/* CSS Custom Properties */
:root {
    /* Colors */
    --primary-color: #6366f1;
    --primary-dark: #4f46e5;
    --primary-light: #8b5cf6;
    --secondary-color: #06b6d4;
    --accent-color: #f59e0b;
    --success-color: #10b981;
    --warning-color: #f59e0b;
    --error-color: #ef4444;
    
    /* Neutrals */
    --white: #ffffff;
    --gray-50: #f9fafb;
    --gray-100: #f3f4f6;
    --gray-200: #e5e7eb;
    --gray-300: #d1d5db;
    --gray-400: #9ca3af;
    --gray-500: #6b7280;
    --gray-600: #4b5563;
    --gray-700: #374151;
    --gray-800: #1f2937;
    --gray-900: #111827;
    
    /* Typography */
    --font-family: 'Inter', -apple-system, BlinkMacSystemFont, 'Segoe UI', Roboto, sans-serif;
    --font-weight-normal: 400;
    --font-weight-medium: 500;
    --font-weight-semibold: 600;
    --font-weight-bold: 700;
    
    /* Spacing */
    --space-xs: 0.25rem;
    --space-sm: 0.5rem;
    --space-md: 1rem;
    --space-lg: 1.5rem;
    --space-xl: 2rem;
    --space-2xl: 3rem;
    --space-3xl: 4rem;
    
    /* Border Radius */
    --radius-sm: 0.375rem;
    --radius-md: 0.5rem;
    --radius-lg: 0.75rem;
    --radius-xl: 1rem;
    
    /* Shadows */
    --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);
    
    /* Transitions */
    --transition-fast: 150ms ease-in-out;
    --transition-normal: 250ms ease-in-out;
    --transition-slow: 350ms ease-in-out;
    
    /* Container */
    --container-max-width: 1200px;
    --container-padding: var(--space-md);
}

/* Reset and Base Styles */
*,
*::before,
*::after {
    box-sizing: border-box;
    margin: 0;
    padding: 0;
}

html {
    scroll-behavior: smooth;
    font-size: 16px;
}

body {
    font-family: var(--font-family);
    font-weight: var(--font-weight-normal);
    line-height: 1.6;
    color: var(--gray-800);
    background-color: var(--white);
    -webkit-font-smoothing: antialiased;
    -moz-osx-font-smoothing: grayscale;
}

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

/* Typography */
h1, h2, h3, h4, h5, h6 {
    font-weight: var(--font-weight-bold);
    line-height: 1.2;
    margin-bottom: var(--space-md);
}

h1 {
    font-size: clamp(2rem, 5vw, 3.5rem);
}

h2 {
    font-size: clamp(1.75rem, 4vw, 2.5rem);
}

h3 {
    font-size: clamp(1.25rem, 3vw, 1.75rem);
}

p {
    margin-bottom: var(--space-md);
}

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

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

/* Buttons */
.btn {
    display: inline-flex;
    align-items: center;
    justify-content: center;
    gap: var(--space-sm);
    padding: var(--space-md) var(--space-xl);
    font-family: var(--font-family);
    font-weight: var(--font-weight-medium);
    font-size: 1rem;
    line-height: 1;
    border: none;
    border-radius: var(--radius-md);
    cursor: pointer;
    transition: all var(--transition-fast);
    text-decoration: none;
}

.btn:focus {
    outline: 2px solid var(--primary-color);
    outline-offset: 2px;
}

/* Utility Classes */
.gradient-text {
    background: linear-gradient(135deg, var(--primary-color), var(--primary-light));
    -webkit-background-clip: text;
    -webkit-text-fill-color: transparent;
    background-clip: text;
}

.visually-hidden {
    position: absolute;
    width: 1px;
    height: 1px;
    padding: 0;
    margin: -1px;
    overflow: hidden;
    clip: rect(0, 0, 0, 0);
    white-space: nowrap;
    border: 0;
}

/* Header */
.header {
    position: sticky;
    top: 0;
    z-index: 100;
    background: rgba(255, 255, 255, 0.95);
    backdrop-filter: blur(10px);
    border-bottom: 1px solid var(--gray-200);
}

.nav {
    display: flex;
    align-items: center;
    justify-content: space-between;
    height: 4rem;
}

.nav-brand {
    display: flex;
    align-items: center;
    gap: var(--space-sm);
    font-weight: var(--font-weight-bold);
    font-size: 1.25rem;
    color: var(--gray-900);
}

.brand-icon {
    width: 2rem;
    height: 2rem;
    color: var(--primary-color);
}

.nav-menu {
    display: flex;
    align-items: center;
    gap: var(--space-xl);
    list-style: none;
}

.nav-link {
    font-weight: var(--font-weight-medium);
    color: var(--gray-600);
    transition: color var(--transition-fast);
    position: relative;
}

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

.nav-link.active::after {
    content: '';
    position: absolute;
    bottom: -0.5rem;
    left: 0;
    right: 0;
    height: 2px;
    background: var(--primary-color);
    border-radius: 1px;
}

.nav-toggle {
    display: none;
    flex-direction: column;
    gap: 4px;
    cursor: pointer;
}

.nav-toggle span {
    width: 24px;
    height: 2px;
    background: var(--gray-700);
    border-radius: 1px;
    transition: all var(--transition-normal);
}

/* Hero Section */
.hero {
    padding: var(--space-3xl) 0;
    background: linear-gradient(135deg, var(--gray-50) 0%, var(--white) 100%);
    min-height: 90vh;
    display: flex;
    align-items: center;
}

.hero-content {
    text-align: center;
    max-width: 800px;
    margin: 0 auto;
}

.hero-title {
    margin-bottom: var(--space-lg);
    color: var(--gray-900);
}

.hero-description {
    font-size: 1.125rem;
    color: var(--gray-600);
    margin-bottom: var(--space-2xl);
    max-width: 600px;
    margin-left: auto;
    margin-right: auto;
}

/* URL Shortener Form */
.shortener-form {
    max-width: 600px;
    margin: 0 auto;
}

.url-form {
    margin-bottom: var(--space-xl);
}

.input-group {
    display: flex;
    gap: var(--space-sm);
    background: var(--white);
    border: 2px solid var(--gray-200);
    border-radius: var(--radius-lg);
    padding: var(--space-sm);
    box-shadow: var(--shadow-md);
    transition: all var(--transition-fast);
}

.input-group:focus-within {
    border-color: var(--primary-color);
    box-shadow: var(--shadow-lg), 0 0 0 3px rgba(99, 102, 241, 0.1);
}

.url-input {
    flex: 1;
    border: none;
    outline: none;
    font-size: 1rem;
    padding: var(--space-md);
    background: transparent;
    color: var(--gray-900);
}

.url-input::placeholder {
    color: var(--gray-400);
}

.shorten-btn {
    background: var(--primary-color);
    color: var(--white);
    border: none;
    border-radius: var(--radius-md);
    padding: var(--space-md) var(--space-xl);
    font-weight: var(--font-weight-medium);
    cursor: pointer;
    transition: all var(--transition-fast);
    display: flex;
    align-items: center;
    gap: var(--space-sm);
    white-space: nowrap;
}

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

.shorten-btn:active {
    transform: translateY(0);
}

.btn-icon {
    width: 1.25rem;
    height: 1.25rem;
}

/* Result Container */
.result-container {
    opacity: 0;
    animation: fadeInUp 0.6s ease-out 0.5s forwards;
}

.result-card {
    background: var(--white);
    border: 1px solid var(--gray-200);
    border-radius: var(--radius-xl);
    padding: var(--space-xl);
    box-shadow: var(--shadow-lg);
    text-align: left;
}

.result-header {
    display: flex;
    align-items: center;
    justify-content: space-between;
    margin-bottom: var(--space-lg);
}

.result-header h3 {
    color: var(--gray-900);
    margin: 0;
}

.success-icon {
    width: 1.5rem;
    height: 1.5rem;
    color: var(--success-color);
}

.url-display {
    margin-bottom: var(--space-lg);
}

.original-url,
.short-url {
    display: flex;
    align-items: center;
    gap: var(--space-md);
    padding: var(--space-md);
    border-radius: var(--radius-md);
    margin-bottom: var(--space-sm);
}

.original-url {
    background: var(--gray-50);
}

.short-url {
    background: linear-gradient(135deg, var(--primary-color), var(--primary-light));
    color: var(--white);
    position: relative;
}

.url-label {
    font-weight: var(--font-weight-semibold);
    min-width: 60px;
    font-size: 0.875rem;
}

.url-text {
    flex: 1;
    font-family: monospace;
    font-size: 0.875rem;
    word-break: break-all;
}

.url-text.short {
    color: var(--white);
    font-weight: var(--font-weight-medium);
}

.copy-btn {
    background: rgba(255, 255, 255, 0.2);
    border: none;
    border-radius: var(--radius-sm);
    padding: var(--space-sm);
    color: var(--white);
    cursor: pointer;
    transition: all var(--transition-fast);
    display: flex;
    align-items: center;
    justify-content: center;
}

.copy-btn:hover {
    background: rgba(255, 255, 255, 0.3);
    transform: scale(1.05);
}

.copy-icon {
    width: 1rem;
    height: 1rem;
}

.result-stats {
    display: flex;
    gap: var(--space-xl);
}

.stat {
    text-align: center;
}

.stat-value {
    display: block;
    font-size: 1.5rem;
    font-weight: var(--font-weight-bold);
    color: var(--primary-color);
}

.stat-label {
    font-size: 0.875rem;
    color: var(--gray-600);
}

/* Features Section */
.features {
    padding: var(--space-3xl) 0;
    background: var(--white);
}

.section-header {
    text-align: center;
    margin-bottom: var(--space-3xl);
}

.section-title {
    color: var(--gray-900);
    margin-bottom: var(--space-md);
}

.section-description {
    font-size: 1.125rem;
    color: var(--gray-600);
    max-width: 600px;
    margin: 0 auto;
}

.features-grid {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(300px, 1fr));
    gap: var(--space-xl);
}

.feature-card {
    padding: var(--space-xl);
    border-radius: var(--radius-xl);
    border: 1px solid var(--gray-200);
    transition: all var(--transition-normal);
    text-align: center;
}

.feature-card:hover {
    transform: translateY(-4px);
    box-shadow: var(--shadow-xl);
    border-color: var(--primary-color);
}

.feature-icon {
    width: 3rem;
    height: 3rem;
    margin: 0 auto var(--space-lg);
    padding: var(--space-md);
    background: linear-gradient(135deg, var(--primary-color), var(--primary-light));
    border-radius: var(--radius-lg);
    color: var(--white);
    display: flex;
    align-items: center;
    justify-content: center;
}

.feature-icon svg {
    width: 1.5rem;
    height: 1.5rem;
}

.feature-title {
    color: var(--gray-900);
    margin-bottom: var(--space-md);
}

.feature-description {
    color: var(--gray-600);
    margin: 0;
}

/* Footer */
.footer {
    background: var(--gray-900);
    color: var(--gray-300);
    padding: var(--space-3xl) 0 var(--space-xl);
}

.footer-content {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(250px, 1fr));
    gap: var(--space-2xl);
    margin-bottom: var(--space-2xl);
}

.footer-brand {
    display: flex;
    align-items: center;
    gap: var(--space-sm);
    font-weight: var(--font-weight-bold);
    font-size: 1.25rem;
    color: var(--white);
    margin-bottom: var(--space-md);
}

.footer-description {
    color: var(--gray-400);
    line-height: 1.6;
}

.footer-title {
    color: var(--white);
    font-weight: var(--font-weight-semibold);
    margin-bottom: var(--space-md);
}

.footer-links {
    list-style: none;
}

.footer-links li {
    margin-bottom: var(--space-sm);
}

.footer-links a {
    color: var(--gray-400);
    transition: color var(--transition-fast);
}

.footer-links a:hover {
    color: var(--white);
}

.footer-contact {
    list-style: none;
}

.footer-contact li {
    display: flex;
    align-items: center;
    gap: var(--space-sm);
    margin-bottom: var(--space-md);
    color: var(--gray-400);
}

.footer-contact svg {
    width: 1rem;
    height: 1rem;
    flex-shrink: 0;
}

.footer-bottom {
    display: flex;
    justify-content: space-between;
    align-items: center;
    padding-top: var(--space-xl);
    border-top: 1px solid var(--gray-800);
}

.social-links {
    display: flex;
    gap: var(--space-md);
}

.social-link {
    display: flex;
    align-items: center;
    justify-content: center;
    width: 2.5rem;
    height: 2.5rem;
    border-radius: var(--radius-md);
    background: var(--gray-800);
    color: var(--gray-400);
    transition: all var(--transition-fast);
}

.social-link:hover {
    background: var(--primary-color);
    color: var(--white);
    transform: translateY(-2px);
}

.social-link svg {
    width: 1.25rem;
    height: 1.25rem;
}

/* Animations */
@keyframes fadeInUp {
    from {
        opacity: 0;
        transform: translateY(20px);
    }
    to {
        opacity: 1;
        transform: translateY(0);
    }
}

/* Responsive Design */
@media (max-width: 768px) {
    :root {
        --container-padding: var(--space-md);
    }
    
    .nav-menu {
        display: none;
    }
    
    .nav-toggle {
        display: flex;
    }
    
    .hero {
        padding: var(--space-2xl) 0;
        min-height: 80vh;
    }
    
    .hero-title {
        font-size: 2rem;
    }
    
    .input-group {
        flex-direction: column;
        gap: var(--space-md);
    }
    
    .shorten-btn {
        justify-content: center;
        width: 100%;
    }
    
    .features-grid {
        grid-template-columns: 1fr;
        gap: var(--space-lg);
    }
    
    .footer-content {
        grid-template-columns: 1fr;
        gap: var(--space-xl);
    }
    
    .footer-bottom {
        flex-direction: column;
        gap: var(--space-md);
        text-align: center;
    }
    
    .original-url,
    .short-url {
        flex-direction: column;
        align-items: flex-start;
        gap: var(--space-sm);
    }
    
    .result-stats {
        justify-content: center;
    }
}

@media (max-width: 480px) {
    .container {
        padding: 0 var(--space-sm);
    }
    
    .hero-content {
        text-align: center;
    }
    
    .result-card {
        padding: var(--space-lg);
    }
    
    .feature-card {
        padding: var(--space-lg);
    }
}

/* Focus styles for accessibility */
.url-input:focus,
.shorten-btn:focus,
.copy-btn:focus,
.nav-link:focus {
    outline: 2px solid var(--primary-color);
    outline-offset: 2px;
}

/* Hover effects for interactive elements */
.feature-card:hover .feature-icon {
    transform: scale(1.05);
}

.copy-btn:active {
    transform: scale(0.95);
}

/* Print styles */
@media print {
    .nav-toggle,
    .copy-btn,
    .social-links {
        display: none;
    }
    
    .hero {
        min-height: auto;
        padding: var(--space-lg) 0;
    }
    
    * {
        color: black !important;
        background: white !important;
    }
}

/* Dark mode support (hidden by default) */
@media (prefers-color-scheme: dark) {
    /* Dark mode styles would go here if needed */
}

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