:root {
    /* Light theme colors */
    --primary-color: #007bff;
    --secondary-color: #6c757d;
    --success-color: #28a745;
    --danger-color: #dc3545;
    --warning-color: #ffc107;
    --info-color: #17a2b8;
    
    --bg-color: #ffffff;
    --surface-color: #ffffff;
    --text-primary: #212529;
    --text-secondary: #6c757d;
    --text-muted: #868e96;
    --border-color: #e9ecef;
    --hover-color: #f8f9fa;
    
    /* Shadows */
    --shadow-sm: 0 0.125rem 0.25rem rgba(0, 0, 0, 0.075);
    --shadow: 0 0.5rem 1rem rgba(0, 0, 0, 0.15);
    --shadow-lg: 0 1rem 3rem rgba(0, 0, 0, 0.175);
    
    /* Layout */
    --border-radius: 0.375rem;
    --border-radius-lg: 0.5rem;
    --transition: all 0.15s ease-in-out;
    
    /* Typography */
    --font-family: -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, "Helvetica Neue", Arial, sans-serif;
    --font-size-sm: 0.875rem;
    --font-size-base: 1rem;
    --font-size-lg: 1.125rem;
    --font-size-xl: 1.25rem;
}

/* Dark theme */
[data-theme="dark"] {
    --bg-color: #1a1a1a;
    --surface-color: #2d2d2d;
    --text-primary: #ffffff;
    --text-secondary: #b3b3b3;
    --text-muted: #999999;
    --border-color: #404040;
    --hover-color: #333333;
    --shadow-sm: 0 0.125rem 0.25rem rgba(0, 0, 0, 0.3);
    --shadow: 0 0.5rem 1rem rgba(0, 0, 0, 0.4);
    --shadow-lg: 0 1rem 3rem rgba(0, 0, 0, 0.5);
}

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

body {
    font-family: var(--font-family);
    background-color: var(--bg-color);
    color: var(--text-primary);
    line-height: 1.6;
    transition: var(--transition);
}

.container {
    max-width: 1200px;
    margin: 0 auto;
    padding: 0 1rem;
}

/* Header */
.header {
    background-color: var(--surface-color);
    border-bottom: 1px solid var(--border-color);
    position: sticky;
    top: 0;
    z-index: 1000;
}

.navbar {
    padding: 1rem 0;
}

.nav-container {
    display: flex;
    align-items: center;
    justify-content: space-between;
    max-width: 1200px;
    margin: 0 auto;
    padding: 0 1rem;
}

.nav-brand {
    display: flex;
    align-items: center;
    text-decoration: none;
    color: var(--text-primary);
}

.brand-logo {
    height: 32px;
    width: 32px;
    margin-right: 0.5rem;
}

.brand-text {
    font-size: 1.5rem;
    font-weight: 700;
    color: var(--primary-color);
}

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

.nav-link {
    color: var(--text-secondary);
    text-decoration: none;
    font-weight: 500;
    transition: var(--transition);
    padding: 0.5rem 0;
}

.nav-link:hover {
    color: var(--primary-color);
}

.nav-actions {
    display: flex;
    align-items: center;
    gap: 1rem;
}

.theme-toggle {
    background: none;
    border: 1px solid var(--border-color);
    border-radius: var(--border-radius);
    padding: 0.5rem;
    cursor: pointer;
    font-size: 1.2rem;
    color: var(--text-primary);
    transition: var(--transition);
}

.theme-toggle:hover {
    background-color: var(--hover-color);
}

.mobile-menu-toggle {
    display: none;
    flex-direction: column;
    background: none;
    border: none;
    cursor: pointer;
    padding: 0.5rem;
}

.mobile-menu-toggle span {
    width: 20px;
    height: 2px;
    background-color: var(--text-primary);
    margin: 2px 0;
    transition: var(--transition);
}

/* Hero Text Section */
.hero-text-section {
    padding: 3rem 0;
    text-align: center;
    background-color: var(--bg-color);
}

.hero-title {
    font-size: 2.5rem;
    font-weight: 700;
    color: var(--text-primary);
    margin-bottom: 1rem;
}

.hero-description {
    font-size: var(--font-size-lg);
    color: var(--text-secondary);
    max-width: 800px;
    margin: 0 auto;
    line-height: 1.6;
}

/* Tools Section */
.tools-section {
    padding: 2rem 0 4rem;
}

.category-filters {
    display: flex;
    gap: 0.5rem;
    margin-bottom: 2rem;
    flex-wrap: wrap;
    justify-content: center;
}

.filter-btn {
    background-color: var(--surface-color);
    border: 1px solid var(--border-color);
    color: var(--text-secondary);
    padding: 0.5rem 1rem;
    border-radius: var(--border-radius);
    cursor: pointer;
    font-size: var(--font-size-sm);
    font-weight: 500;
    transition: var(--transition);
    white-space: nowrap;
}

.filter-btn:hover,
.filter-btn.active {
    background-color: var(--primary-color);
    color: white;
    border-color: var(--primary-color);
}

.tools-grid {
    display: grid;
    grid-template-columns: repeat(auto-fill, minmax(200px, 1fr));
    gap: 1rem;
    margin-top: 2rem;
}

.tool-card {
    background-color: var(--surface-color);
    border: 1px solid var(--border-color);
    border-radius: var(--border-radius);
    padding: 1.5rem;
    text-decoration: none;
    color: var(--text-primary);
    transition: var(--transition);
    display: flex;
    flex-direction: column;
    align-items: center;
    text-align: center;
    position: relative;
    min-height: 160px;
}

.tool-card:hover {
    transform: translateY(-2px);
    box-shadow: var(--shadow);
    border-color: var(--primary-color);
}

.tool-icon {
    font-size: 2.5rem;
    margin-bottom: 0.75rem;
    display: block;
}

.tool-title {
    font-size: var(--font-size-base);
    font-weight: 600;
    margin-bottom: 0.5rem;
    color: var(--text-primary);
}

.tool-description {
    font-size: var(--font-size-sm);
    color: var(--text-secondary);
    line-height: 1.4;
    flex-grow: 1;
}

.tool-category {
    position: absolute;
    top: 0.5rem;
    right: 0.5rem;
    background-color: var(--primary-color);
    color: white;
    padding: 0.25rem 0.5rem;
    border-radius: var(--border-radius);
    font-size: 0.75rem;
    font-weight: 500;
}

/* Footer */
.footer {
    background-color: var(--surface-color);
    border-top: 1px solid var(--border-color);
    padding: 3rem 0 1rem;
    margin-top: 4rem;
}

.footer-content {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(200px, 1fr));
    gap: 2rem;
    margin-bottom: 2rem;
}

.footer-section h3 {
    font-size: var(--font-size-base);
    font-weight: 600;
    color: var(--text-primary);
    margin-bottom: 1rem;
}

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

.footer-section ul li {
    margin-bottom: 0.5rem;
}

.footer-section ul li a {
    color: var(--text-secondary);
    text-decoration: none;
    font-size: var(--font-size-sm);
    transition: var(--transition);
}

.footer-section ul li a:hover {
    color: var(--primary-color);
}

.footer-bottom {
    display: flex;
    justify-content: space-between;
    align-items: center;
    padding-top: 2rem;
    border-top: 1px solid var(--border-color);
    flex-wrap: wrap;
    gap: 1rem;
}

.footer-bottom p {
    color: var(--text-muted);
    font-size: var(--font-size-sm);
}

.footer-social {
    display: flex;
    gap: 1rem;
}

.footer-social a {
    text-decoration: none;
    font-size: 1.2rem;
    transition: var(--transition);
}

.footer-social a:hover {
    transform: scale(1.1);
}

/* Section Title */
.section-title {
    text-align: center;
    font-size: 2.5rem;
    font-weight: 600;
    margin-bottom: 3rem;
    color: var(--text-primary);
}

/* Main Content */
.main-content {
    min-height: calc(100vh - 80px);
}

/* Responsive Design */
@media (max-width: 768px) {
    .nav-menu {
        display: none;
        position: absolute;
        top: 100%;
        left: 0;
        right: 0;
        background-color: var(--surface-color);
        border-top: 1px solid var(--border-color);
        flex-direction: column;
        padding: 1rem;
        gap: 0.5rem;
    }

    .nav-menu.active {
        display: flex;
    }

    .mobile-menu-toggle {
        display: flex;
    }

    .hero-title {
        font-size: 2rem;
    }

    .hero-description {
        font-size: var(--font-size-base);
    }

    .category-filters {
        justify-content: flex-start;
        overflow-x: auto;
        padding-bottom: 0.5rem;
    }

    .tools-grid {
        grid-template-columns: repeat(auto-fill, minmax(150px, 1fr));
        gap: 0.75rem;
    }

    .tool-card {
        padding: 1rem;
        min-height: 140px;
    }

    .tool-icon {
        font-size: 2rem;
    }

    .footer-content {
        grid-template-columns: repeat(2, 1fr);
        gap: 1.5rem;
    }

    .footer-bottom {
        flex-direction: column;
        text-align: center;
    }
}

@media (max-width: 480px) {
    .container {
        padding: 0 0.75rem;
    }

    .hero-text-section {
        padding: 2rem 0;
    }

    .tools-grid {
        grid-template-columns: repeat(2, 1fr);
    }

    .footer-content {
        grid-template-columns: 1fr;
    }

    .section-title {
        font-size: 2rem;
    }
}

/* Hidden class for filtering */
.hidden {
    display: none !important;
}

/* Loading states */
.loading {
    opacity: 0.5;
    pointer-events: none;
}

/* Smooth transitions for theme switching */
* {
    transition: background-color 0.15s ease-in-out, 
                border-color 0.15s ease-in-out, 
                color 0.15s ease-in-out;
}

/* Utility Classes */
.text-center {
    text-align: center;
}

.text-left {
    text-align: left;
}

.text-right {
    text-align: right;
}

.d-flex {
    display: flex;
}

.d-grid {
    display: grid;
}

.d-none {
    display: none;
}

.d-block {
    display: block;
}

/* Button Utilities */
.btn {
    padding: 0.75rem 1.5rem;
    border: none;
    border-radius: var(--border-radius);
    font-weight: 500;
    cursor: pointer;
    transition: var(--transition);
    text-decoration: none;
    display: inline-block;
    text-align: center;
}

.btn-primary {
    background-color: var(--primary-color);
    color: white;
}

.btn-primary:hover {
    transform: translateY(-1px);
    box-shadow: var(--shadow);
}

.btn-secondary {
    background-color: var(--secondary-color);
    color: white;
}

.btn-secondary:hover {
    transform: translateY(-1px);
    box-shadow: var(--shadow);
}

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

.btn-outline:hover {
    background-color: var(--hover-color);
    border-color: var(--primary-color);
    color: var(--primary-color);
}

/* Form Elements */
.form-control {
    width: 100%;
    padding: 0.75rem;
    border: 1px solid var(--border-color);
    border-radius: var(--border-radius);
    background-color: var(--surface-color);
    color: var(--text-primary);
    font-size: var(--font-size-base);
    transition: var(--transition);
}

.form-control:focus {
    outline: none;
    border-color: var(--primary-color);
    box-shadow: 0 0 0 0.2rem rgba(0, 123, 255, 0.25);
}

/* Alert Components */
.alert {
    padding: 1rem;
    border-radius: var(--border-radius);
    margin: 1rem 0;
}

.alert-success {
    background-color: #d4edda;
    border: 1px solid #c3e6cb;
    color: #155724;
}

.alert-danger {
    background-color: #f8d7da;
    border: 1px solid #f5c6cb;
    color: #721c24;
}

.alert-warning {
    background-color: #fff3cd;
    border: 1px solid #ffeaa7;
    color: #856404;
}

.alert-info {
    background-color: #cce7f0;
    border: 1px solid #bee5eb;
    color: #0c5460;
}

/* Dark mode adjustments for alerts */
[data-theme="dark"] .alert-success {
    background-color: rgba(40, 167, 69, 0.2);
    border-color: rgba(40, 167, 69, 0.3);
    color: #b8e6c1;
}

[data-theme="dark"] .alert-danger {
    background-color: rgba(220, 53, 69, 0.2);
    border-color: rgba(220, 53, 69, 0.3);
    color: #f1aeb5;
}

[data-theme="dark"] .alert-warning {
    background-color: rgba(255, 193, 7, 0.2);
    border-color: rgba(255, 193, 7, 0.3);
    color: #fff3cd;
}

[data-theme="dark"] .alert-info {
    background-color: rgba(23, 162, 184, 0.2);
    border-color: rgba(23, 162, 184, 0.3);
    color: #bee5eb;
}

/* Animation Classes */
.fade-in {
    animation: fadeIn 0.3s ease-in;
}

.slide-up {
    animation: slideUp 0.3s ease-out;
}

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

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

/* Scroll behavior */
html {
    scroll-behavior: smooth;
}

/* Focus styles for accessibility */
*:focus-visible {
    outline: 2px solid var(--primary-color);
    outline-offset: 2px;
}

/* High contrast mode support */
@media (prefers-contrast: high) {
    :root {
        --border-color: #000000;
        --text-primary: #000000;
        --bg-color: #ffffff;
    }
    
    [data-theme="dark"] {
        --border-color: #ffffff;
        --text-primary: #ffffff;
        --bg-color: #000000;
    }
}

/* Reduced motion support */
@media (prefers-reduced-motion: reduce) {
    * {
        animation-duration: 0.01ms !important;
        animation-iteration-count: 1 !important;
        transition-duration: 0.01ms !important;
    }
    
    html {
        scroll-behavior: auto;
    }
}