:root {
    /* Light mode variables */
    --primary: #1a1a1a;
    --background: #fdfdfd;
    --surface: #f5f5f5;
    --surface-hover: #eeeeee;
    --text: #1a1a1a;
    --text-secondary: rgba(26, 26, 26, 0.65);
    
    /* Dark mode variables - only applied with .dark-theme class */
    --primary-dark: #ffffff;
    --background-dark: #121212;
    --surface-dark: #1e1e1e;
    --surface-hover-dark: #282828;
    --text-dark: #e0e0e0;
    --text-secondary-dark: rgba(224, 224, 224, 0.65);
    
    /* Shared variables */
    --max-width: 1300px;
    --nav-height: 70px;
}

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

html.dark-theme {
    --primary: var(--primary-dark);
    --background: var(--background-dark);
    --surface: var(--surface-dark);
    --surface-hover: var(--surface-hover-dark);
    --text: var(--text-dark);
    --text-secondary: var(--text-secondary-dark);
}

body {
    font-family: 'Inter', -apple-system, BlinkMacSystemFont, 'Segoe UI', Roboto, Oxygen, Ubuntu, Cantarell, sans-serif;
    background: var(--background);
    color: var(--text);
    line-height: 1.6;
    overflow-x: hidden;
    transition: background-color 0.3s ease, color 0.3s ease;
    -webkit-font-smoothing: antialiased;
    -moz-osx-font-smoothing: grayscale;
}

nav {
    position: fixed;
    top: 0;
    width: 100%;
    height: var(--nav-height);
    padding: 0 2.5rem;
    background: rgba(var(--background), 0.8);
    backdrop-filter: blur(12px);
    display: flex;
    justify-content: center;
    align-items: center;
    z-index: 1000;
    border-bottom: 1px solid rgba(128, 128, 128, 0.1);
    transition: background-color 0.3s ease, border-color 0.3s ease;
}

html.dark-theme nav {
    background: rgba(18, 18, 18, 0.8);
}

.nav-links {
    display: flex;
    gap: 3rem;
    align-items: center;
}

.nav-links a {
    color: var(--text);
    text-decoration: none;
    font-weight: 500;
    font-size: 0.95rem;
    letter-spacing: 0.2px;
    transition: all 0.3s ease;
    opacity: 0.75;
}

.nav-links a:hover {
    opacity: 1;
}

main {
    margin-top: var(--nav-height);
    padding: 0;
}

.hero {
    min-height: 85vh;
    display: flex;
    align-items: center;
    padding: 4rem 4rem;
    background: var(--background);
}

.hero-content {
    max-width: var(--max-width);
    margin: 0 auto;
    width: 100%;
    animation: fadeIn 1s ease-out;
    display: flex;
    align-items: center;
    gap: 5rem;
}

@keyframes fadeIn {
    from {
        opacity: 0;
        transform: translateY(20px);
    }
    to {
        opacity: 1;
        transform: translateY(0);
    }
}

@keyframes fadeInAndScale {
    from {
        opacity: 0;
        transform: scale(0.9);
    }
    to {
        opacity: 1;
        transform: scale(1);
    }
}

.hero-logo {
    flex-shrink: 0;
    animation: fadeInAndScale 1.2s ease-out;
}

.hero-logo img {
    width: 380px;
    height: 380px;
    filter: drop-shadow(0 8px 16px rgba(128, 128, 128, 0.15));
    transition: all 0.5s ease;
}

.hero-logo img:hover {
    transform: translateY(-8px);
    filter: drop-shadow(0 16px 24px rgba(128, 128, 128, 0.2));
}

.company-name {
    font-size: 4.5rem;
    font-weight: 800;
    margin-bottom: 1.2rem;
    line-height: 1.05;
    letter-spacing: -2px;
    color: var(--primary);
    text-align: left;
}

h1 {
    font-size: 1.9rem;
    font-weight: 600;
    margin-bottom: 1.2rem;
    line-height: 1.4;
    color: var(--text);
    max-width: 700px;
    text-align: left;
}

.subtitle {
    font-size: 1.2rem;
    color: var(--text-secondary);
    line-height: 1.5;
    margin-bottom: 0;
    max-width: 700px;
    text-align: left;
}

.hero-text {
    flex: 1;
}

.research-areas {
    max-width: var(--max-width);
    margin: 0 auto;
    padding: 6rem 4rem;
    background: var(--background);
    transition: background-color 0.3s ease;
}

.research-top {
    padding-top: 4rem;
    padding-bottom: 7rem;
}

h2 {
    font-size: 2.8rem;
    margin-bottom: 3.5rem;
    text-align: center;
    font-weight: 700;
    letter-spacing: -1px;
}

.research-grid {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(320px, 1fr));
    gap: 2.5rem;
    margin-top: 2rem;
}

.research-card {
    background: var(--surface);
    padding: 2.8rem;
    border-radius: 18px;
    transition: all 0.4s ease;
    border: 1px solid transparent;
}

html:not(.dark-theme) .research-card {
    border-color: rgba(0, 0, 0, 0.05);
}

html.dark-theme .research-card {
    border-color: rgba(255, 255, 255, 0.08);
}

.research-card:hover {
    transform: translateY(-8px);
    background: var(--surface-hover);
    border-color: rgba(128, 128, 128, 0.15);
    box-shadow: 0 15px 30px rgba(0, 0, 0, 0.05);
}

html.dark-theme .research-card:hover {
    box-shadow: 0 15px 30px rgba(0, 0, 0, 0.15);
}

.research-card h3 {
    font-size: 1.5rem;
    margin-bottom: 1rem;
    color: var(--primary);
    font-weight: 600;
}

.research-card p {
    color: var(--text-secondary);
    font-size: 1.1rem;
    line-height: 1.6;
}

footer {
    text-align: center;
    padding: 2.5rem 2rem;
    background: var(--surface);
    color: var(--text-secondary);
    font-size: 0.9rem;
    transition: background-color 0.3s ease, color 0.3s ease;
}

.footer-content {
    max-width: var(--max-width);
    margin: 0 auto;
    display: flex;
    flex-direction: column;
    align-items: center;
    gap: 1rem;
}

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

.contact-email {
    margin-top: 0;
}

.contact-email a,
.social-link {
    color: var(--text-secondary);
    text-decoration: none;
    transition: color 0.3s ease, opacity 0.3s ease;
    display: inline-flex;
    align-items: center;
}

.contact-email a:hover,
.social-link:hover {
    color: var(--text);
    opacity: 0.9;
    text-decoration: none;
}

.social-link svg {
    width: 20px;
    height: 20px;
}

/* Theme toggle button styles */
#theme-toggle {
    background: none;
    border: none;
    padding: 0;
    color: var(--text);
    cursor: pointer;
    display: flex;
    align-items: center;
    justify-content: center;
    width: 40px;
    height: 40px;
    border-radius: 50%;
    transition: all 0.3s ease;
}

#theme-toggle:hover {
    background: var(--surface);
}

#theme-toggle svg {
    transition: all 0.3s ease;
}

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

.dark-theme #theme-toggle .moon {
    display: none;
}

.dark-theme #theme-toggle .sun {
    display: block;
}

@media (max-width: 1200px) {
    .hero-logo img {
        width: 320px;
        height: 320px;
    }
    
    .company-name {
        font-size: 4rem;
    }

    h1 {
        font-size: 1.7rem;
    }

    .subtitle {
        font-size: 1.1rem;
    }
}

@media (max-width: 968px) {
    nav {
        padding: 0 1.5rem;
    }

    .hero {
        padding: 3rem 2rem 5rem;
    }
    
    .hero-logo img {
        width: 280px;
        height: 280px;
    }

    .hero-content {
        flex-direction: column;
        text-align: left;
        align-items: flex-start;
        gap: 3rem;
    }

    .company-name {
        font-size: 3.5rem;
    }

    h1 {
        font-size: 1.6rem;
    }
}

@media (max-width: 768px) {
    nav {
        padding: 0 1rem;
    }

    .nav-links {
        gap: 1.5rem;
    }

    .hero {
        padding: 1rem 1rem 3rem;
    }

    .company-name {
        font-size: 2.8rem;
    }

    h1 {
        font-size: 1.5rem;
    }

    .subtitle {
        font-size: 1.05rem;
    }

    .research-areas {
        padding: 3rem 1.5rem;
    }

    .research-grid {
        grid-template-columns: 1fr;
        gap: 2rem;
    }

    h2 {
        font-size: 2.2rem;
    }
}