:root {
    /* Light Theme Colors */
    --bg-primary: #f8fafc;
    --bg-secondary: #ffffff;
    --bg-tertiary: #f1f5f9;
    --text-primary: #1e293b;
    --text-secondary: #64748b;
    --text-muted: #94a3b8;
    --accent: #3b82f6;
    --accent-hover: #2563eb;
    --border: #e2e8f0;
    --shadow: rgba(0, 0, 0, 0.1);
    --success: #10b981;
    --error: #ef4444;
    --warning: #f59e0b;
    
    /* Glass Effect */
    --glass-bg: rgba(255, 255, 255, 0.8);
    --glass-border: rgba(255, 255, 255, 0.2);
    
    /* Transitions */
    --transition: all 0.3s cubic-bezier(0.4, 0, 0.2, 1);
}

[data-theme="dark"] {
    /* Dark Theme Colors */
    --bg-primary: #0f172a;
    --bg-secondary: #1e293b;
    --bg-tertiary: #334155;
    --text-primary: #f8fafc;
    --text-secondary: #cbd5e1;
    --text-muted: #64748b;
    --accent: #60a5fa;
    --accent-hover: #3b82f6;
    --border: #334155;
    --shadow: rgba(0, 0, 0, 0.3);
    --glass-bg: rgba(30, 41, 59, 0.8);
    --glass-border: rgba(255, 255, 255, 0.1);
}

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

body {
    font-family: 'Inter', -apple-system, BlinkMacSystemFont, 'Segoe UI', Roboto, sans-serif;
    background: var(--bg-primary);
    color: var(--text-primary);
    line-height: 1.6;
    min-height: 100vh;
    transition: var(--transition);
    overflow-x: hidden;
}

/* Theme Toggle */
.theme-toggle {
    position: fixed;
    top: 20px;
    right: 20px;
    z-index: 1000;
}

.theme-toggle button {
    background: var(--glass-bg);
    border: 1px solid var(--glass-border);
    border-radius: 50%;
    width: 50px;
    height: 50px;
    display: flex;
    align-items: center;
    justify-content: center;
    cursor: pointer;
    transition: var(--transition);
    backdrop-filter: blur(10px);
    color: var(--text-primary);
    font-size: 1.2rem;
}

.theme-toggle button:hover {
    transform: scale(1.1);
    background: var(--accent);
    color: white;
}

/* Container */
.container {
    max-width: 1200px;
    margin: 0 auto;
    padding: 2rem;
    min-height: 100vh;
    display: flex;
    flex-direction: column;
    justify-content: center;
}

/* Header */
header {
    text-align: center;
    margin-bottom: 3rem;
}

header h1 {
    font-size: 2.5rem;
    font-weight: 700;
    margin-bottom: 0.5rem;
    background: linear-gradient(135deg, var(--accent), var(--accent-hover));
    -webkit-background-clip: text;
    -webkit-text-fill-color: transparent;
    background-clip: text;
}

header p {
    color: var(--text-secondary);
    font-size: 1.1rem;
}

/* Main Content */
.main-content {
    display: grid;
    grid-template-columns: 1fr 1fr;
    gap: 2rem;
    align-items: start;
}

/* Input Section */
.input-section {
    background: var(--glass-bg);
    border: 1px solid var(--glass-border);
    border-radius: 20px;
    padding: 2rem;
    backdrop-filter: blur(10px);
    box-shadow: 0 8px 32px var(--shadow);
}

.input-group {
    margin-bottom: 1.5rem;
}

.input-group label {
    display: block;
    margin-bottom: 0.5rem;
    font-weight: 500;
    color: var(--text-primary);
}

.input-group input,
.input-group select {
    width: 100%;
    padding: 0.75rem 1rem;
    border: 1px solid var(--border);
    border-radius: 10px;
    background: var(--bg-secondary);
    color: var(--text-primary);
    font-size: 1rem;
    transition: var(--transition);
}

.input-group input:focus,
.input-group select:focus {
    outline: none;
    border-color: var(--accent);
    box-shadow: 0 0 0 3px rgba(59, 130, 246, 0.1);
}

/* Customization Section */
.customization-section {
    background: var(--glass-bg);
    border: 1px solid var(--glass-border);
    border-radius: 20px;
    padding: 2rem;
    backdrop-filter: blur(10px);
    box-shadow: 0 8px 32px var(--shadow);
}

.customization-section h3 {
    margin-bottom: 1.5rem;
    color: var(--text-primary);
}

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

.custom-group label {
    display: block;
    margin-bottom: 0.5rem;
    font-size: 0.9rem;
    color: var(--text-secondary);
}

.custom-group input[type="color"] {
    width: 100%;
    height: 40px;
    border: none;
    border-radius: 8px;
    cursor: pointer;
}

/* Generate Button */
.generate-btn {
    width: 100%;
    padding: 1rem 2rem;
    background: linear-gradient(135deg, var(--accent), var(--accent-hover));
    color: white;
    border: none;
    border-radius: 12px;
    font-size: 1.1rem;
    font-weight: 600;
    cursor: pointer;
    transition: var(--transition);
    display: flex;
    align-items: center;
    justify-content: center;
    gap: 0.5rem;
    box-shadow: 0 4px 15px rgba(59, 130, 246, 0.3);
}

.generate-btn:hover:not(:disabled) {
    transform: translateY(-2px);
    box-shadow: 0 8px 25px rgba(59, 130, 246, 0.4);
}

.generate-btn:disabled {
    opacity: 0.6;
    cursor: not-allowed;
    transform: none;
}

/* Loading Spinner */
.loading-spinner {
    width: 20px;
    height: 20px;
    border: 2px solid rgba(255, 255, 255, 0.3);
    border-top: 2px solid white;
    border-radius: 50%;
    animation: spin 1s linear infinite;
}

@keyframes spin {
    0% { transform: rotate(0deg); }
    100% { transform: rotate(360deg); }
}

/* Results Section */
.results-section {
    background: var(--glass-bg);
    border: 1px solid var(--glass-border);
    border-radius: 20px;
    padding: 2rem;
    backdrop-filter: blur(10px);
    box-shadow: 0 8px 32px var(--shadow);
    text-align: center;
}

.qr-display {
    margin: 2rem 0;
}

.qr-display img {
    max-width: 100%;
    height: auto;
    border-radius: 15px;
    box-shadow: 0 4px 20px var(--shadow);
}

.qr-actions {
    display: flex;
    gap: 1rem;
    justify-content: center;
    flex-wrap: wrap;
}

.action-btn {
    padding: 0.75rem 1.5rem;
    background: var(--bg-secondary);
    color: var(--text-primary);
    border: 1px solid var(--border);
    border-radius: 8px;
    cursor: pointer;
    transition: var(--transition);
    display: flex;
    align-items: center;
    gap: 0.5rem;
}

.action-btn:hover {
    background: var(--accent);
    color: white;
    border-color: var(--accent);
}

/* Hidden Elements */
.hidden {
    display: none !important;
}

/* Responsive Design */
@media (max-width: 1024px) {
    .main-content {
        grid-template-columns: 1fr;
    }
    
    .container {
        padding: 1rem;
    }
    
    .input-section,
    .customization-section,
    .results-section {
        padding: 1.5rem;
    }
    
    .custom-row {
        grid-template-columns: 1fr;
    }
    
    header h1 {
        font-size: 2rem;
    }
}

@media (max-width: 768px) {
    .container {
        padding: 1rem;
    }
    
    .input-section,
    .customization-section,
    .results-section {
        padding: 1.5rem;
    }
    
    .custom-row {
        grid-template-columns: 1fr;
    }
    
    header h1 {
        font-size: 1.8rem;
    }
}

@media (max-width: 480px) {
    .container {
        padding: 0.5rem;
    }
    
    .input-section,
    .customization-section,
    .results-section {
        padding: 1rem;
    }
    
    .qr-actions {
        flex-direction: column;
    }
}

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

.fade-in {
    animation: fadeIn 0.5s ease-out;
}

/* Scrollbar */
::-webkit-scrollbar {
    width: 8px;
}

::-webkit-scrollbar-track {
    background: var(--bg-primary);
}

::-webkit-scrollbar-thumb {
    background: var(--border);
    border-radius: 4px;
}

::-webkit-scrollbar-thumb:hover {
    background: var(--accent);
}