:root {
    /* Color Palette */
    --primary-gradient: linear-gradient(135deg, #667eea 0%, #764ba2 100%);
    --primary-dark: #5568d3;
    --primary-light: #7c8cf5;
    --accent-gradient: linear-gradient(135deg, #f093fb 0%, #f5576c 100%);
    
    --text-primary: #1a1a2e;
    --text-secondary: #4a5568;
    --text-light: #718096;
    
    --bg-primary: #ffffff;
    --bg-secondary: #f7fafc;
    --bg-card: #ffffff;
    
    --success: #48bb78;
    --success-light: #c6f6d5;
    --error: #f56565;
    --error-light: #fed7d7;
    
    /* Spacing */
    --spacing-xs: 0.5rem;
    --spacing-sm: 0.75rem;
    --spacing-md: 1rem;
    --spacing-lg: 1.5rem;
    --spacing-xl: 2rem;
    --spacing-2xl: 3rem;
    --spacing-3xl: 4rem;
    
    /* Shadows */
    --shadow-sm: 0 1px 3px rgba(0, 0, 0, 0.12), 0 1px 2px rgba(0, 0, 0, 0.08);
    --shadow-md: 0 4px 6px rgba(0, 0, 0, 0.1), 0 2px 4px rgba(0, 0, 0, 0.06);
    --shadow-lg: 0 10px 15px rgba(0, 0, 0, 0.1), 0 4px 6px rgba(0, 0, 0, 0.05);
    --shadow-xl: 0 20px 25px rgba(0, 0, 0, 0.15), 0 10px 10px rgba(0, 0, 0, 0.04);
    --shadow-glow: 0 0 20px rgba(102, 126, 234, 0.3);
    
    /* Border Radius */
    --radius-sm: 0.375rem;
    --radius-md: 0.5rem;
    --radius-lg: 0.75rem;
    --radius-xl: 1rem;
    --radius-2xl: 1.5rem;
    
    /* Transitions */
    --transition-fast: 150ms cubic-bezier(0.4, 0, 0.2, 1);
    --transition-base: 250ms cubic-bezier(0.4, 0, 0.2, 1);
    --transition-slow: 350ms cubic-bezier(0.4, 0, 0.2, 1);
}

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

body {
    font-family: 'Inter', -apple-system, BlinkMacSystemFont, 'Segoe UI', Roboto, sans-serif;
    background: var(--bg-secondary);
    color: var(--text-primary);
    line-height: 1.6;
    min-height: 100vh;
    display: flex;
    flex-direction: column;
    -webkit-font-smoothing: antialiased;
    -moz-osx-font-smoothing: grayscale;
}

.container {
    width: 100%;
    max-width: 800px;
    margin: 0 auto;
    padding: var(--spacing-lg);
    flex: 1;
    display: flex;
    flex-direction: column;
}

/* Header Styles */
.header {
    text-align: center;
    margin-bottom: var(--spacing-3xl);
    animation: fadeInDown 0.6s ease-out;
}

.header-content {
    padding: var(--spacing-xl) 0;
}

.main-title {
    font-family: 'Poppins', sans-serif;
    font-size: clamp(2rem, 5vw, 3rem);
    font-weight: 800;
    margin-bottom: var(--spacing-md);
    line-height: 1.2;
}

.gradient-text {
    background: var(--primary-gradient);
    -webkit-background-clip: text;
    -webkit-text-fill-color: transparent;
    background-clip: text;
}

.subtitle {
    font-size: clamp(1rem, 2.5vw, 1.25rem);
    color: var(--text-secondary);
    font-weight: 400;
}

/* Main Content */
.main-content {
    flex: 1;
}

.generator-section {
    background: var(--bg-card);
    border-radius: var(--radius-2xl);
    padding: var(--spacing-2xl);
    box-shadow: var(--shadow-lg);
    margin-bottom: var(--spacing-3xl);
    animation: fadeInUp 0.6s ease-out 0.2s both;
}

/* Input Section */
.input-container {
    margin-bottom: var(--spacing-xl);
}

.input-label {
    display: block;
    font-weight: 600;
    font-size: 0.95rem;
    color: var(--text-primary);
    margin-bottom: var(--spacing-sm);
    letter-spacing: 0.01em;
}

.input-wrapper {
    display: flex;
    gap: var(--spacing-md);
    flex-wrap: wrap;
}

.url-input {
    flex: 1;
    min-width: 250px;
    padding: var(--spacing-md) var(--spacing-lg);
    font-size: 1rem;
    font-family: inherit;
    border: 2px solid #e2e8f0;
    border-radius: var(--radius-lg);
    background: var(--bg-primary);
    color: var(--text-primary);
    transition: all var(--transition-base);
    outline: none;
}

.url-input:focus {
    border-color: var(--primary-dark);
    box-shadow: 0 0 0 3px rgba(102, 126, 234, 0.1);
    transform: translateY(-1px);
}

.url-input::placeholder {
    color: var(--text-light);
}

.url-input.error {
    border-color: var(--error);
}

.generate-btn {
    display: inline-flex;
    align-items: center;
    gap: var(--spacing-sm);
    padding: var(--spacing-md) var(--spacing-xl);
    font-size: 1rem;
    font-weight: 600;
    font-family: inherit;
    color: white;
    background: var(--primary-gradient);
    border: none;
    border-radius: var(--radius-lg);
    cursor: pointer;
    transition: all var(--transition-base);
    box-shadow: var(--shadow-md);
    white-space: nowrap;
}

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

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

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

.btn-icon {
    transition: transform var(--transition-base);
}

.generate-btn:hover .btn-icon {
    transform: rotate(90deg);
}

/* Error Message */
.error-message {
    margin-top: var(--spacing-md);
    padding: var(--spacing-md) var(--spacing-lg);
    background: var(--error-light);
    border-left: 4px solid var(--error);
    border-radius: var(--radius-md);
    color: #742a2a;
    font-size: 0.9rem;
    font-weight: 500;
    display: none;
    animation: slideInDown 0.3s ease-out;
}

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

/* Loading State */
.loading-state {
    display: none;
    flex-direction: column;
    align-items: center;
    justify-content: center;
    padding: var(--spacing-3xl);
    gap: var(--spacing-lg);
}

.loading-state.show {
    display: flex;
}

.spinner {
    width: 50px;
    height: 50px;
    border: 4px solid #e2e8f0;
    border-top-color: var(--primary-dark);
    border-radius: 50%;
    animation: spin 0.8s linear infinite;
}

.loading-text {
    color: var(--text-secondary);
    font-weight: 500;
}

/* Result Container */
.result-container {
    display: none;
    animation: fadeIn 0.5s ease-out;
}

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

.qr-preview-card {
    text-align: center;
    padding: var(--spacing-xl);
}

.result-title {
    font-family: 'Poppins', sans-serif;
    font-size: 1.5rem;
    font-weight: 700;
    color: var(--text-primary);
    margin-bottom: var(--spacing-xl);
}

.qr-image-wrapper {
    display: inline-block;
    padding: var(--spacing-xl);
    background: white;
    border-radius: var(--radius-xl);
    box-shadow: var(--shadow-lg);
    margin-bottom: var(--spacing-xl);
    transition: transform var(--transition-base);
}

.qr-image-wrapper:hover {
    transform: scale(1.02);
}

.qr-image {
    display: block;
    max-width: 100%;
    height: auto;
    border-radius: var(--radius-md);
}

.qr-description {
    color: var(--text-secondary);
    font-size: 0.95rem;
    margin-bottom: var(--spacing-xl);
}

.download-btn {
    display: inline-flex;
    align-items: center;
    gap: var(--spacing-sm);
    padding: var(--spacing-md) var(--spacing-2xl);
    font-size: 1rem;
    font-weight: 600;
    font-family: inherit;
    color: white;
    background: var(--accent-gradient);
    border: none;
    border-radius: var(--radius-lg);
    cursor: pointer;
    transition: all var(--transition-base);
    box-shadow: var(--shadow-md);
}

.download-btn:hover {
    transform: translateY(-2px);
    box-shadow: var(--shadow-xl);
}

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

.download-icon {
    transition: transform var(--transition-base);
}

.download-btn:hover .download-icon {
    transform: translateY(2px);
}

/* Features Section */
.features-section {
    margin-bottom: var(--spacing-3xl);
    animation: fadeInUp 0.6s ease-out 0.4s both;
}

.features-title {
    font-family: 'Poppins', sans-serif;
    font-size: 1.75rem;
    font-weight: 700;
    text-align: center;
    margin-bottom: var(--spacing-2xl);
    color: var(--text-primary);
}

.features-grid {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(200px, 1fr));
    gap: var(--spacing-lg);
}

.feature-card {
    background: var(--bg-card);
    padding: var(--spacing-xl);
    border-radius: var(--radius-xl);
    box-shadow: var(--shadow-md);
    text-align: center;
    transition: all var(--transition-base);
}

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

.feature-icon {
    font-size: 2.5rem;
    margin-bottom: var(--spacing-md);
}

.feature-heading {
    font-size: 1.1rem;
    font-weight: 600;
    color: var(--text-primary);
    margin-bottom: var(--spacing-sm);
}

.feature-text {
    font-size: 0.9rem;
    color: var(--text-secondary);
    line-height: 1.5;
}

/* Footer */
.footer {
    text-align: center;
    padding: var(--spacing-xl) 0;
    margin-top: auto;
}

.footer-text {
    color: var(--text-light);
    font-size: 0.9rem;
}

.footer-link {
    color: var(--primary-dark);
    text-decoration: none;
    font-weight: 600;
    transition: color var(--transition-fast);
}

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

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

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

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

@keyframes slideInDown {
    from {
        opacity: 0;
        transform: translateY(-10px);
    }
    to {
        opacity: 1;
        transform: translateY(0);
    }
}

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

/* Responsive Design */
@media (max-width: 768px) {
    .container {
        padding: var(--spacing-md);
    }
    
    .generator-section {
        padding: var(--spacing-lg);
    }
    
    .input-wrapper {
        flex-direction: column;
    }
    
    .url-input {
        min-width: 100%;
    }
    
    .generate-btn {
        width: 100%;
        justify-content: center;
    }
    
    .features-grid {
        grid-template-columns: 1fr;
    }
}

@media (max-width: 480px) {
    .header-content {
        padding: var(--spacing-lg) 0;
    }
    
    .main-title {
        font-size: 1.75rem;
    }
    
    .subtitle {
        font-size: 1rem;
    }
    
    .qr-image-wrapper {
        padding: var(--spacing-lg);
    }
}

/* Print Styles */
@media print {
    body {
        background: white;
    }
    
    .header, .features-section, .footer, .generate-btn {
        display: none;
    }
    
    .result-container {
        box-shadow: none;
    }
}