:root {
    /* Color Palette */
    --color-primary: #1a365d;
    --color-primary-light: #2c4c7c;
    --color-secondary: #c5704b;
    --color-accent: #739e82;
    --color-gray-100: #f8f8f8;
    --color-gray-200: #e9e9e9;
    --color-gray-300: #d1d1d1;
    --color-gray-400: #ababab;
    --color-gray-500: #808080;
    --color-gray-600: #595959;
    --color-gray-700: #383838;
    --color-gray-800: #1f1f1f;
    --color-gray-900: #121212;

    /* Typography */
    --font-heading: 'Merriweather', Georgia, serif;
    --font-body: 'Open Sans', -apple-system, BlinkMacSystemFont, sans-serif;

    /* Spacing */
    --space-xs: 0.25rem;
    --space-sm: 0.5rem;
    --space-md: 1rem;
    --space-lg: 2rem;
    --space-xl: 3rem;
    --space-xxl: 5rem;

    /* Borders & Shadows */
    --border-radius-sm: 0.25rem;
    --border-radius-md: 0.5rem;
    --border-radius-lg: 1rem;
    --shadow-sm: 0 1px 3px rgba(0, 0, 0, 0.12), 0 1px 2px rgba(0, 0, 0, 0.24);
    --shadow-md: 0 4px 6px rgba(0, 0, 0, 0.1);
    --shadow-lg: 0 10px 20px rgba(0, 0, 0, 0.1);

    /* Transitions */
    --transition-fast: 150ms ease;
    --transition-normal: 300ms ease;
    --transition-slow: 500ms ease;
}

/* Dark Mode */
.dark-mode {
    --color-primary: #4a6d9a;
    --color-primary-light: #5d7ea8;
    --color-secondary: #b36d4d;
    --color-accent: #5a8c70;

    --color-gray-100: #121212;
    --color-gray-200: #1a1a1a;
    --color-gray-300: #242424;
    --color-gray-400: #333333;
    --color-gray-500: #555555;
    --color-gray-600: #777777;
    --color-gray-700: #aaaaaa;
    --color-gray-800: #cccccc;
    --color-gray-900: #eeeeee;

    --background-color: var(--color-gray-100);
    --text-color: var(--color-gray-700);
    --card-background: var(--color-gray-300);

    color-scheme: dark;
}

/* Dark mode component overrides */
.dark-mode .header {
    background-color: var(--color-gray-200);
    box-shadow: 0 2px 10px rgba(0, 0, 0, 0.5);
}

.dark-mode .nav a {
    color: var(--color-gray-600);
}

.dark-mode .nav a:hover,
.dark-mode .nav a.active {
    color: var(--color-primary-light);
}

.dark-mode .logo {
    color: var(--color-primary-light);
}

.dark-mode .logo-icon {
    background-color: var(--color-gray-300);
    color: var(--color-primary-light);
}

.dark-mode .hero {
    background: linear-gradient(135deg, var(--color-gray-300) 0%, var(--color-gray-200) 100%);
}

.dark-mode .btn-primary {
    background-color: var(--color-secondary);
    border-color: var(--color-secondary);
}

.dark-mode .btn-primary:hover {
    background-color: transparent;
    color: var(--color-secondary);
}

.dark-mode .btn-secondary {
    border-color: var(--color-gray-500);
    color: var(--color-gray-700);
}

.dark-mode .btn-secondary:hover {
    background-color: var(--color-gray-400);
    color: var(--color-gray-900);
}

.dark-mode .profile-section,
.dark-mode .bio-section,
.dark-mode .research-section,
.dark-mode .education-section,
.dark-mode .research-area,
.dark-mode .publication-highlight,
.dark-mode .publication-card,
.dark-mode .talk-card,
.dark-mode .award-card,
.dark-mode .contact-card,
.dark-mode .contact-info-container,
.dark-mode .upcoming-talks,
.dark-mode .other-recognition {
    background-color: var(--card-background);
    box-shadow: 0 4px 6px rgba(0, 0, 0, 0.3);
}

.dark-mode .footer {
    background-color: var(--color-gray-300);
}

.dark-mode .footer-section a {
    color: var(--color-gray-800);
}

.dark-mode .footer-section a:hover {
    color: var(--color-secondary);
}

.dark-mode .footer-bottom p {
    color: var(--color-gray-600);
}

.dark-mode .theme-toggle:hover {
    background-color: var(--color-gray-700);
}

@media (max-width: 1024px) {
    .dark-mode .nav {
        background-color: var(--color-gray-900);
    }
}