:root {
    /* Modern Biotech Color Palette */
    --color-primary: #00D9A3;
    --color-primary-dark: #00B88A;
    --color-primary-light: #33E3B8;

    --color-secondary: #0066FF;
    --color-secondary-dark: #0052CC;
    --color-secondary-light: #3385FF;

    --color-accent: #8B5CF6;
    --color-accent-dark: #7C3AED;
    --color-accent-light: #A78BFA;

    --color-biology: #00D9A3;
    --color-chemistry: #0066FF;
    --color-genetics: #8B5CF6;
    --color-bioengineering: #FF6B9D;

    /* Neutrals - Dark Theme (Default) */
    --color-bg: #0A0E1A;
    --color-bg-secondary: #141927;
    --color-bg-tertiary: #1E2535;
    --color-surface: #252D3F;
    --color-surface-hover: #2D3548;

    --color-text-primary: #FFFFFF;
    --color-text-secondary: #B4BCD0;
    --color-text-muted: #6B7280;

    --color-border: #2D3548;
    --color-border-light: #3D4558;

    /* Gradients */
    --gradient-primary: linear-gradient(135deg, #00D9A3 0%, #0066FF 100%);
    --gradient-secondary: linear-gradient(135deg, #8B5CF6 0%, #FF6B9D 100%);
    --gradient-hero: linear-gradient(135deg, rgba(0, 217, 163, 0.1) 0%, rgba(0, 102, 255, 0.1) 100%);

    /* Spacing */
    --spacing-xs: 0.5rem;
    --spacing-sm: 1rem;
    --spacing-md: 1.5rem;
    --spacing-lg: 2rem;
    --spacing-xl: 3rem;
    --spacing-2xl: 4rem;

    /* Typography */
    --font-family: 'Inter', -apple-system, BlinkMacSystemFont, 'Segoe UI', sans-serif;
    --font-size-xs: 0.75rem;
    --font-size-sm: 0.875rem;
    --font-size-base: 1rem;
    --font-size-lg: 1.125rem;
    --font-size-xl: 1.25rem;
    --font-size-2xl: 1.5rem;
    --font-size-3xl: 2rem;
    --font-size-4xl: 2.5rem;
    --font-size-5xl: 3rem;

    /* Shadows */
    --shadow-sm: 0 1px 2px 0 rgba(0, 0, 0, 0.3);
    --shadow-md: 0 4px 6px -1px rgba(0, 0, 0, 0.4), 0 2px 4px -1px rgba(0, 0, 0, 0.3);
    --shadow-lg: 0 10px 15px -3px rgba(0, 0, 0, 0.5), 0 4px 6px -2px rgba(0, 0, 0, 0.4);
    --shadow-xl: 0 20px 25px -5px rgba(0, 0, 0, 0.6), 0 10px 10px -5px rgba(0, 0, 0, 0.5);
    --shadow-glow: 0 0 20px rgba(0, 217, 163, 0.3);

    /* Border Radius */
    --radius-sm: 0.375rem;
    --radius-md: 0.5rem;
    --radius-lg: 0.75rem;
    --radius-xl: 1rem;
    --radius-2xl: 1.5rem;
    --radius-full: 9999px;

    /* Transitions */
    --transition-fast: 150ms cubic-bezier(0.4, 0, 0.2, 1);
    --transition-base: 300ms cubic-bezier(0.4, 0, 0.2, 1);
    --transition-slow: 500ms cubic-bezier(0.4, 0, 0.2, 1);
}

/* Light Theme */
[data-theme="light"] {
    /* Neutrals - Light Theme */
    --color-bg: #FFFFFF;
    --color-bg-secondary: #F8F9FA;
    --color-bg-tertiary: #F1F3F5;
    --color-surface: #FFFFFF;
    --color-surface-hover: #F8F9FA;

    --color-text-primary: #1A1D29;
    --color-text-secondary: #4A5568;
    --color-text-muted: #718096;

    --color-border: #E2E8F0;
    --color-border-light: #CBD5E0;

    /* Gradients for light theme */
    --gradient-hero: linear-gradient(135deg, rgba(0, 217, 163, 0.08) 0%, rgba(0, 102, 255, 0.08) 100%);

    /* Shadows for light theme */
    --shadow-sm: 0 1px 2px 0 rgba(0, 0, 0, 0.05);
    --shadow-md: 0 4px 6px -1px rgba(0, 0, 0, 0.1), 0 2px 4px -1px rgba(0, 0, 0, 0.06);
    --shadow-lg: 0 10px 15px -3px rgba(0, 0, 0, 0.1), 0 4px 6px -2px rgba(0, 0, 0, 0.05);
    --shadow-xl: 0 20px 25px -5px rgba(0, 0, 0, 0.1), 0 10px 10px -5px rgba(0, 0, 0, 0.04);
    --shadow-glow: 0 0 20px rgba(0, 217, 163, 0.2);
}

/* Reset & Base Styles */
* {
    margin: 0;
    padding: 0;
    box-sizing: border-box;
}

body {
    font-family: var(--font-family);
    background-color: var(--color-bg);
    color: var(--color-text-primary);
    line-height: 1.6;
    -webkit-font-smoothing: antialiased;
    -moz-osx-font-smoothing: grayscale;
    transition: background-color var(--transition-base), color var(--transition-base);
}

/* Typography */
h1,
h2,
h3,
h4,
h5,
h6 {
    font-weight: 700;
    line-height: 1.2;
    margin-bottom: var(--spacing-md);
    color: var(--color-text-primary);
}

h1 {
    font-size: var(--font-size-5xl);
}

h2 {
    font-size: var(--font-size-4xl);
}

h3 {
    font-size: var(--font-size-3xl);
}

h4 {
    font-size: var(--font-size-2xl);
}

h5 {
    font-size: var(--font-size-xl);
}

h6 {
    font-size: var(--font-size-lg);
}

p {
    margin-bottom: var(--spacing-sm);
    color: var(--color-text-secondary);
}

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

a:hover {
    color: var(--color-primary-light);
}

/* Container */
.container {
    max-width: 1280px;
    margin: 0 auto;
    padding: 0 var(--spacing-md);
}

/* Navigation */
.navbar {
    background: rgba(20, 25, 39, 0.95);
    backdrop-filter: blur(10px);
    border-bottom: 1px solid var(--color-border);
    position: sticky;
    top: 0;
    z-index: 1000;
    padding: var(--spacing-sm) 0;
}

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

.navbar-brand {
    font-size: var(--font-size-2xl);
    font-weight: 800;
    background: var(--gradient-primary);
    -webkit-background-clip: text;
    -webkit-text-fill-color: transparent;
    background-clip: text;
}

.navbar-nav {
    display: flex;
    gap: var(--spacing-lg);
    list-style: none;
    align-items: center;
}

/* Hamburger Menu */
.hamburger {
    display: none;
    flex-direction: column;
    gap: 4px;
    background: none;
    border: none;
    cursor: pointer;
    padding: 8px;
}

.hamburger span {
    width: 24px;
    height: 2px;
    background: var(--color-text-primary);
    transition: all var(--transition-base);
    border-radius: 2px;
}

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

.hamburger.active span:nth-child(2) {
    opacity: 0;
}

.hamburger.active span:nth-child(3) {
    transform: rotate(-45deg) translate(7px, -6px);
}

.navbar-nav a {
    color: var(--color-text-secondary);
    font-weight: 500;
    transition: all var(--transition-fast);
    padding: var(--spacing-xs) var(--spacing-sm);
    border-radius: var(--radius-md);
}

.navbar-nav a:hover {
    color: var(--color-primary);
    background: rgba(0, 217, 163, 0.1);
}

.navbar-nav a.active {
    color: var(--color-primary);
}

/* Hero Section */
.hero {
    background: var(--gradient-hero);
    padding: var(--spacing-2xl) 0;
    margin-bottom: var(--spacing-xl);
    border-radius: var(--radius-2xl);
    position: relative;
    overflow: hidden;
}

.hero::before {
    content: '';
    position: absolute;
    top: 0;
    left: 0;
    right: 0;
    bottom: 0;
    background: url('data:image/svg+xml,<svg width="100" height="100" xmlns="http://www.w3.org/2000/svg"><path d="M50 0 L50 100 M0 50 L100 50" stroke="rgba(0,217,163,0.05)" stroke-width="1"/></svg>');
    opacity: 0.3;
}

.hero-content {
    position: relative;
    z-index: 1;
}

.hero h1 {
    font-size: var(--font-size-5xl);
    margin-bottom: var(--spacing-md);
}

.hero p {
    font-size: var(--font-size-xl);
    color: var(--color-text-secondary);
}

/* Category Filters */
.category-filters {
    display: flex;
    gap: var(--spacing-sm);
    margin-bottom: var(--spacing-xl);
    flex-wrap: wrap;
}

.category-filter {
    padding: var(--spacing-sm) var(--spacing-lg);
    background: var(--color-surface);
    border: 1px solid var(--color-border);
    border-radius: var(--radius-full);
    color: var(--color-text-secondary);
    font-weight: 600;
    cursor: pointer;
    transition: all var(--transition-base);
}

.category-filter:hover {
    background: var(--color-surface-hover);
    border-color: var(--color-border-light);
    transform: translateY(-2px);
}

.category-filter.active {
    background: var(--gradient-primary);
    color: white;
    border-color: transparent;
}

/* Article Grid */
.article-grid {
    display: grid;
    grid-template-columns: repeat(auto-fill, minmax(350px, 1fr));
    gap: var(--spacing-lg);
    margin-bottom: var(--spacing-xl);
}

/* Article Card */
.article-card {
    background: var(--color-bg-secondary);
    border: 1px solid var(--color-border);
    border-radius: var(--radius-xl);
    overflow: hidden;
    transition: all var(--transition-base);
    cursor: pointer;
    display: flex;
    flex-direction: column;
}

.article-card:hover {
    border-color: var(--color-border-light);
    transform: translateY(-8px);
    box-shadow: var(--shadow-xl);
}

.article-card-image {
    width: 100%;
    height: 220px;
    object-fit: cover;
    background: var(--color-surface);
}

.article-card-content {
    padding: var(--spacing-lg);
    flex: 1;
    display: flex;
    flex-direction: column;
}

.article-card-title {
    font-size: var(--font-size-xl);
    font-weight: 700;
    margin-bottom: var(--spacing-sm);
    color: var(--color-text-primary);
}

.article-card-excerpt {
    color: var(--color-text-secondary);
    margin-bottom: var(--spacing-md);
    flex: 1;
}

.article-card-meta {
    display: flex;
    justify-content: space-between;
    align-items: center;
    font-size: var(--font-size-sm);
    color: var(--color-text-muted);
}

/* Badges */
.badge {
    display: inline-flex;
    align-items: center;
    padding: 0.25rem 0.75rem;
    font-size: var(--font-size-xs);
    font-weight: 600;
    border-radius: var(--radius-full);
    text-transform: uppercase;
    letter-spacing: 0.05em;
}

.badge-biology {
    background: rgba(0, 217, 163, 0.15);
    color: var(--color-biology);
    border: 1px solid rgba(0, 217, 163, 0.3);
}

.badge-chemistry {
    background: rgba(0, 102, 255, 0.15);
    color: var(--color-chemistry);
    border: 1px solid rgba(0, 102, 255, 0.3);
}

.badge-genetics {
    background: rgba(139, 92, 246, 0.15);
    color: var(--color-genetics);
    border: 1px solid rgba(139, 92, 246, 0.3);
}

.badge-bioengineering {
    background: rgba(255, 107, 157, 0.15);
    color: var(--color-bioengineering);
    border: 1px solid rgba(255, 107, 157, 0.3);
}

/* Buttons */
.btn {
    display: inline-flex;
    align-items: center;
    justify-content: center;
    padding: var(--spacing-sm) var(--spacing-lg);
    font-size: var(--font-size-base);
    font-weight: 600;
    border: none;
    border-radius: var(--radius-lg);
    cursor: pointer;
    transition: all var(--transition-base);
    text-decoration: none;
    gap: var(--spacing-xs);
}

.btn-primary {
    background: var(--gradient-primary);
    color: white;
    box-shadow: var(--shadow-md);
}

.btn-primary:hover {
    transform: translateY(-2px);
    box-shadow: var(--shadow-lg), var(--shadow-glow);
}

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

.btn-secondary:hover {
    background: var(--color-surface-hover);
    border-color: var(--color-border-light);
}

/* Form Elements */
input,
textarea,
select {
    width: 100%;
    padding: var(--spacing-sm);
    background: var(--color-surface);
    border: 1px solid var(--color-border);
    border-radius: var(--radius-md);
    color: var(--color-text-primary);
    font-family: var(--font-family);
    font-size: var(--font-size-base);
    transition: all var(--transition-fast);
}

input:focus,
textarea:focus,
select:focus {
    outline: none;
    border-color: var(--color-primary);
    box-shadow: 0 0 0 3px rgba(0, 217, 163, 0.1);
}

textarea {
    resize: vertical;
    min-height: 120px;
}

label {
    display: block;
    margin-bottom: var(--spacing-xs);
    font-weight: 500;
    color: var(--color-text-primary);
}

/* Footer */
.footer {
    background: var(--color-bg-secondary);
    border-top: 1px solid var(--color-border);
    padding: var(--spacing-xl) 0;
    margin-top: var(--spacing-2xl);
}

.footer-content {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(250px, 1fr));
    gap: var(--spacing-xl);
    margin-bottom: var(--spacing-lg);
}

.footer-section h3 {
    font-size: var(--font-size-lg);
    margin-bottom: var(--spacing-sm);
}

.footer-section ul {
    list-style: none;
}

.footer-section ul li {
    margin-bottom: var(--spacing-xs);
}

.footer-bottom {
    text-align: center;
    padding-top: var(--spacing-lg);
    border-top: 1px solid var(--color-border);
    color: var(--color-text-muted);
}

/* Animations */
@keyframes fadeIn {
    from {
        opacity: 0;
        transform: translateY(20px);
    }

    to {
        opacity: 1;
        transform: translateY(0);
    }
}

@keyframes slideIn {
    from {
        opacity: 0;
        transform: translateX(-20px);
    }

    to {
        opacity: 1;
        transform: translateX(0);
    }
}

.fade-in {
    animation: fadeIn var(--transition-base) ease-out;
}

.slide-in {
    animation: slideIn var(--transition-base) ease-out;
}

/* Loading */
.loading {
    display: inline-block;
    width: 20px;
    height: 20px;
    border: 3px solid var(--color-border);
    border-top-color: var(--color-primary);
    border-radius: 50%;
    animation: spin 0.8s linear infinite;
}

@keyframes spin {
    to {
        transform: rotate(360deg);
    }
}

/* Responsive */
@media (max-width: 768px) {
    :root {
        --font-size-5xl: 2rem;
        --font-size-4xl: 1.75rem;
        --font-size-3xl: 1.5rem;
    }

    .container {
        padding: 0 var(--spacing-sm);
    }

    /* Mobile Navigation */
    .navbar .container {
        flex-wrap: wrap;
    }

    .hamburger {
        display: flex;
        order: 3;
    }

    .navbar-brand {
        order: 1;
        font-size: var(--font-size-xl);
    }

    .theme-toggle {
        order: 2;
        margin-left: auto;
        margin-right: var(--spacing-sm);
    }

    .navbar-nav {
        order: 4;
        width: 100%;
        flex-direction: column;
        gap: 0;
        max-height: 0;
        overflow: hidden;
        transition: max-height var(--transition-base);
        background: var(--color-bg-secondary);
        border-radius: var(--radius-lg);
        margin-top: var(--spacing-sm);
    }

    .navbar-nav.active {
        max-height: 500px;
        padding: var(--spacing-sm) 0;
    }

    .navbar-nav li {
        width: 100%;
    }

    .navbar-nav a,
    .navbar-nav .search-bar {
        width: 100%;
        padding: var(--spacing-sm) var(--spacing-md);
        display: block;
    }

    .navbar-nav .theme-toggle {
        display: none;
        /* Hide duplicate theme toggle in menu */
    }

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

    .category-filters {
        overflow-x: auto;
        flex-wrap: nowrap;
        padding-bottom: var(--spacing-xs);
    }

    .category-filter {
        white-space: nowrap;
    }

    /* Hero adjustments */
    .hero {
        padding: var(--spacing-lg) 0;
    }

    .hero h1 {
        font-size: var(--font-size-3xl);
    }
}

/* Search Bar */
.search-bar {
    position: relative;
    max-width: 400px;
}

.search-bar input {
    padding-right: 40px;
}

.search-bar button {
    position: absolute;
    right: 8px;
    top: 50%;
    transform: translateY(-50%);
    background: transparent;
    border: none;
    color: var(--color-text-muted);
    cursor: pointer;
}