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

:root {
    --primary: #2563eb;
    --primary-hover: #1d4ed8;
    --bg: #0f172a;
    --bg-secondary: #1e293b;
    --text-primary: #f8fafc;
    --text-secondary: #cbd5e1;
    --border: #334155;
    --success: #10b981;
    --error: #ef4444;
    --radius: 8px;
    --shadow: 0 4px 6px -1px rgb(0 0 0 / 0.1), 0 2px 4px -2px rgb(0 0 0 / 0.1);
    --shadow-lg: 0 20px 25px -5px rgb(0 0 0 / 0.1), 0 8px 10px -6px rgb(0 0 0 / 0.1);
}

html {
    scroll-behavior: smooth;
}

body {
    font-family: -apple-system, BlinkMacSystemFont, 'Segoe UI', 'Roboto', 'Oxygen',
        'Ubuntu', 'Cantarell', 'Fira Sans', 'Droid Sans', 'Helvetica Neue',
        sans-serif;
    background: linear-gradient(135deg, var(--bg) 0%, #020617 100%);
    color: var(--text-primary);
    line-height: 1.6;
    min-height: 100vh;
    -webkit-font-smoothing: antialiased;
    -moz-osx-font-smoothing: grayscale;
}

/* Header */
.header {
    border-bottom: 1px solid var(--border);
    background: rgba(15, 23, 42, 0.8);
    backdrop-filter: blur(10px);
    position: sticky;
    top: 0;
    z-index: 100;
}

.nav-container {
    max-width: 1200px;
    margin: 0 auto;
    padding: 1rem 2rem;
    display: flex;
    justify-content: space-between;
    align-items: center;
}

.logo {
    display: flex;
    align-items: center;
    gap: 0.5rem;
    font-size: 1.25rem;
    font-weight: 700;
    color: var(--text-primary);
    text-decoration: none;
}

.logo-icon {
    width: 32px;
    height: 32px;
    background: linear-gradient(135deg, var(--primary) 0%, #3b82f6 100%);
    border-radius: var(--radius);
    display: flex;
    align-items: center;
    justify-content: center;
    font-size: 1.25rem;
}

.nav-links {
    display: flex;
    gap: 2rem;
    list-style: none;
}

.nav-links a {
    color: var(--text-secondary);
    text-decoration: none;
    font-weight: 500;
    transition: color 0.2s;
}

.nav-links a:hover {
    color: var(--text-primary);
}

/* Main */
.main {
    max-width: 1200px;
    margin: 0 auto;
    padding: 2rem;
}

/* Hero Section */
.hero {
    text-align: center;
    padding: 4rem 1rem 3rem;
    max-width: 800px;
    margin: 0 auto;
}

.hero-title {
    font-size: clamp(2rem, 5vw, 3.5rem);
    font-weight: 800;
    line-height: 1.2;
    margin-bottom: 1rem;
    background: linear-gradient(135deg, var(--text-primary) 0%, var(--text-secondary) 100%);
    -webkit-background-clip: text;
    -webkit-text-fill-color: transparent;
    background-clip: text;
}

.hero-subtitle {
    font-size: clamp(1rem, 2vw, 1.25rem);
    color: var(--text-secondary);
    margin-bottom: 2rem;
}

/* Shortener Card */
.shortener-card {
    background: var(--bg-secondary);
    border: 1px solid var(--border);
    border-radius: 12px;
    padding: 2rem;
    max-width: 700px;
    margin: 0 auto 3rem;
    box-shadow: var(--shadow-lg);
}

.shortener-form {
    display: flex;
    gap: 0.75rem;
    flex-direction: column;
}

.input-group {
    display: flex;
    gap: 0.75rem;
}

.url-input {
    flex: 1;
    padding: 0.875rem 1rem;
    background: var(--bg);
    border: 1px solid var(--border);
    border-radius: var(--radius);
    color: var(--text-primary);
    font-size: 1rem;
    font-family: inherit;
    transition: border-color 0.2s, box-shadow 0.2s;
}

.url-input:focus {
    outline: none;
    border-color: var(--primary);
    box-shadow: 0 0 0 3px rgba(37, 99, 235, 0.1);
}

.url-input::placeholder {
    color: #64748b;
}

.shorten-btn {
    padding: 0.875rem 2rem;
    background: linear-gradient(135deg, var(--primary) 0%, #3b82f6 100%);
    color: white;
    border: none;
    border-radius: var(--radius);
    font-size: 1rem;
    font-weight: 600;
    cursor: pointer;
    transition: transform 0.2s, box-shadow 0.2s;
    font-family: inherit;
    white-space: nowrap;
}

.shorten-btn:hover:not(:disabled) {
    transform: translateY(-2px);
    box-shadow: 0 10px 15px -3px rgba(37, 99, 235, 0.3);
}

.shorten-btn:active:not(:disabled) {
    transform: translateY(0);
}

.shorten-btn:disabled {
    opacity: 0.6;
    cursor: not-allowed;
}

.advanced-toggle {
    background: none;
    border: none;
    color: var(--primary);
    cursor: pointer;
    font-size: 0.875rem;
    font-weight: 500;
    text-align: left;
    padding: 0.25rem 0;
    font-family: inherit;
}

.advanced-toggle:hover {
    text-decoration: underline;
}

.advanced-options {
    display: none;
    flex-direction: column;
    gap: 0.5rem;
}

.advanced-options.active {
    display: flex;
}

.custom-label {
    font-size: 0.875rem;
    color: var(--text-secondary);
    font-weight: 500;
}

.custom-input {
    padding: 0.75rem 1rem;
    background: var(--bg);
    border: 1px solid var(--border);
    border-radius: var(--radius);
    color: var(--text-primary);
    font-size: 0.9rem;
    font-family: inherit;
}

.custom-input:focus {
    outline: none;
    border-color: var(--primary);
    box-shadow: 0 0 0 3px rgba(37, 99, 235, 0.1);
}

/* Result */
.result-container {
    display: none;
    margin-top: 1.5rem;
    padding: 1rem;
    background: var(--bg);
    border: 1px solid var(--border);
    border-radius: var(--radius);
}

.result-container.active {
    display: block;
}

.result-label {
    font-size: 0.875rem;
    color: var(--text-secondary);
    margin-bottom: 0.5rem;
    font-weight: 500;
}

.result-row {
    display: flex;
    gap: 0.5rem;
    align-items: center;
}

.result-url {
    flex: 1;
    padding: 0.75rem 1rem;
    background: var(--bg-secondary);
    border: 1px solid var(--border);
    border-radius: var(--radius);
    color: var(--success);
    font-family: 'Courier New', monospace;
    font-size: 0.9rem;
    word-break: break-all;
}

.copy-btn {
    padding: 0.75rem 1.5rem;
    background: var(--bg-secondary);
    color: var(--text-primary);
    border: 1px solid var(--border);
    border-radius: var(--radius);
    cursor: pointer;
    font-weight: 500;
    transition: background 0.2s;
    font-family: inherit;
    white-space: nowrap;
}

.copy-btn:hover {
    background: var(--border);
}

.copy-btn.copied {
    background: var(--success);
    border-color: var(--success);
    color: white;
}

.error-message {
    display: none;
    margin-top: 1rem;
    padding: 0.75rem 1rem;
    background: rgba(239, 68, 68, 0.1);
    border: 1px solid rgba(239, 68, 68, 0.3);
    border-radius: var(--radius);
    color: var(--error);
    font-size: 0.9rem;
}

.error-message.active {
    display: block;
}

/* Features Section */
.features {
    padding: 3rem 0;
}

.section-title {
    text-align: center;
    font-size: 2rem;
    font-weight: 700;
    margin-bottom: 0.5rem;
}

.section-subtitle {
    text-align: center;
    color: var(--text-secondary);
    margin-bottom: 2.5rem;
    font-size: 1.1rem;
}

.features-grid {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(280px, 1fr));
    gap: 1.5rem;
}

.feature-card {
    background: var(--bg-secondary);
    border: 1px solid var(--border);
    border-radius: 12px;
    padding: 1.5rem;
    transition: transform 0.2s, border-color 0.2s;
}

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

.feature-icon {
    width: 48px;
    height: 48px;
    background: linear-gradient(135deg, rgba(37, 99, 235, 0.2) 0%, rgba(59, 130, 246, 0.2) 100%);
    border-radius: var(--radius);
    display: flex;
    align-items: center;
    justify-content: center;
    font-size: 1.5rem;
    margin-bottom: 1rem;
}

.feature-title {
    font-size: 1.25rem;
    font-weight: 600;
    margin-bottom: 0.5rem;
}

.feature-desc {
    color: var(--text-secondary);
    font-size: 0.95rem;
}

/* Footer */
.footer {
    border-top: 1px solid var(--border);
    margin-top: 4rem;
    padding: 2rem 0;
    text-align: center;
}

.footer-content {
    max-width: 1200px;
    margin: 0 auto;
    padding: 0 2rem;
    color: var(--text-secondary);
    font-size: 0.9rem;
}

/* Responsive */
@media (max-width: 640px) {
    .nav-container {
        padding: 1rem;
    }
    
    .nav-links {
        gap: 1rem;
    }
    
    .main {
        padding: 1rem;
    }
    
    .hero {
        padding: 2rem 0.5rem;
    }
    
    .shortener-card {
        padding: 1.5rem;
    }
    
    .input-group {
        flex-direction: column;
    }
    
    .shorten-btn {
        width: 100%;
    }
    
    .result-row {
        flex-direction: column;
    }
    
    .result-url {
        width: 100%;
    }
    
    .copy-btn {
        width: 100%;
    }
}