/* ============================================================
   SENSE Lab — Academic Research Group Website
   Modern, elegant, high-impact stylesheet
   ============================================================ */

@import url('https://fonts.googleapis.com/css2?family=Inter:wght@300;400;500;600;700&family=Plus+Jakarta+Sans:ital,wght@0,300;0,400;0,500;0,600;0,700;1,400&display=swap');

:root {
  /* Colors - Light Theme (Default Monochrome) */
  --color-primary: #000000;         /* Pure Black */
  --color-primary-hover: #262626;   /* Zinc-800 */
  --color-primary-light: #f4f4f5;   /* Zinc-100 */
  --color-secondary: #525252;       /* Neutral-600 */
  --color-secondary-hover: #262626; /* Neutral-800 */
  --color-secondary-light: #fafafa; /* Zinc-50 */
  --color-accent: #000000;          /* Black Accent */
  --color-accent-hover: #262626;
  
  --color-bg-base: #ffffff;         /* Pure white background */
  --color-bg-surface: #ffffff;      /* Pure white cards & sections */
  --color-bg-alt: #fafafa;          /* Light gray alt sections */
  --color-bg-nav: rgba(255, 255, 255, 0.8);
  --color-bg-nav-solid: #ffffff;
  
  --color-text: #000000;            /* Pure black headings & text */
  --color-text-muted: #525252;      /* Neutral-600 */
  --color-border: #e5e5e5;          /* Neutral-200 */
  --color-shadow: rgba(0, 0, 0, 0.04);
  --color-card-border: #e5e5e5;
  
  --hero-glow-1: rgba(0, 0, 0, 0.015);
  --hero-glow-2: rgba(0, 0, 0, 0.008);
  
  /* Typography */
  --font-body: "Inter", system-ui, -apple-system, sans-serif;
  --font-heading: "Plus Jakarta Sans", system-ui, sans-serif;
  --base-size: 1rem;       /* 16px */
  --line-height: 1.7;
  --heading-line-height: 1.25;

  /* Layout */
  --max-width: 960px;
  --nav-height: 70px;
  --section-pad-y: 5.5rem;
  --section-pad-x: 1.5rem;

  /* Misc */
  --radius-sm: 6px;
  --radius: 10px;
  --radius-lg: 16px;
  --transition-fast: 0.15s ease;
  --transition: 0.3s cubic-bezier(0.4, 0, 0.2, 1);
  --card-shadow: 0 1px 3px var(--color-shadow), 0 1px 2px -1px var(--color-shadow);
  --card-shadow-hover: 0 10px 25px -5px rgba(0, 0, 0, 0.08), 0 8px 10px -6px rgba(0, 0, 0, 0.04);
}

@media (prefers-color-scheme: dark) {
  :root {
    /* Colors - Dark Theme (Obsidian Monochrome) */
    --color-primary: #ffffff;         /* Pure White */
    --color-primary-hover: #e5e5e5;   /* Neutral-200 */
    --color-primary-light: #171717;   /* Neutral-900 */
    --color-secondary: #a3a3a3;       /* Neutral-400 */
    --color-secondary-hover: #d4d4d4; /* Neutral-300 */
    --color-secondary-light: #171717; /* Neutral-900 */
    --color-accent: #ffffff;
    --color-accent-hover: #e5e5e5;
    
    --color-bg-base: #0a0a0a;         /* Pure dark background */
    --color-bg-surface: #0a0a0a;      /* Dark cards */
    --color-bg-alt: #171717;          /* Alt sections background */
    --color-bg-nav: rgba(10, 10, 10, 0.8);
    --color-bg-nav-solid: #0a0a0a;
    
    --color-text: #ffffff;            /* Pure white text */
    --color-text-muted: #a3a3a3;      /* Neutral-400 */
    --color-border: #262626;          /* Neutral-800 */
    --color-shadow: rgba(0, 0, 0, 0.5);
    --color-card-border: #262626;
    
    --hero-glow-1: rgba(255, 255, 255, 0.02);
    --hero-glow-2: rgba(255, 255, 255, 0.01);
  }
}

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

html {
  scroll-behavior: smooth;
  scroll-padding-top: 85px;
  -webkit-text-size-adjust: 100%;
}

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

img,
picture,
video,
svg {
  display: block;
  max-width: 100%;
}

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

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

ul,
ol {
  list-style: none;
}

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

/* ----- Animations ----- */
@keyframes fadeInUp {
  from {
    opacity: 0;
    transform: translateY(16px);
  }
  to {
    opacity: 1;
    transform: translateY(0);
  }
}

main {
  animation: fadeInUp 0.6s cubic-bezier(0.16, 1, 0.3, 1) forwards;
}

/* ----- Typography ----- */
h1, h2, h3, h4, h5, h6 {
  font-family: var(--font-heading);
  line-height: var(--heading-line-height);
  color: var(--color-text);
  font-weight: 700;
  letter-spacing: -0.02em;
}

h1 { font-size: 2.75rem; }
h2 { font-size: 2rem; }
h3 { font-size: 1.45rem; }
h4 { font-size: 1.15rem; }

p + p {
  margin-top: 1rem;
}

/* ----- Layout Helpers ----- */
.container {
  width: 100%;
  max-width: var(--max-width);
  margin-inline: auto;
  padding-inline: var(--section-pad-x);
}

section {
  padding-block: var(--section-pad-y);
}

/* Alternating section backgrounds */
section:nth-of-type(even) {
  background-color: var(--color-bg-alt);
}

section:nth-of-type(odd) {
  background-color: var(--color-bg-base);
}

/* ----- Section Headers ----- */
section h2 {
  text-align: center;
  margin-bottom: 3.5rem;
  padding-bottom: 1rem;
  position: relative;
}

section h2::after {
  content: "";
  position: absolute;
  bottom: 0;
  left: 50%;
  transform: translateX(-50%);
  width: 60px;
  height: 4px;
  background: linear-gradient(90deg, var(--color-primary), var(--color-secondary));
  border-radius: 99px;
}

section > .container > h3 {
  margin-top: 3.5rem;
  margin-bottom: 1.5rem;
  font-size: 1.45rem;
  color: var(--color-text);
}

section > .container > h3:first-of-type {
  margin-top: 1.5rem;
}

/* ============================================================
   NAVIGATION
   ============================================================ */
nav {
  position: fixed;
  top: 0;
  left: 0;
  right: 0;
  z-index: 1000;
  background-color: var(--color-bg-nav);
  backdrop-filter: blur(12px) saturate(180%);
  -webkit-backdrop-filter: blur(12px) saturate(180%);
  border-bottom: 1px solid var(--color-border);
  height: var(--nav-height);
  display: flex;
  align-items: center;
  transition: background-color var(--transition), box-shadow var(--transition);
}

nav.scrolled {
  box-shadow: 0 4px 20px -2px rgba(15, 23, 42, 0.08);
}

.nav-container {
  width: 100%;
  max-width: var(--max-width);
  margin-inline: auto;
  padding-inline: var(--section-pad-x);
  display: flex;
  justify-content: space-between;
  align-items: center;
}

.nav-brand {
  display: inline-flex;
  align-items: center;
  gap: 0.6rem;
  font-family: var(--font-heading);
  font-size: 1.4rem;
  font-weight: 800;
  color: var(--color-text);
  text-decoration: none;
  letter-spacing: 0.05em;
  text-transform: uppercase;
  transition: opacity var(--transition-fast);
}

.nav-brand:hover {
  text-decoration: none;
  opacity: 0.85;
}

.nav-logo-svg {
  width: 26px;
  height: 26px;
  color: var(--color-text);
  flex-shrink: 0;
  display: block;
}

.nav-brand-text {
  display: inline-flex;
  align-items: baseline;
  gap: 0.2rem;
}

.nav-brand-subtext {
  font-size: 0.95rem;
  font-weight: 400;
  color: var(--color-text-muted);
  text-transform: uppercase;
  letter-spacing: 0.05em;
}

.nav-links {
  display: flex;
  gap: 2rem;
  align-items: center;
}

.nav-links a {
  color: var(--color-text-muted);
  font-size: 0.95rem;
  font-weight: 500;
  text-decoration: none;
  transition: color var(--transition-fast);
  position: relative;
  padding-block: 0.25rem;
}

.nav-links a:hover,
.nav-links a:focus-visible {
  color: var(--color-text);
  text-decoration: none;
}

.nav-links a.active {
  color: var(--color-primary);
  font-weight: 600;
}

.nav-links a.active::after {
  content: "";
  position: absolute;
  bottom: -4px;
  left: 0;
  right: 0;
  height: 2px;
  background: linear-gradient(90deg, var(--color-primary), var(--color-secondary));
  border-radius: 99px;
}

/* Hamburger toggle */
.nav-toggle {
  display: none;
  flex-direction: column;
  justify-content: center;
  gap: 6px;
  width: 30px;
  height: 30px;
  cursor: pointer;
  background: none;
  border: none;
  padding: 0;
}

.nav-toggle span {
  display: block;
  width: 100%;
  height: 2px;
  background-color: var(--color-text);
  border-radius: 2px;
  transition: transform var(--transition), opacity var(--transition);
}

.nav-toggle[aria-expanded="true"] span:nth-child(1) {
  transform: translateY(8px) rotate(45deg);
}

.nav-toggle[aria-expanded="true"] span:nth-child(2) {
  opacity: 0;
}

.nav-toggle[aria-expanded="true"] span:nth-child(3) {
  transform: translateY(-8px) rotate(-45deg);
}

/* ============================================================
   HERO SECTION
   ============================================================ */
#hero {
  background-color: var(--color-bg-base);
  position: relative;
  overflow: hidden;
  text-align: center;
  padding-block: 8rem 6rem;
  margin-top: 0; /* Changed since nav is sticky, handled by padding */
}

/* Subtle glow gradients in background */
#hero::before,
#hero::after {
  content: "";
  position: absolute;
  border-radius: 50%;
  filter: blur(100px);
  z-index: 1;
  pointer-events: none;
}

#hero::before {
  top: -10%;
  left: 10%;
  width: 300px;
  height: 300px;
  background-color: var(--hero-glow-1);
}

#hero::after {
  bottom: -10%;
  right: 10%;
  width: 350px;
  height: 350px;
  background-color: var(--hero-glow-2);
}

.hero-content {
  position: relative;
  z-index: 2;
  max-width: 720px;
  margin-inline: auto;
}

#hero h1 {
  color: var(--color-text);
  font-size: 3.5rem;
  margin-bottom: 0.75rem;
  letter-spacing: -0.04em;
  font-weight: 800;
  background: linear-gradient(135deg, var(--color-text) 50%, var(--color-primary));
  background-clip: text;
  -webkit-background-clip: text;
  -webkit-text-fill-color: transparent;
}

.hero-subtitle {
  font-size: 1.4rem;
  color: var(--color-primary);
  margin-bottom: 1.5rem;
  font-weight: 600;
  letter-spacing: -0.01em;
  font-family: var(--font-heading);
}

.hero-affiliation {
  font-size: 0.95rem;
  color: var(--color-text-muted);
  margin-bottom: 0.75rem;
  line-height: 1.6;
}

.hero-affiliation a {
  color: var(--color-text);
  font-weight: 500;
  text-decoration: underline;
  text-decoration-color: var(--color-border);
  text-underline-offset: 4px;
}

.hero-affiliation a:hover {
  color: var(--color-primary);
  text-decoration-color: var(--color-primary);
}

.hero-pi {
  font-size: 1.15rem;
  color: var(--color-text);
  font-weight: 600;
  margin-bottom: 2.5rem;
}

.hero-pi a {
  color: inherit;
  text-decoration: underline;
  text-decoration-color: currentColor;
  text-decoration-thickness: 2px;
  text-underline-offset: 4px;
}

.hero-pi a:hover {
  color: var(--color-primary);
  text-decoration-color: var(--color-primary);
}

.hero-cta {
  margin-top: 2rem;
  padding-top: 2rem;
  border-top: 1px solid var(--color-border);
}

.hero-cta p {
  font-size: 1rem;
  color: var(--color-text-muted);
  margin-bottom: 1.25rem;
}

/* ============================================================
   BUTTONS
   ============================================================ */
.btn-primary {
  display: inline-block;
  background-color: var(--color-primary);
  color: var(--color-bg-base) !important;
  font-weight: 700;
  font-size: 0.95rem;
  padding: 0.75rem 2rem;
  border-radius: var(--radius-sm);
  border: 1px solid var(--color-primary);
  text-decoration: none;
  box-shadow: 0 4px 12px var(--color-shadow);
  transition: background-color var(--transition-fast), border-color var(--transition-fast), color var(--transition-fast), transform var(--transition-fast), box-shadow var(--transition-fast);
}

.btn-primary:hover,
.btn-primary:focus-visible {
  background-color: transparent;
  color: var(--color-primary) !important;
  text-decoration: none;
  transform: translateY(-2px);
  box-shadow: 0 6px 16px var(--color-shadow);
}

.btn-outline {
  display: inline-block;
  border: 1px solid var(--color-border);
  color: var(--color-text);
  font-weight: 700;
  font-size: 0.95rem;
  padding: 0.7rem 1.85rem;
  border-radius: var(--radius-sm);
  text-decoration: none;
  background: transparent;
  transition: border-color var(--transition-fast), background-color var(--transition-fast), color var(--transition-fast), transform var(--transition-fast);
}

.btn-outline:hover,
.btn-outline:focus-visible {
  border-color: var(--color-primary);
  color: var(--color-primary);
  background-color: var(--color-primary-light);
  text-decoration: none;
  transform: translateY(-1px);
}

/* ============================================================
   ABOUT SECTION
   ============================================================ */
.about-container {
  max-width: 760px;
  margin-inline: auto;
  text-align: center;
  margin-bottom: 4rem;
}

.about-text {
  font-size: 1.15rem;
  line-height: 1.8;
  color: var(--color-text);
}

.about-text strong {
  font-weight: 600;
  color: var(--color-primary);
}

.info-card {
  background-color: var(--color-bg-surface);
  border-radius: var(--radius);
  border: 1px solid var(--color-card-border);
  padding: 2rem;
  box-shadow: var(--card-shadow);
  text-align: left;
  transition: border-color var(--transition), box-shadow var(--transition), transform var(--transition);
}

.info-card:hover {
  border-color: var(--color-primary);
  box-shadow: var(--card-shadow-hover);
  transform: translateY(-4px);
}

.info-card-title {
  color: var(--color-text);
  font-family: var(--font-heading);
  font-size: 1.1rem;
  font-weight: 700;
  text-transform: uppercase;
  letter-spacing: 0.05em;
  margin-bottom: 0.75rem;
  display: flex;
  align-items: center;
  gap: 0.5rem;
}

.info-card-title::before {
  content: "";
  display: inline-block;
  width: 6px;
  height: 6px;
  background-color: var(--color-primary);
  border-radius: 50%;
}

.info-card-text {
  font-size: 0.95rem;
  color: var(--color-text-muted);
  line-height: 1.6;
}

/* ============================================================
   RESEARCH / AREAS
   ============================================================ */
#research .research-intro {
  max-width: 760px;
  margin-inline: auto;
  margin-bottom: 4rem;
  font-size: 1.1rem;
  line-height: 1.8;
}

.research-area {
  background-color: var(--color-bg-surface);
  border: 1px solid var(--color-card-border);
  border-radius: var(--radius-lg);
  padding: 2.25rem;
  margin-bottom: 2rem;
  box-shadow: var(--card-shadow);
  transition: border-color var(--transition), box-shadow var(--transition);
}

.research-area:hover {
  border-color: var(--color-primary);
  box-shadow: var(--card-shadow-hover);
}

.research-area h4 {
  font-size: 1.35rem;
  color: var(--color-text);
  margin-bottom: 1rem;
  font-weight: 700;
  display: flex;
  align-items: center;
  gap: 0.75rem;
}

.research-area h4::before {
  content: "";
  display: block;
  width: 4px;
  height: 18px;
  background: linear-gradient(180deg, var(--color-primary), var(--color-secondary));
  border-radius: 99px;
}

.research-area p {
  font-size: 1rem;
  color: var(--color-text);
  line-height: 1.7;
}

.research-area p a {
  font-weight: 600;
  text-decoration: underline;
  text-decoration-color: var(--color-border);
  text-underline-offset: 3px;
}

.research-area p a:hover {
  color: var(--color-primary);
  text-decoration-color: var(--color-primary);
}

#research .research-questions {
  max-width: 720px;
  margin-inline: auto;
  margin-bottom: 3.5rem;
  background-color: var(--color-bg-surface);
  border: 1px solid var(--color-border);
  border-radius: var(--radius);
  padding: 2rem;
  box-shadow: var(--card-shadow);
}

#research .research-questions li {
  position: relative;
  padding-left: 1.75rem;
  margin-bottom: 1rem;
  line-height: 1.65;
  font-size: 1.05rem;
}

#research .research-questions li:last-child {
  margin-bottom: 0;
}

#research .research-questions li::before {
  content: "→";
  position: absolute;
  left: 0;
  color: var(--color-primary);
  font-weight: 700;
}

/* ============================================================
   AWARDS
   ============================================================ */
.awards-list {
  max-width: 720px;
  margin-inline: auto;
  background-color: var(--color-bg-surface);
  border: 1px solid var(--color-border);
  border-radius: var(--radius-lg);
  padding: 2.25rem;
  box-shadow: var(--card-shadow);
}

.awards-list li {
  display: flex;
  gap: 1.25rem;
  align-items: baseline;
  padding-block: 0.85rem;
  border-bottom: 1px solid var(--color-border);
  line-height: 1.6;
  font-size: 0.98rem;
}

.awards-list li:last-child {
  border-bottom: none;
}

.award-year {
  flex-shrink: 0;
  font-family: var(--font-body);
  font-size: 0.85rem;
  font-weight: 700;
  color: var(--color-primary);
  background-color: var(--color-primary-light);
  padding: 0.2rem 0.65rem;
  border-radius: var(--radius-sm);
  min-width: 3.8rem;
  text-align: center;
}

/* ============================================================
   TABLES (Research / Sponsors)
   ============================================================ */
.tools-table-wrapper {
  overflow-x: auto;
  margin-block: 2.5rem;
  border: 1px solid var(--color-border);
  border-radius: var(--radius);
  box-shadow: var(--card-shadow);
}

.tools-table {
  width: 100%;
  border-collapse: collapse;
  text-align: left;
  background-color: var(--color-bg-surface);
}

.tools-table th,
.tools-table td {
  padding: 1.1rem 1.5rem;
}

.tools-table th {
  background-color: var(--color-bg-alt);
  color: var(--color-text);
  font-family: var(--font-heading);
  font-weight: 700;
  font-size: 0.88rem;
  text-transform: uppercase;
  letter-spacing: 0.05em;
  border-bottom: 1px solid var(--color-border);
}

.tools-table td {
  border-bottom: 1px solid var(--color-border);
  font-size: 0.95rem;
  color: var(--color-text);
}

.tools-table tr:last-child td {
  border-bottom: none;
}

.tools-table tr {
  transition: background-color var(--transition-fast);
}

.tools-table tr:hover td {
  background-color: rgba(79, 70, 229, 0.015);
}

.tools-table a {
  font-weight: 600;
  text-decoration: underline;
  text-decoration-color: var(--color-border);
}

.tools-table a:hover {
  text-decoration-color: var(--color-primary);
}

/* ============================================================
   SPONSORS GRID
   ============================================================ */
.sponsors-container {
  display: flex;
  flex-direction: column;
  gap: 3rem;
  margin-block: 3.5rem 2rem;
}

.sponsors-group {
  display: flex;
  flex-direction: column;
  gap: 1.25rem;
}

.sponsors-group h4 {
  font-family: var(--font-heading);
  font-size: 1.05rem;
  font-weight: 700;
  text-transform: uppercase;
  letter-spacing: 0.05em;
  color: var(--color-text-muted);
  border-bottom: 1px solid var(--color-border);
  padding-bottom: 0.5rem;
  margin-bottom: 0.25rem;
}

.sponsors-grid {
  display: grid;
  grid-template-columns: repeat(auto-fill, minmax(220px, 1fr));
  gap: 1.5rem;
}

.sponsor-card {
  background-color: var(--color-bg-surface);
  border: 1px solid var(--color-card-border);
  border-radius: var(--radius);
  padding: 1.5rem;
  display: flex;
  flex-direction: column;
  align-items: center;
  justify-content: center;
  height: 105px;
  box-shadow: var(--card-shadow);
  transition: border-color var(--transition), box-shadow var(--transition), transform var(--transition);
  position: relative;
  overflow: hidden;
  text-decoration: none;
  color: inherit;
}

.sponsor-card::before {
  content: "";
  position: absolute;
  top: 0;
  left: 0;
  right: 0;
  height: 3px;
  background: linear-gradient(90deg, var(--color-primary), var(--color-secondary));
  opacity: 0;
  transition: opacity var(--transition);
}

.sponsor-card:hover {
  border-color: var(--color-primary);
  box-shadow: var(--card-shadow-hover);
  transform: translateY(-4px);
}

.sponsor-card:hover::before {
  opacity: 1;
}

.sponsor-logo {
  max-width: 100%;
  max-height: 52px;
  width: auto;
  height: auto;
  opacity: 0.7;
  filter: grayscale(100%);
  transition: opacity var(--transition), filter var(--transition), transform var(--transition);
}

@media (prefers-color-scheme: dark) {
  .sponsor-logo {
    filter: grayscale(100%) invert(0.08);
  }
}

.sponsor-card:hover .sponsor-logo {
  opacity: 1;
  filter: grayscale(0%) invert(0);
  transform: scale(1.02);
}

/* Visually hidden sponsor name for accessibility */
.sponsor-name {
  position: absolute;
  width: 1px;
  height: 1px;
  padding: 0;
  margin: -1px;
  overflow: hidden;
  clip: rect(0, 0, 0, 0);
  white-space: nowrap;
  border: 0;
}

/* ============================================================
   PUBLICATIONS
   ============================================================ */
.section-alt {
  background-color: var(--color-bg-alt) !important;
}

/* Filter Panel Styles */
.filter-wrapper {
  background-color: var(--color-bg-surface);
  border: 1px solid var(--color-card-border);
  border-radius: var(--radius);
  padding: 1.75rem;
  margin-bottom: 2.5rem;
  box-shadow: var(--card-shadow);
  display: flex;
  flex-direction: column;
  gap: 1.25rem;
  animation: fadeInUp 0.4s cubic-bezier(0.16, 1, 0.3, 1) forwards;
  text-align: left;
}

.filter-search-row {
  display: flex;
  gap: 1rem;
  align-items: center;
  width: 100%;
}

.search-input-wrapper {
  position: relative;
  flex-grow: 1;
  display: flex;
  align-items: center;
}

.search-icon {
  position: absolute;
  left: 1rem;
  width: 1.25rem;
  height: 1.25rem;
  color: var(--color-text-muted);
  pointer-events: none;
  transition: color var(--transition-fast);
}

.search-input-wrapper input {
  width: 100%;
  padding: 0.75rem 1rem 0.75rem 2.75rem;
  font-family: var(--font-body);
  font-size: 0.95rem;
  color: var(--color-text);
  background-color: var(--color-bg-base);
  border: 1px solid var(--color-border);
  border-radius: var(--radius-sm);
  transition: border-color var(--transition-fast), box-shadow var(--transition-fast);
}

.search-input-wrapper input:focus {
  outline: none;
  border-color: var(--color-primary);
  box-shadow: 0 0 0 3px rgba(79, 70, 229, 0.15);
}

@media (prefers-color-scheme: dark) {
  .search-input-wrapper input:focus {
    box-shadow: 0 0 0 3px rgba(129, 140, 248, 0.25);
  }
}

.search-input-wrapper input:focus + .search-icon {
  color: var(--color-primary);
}

.clear-input-btn {
  position: absolute;
  right: 1rem;
  background: none;
  border: none;
  font-size: 1.35rem;
  color: var(--color-text-muted);
  padding: 0.25rem;
  cursor: pointer;
  line-height: 1;
  border-radius: 50%;
  display: flex;
  align-items: center;
  justify-content: center;
  transition: color var(--transition-fast), background-color var(--transition-fast);
}

.clear-input-btn:hover {
  color: var(--color-text);
  background-color: var(--color-bg-alt);
}

.filter-controls-grid {
  display: grid;
  grid-template-columns: repeat(4, 1fr);
  gap: 1rem;
}

@media (max-width: 768px) {
  .filter-search-row {
    flex-direction: column;
    align-items: stretch;
  }
  .filter-controls-grid {
    grid-template-columns: repeat(2, 1fr);
  }
}

@media (max-width: 480px) {
  .filter-controls-grid {
    grid-template-columns: 1fr;
  }
}

.filter-col {
  display: flex;
  flex-direction: column;
  gap: 0.4rem;
}

.filter-col label {
  font-family: var(--font-heading);
  font-size: 0.82rem;
  font-weight: 700;
  text-transform: uppercase;
  letter-spacing: 0.05em;
  color: var(--color-text-muted);
}

.filter-col select {
  font-family: var(--font-body);
  font-size: 0.92rem;
  color: var(--color-text);
  background-color: var(--color-bg-base);
  border: 1px solid var(--color-border);
  border-radius: var(--radius-sm);
  padding: 0.65rem 1rem;
  cursor: pointer;
  transition: border-color var(--transition-fast), box-shadow var(--transition-fast);
  outline: none;
  appearance: none;
  background-image: url("data:image/svg+xml;charset=UTF-8,%3csvg xmlns='http://www.w3.org/2000/svg' viewBox='0 0 24 24' fill='none' stroke='%2364748b' stroke-width='2' stroke-linecap='round' stroke-linejoin='round'%3e%3cpolyline points='6 9 12 15 18 9'%3e%3c/polyline%3e%3c/svg%3e");
  background-repeat: no-repeat;
  background-position: right 0.75rem center;
  background-size: 1rem;
  padding-right: 2.25rem;
}

.filter-col select:focus {
  border-color: var(--color-primary);
  box-shadow: 0 0 0 3px rgba(79, 70, 229, 0.15);
}

@media (prefers-color-scheme: dark) {
  .filter-col select {
    background-image: url("data:image/svg+xml;charset=UTF-8,%3csvg xmlns='http://www.w3.org/2000/svg' viewBox='0 0 24 24' fill='none' stroke='%239ca3af' stroke-width='2' stroke-linecap='round' stroke-linejoin='round'%3e%3cpolyline points='6 9 12 15 18 9'%3e%3c/polyline%3e%3c/svg%3e");
  }
  .filter-col select:focus {
    box-shadow: 0 0 0 3px rgba(129, 140, 248, 0.25);
  }
}

.filter-status-row {
  display: flex;
  justify-content: space-between;
  align-items: center;
  border-top: 1px solid var(--color-border);
  padding-top: 1rem;
  font-size: 0.88rem;
  color: var(--color-text-muted);
}

.btn-text {
  background: none;
  border: none;
  color: var(--color-primary);
  font-weight: 600;
  font-size: 0.88rem;
  padding: 0.2rem 0.5rem;
  border-radius: var(--radius-sm);
  cursor: pointer;
  transition: color var(--transition-fast), background-color var(--transition-fast);
}

.btn-text:hover {
  color: var(--color-primary-hover);
  background-color: var(--color-primary-light);
}

/* Hidden elements for filtering */
.pub-entry.hidden {
  display: none !important;
}

.pub-group.hidden {
  display: none !important;
}

.pub-year.hidden {
  display: none !important;
}

/* Collapsible year sections */
.pub-year {
  margin-bottom: 2rem;
  background: var(--color-bg-surface);
  border: 1px solid var(--color-card-border);
  border-radius: var(--radius);
  overflow: hidden;
  box-shadow: var(--card-shadow);
  transition: border-color var(--transition), box-shadow var(--transition);
}

.pub-year:hover {
  border-color: var(--color-primary);
}

.year-header {
  display: flex;
  align-items: center;
  gap: 0.75rem;
  cursor: pointer;
  padding: 1.25rem 1.75rem;
  background: var(--color-bg-surface);
  list-style: none;
  user-select: none;
}

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

.year-header h3 {
  margin: 0;
  font-size: 1.45rem;
  font-family: var(--font-heading);
  color: var(--color-text);
  font-weight: 700;
}

.year-header::after {
  content: "";
  display: inline-block;
  width: 8px;
  height: 8px;
  border-right: 2px solid var(--color-text-muted);
  border-bottom: 2px solid var(--color-text-muted);
  transform: rotate(-45deg);
  transition: transform var(--transition);
  margin-left: auto;
}

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

.pub-year[open] .year-header {
  border-bottom: 1px solid var(--color-border);
}

.pub-year[open] > .pub-group {
  padding-inline: 1.75rem;
}

.pub-year[open] > .pub-group:first-of-type {
  padding-top: 1.5rem;
}

.pub-year[open] > .pub-group:last-of-type {
  padding-bottom: 1.75rem;
}

.pub-group {
  margin-bottom: 1.75rem;
}

.pub-group:last-of-type {
  margin-bottom: 0;
}

.pub-group h4 {
  font-family: var(--font-heading);
  font-size: 1rem;
  font-weight: 700;
  color: var(--color-primary);
  text-transform: uppercase;
  letter-spacing: 0.05em;
  margin-bottom: 1rem;
  padding-bottom: 0.4rem;
  border-bottom: 1px solid var(--color-border);
}

.award-badge {
  display: inline-block;
  font-size: 0.78rem;
  color: #c2410c;
  background-color: #ffedd5;
  font-weight: 700;
  padding: 0.15rem 0.5rem;
  border-radius: var(--radius-sm);
  margin-left: 0.25rem;
  vertical-align: middle;
  text-transform: uppercase;
  letter-spacing: 0.02em;
}

@media (prefers-color-scheme: dark) {
  .award-badge {
    color: #fdba74;
    background-color: #451a03;
  }
}

/* Publication entries */
.pub-entry {
  margin-bottom: 1.25rem;
  padding-left: 1.25rem;
  border-left: 3px solid var(--color-border);
  padding-top: 0.25rem;
  padding-bottom: 0.25rem;
  position: relative;
  transition: border-color var(--transition-fast);
}

.pub-entry:hover {
  border-color: var(--color-primary);
}

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

.pub-entry strong {
  color: var(--color-accent);
}

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

.pub-title {
  font-weight: 600;
  color: var(--color-text);
  line-height: 1.5;
}

.pub-venue {
  font-style: italic;
  color: var(--color-text-muted);
  font-size: 0.92rem;
}

.pub-links {
  display: inline-block;
  margin-left: 0.5rem;
}

.pub-links a {
  display: inline-block;
  font-size: 0.72rem;
  font-weight: 700;
  text-transform: uppercase;
  letter-spacing: 0.06em;
  padding: 0.15rem 0.6rem;
  border-radius: 99px;
  background-color: var(--color-primary-light);
  color: var(--color-primary);
  text-decoration: none;
  transition: background-color var(--transition-fast), color var(--transition-fast), transform var(--transition-fast);
}

.pub-links a:hover,
.pub-links a:focus-visible {
  background-color: var(--color-primary);
  color: #ffffff;
  text-decoration: none;
  transform: translateY(-1px);
}

/* Journal / conference subheadings inside a year */
.pub-subheading {
  font-family: var(--font-heading);
  font-size: 1.05rem;
  font-weight: 700;
  color: var(--color-primary);
  text-transform: uppercase;
  letter-spacing: 0.05em;
  margin-top: 1.75rem;
  margin-bottom: 1rem;
  padding-bottom: 0.4rem;
  border-bottom: 1px solid var(--color-border);
}

/* ============================================================
   PEOPLE SECTION
   ============================================================ */
#people h3 {
  margin-top: 3.5rem;
  margin-bottom: 1.75rem;
  font-size: 1.5rem;
  border-bottom: 1px solid var(--color-border);
  padding-bottom: 0.5rem;
  color: var(--color-text);
}

#people h3:first-of-type {
  margin-top: 0;
}

.people-grid {
  display: grid;
  grid-template-columns: repeat(4, 1fr);
  gap: 2rem;
}

@media (min-width: 1024px) {
  .people-grid.grid-3-col {
    grid-template-columns: repeat(3, 1fr);
  }
}

.person-card {
  background-color: var(--color-bg-surface);
  border: 1px solid var(--color-card-border);
  border-radius: var(--radius-lg);
  padding: 2rem 1.25rem;
  text-align: center;
  box-shadow: var(--card-shadow);
  transition: border-color var(--transition), box-shadow var(--transition), transform var(--transition);
}

.person-card:hover {
  border-color: var(--color-primary);
  box-shadow: var(--card-shadow-hover);
  transform: translateY(-4px);
}

.person-photo {
  width: 110px;
  height: 110px;
  border-radius: 50%;
  object-fit: cover;
  border: 3px solid var(--color-border);
  margin-inline: auto;
  margin-bottom: 1.25rem;
  transition: border-color var(--transition);
}

.person-photo-link {
  display: inline-block;
  border-radius: 50%;
  margin-bottom: 1.25rem;
}

.person-photo-link .person-photo {
  display: block;
  margin-bottom: 0;
}

.person-photo-link:focus-visible {
  outline: 3px solid var(--color-primary);
  outline-offset: 4px;
}

.person-card:hover .person-photo {
  border-color: var(--color-primary);
}

.person-photo.placeholder {
  background: linear-gradient(135deg, var(--color-primary), var(--color-secondary));
  color: #ffffff;
  display: flex;
  align-items: center;
  justify-content: center;
  font-family: var(--font-heading);
  font-size: 1.5rem;
  font-weight: 700;
  letter-spacing: 0.05em;
  text-shadow: 0 2px 4px rgba(0, 0, 0, 0.1);
  box-shadow: inset 0 2px 4px rgba(255, 255, 255, 0.2);
}

.person-card h4 {
  font-size: 1.1rem;
  margin-bottom: 0.35rem;
  font-weight: 700;
  color: var(--color-text);
}

.person-role {
  font-size: 0.88rem;
  color: var(--color-primary);
  font-weight: 600;
  margin-bottom: 0.25rem;
}

.person-topic {
  font-size: 0.85rem;
  color: var(--color-text-muted);
  font-style: italic;
  margin-bottom: 0.5rem;
  line-height: 1.4;
}

.person-affiliation {
  font-size: 0.85rem;
  color: var(--color-text-muted);
  margin-bottom: 0.75rem;
}

.person-links {
  display: flex;
  gap: 0.75rem;
  justify-content: center;
  flex-wrap: wrap;
}

.person-links a {
  font-size: 0.82rem;
  font-weight: 600;
  text-decoration: underline;
  text-decoration-color: var(--color-border);
}

.person-links a:hover {
  text-decoration-color: var(--color-primary);
}

.alumni-list-wrapper {
  max-width: 720px;
  margin-inline: auto;
  margin-top: 1.5rem;
}

.alumni-simple-list {
  list-style: none;
  padding: 0;
}

.alumni-simple-list li {
  padding-block: 0.75rem;
  border-bottom: 1px dashed var(--color-border);
  font-size: 0.98rem;
  color: var(--color-text);
  line-height: 1.6;
}

.alumni-simple-list li:last-child {
  border-bottom: none;
}

.alumni-simple-list strong {
  font-weight: 600;
  color: var(--color-text);
}

/* ============================================================
   TEACHING SECTION
   ============================================================ */
.teaching-university-heading {
  margin-top: 3.5rem;
  margin-bottom: 2rem;
  color: var(--color-text);
  border-bottom: 2px solid var(--color-primary);
  padding-bottom: 0.5rem;
  font-family: var(--font-heading);
  font-size: 1.5rem;
}

.teaching-university-heading:first-of-type {
  margin-top: 1.5rem;
}

.teaching-list {
  max-width: 720px;
  margin-inline: auto;
  margin-bottom: 3rem;
}

.teaching-list:last-of-type {
  margin-bottom: 0;
}

.course-item {
  margin-bottom: 2rem;
  background-color: var(--color-bg-surface);
  border: 1px solid var(--color-border);
  border-radius: var(--radius);
  padding: 1.75rem;
  box-shadow: var(--card-shadow);
  transition: border-color var(--transition-fast);
}

.course-item:hover {
  border-color: var(--color-primary);
}

.course-item h3 {
  font-size: 1.15rem;
  margin-bottom: 0.5rem;
  color: var(--color-text);
}

.course-item p {
  font-size: 0.98rem;
  color: var(--color-text);
  line-height: 1.6;
}

.course-item .course-meta {
  font-size: 0.85rem;
  color: var(--color-primary);
  font-weight: 600;
  margin-bottom: 0.75rem;
  text-transform: uppercase;
  letter-spacing: 0.04em;
}

/* ============================================================
   CONTACT SECTION
   ============================================================ */
#contact {
  text-align: center;
}

.contact-info {
  display: flex;
  justify-content: center;
  gap: 4rem;
  flex-wrap: wrap;
  margin-top: 2rem;
}

.contact-item {
  background-color: var(--color-bg-surface);
  border: 1px solid var(--color-border);
  border-radius: var(--radius);
  padding: 2rem 2.5rem;
  min-width: 250px;
  box-shadow: var(--card-shadow);
  transition: border-color var(--transition-fast);
}

.contact-item:hover {
  border-color: var(--color-primary);
}

.contact-item h4 {
  font-size: 0.85rem;
  text-transform: uppercase;
  letter-spacing: 0.08em;
  color: var(--color-primary);
  margin-bottom: 0.75rem;
  font-weight: 700;
}

.contact-item p {
  font-size: 1rem;
  color: var(--color-text);
  line-height: 1.6;
}

/* ============================================================
   FOOTER
   ============================================================ */
footer {
  background-color: var(--color-bg-surface);
  color: var(--color-text-muted);
  text-align: center;
  padding: 2.5rem var(--section-pad-x);
  font-size: 0.9rem;
  border-top: 1px solid var(--color-border);
}

footer a {
  color: var(--color-primary);
  font-weight: 600;
}

footer a:hover {
  color: var(--color-primary-hover);
  text-decoration: underline;
}

/* ============================================================
   UTILITY CLASSES
   ============================================================ */
.text-center { text-align: center; }
.text-muted  { color: var(--color-text-muted); }
.mb-1 { margin-bottom: 0.5rem; }
.mb-2 { margin-bottom: 1rem; }
.mt-1 { margin-top: 0.5rem; }
.mt-2 { margin-top: 1rem; }

.bullet-list {
  list-style: disc;
  padding-left: 1.5rem;
  margin-top: 0.75rem;
}

.bullet-list li {
  margin-bottom: 0.5rem;
  font-size: 0.98rem;
  line-height: 1.6;
}

.bullet-list li:last-child {
  margin-bottom: 0;
}


.section-cta {
  margin-top: 4rem;
  border-top: 1px solid var(--color-border);
  padding-top: 2.5rem;
  text-align: center;
}

.section-cta p {
  font-size: 1.05rem;
  color: var(--color-text-muted);
  margin-bottom: 1.25rem;
}

/* ============================================================
   RESPONSIVE — Mobile-first, desktop at 768px
   ============================================================ */

/* ---- Mobile (< 768px) ---- */
@media (max-width: 767px) {
  :root {
    --section-pad-y: 4rem;
    --section-pad-x: 1.25rem;
  }

  h1 { font-size: 2.25rem; }
  h2 { font-size: 1.65rem; }

  /* Nav: hamburger visible */
  .nav-toggle {
    display: flex;
  }

  .nav-links {
    position: fixed;
    top: var(--nav-height);
    left: 0;
    right: 0;
    background-color: var(--color-bg-nav-solid);
    border-bottom: 1px solid var(--color-border);
    flex-direction: column;
    gap: 0;
    padding: 0.5rem 0;
    transform: translateY(-120%);
    opacity: 0;
    pointer-events: none;
    transition: transform var(--transition), opacity var(--transition);
    box-shadow: 0 10px 15px -3px rgba(15, 23, 42, 0.05);
  }

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

  .nav-links a {
    display: block;
    width: 100%;
    text-align: center;
    padding: 1rem 1.5rem;
    font-size: 1.05rem;
  }

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

  /* Hero */
  #hero {
    padding-block: 6rem 4rem;
  }

  #hero h1 {
    font-size: 2.5rem;
  }

  .hero-subtitle {
    font-size: 1.2rem;
  }

  /* Grids and Tables */
  .people-grid {
    grid-template-columns: 1fr;
    max-width: 320px;
    margin-inline: auto;
  }

  /* Publications */
  .year-header {
    font-size: 1.25rem;
    padding: 1.1rem 1.25rem;
  }
  
  .pub-year[open] > .pub-group {
    padding-inline: 1.25rem;
  }
  
  .contact-info {
    flex-direction: column;
    align-items: center;
    gap: 1.5rem;
  }
  
  .contact-item {
    width: 100%;
    max-width: 350px;
  }
}

/* ---- Tablet (768px – 1023px) ---- */
@media (min-width: 768px) and (max-width: 1023px) {
  .people-grid {
    grid-template-columns: repeat(2, 1fr);
  }
}

/* ---- Desktop (≥ 768px) ---- */
@media (min-width: 768px) {
  .nav-toggle {
    display: none;
  }

  .nav-links {
    display: flex;
  }
}

/* ---- Large Desktop (≥ 1024px) ---- */
@media (min-width: 1024px) {
  .people-grid {
    grid-template-columns: repeat(4, 1fr);
  }
}

/* ============================================================
   PROFILE PAGE (Weiyi Shang)
   ============================================================ */
.profile-hero {
  display: grid;
  grid-template-columns: 280px 1fr;
  gap: 3rem;
  align-items: start;
  margin-bottom: 4rem;
}

.profile-photo-wrapper {
  position: relative;
}

.profile-photo-wrapper img {
  width: 100%;
  aspect-ratio: 1 / 1.1;
  object-fit: cover;
  border-radius: var(--radius);
  border: 1px solid var(--color-border);
  box-shadow: var(--card-shadow);
  transition: transform var(--transition);
}

.profile-photo-wrapper:hover img {
  transform: translateY(-2px);
}

.profile-title {
  font-size: 2.5rem;
  font-weight: 800;
  margin-bottom: 0.5rem;
  letter-spacing: -0.03em;
}

.profile-subtitle {
  font-size: 1.25rem;
  color: var(--color-primary);
  font-weight: 600;
  margin-bottom: 1.25rem;
}

.profile-affiliations {
  color: var(--color-text-muted);
  line-height: 1.6;
  margin-bottom: 2rem;
}

.profile-affiliations a {
  font-weight: 500;
  text-decoration: underline;
  text-decoration-color: var(--color-border);
}

.profile-affiliations a:hover {
  text-decoration-color: var(--color-primary);
}

.profile-quick-links {
  display: flex;
  gap: 1.5rem;
  flex-wrap: wrap;
  align-items: center;
}

/* Timeline Layout for Education and Awards */
.profile-timeline {
  position: relative;
  padding-left: 2rem;
  margin-block: 2rem;
}

.profile-timeline::before {
  content: "";
  position: absolute;
  left: 6px;
  top: 8px;
  bottom: 8px;
  width: 2px;
  background-color: var(--color-border);
}

.timeline-item {
  position: relative;
  margin-bottom: 2rem;
}

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

.timeline-item::before {
  content: "";
  position: absolute;
  left: -2rem;
  top: 8px;
  width: 14px;
  height: 14px;
  border-radius: 50%;
  background-color: var(--color-bg-base);
  border: 2px solid var(--color-primary);
  transform: translateX(-6px);
  transition: background-color var(--transition-fast);
}

.timeline-item:hover::before {
  background-color: var(--color-primary);
}

.timeline-date {
  font-family: var(--font-heading);
  font-size: 0.9rem;
  font-weight: 700;
  color: var(--color-primary);
  margin-bottom: 0.25rem;
  text-transform: uppercase;
  letter-spacing: 0.05em;
}

.timeline-content h4 {
  font-size: 1.15rem;
  margin-bottom: 0.5rem;
}

.timeline-content p {
  color: var(--color-text-muted);
  font-size: 0.95rem;
  line-height: 1.5;
}

.timeline-content p a {
  text-decoration: underline;
  text-decoration-color: var(--color-border);
}

.timeline-content p a:hover {
  text-decoration-color: var(--color-primary);
}

.qa-grid {
  display: grid;
  grid-template-columns: repeat(auto-fill, minmax(280px, 1fr));
  gap: 1.5rem;
  margin-top: 1.5rem;
}

.qa-card {
  background-color: var(--color-bg-surface);
  border: 1px solid var(--color-card-border);
  border-radius: var(--radius);
  padding: 1.5rem;
  box-shadow: var(--card-shadow);
  transition: transform var(--transition), border-color var(--transition), box-shadow var(--transition);
}

.qa-card:hover {
  transform: translateY(-4px);
  border-color: var(--color-primary);
  box-shadow: var(--card-shadow-hover);
}

.qa-number {
  font-family: var(--font-heading);
  font-size: 1.5rem;
  font-weight: 800;
  color: var(--color-secondary);
  opacity: 0.3;
  margin-bottom: 0.5rem;
}

.qa-card p {
  font-size: 0.98rem;
  line-height: 1.6;
}

.profile-teaching-list {
  display: grid;
  gap: 1.75rem;
  margin-top: 1.25rem;
}

.profile-teaching-group h4 {
  color: var(--color-text);
  font-family: var(--font-heading);
  font-size: 1rem;
  font-weight: 700;
  margin-bottom: 0.85rem;
  padding-bottom: 0.4rem;
  border-bottom: 1px solid var(--color-border);
}

.profile-teaching-group ul {
  display: grid;
  gap: 1rem;
  list-style: none;
}

.profile-teaching-group li {
  display: grid;
  gap: 0.3rem;
}

.profile-teaching-group strong {
  color: var(--color-text);
  font-size: 0.98rem;
  line-height: 1.45;
}

.profile-teaching-group span {
  color: var(--color-primary);
  font-size: 0.82rem;
  font-weight: 600;
  line-height: 1.45;
  text-transform: uppercase;
  letter-spacing: 0.04em;
}

/* Media Queries for profile */
@media (max-width: 767px) {
  .profile-hero {
    grid-template-columns: 1fr;
    gap: 2rem;
    text-align: center;
  }
  
  .profile-photo-wrapper {
    max-width: 240px;
    margin-inline: auto;
  }

  .profile-quick-links {
    justify-content: center;
  }
  
  .profile-title {
    font-size: 2rem;
  }
}