190  ';
}

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

/* ============================================================
   PLAYGROUND CONTROLS
   ============================================================ */

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

.pg-controls {
  display: flex;
  flex-wrap: wrap;
  gap: 1.5rem;
  align-items: flex-start;
  background: var(--bg-subtle);
  border: 1px solid var(--border);
  border-radius: var(--radius-lg);
  padding: 1.25rem 1.5rem;
  margin-bottom: 1.5rem;
}

.pg-control-group {
  display: flex;
  flex-direction: column;
  gap: 0.5rem;
}

.pg-label {
  font-family: var(--font-body);
  font-size: var(--text-xs);
  font-variant: small-caps;
  font-weight: 600;
  letter-spacing: 0.04em;
  color: var(--text-muted);
}

.pg-dataset-btns {
  display: flex;
  gap: 0.35rem;
}

.pg-dataset-btn {
  padding: 0.4rem 0.75rem;
  font-size: var(--text-sm);
  font-family: var(--font-body);
  border-radius: var(--radius);
  background: transparent;
  border: 1px solid var(--border);
  color: var(--text-secondary);
  cursor: pointer;
  transition: all var(--transition);
  min-height: 44px;
}

.pg-dataset-btn:hover {
  border-color: var(--accent);
  color: var(--text);
}

.pg-dataset-btn.active {
  background: var(--accent);
  border-color: var(--accent);
  color: var(--bg);
}

.pg-layer-btns {
  display: flex;
  gap: 0.35rem;
}

.pg-btn-sm {
  padding: 0.35rem 0.65rem;
  font-size: var(--text-sm);
  font-family: var(--font-body);
  border-radius: var(--radius);
  background: transparent;
  border: 1px solid var(--border);
  color: var(--text-secondary);
  cursor: pointer;
  transition: all var(--transition);
  min-height: 44px;
  display: flex;
  align-items: center;
  justify-content: center;
}

.pg-btn-sm:hover {
  border-color: var(--accent);
  color: var(--text);
}

.pg-layer-neurons {
  display: flex;
  gap: 0.5rem;
  flex-wrap: wrap;
}

.layer-neuron-control {
  display: flex;
  align-items: center;
  gap: 0.25rem;
  border-radius: var(--radius);
  padding: 0.2rem 0.4rem;
}

.layer-label {
  font-family: var(--font-body);
  font-size: var(--text-xs);
  color: var(--text-muted);
  margin-right: 0.15rem;
}

.neuron-btn {
  width: 28px;
  height: 28px;
  font-size: var(--text-sm);
  font-family: var(--font-body);
  border-radius: var(--radius);
  background: transparent;
  border: 1px solid var(--border);
  color: var(--text-secondary);
  cursor: pointer;
  display: flex;
  align-items: center;
  justify-content: center;
  transition: all var(--transition);
  padding: 0;
}

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

.neuron-count {
  font-family: var(--font-body);
  font-size: var(--text-sm);
  color: var(--accent);
  min-width: 16px;
  text-align: center;
}

.pg-select {
  padding: 0.4rem 0.65rem;
  font-size: var(--text-sm);
  font-family: var(--font-body);
  border-radius: var(--radius);
  background: var(--bg);
  border: 1px solid var(--border);
  color: var(--text);
  cursor: pointer;
}

.pg-select:focus-visible {
  box-shadow: 0 0 0 2px var(--accent);
  outline: 2px solid transparent;
}

.pg-slider {
  -webkit-appearance: none;
  appearance: none;
  width: 120px;
  height: 4px;
  background: var(--border);
  border-radius: 2px;
  outline: none;
}

.pg-slider:focus-visible {
  outline: 2px solid var(--accent);
  outline-offset: 2px;
}

.pg-slider::-webkit-slider-thumb {
  -webkit-appearance: none;
  appearance: none;
  width: 14px;
  height: 14px;
  border-radius: 50%;
  background: var(--accent);
  cursor: pointer;
}

.pg-slider::-moz-range-thumb {
  width: 14px;
  height: 14px;
  border-radius: 50%;
  background: var(--accent);
  cursor: pointer;
  border: none;
}

.pg-lr-value {
  font-size: var(--text-sm);
  color: var(--text-secondary);
}

.pg-playback {
  display: flex;
  gap: 0.35rem;
}

.pg-stats {
  flex-direction: row;
  gap: 1.5rem;
  align-items: flex-start;
  margin-left: auto;
}

.pg-stat {
  display: flex;
  flex-direction: column;
  gap: 0.25rem;
}

.pg-stat-value {
  font-size: 1.1rem;
  color: var(--accent);
}

.pg-canvases {
  display: grid;
  grid-template-columns: 1fr 1fr;
  gap: 1.5rem;
}

.pg-canvas-wrap {
  display: flex;
  flex-direction: column;
  gap: 0.5rem;
}

.pg-canvas-label {
  font-family: var(--font-body);
  font-size: var(--text-xs);
  font-variant: small-caps;
  font-weight: 600;
  letter-spacing: 0.04em;
  color: var(--text-muted);
}

.pg-canvas-container {
  aspect-ratio: 1;
  background: var(--bg-subtle);
  border: 1px solid var(--border);
  border-radius: var(--radius-lg);
  overflow: hidden;
  position: relative;
}

.pg-canvas-container canvas {
  display: block;
  width: 100%;
  height: 100%;
}

/* ============================================================
   GRADIENT DESCENT
   ============================================================ */

.gd-canvas-wrap {
  max-width: 800px;
  margin: 0 auto;
}

.gd-canvas-container {
  aspect-ratio: 4 / 3;
  background: var(--bg-subtle);
  border: 1px solid var(--border);
  border-radius: var(--radius-lg);
  overflow: hidden;
  position: relative;
  cursor: crosshair;
}

.gd-canvas-container canvas {
  display: block;
  width: 100%;
  height: 100%;
}

.gd-hint {
  text-align: center;
  font-size: var(--text-sm);
  color: var(--text-muted);
  margin-top: 0.75rem;
}

/* ============================================================
   CHECKBOXES (ACCESSIBLE)
   ============================================================ */

.pg-checkbox-group {
  display: flex;
  gap: 0.75rem;
}

.pg-checkbox-label {
  display: flex;
  align-items: center;
  gap: 0.35rem;
  font-size: var(--text-sm);
  color: var(--text-secondary);
  cursor: pointer;
}

.pg-checkbox-label input[type="checkbox"] {
  /* Hidden accessibly — not display:none */
  position: absolute;
  width: 1px;
  height: 1px;
  padding: 0;
  margin: -1px;
  overflow: hidden;
  clip: rect(0, 0, 0, 0);
  white-space: nowrap;
  border: 0;
}

.pg-checkbox-dot {
  width: 12px;
  height: 12px;
  border-radius: 3px;
  border: 2px solid var(--border);
  transition: all var(--transition);
  flex-shrink: 0;
}

.pg-checkbox-label input:checked + .pg-checkbox-dot {
  border-color: transparent;
}

.pg-checkbox-label input:checked + .pg-checkbox-dot.sgd {
  background: var(--accent);
}

.pg-checkbox-label input:checked + .pg-checkbox-dot.momentum {
  background: #5a8a6a;
}

.pg-checkbox-label input:checked + .pg-checkbox-dot.adam {
  background: #8a7a5a;
}

.pg-checkbox-label input:focus-visible + .pg-checkbox-dot {
  box-shadow: 0 0 0 2px var(--accent);
}

/* ============================================================
   KERNEL DISPLAY
   ============================================================ */

.kernel-display {
  background: var(--bg-subtle);
  border: 1px solid var(--border);
  border-radius: var(--radius-lg);
  padding: 1.25rem 1.5rem;
  margin-top: 1rem;
}

.kernel-display-label {
  font-family: var(--font-body);
  font-size: var(--text-xs);
  font-variant: small-caps;
  font-weight: 600;
  letter-spacing: 0.04em;
  color: var(--text-muted);
  margin-bottom: 0.75rem;
}

.kernel-grid {
  display: grid;
  grid-template-columns: repeat(3, 1fr);
  gap: 4px;
  max-width: 200px;
}

.kernel-cell {
  aspect-ratio: 1;
  display: flex;
  align-items: center;
  justify-content: center;
  font-family: var(--font-mono);
  font-size: var(--text-sm);
  color: var(--text-secondary);
  background: var(--bg);
  border: 1px solid var(--border);
  border-radius: 4px;
}

.kernel-cell.positive {
  color: var(--accent);
}

.kernel-cell.negative {
  color: #c05a5a;
}

.kernel-input {
  width: 100%;
  height: 100%;
  background: var(--bg);
  border: 1px solid var(--border);
  border-radius: 4px;
  color: var(--text);
  font-family: var(--font-mono);
  font-size: var(--text-sm);
  text-align: center;
  padding: 0;
}

.kernel-input:focus-visible {
  box-shadow: 0 0 0 2px var(--accent);
  outline: 2px solid transparent;
  border-color: transparent;
}

/* ============================================================
   PAPER PAGE
   ============================================================ */

.paper-layout {
  display: grid;
  grid-template-columns: 220px 1fr;
  gap: 3rem;
  max-width: var(--max-width);
  margin: 0 auto;
  padding: calc(var(--nav-height) + var(--space-lg)) 1.5rem var(--space-xl);
}

.paper-toc {
  position: sticky;
  top: calc(var(--nav-height) + 2rem);
  align-self: start;
  max-height: calc(100vh - var(--nav-height) - 4rem);
  overflow-y: auto;
}

.paper-toc h4 {
  font-family: var(--font-body);
  font-size: var(--text-xs);
  font-variant: small-caps;
  font-weight: 600;
  letter-spacing: 0.04em;
  color: var(--text-muted);
  margin-bottom: 1rem;
}

.paper-toc a {
  display: block;
  font-family: var(--font-body);
  font-size: var(--text-sm);
  color: var(--text-secondary);
  padding: 0.35rem 0;
  padding-left: 0.75rem;
  border-left: 2px solid var(--border);
  transition: color var(--transition), border-color var(--transition);
}

.paper-toc a:hover,
.paper-toc a.active {
  color: var(--text);
  border-left-color: var(--accent);
}

.paper-toc a.sub {
  padding-left: 1.5rem;
  font-size: var(--text-xs);
}

.paper-content {
  max-width: 760px;
}

.paper-header {
  margin-bottom: 3rem;
  padding-bottom: 2rem;
  border-bottom: 1px solid var(--border);
}

.paper-header h1 {
  font-family: var(--font-heading);
  font-size: var(--text-2xl);
  line-height: 1.3;
  font-weight: 600;
  margin-bottom: 1rem;
}

.paper-meta {
  color: var(--text-secondary);
  font-size: var(--text-sm);
  margin-bottom: 1rem;
}

.paper-keywords {
  display: flex;
  flex-wrap: wrap;
  gap: 0.4rem;
}

.paper-keywords span {
  font-family: var(--font-body);
  font-size: var(--text-xs);
  font-variant: small-caps;
  padding: 0.2rem 0.6rem;
  border-radius: 999px;
  border: 1px solid var(--border);
  color: var(--text-muted);
}

.paper-content h2 {
  font-family: var(--font-heading);
  font-size: var(--text-xl);
  margin-top: 3rem;
  margin-bottom: 1rem;
  padding-top: 1rem;
  color: var(--text);
}

.paper-content h3 {
  font-family: var(--font-heading);
  font-size: 1.15rem;
  margin-top: 2rem;
  margin-bottom: 0.75rem;
  color: var(--text);
}

.paper-content p {
  font-family: var(--font-body);
  color: var(--text-secondary);
  font-size: var(--text-base);
  line-height: 1.8;
  margin-bottom: 1.25rem;
}

.paper-content .math-block {
  background: var(--bg-subtle);
  border: 1px solid var(--border);
  border-radius: var(--radius);
  padding: 1.25rem 1.5rem;
  margin: 1.5rem 0;
  overflow-x: auto;
  text-align: center;
  font-size: 1rem;
}

.paper-content table {
  width: 100%;
  border-collapse: collapse;
  margin: 1.5rem 0;
  font-size: var(--text-sm);
}

.paper-content thead {
  background: var(--bg-subtle);
}

.paper-content th {
  font-family: var(--font-body);
  font-weight: 600;
  text-align: left;
  padding: 0.75rem 1rem;
  border-bottom: 2px solid var(--border);
  color: var(--text);
  font-size: var(--text-sm);
}

.paper-content td {
  padding: 0.65rem 1rem;
  border-bottom: 1px solid var(--border);
  color: var(--text-secondary);
}

.paper-content tbody tr:hover {
  background: var(--bg-subtle);
}

.paper-content figure {
  margin: 2rem 0;
  background: var(--bg-subtle);
  border: 1px solid var(--border);
  border-radius: var(--radius-lg);
  padding: 1.5rem;
  text-align: center;
}

.paper-content figure img {
  margin: 0 auto 1rem;
  border-radius: var(--radius);
  max-width: 100%;
}

.paper-content figcaption {
  font-family: var(--font-body);
  font-size: var(--text-sm);
  color: var(--text-muted);
  line-height: 1.5;
}

.paper-content .figure-placeholder {
  width: 100%;
  height: 300px;
  background: var(--bg-subtle);
  border-radius: var(--radius);
  display: flex;
  align-items: center;
  justify-content: center;
  color: var(--text-muted);
  font-size: var(--text-sm);
  margin-bottom: 1rem;
}

.paper-content .references {
  margin-top: 3rem;
  padding-top: 2rem;
  border-top: 1px solid var(--border);
}

.paper-content .references p {
  font-size: var(--text-sm);
  padding-left: 2rem;
  text-indent: -2rem;
  margin-bottom: 0.75rem;
}

.paper-download {
  display: inline-flex;
  align-items: center;
  gap: 0.5rem;
  margin-top: 1rem;
}

.toc-toggle {
  display: none;
  width: 100%;
  padding: 0.75rem 1rem;
  background: var(--bg-subtle);
  border: 1px solid var(--border);
  border-radius: var(--radius);
  color: var(--text);
  font-family: var(--font-body);
  font-size: var(--text-sm);
  text-align: left;
  margin-bottom: 1rem;
  min-height: 44px;
}

.toc-toggle::after {
  content: '+';
  float: right;
}

.toc-toggle.open::after {
  content: '-';
}

/* ============================================================
   RESPONSIVE
   ============================================================ */

@media (max-width: 1024px) {
  .paper-layout {
    grid-template-columns: 1fr;
  }

  .paper-toc {
    position: static;
    max-height: none;
  }

  .paper-toc.collapsed {
    display: none;
  }

  .toc-toggle {
    display: block;
  }

  .pg-controls {
    gap: 1rem;
  }

  .pg-stats {
    margin-left: 0;
  }
}

@media (max-width: 768px) {
  .nav-links {
    display: none;
    position: fixed;
    top: var(--nav-height);
    left: 0;
    right: 0;
    bottom: 0;
    background: var(--bg);
    flex-direction: column;
    align-items: center;
    justify-content: center;
    gap: 2.5rem;
    z-index: 999;
  }

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

  .nav-links a {
    font-size: var(--text-lg);
  }

  .nav-toggle {
    display: flex;
  }

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

  .hero-viz {
    order: -1;
  }

  .two-col {
    grid-template-columns: 1fr;
  }

  .two-col-left {
    border-right: none;
    border-bottom: 1px solid var(--border);
    padding: var(--space-lg) 0;
  }

  .two-col-right {
    padding: var(--space-lg) 0;
  }

  .pg-canvases {
    grid-template-columns: 1fr;
  }

  .pg-controls {
    gap: 1rem;
  }

  .pg-stats {
    margin-left: 0;
    flex-direction: row;
    gap: 1.5rem;
  }

  .pg-slider {
    width: 100px;
  }

  .footer .container {
    flex-direction: column;
    gap: 1rem;
    text-align: center;
  }

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

  .research-entry.featured {
    padding-left: 1rem;
  }
}

@media (max-width: 480px) {
  .container {
    padding: 0 1rem;
  }

  .hero-text h1 {
    font-size: clamp(1.75rem, 5vw, 2rem);
  }

  .hero-ctas {
    flex-direction: column;
  }

  .btn {
    justify-content: center;
  }

  .pg-dataset-btns {
    flex-wrap: wrap;
  }

  .pg-slider {
    width: 80px;
  }
}

/* ============================================================
   REDUCED MOTION
   ============================================================ */

@media (prefers-reduced-motion: reduce) {
  html {
    scroll-behavior: auto;
  }

  *, *::before, *::after {
    transition-duration: 0.01ms !important;
    animation-duration: 0.01ms !important;
  }
}