:root {
  --color-bg: #ffffff;
  --color-text: #111827;
  --color-text-secondary: #4b5563;
  --color-text-light: #6b7280;
  --color-border: #e5e7eb;
  --color-accent: #2563eb;
  --color-accent-hover: #1d4ed8;
  --color-card-bg: #ffffff;
  --color-shadow-sm: rgba(0, 0, 0, 0.04);
  --color-shadow: rgba(0, 0, 0, 0.06);
  --color-shadow-md: rgba(0, 0, 0, 0.1);
  --color-shadow-lg: rgba(0, 0, 0, 0.15);

  --font-sans: -apple-system, BlinkMacSystemFont, 'Segoe UI', 'Roboto', 'Oxygen', 'Ubuntu', 'Cantarell', sans-serif;
  --font-display: 'Inter', -apple-system, BlinkMacSystemFont, sans-serif;

  --max-width: 1200px;
  --spacing-xs: 0.5rem;
  --spacing-sm: 1rem;
  --spacing-md: 1.5rem;
  --spacing-lg: 2rem;
  --spacing-xl: 3rem;
  --spacing-2xl: 4rem;

  --radius-sm: 0.5rem;
  --radius: 0.75rem;
  --radius-lg: 1rem;
  --transition: all 0.2s cubic-bezier(0.4, 0, 0.2, 1);
}

* {
  margin: 0;
  padding: 0;
  box-sizing: border-box;
}

html {
  scroll-behavior: smooth;
}

body {
  font-family: var(--font-sans);
  font-size: 16px;
  line-height: 1.6;
  color: var(--color-text);
  background-color: var(--color-bg);
  -webkit-font-smoothing: antialiased;
  -moz-osx-font-smoothing: grayscale;
  animation: fadeIn 0.4s ease-out;
}

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

/* Accessibility - Focus styles */
*:focus-visible {
  outline: 2px solid var(--color-accent);
  outline-offset: 2px;
  border-radius: 0.25rem;
}

/* Skip to main content link for accessibility */
.skip-to-main {
  position: absolute;
  top: -100px;
  left: 0;
  background: var(--color-accent);
  color: white;
  padding: 0.75rem 1.5rem;
  text-decoration: none;
  border-radius: 0 0 0.5rem 0;
  z-index: 1001;
  font-weight: 600;
  transition: top 0.3s;
}

.skip-to-main:focus {
  top: 0;
}

/* Navigation */
.nav {
  position: fixed;
  top: 0;
  left: 0;
  right: 0;
  background-color: rgba(255, 255, 255, 0.85);
  backdrop-filter: blur(12px);
  -webkit-backdrop-filter: blur(12px);
  border-bottom: 1px solid var(--color-border);
  z-index: 1000;
}

.nav-container {
  max-width: var(--max-width);
  margin: 0 auto;
  padding: 0 var(--spacing-lg);
  display: flex;
  justify-content: center;
  align-items: center;
  height: 64px;
}

.nav-menu {
  display: flex;
  gap: 2rem;
  list-style: none;
}

.nav-menu a {
  color: var(--color-text-secondary);
  text-decoration: none;
  font-weight: 500;
  font-size: 0.9375rem;
  transition: var(--transition);
  padding: var(--spacing-xs) var(--spacing-sm);
  border-radius: var(--radius-sm);
}

.nav-menu a:hover {
  color: var(--color-text);
  background-color: rgba(37, 99, 235, 0.06);
}

.nav-menu a.active {
  color: var(--color-accent);
  font-weight: 600;
  position: relative;
}

.nav-menu a.active::after {
  content: '';
  position: absolute;
  bottom: -1px;
  left: 0.5rem;
  right: 0.5rem;
  height: 2px;
  background-color: var(--color-accent);
  border-radius: 2px;
}

.nav-toggle {
  display: none;
  flex-direction: column;
  gap: 5px;
  background: none;
  border: none;
  cursor: pointer;
  padding: 0.5rem;
}

.nav-toggle span {
  display: block;
  width: 24px;
  height: 2px;
  background-color: var(--color-text);
  transition: var(--transition);
}

/* Main Container */
.container {
  max-width: var(--max-width);
  margin: 0 auto;
  padding: 0 var(--spacing-lg);
  padding-top: calc(64px + 2.5rem);
  padding-bottom: var(--spacing-2xl);
}

.layout {
  display: grid;
  grid-template-columns: 280px 1fr;
  gap: 3.5rem;
  align-items: start;
}

/* Profile Sidebar */
.profile {
  position: sticky;
  top: calc(64px + var(--spacing-lg));
}

.profile-image {
  width: 180px;
  height: 180px;
  border-radius: 50%;
  object-fit: cover;
  margin-bottom: var(--spacing-md);
  border: 2px solid var(--color-border);
  box-shadow: 0 4px 12px var(--color-shadow-sm);
  transition: var(--transition);
}

.profile-image:hover {
  border-color: var(--color-accent);
  box-shadow: 0 8px 20px var(--color-shadow-md);
}

.profile-name {
  font-family: var(--font-display);
  font-size: 2rem;
  font-weight: 700;
  margin-bottom: 0.5rem;
  line-height: 1.2;
}

.profile-title,
.profile-company,
.profile-location {
  color: var(--color-text-secondary);
  font-size: 0.9375rem;
  margin-bottom: 0.3rem;
  line-height: 1.4;
}

.profile-title {
  font-weight: 500;
}

.profile-links {
  margin-top: 1.75rem;
  display: flex;
  flex-direction: column;
  gap: 0.25rem;
}

.profile-links a {
  display: flex;
  align-items: center;
  gap: 0.625rem;
  color: var(--color-text-secondary);
  text-decoration: none;
  font-size: 0.9375rem;
  font-weight: 500;
  transition: var(--transition);
  padding: 0.5rem 0.625rem;
  border-radius: var(--radius-sm);
  margin-left: -0.625rem;
}

.profile-links a:hover {
  color: var(--color-accent);
  background-color: rgba(37, 99, 235, 0.06);
}

.profile-links i {
  width: 20px;
  text-align: center;
}

/* Main Content */
.main-content {
  min-width: 0;
}

section {
  margin-bottom: 3.5rem;
}

section:first-child {
  margin-bottom: 3rem;
}

section:last-child {
  margin-bottom: 0;
}

h1, h2 {
  font-family: var(--font-display);
  font-weight: 700;
  line-height: 1.2;
  margin-bottom: 1.75rem;
  color: var(--color-text);
  letter-spacing: -0.02em;
}

h1 {
  font-size: 2.5rem;
}

h2 {
  font-size: 1.875rem;
}

h3 {
  font-family: var(--font-display);
  font-size: 1.375rem;
  font-weight: 600;
  line-height: 1.3;
  margin-bottom: 1.5rem;
  color: var(--color-text);
  letter-spacing: -0.015em;
}

h4 {
  font-size: 1.0625rem;
  font-weight: 600;
  margin-bottom: var(--spacing-xs);
  color: var(--color-text);
  line-height: 1.4;
}

p {
  margin-bottom: 1.125rem;
  color: var(--color-text-secondary);
  line-height: 1.65;
  font-size: 1rem;
}

p:last-child {
  margin-bottom: 0;
}

ul {
  margin-bottom: var(--spacing-md);
  padding-left: 1.25rem;
}

li {
  margin-bottom: 0.4rem;
  color: var(--color-text-secondary);
  line-height: 1.5;
}

li:last-child {
  margin-bottom: 0;
}

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

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

a:focus-visible {
  outline: 2px solid var(--color-accent);
  outline-offset: 2px;
  border-radius: 2px;
}

/* Cards */
.card {
  background-color: var(--color-card-bg);
  border: 1px solid var(--color-border);
  border-radius: var(--radius);
  padding: 1.75rem;
  margin-bottom: 2.5rem;
  transition: var(--transition);
  box-shadow: 0 1px 3px var(--color-shadow-sm);
}

.card:hover {
  box-shadow: 0 10px 32px var(--color-shadow-md);
  transform: translateY(-3px);
  border-color: rgba(37, 99, 235, 0.3);
}

/* Experience/Education Items */
.experience-item {
  display: flex;
  gap: 1.25rem;
  margin-bottom: 2.25rem;
  padding-bottom: 1.25rem;
  border-bottom: 1px solid var(--color-border);
  align-items: flex-start;
}

.experience-item:last-child {
  border-bottom: none;
  padding-bottom: 0;
  margin-bottom: 0;
}

.experience-logo {
  flex-shrink: 0;
  width: 52px;
  height: 52px;
  object-fit: contain;
  margin-top: 0.125rem;
}

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

.experience-content h4 {
  color: var(--color-text);
  margin-bottom: 0.625rem;
  font-size: 1.0625rem;
}

.experience-content p {
  margin-bottom: 0.4rem;
  font-size: 0.9375rem;
  line-height: 1.5;
  color: var(--color-text-secondary);
}

.experience-content p strong {
  color: var(--color-text);
  font-weight: 600;
}

.experience-content p:last-child {
  margin-bottom: 0;
}

/* Publication Cards */
.publication-card {
  background-color: var(--color-card-bg);
  border: 1px solid var(--color-border);
  border-radius: var(--radius);
  overflow: hidden;
  margin-bottom: 2.5rem;
  transition: var(--transition);
  box-shadow: 0 1px 3px var(--color-shadow-sm);
}

.publication-card:hover {
  box-shadow: 0 10px 32px var(--color-shadow-md);
  transform: translateY(-3px);
  border-color: rgba(37, 99, 235, 0.3);
}

.publication-image {
  width: 100%;
  height: 240px;
  object-fit: contain;
  background: linear-gradient(to bottom, #f9fafb, #f3f4f6);
  padding: var(--spacing-md);
}

.publication-content {
  padding: 1.75rem;
}

.publication-content h3 {
  color: var(--color-text);
  margin-bottom: 1rem;
  font-size: 1.3125rem;
  line-height: 1.35;
  font-weight: 600;
}

.publication-content p {
  margin-bottom: 1rem;
  line-height: 1.65;
  color: var(--color-text-secondary);
  font-size: 0.9375rem;
}

.publication-content p:last-child {
  margin-top: 1.25rem;
  margin-bottom: 0;
}

/* Patent Cards */
.patent-card {
  background-color: var(--color-card-bg);
  border: 1px solid var(--color-border);
  border-radius: var(--radius);
  padding: 1.75rem;
  margin-bottom: 2.5rem;
  display: flex;
  gap: 1.5rem;
  transition: var(--transition);
  align-items: flex-start;
  box-shadow: 0 1px 3px var(--color-shadow-sm);
}

.patent-card:hover {
  box-shadow: 0 10px 32px var(--color-shadow-md);
  transform: translateY(-3px);
  border-color: rgba(37, 99, 235, 0.3);
}

.patent-image-container {
  flex-shrink: 0;
  width: 200px;
  height: 200px;
  display: flex;
  align-items: center;
  justify-content: center;
  background: linear-gradient(to bottom, #f9fafb, #f3f4f6);
  border-radius: var(--radius-sm);
  padding: 0.75rem;
}

.patent-image {
  width: 100%;
  height: 100%;
  object-fit: contain;
}

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

.patent-content h3 {
  color: var(--color-text);
  font-size: 1.1875rem;
  font-weight: 600;
  margin-bottom: 0.75rem;
  line-height: 1.4;
}

.patent-content p {
  margin-bottom: 0.625rem;
  font-size: 0.9375rem;
  line-height: 1.5;
  color: var(--color-text-secondary);
}

.patent-content p:last-child {
  margin-top: 0.875rem;
  margin-bottom: 0;
}

/* Research Page */
.research-image {
  max-width: 75%;
  height: auto;
  margin: var(--spacing-xl) auto;
  display: block;
  border-radius: var(--radius);
  box-shadow: 0 4px 16px var(--color-shadow);
}

/* Footer */
.footer {
  margin-top: 5rem;
  padding: 2rem 0 1.5rem;
  border-top: 1px solid var(--color-border);
  text-align: center;
  color: var(--color-text-light);
  font-size: 0.875rem;
}

.footer p {
  margin: 0;
}

/* Responsive Design */
@media (max-width: 968px) {
  .layout {
    grid-template-columns: 1fr;
    gap: 2.5rem;
  }

  .profile {
    position: static;
    display: flex;
    flex-direction: column;
    align-items: center;
    text-align: center;
    padding-bottom: 2.5rem;
    border-bottom: 1px solid var(--color-border);
  }

  .profile-links {
    flex-direction: row;
    flex-wrap: wrap;
    justify-content: center;
  }

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

  .patent-image-container {
    width: 100%;
    height: 240px;
  }
}

@media (max-width: 768px) {
  :root {
    --spacing-lg: 1.5rem;
    --spacing-xl: 2rem;
    --spacing-2xl: 3rem;
  }

  .container {
    padding: calc(64px + 2rem) 1.25rem 2.5rem;
  }

  .nav-container {
    justify-content: space-between;
    padding: 0 var(--spacing-md);
  }

  .nav-toggle {
    display: flex;
  }

  .nav-menu {
    position: fixed;
    top: 64px;
    left: 0;
    right: 0;
    background-color: rgba(255, 255, 255, 0.95);
    backdrop-filter: blur(12px);
    -webkit-backdrop-filter: blur(12px);
    flex-direction: column;
    gap: 0;
    padding: var(--spacing-md);
    border-bottom: 1px solid var(--color-border);
    transform: translateY(-100%);
    opacity: 0;
    transition: var(--transition);
    pointer-events: none;
  }

  .nav-menu.active {
    transform: translateY(0);
    opacity: 1;
    pointer-events: all;
  }

  .nav-menu a {
    padding: var(--spacing-md);
    display: block;
  }

  h1 {
    font-size: 2rem;
  }

  h2 {
    font-size: 1.625rem;
  }

  h3 {
    font-size: 1.25rem;
  }

  .profile-image {
    width: 150px;
    height: 150px;
  }

  .profile-name {
    font-size: 1.625rem;
  }

  .experience-item {
    flex-direction: column;
    gap: 0.75rem;
    margin-bottom: 1.75rem;
    padding-bottom: 1rem;
  }

  .experience-logo {
    margin-top: 0;
    width: 48px;
    height: 48px;
  }

  .research-image {
    max-width: 100%;
  }
}

@media (max-width: 480px) {
  .card,
  .publication-card,
  .patent-card {
    margin-left: calc(-1 * var(--spacing-md));
    margin-right: calc(-1 * var(--spacing-md));
    border-radius: 0;
    border-left: none;
    border-right: none;
  }
}

/* Print Styles */
@media print {
  .nav,
  .nav-toggle,
  .skip-to-main {
    display: none !important;
  }

  body {
    padding-top: 0 !important;
    animation: none;
  }

  .container {
    padding-top: 0 !important;
    max-width: 100%;
  }

  .profile {
    position: static !important;
  }

  .publication-card,
  .patent-card,
  .card {
    page-break-inside: avoid;
    box-shadow: none !important;
    border: 1px solid #ddd;
  }

  a {
    text-decoration: underline;
  }

  a[href]:after {
    content: " (" attr(href) ")";
    font-size: 0.8em;
    color: #666;
  }
}

/* Image loading optimization */
img {
  image-rendering: -webkit-optimize-contrast;
  image-rendering: crisp-edges;
  max-width: 100%;
  height: auto;
}

/* Smooth scrolling for reduced motion preference */
@media (prefers-reduced-motion: reduce) {
  *,
  *::before,
  *::after {
    animation-duration: 0.01ms !important;
    animation-iteration-count: 1 !important;
    transition-duration: 0.01ms !important;
    scroll-behavior: auto !important;
  }
}