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

body {
    font-family: -apple-system, BlinkMacSystemFont, 'Segoe UI', Roboto, sans-serif;
    background: linear-gradient(135deg, #667eea 0%, #764ba2 100%);
    min-height: 100vh;
    color: #333;
}

/* Top Navigation */
.top-nav {
    background: white;
    box-shadow: 0 2px 10px rgba(0,0,0,0.1);
    position: sticky;
    top: 0;
    z-index: 1000;
    margin-bottom: 20px;
}

.nav-container {
    max-width: 800px;
    margin: 0 auto;
    padding: 0 20px;
    display: flex;
    justify-content: space-between;
    align-items: center;
    height: 60px;
}

.nav-brand {
    display: flex;
    align-items: center;
    gap: 8px;
    font-weight: 700;
    color: #2d3748;
    font-size: 18px;
}

.nav-icon {
    font-size: 20px;
}

.nav-title {
    font-family: -apple-system, BlinkMacSystemFont, 'Segoe UI', Roboto, sans-serif;
}

.nav-links {
    display: flex;
    gap: 8px;
}

.nav-link {
    display: flex;
    align-items: center;
    gap: 6px;
    padding: 8px 16px;
    border-radius: 8px;
    text-decoration: none;
    color: #718096;
    font-weight: 500;
    font-size: 14px;
    transition: all 0.3s ease;
    border: 2px solid transparent;
}

.nav-link:hover {
    color: #4299e1;
    background: #f7fafc;
}

.nav-link.active {
    color: #4299e1;
    background: #ebf8ff;
    border-color: #bee3f8;
}

.nav-link-icon {
    font-size: 16px;
}

.container {
    max-width: 500px;
    margin: 0 auto;
    width: 100%;
    padding: 0 20px;
}

.card {
    background: white;
    border-radius: 16px;
    box-shadow: 0 10px 40px rgba(0,0,0,0.1);
    overflow: hidden;
}

.header {
    background: white;
    padding: 24px 20px;
    text-align: center;
    border-bottom: 1px solid #f0f0f0;
}

.header h1 {
    color: #2d3748;
    font-size: 24px;
    font-weight: 700;
    margin-bottom: 4px;
}

.subtitle {
    color: #718096;
    font-size: 14px;
    font-weight: 500;
}

.form-section {
    padding: 20px;
}

.form-group {
    margin-bottom: 24px;
}

.section-label {
    display: block;
    font-weight: 600;
    margin-bottom: 16px;
    color: #2d3748;
    font-size: 15px;
}

.bin-input {
    width: 100%;
    padding: 14px 16px;
    border: 2px solid #e2e8f0;
    border-radius: 10px;
    font-size: 16px;
    background: #fafafa;
    transition: all 0.3s ease;
}

.bin-input:focus {
    outline: none;
    border-color: #4299e1;
    background: white;
    box-shadow: 0 0 0 3px rgba(66, 153, 225, 0.1);
}

/* Option Row Layout */
.option-row {
    display: flex;
    align-items: center;
    gap: 16px;
    flex-wrap: wrap;
}

/* Radio Groups */
.radio-group {
    display: flex;
    gap: 20px;
    flex-wrap: wrap;
}

.radio-label {
    display: flex;
    align-items: center;
    cursor: pointer;
    font-size: 14px;
    color: #4a5568;
    padding: 8px 0;
}

.radio-label input[type="radio"] {
    display: none;
}

.radio-checkmark {
    width: 18px;
    height: 18px;
    border: 2px solid #cbd5e0;
    border-radius: 50%;
    margin-right: 10px;
    position: relative;
    transition: all 0.3s ease;
}

.radio-label input[type="radio"]:checked + .radio-checkmark {
    border-color: #4299e1;
    background: #4299e1;
}

.radio-label input[type="radio"]:checked + .radio-checkmark::after {
    content: '';
    position: absolute;
    top: 50%;
    left: 50%;
    transform: translate(-50%, -50%);
    width: 6px;
    height: 6px;
    background: white;
    border-radius: 50%;
}

/* Inline Options */
.inline-options {
    display: none;
    align-items: center;
    gap: 12px;
}

.inline-options.active {
    display: flex;
    animation: slideIn 0.3s ease-out;
}

/* Date Options */
.date-inputs {
    display: flex;
    align-items: center;
    gap: 8px;
}

.select-input {
    padding: 8px 10px;
    border: 2px solid #e2e8f0;
    border-radius: 6px;
    font-size: 13px;
    background: white;
    cursor: pointer;
    min-width: 70px;
    font-family: -apple-system, BlinkMacSystemFont, 'Segoe UI', Roboto, sans-serif;
}

.year-input, .cvv-input {
    padding: 8px 10px;
    border: 2px solid #e2e8f0;
    border-radius: 6px;
    font-size: 13px;
    background: white;
    width: 60px;
    text-align: center;
    font-family: -apple-system, BlinkMacSystemFont, 'Segoe UI', Roboto, sans-serif;
}

.year-input:focus, .cvv-input:focus {
    outline: none;
    border-color: #4299e1;
}

/* Quantity Section */
.quantity-section {
    display: flex;
    align-items: center;
    gap: 16px;
}

.quantity-label {
    font-size: 15px;
    color: #2d3748;
    font-weight: 600;
    min-width: 70px;
}

.quantity-input {
    width: 100px;
    padding: 12px;
    border: 2px solid #e2e8f0;
    border-radius: 8px;
    font-size: 14px;
    background: white;
    text-align: center;
    font-family: -apple-system, BlinkMacSystemFont, 'Segoe UI', Roboto, sans-serif;
}

.quantity-input:focus {
    outline: none;
    border-color: #4299e1;
}

.divider {
    height: 1px;
    background: #e2e8f0;
    margin: 24px 0;
}

/* Action Buttons */
.action-buttons {
    display: grid;
    grid-template-columns: 1fr 1fr;
    gap: 12px;
}

.generate-btn, .copy-btn {
    padding: 16px;
    border: none;
    border-radius: 10px;
    font-size: 15px;
    font-weight: 600;
    cursor: pointer;
    transition: all 0.3s ease;
    display: flex;
    align-items: center;
    justify-content: center;
    gap: 8px;
    font-family: -apple-system, BlinkMacSystemFont, 'Segoe UI', Roboto, sans-serif;
}

.generate-btn {
    background: #4299e1;
    color: white;
}

.generate-btn:hover {
    background: #3182ce;
    transform: translateY(-1px);
}

.generate-btn:disabled {
    background: #cbd5e0;
    cursor: not-allowed;
    transform: none;
}

.copy-btn {
    background: #48bb78;
    color: white;
}

.copy-btn:hover {
    background: #38a169;
    transform: translateY(-1px);
}

.copy-btn:disabled {
    background: #cbd5e0;
    cursor: not-allowed;
    transform: none;
}

.btn-icon {
    font-size: 16px;
}

/* Results Section */
.results-section {
    border-top: 1px solid #f0f0f0;
    padding: 24px 20px;
    display: none;
}

.results-section.active {
    display: block;
}

.results-header {
    display: flex;
    justify-content: space-between;
    align-items: center;
    margin-bottom: 20px;
}

.results-header h3 {
    color: #2d3748;
    font-size: 18px;
    font-weight: 700;
}

.results-controls {
    display: flex;
    align-items: center;
    gap: 12px;
}

.cards-count {
    font-size: 13px;
    color: #718096;
    background: #f7fafc;
    padding: 6px 12px;
    border-radius: 20px;
    font-weight: 600;
}

.clear-btn {
    padding: 8px 16px;
    border: 1px solid #e53e3e;
    background: white;
    color: #e53e3e;
    border-radius: 8px;
    font-size: 13px;
    font-weight: 600;
    cursor: pointer;
    transition: all 0.3s ease;
    display: flex;
    align-items: center;
    gap: 6px;
    font-family: -apple-system, BlinkMacSystemFont, 'Segoe UI', Roboto, sans-serif;
}

.clear-btn:hover {
    background: #e53e3e;
    color: white;
}

.cards-display {
    background: #f8fafc;
    border-radius: 12px;
    padding: 0;
    max-height: 400px;
    overflow-y: auto;
    border: 2px solid #e2e8f0;
    font-family: -apple-system, BlinkMacSystemFont, 'Segoe UI', Roboto, sans-serif;
}

.empty-state {
    text-align: center;
    padding: 40px 20px;
    color: #a0aec0;
    font-family: -apple-system, BlinkMacSystemFont, 'Segoe UI', Roboto, sans-serif;
}

.empty-icon {
    font-size: 48px;
    margin-bottom: 16px;
    opacity: 0.5;
}

.empty-text {
    font-size: 16px;
    font-weight: 600;
    margin-bottom: 8px;
    color: #718096;
}

.empty-subtext {
    font-size: 14px;
    color: #a0aec0;
}

/* Card Items */
.card-item {
    padding: 16px 20px;
    border-bottom: 1px solid #e2e8f0;
    cursor: pointer;
    transition: all 0.3s ease;
    position: relative;
    font-family: -apple-system, BlinkMacSystemFont, 'Segoe UI', Roboto, sans-serif;
    font-size: 14px;
    color: #2d3748;
    background: white;
    font-weight: 500;
}

.card-item:hover {
    background: #f7fafc;
    transform: translateX(4px);
}

.card-item:last-child {
    border-bottom: none;
}

.card-item.copied {
    background: #ebf8ff;
    border-left: 4px solid #4299e1;
    animation: copyFlash 0.5s ease;
}

.card-item::after {
    content: '📋';
    position: absolute;
    right: 20px;
    top: 50%;
    transform: translateY(-50%);
    opacity: 0;
    transition: opacity 0.3s ease;
    font-family: -apple-system, BlinkMacSystemFont, 'Segoe UI', Roboto, sans-serif;
}

.card-item:hover::after {
    opacity: 1;
}

/* Toast Notification */
.toast {
    position: fixed;
    bottom: 20px;
    left: 50%;
    transform: translateX(-50%) translateY(100px);
    background: #2d3748;
    color: white;
    padding: 12px 20px;
    border-radius: 10px;
    display: flex;
    align-items: center;
    gap: 10px;
    box-shadow: 0 4px 20px rgba(0,0,0,0.3);
    opacity: 0;
    transition: all 0.3s ease;
    z-index: 1001;
    font-family: -apple-system, BlinkMacSystemFont, 'Segoe UI', Roboto, sans-serif;
}

.toast.show {
    transform: translateX(-50%) translateY(0);
    opacity: 1;
}

.toast-icon {
    font-size: 16px;
}

.toast-text {
    font-size: 14px;
    font-weight: 500;
}

/* Footer */
.footer {
    background: #f8fafc;
    padding: 20px;
    text-align: center;
    border-top: 1px solid #e2e8f0;
    font-family: -apple-system, BlinkMacSystemFont, 'Segoe UI', Roboto, sans-serif;
}

.footer div {
    color: #718096;
    font-size: 13px;
}

.footer-link {
    color: #4299e1;
    text-decoration: none;
    font-weight: 600;
    transition: color 0.3s ease;
}

.footer-link:hover {
    color: #3182ce;
    text-decoration: underline;
}

/* Animations */
@keyframes slideIn {
    from {
        opacity: 0;
        transform: translateX(-10px);
    }
    to {
        opacity: 1;
        transform: translateX(0);
    }
}

@keyframes copyFlash {
    0% {
        background: #ebf8ff;
        border-left-color: #4299e1;
    }
    50% {
        background: #bee3f8;
        border-left-color: #3182ce;
    }
    100% {
        background: #ebf8ff;
        border-left-color: #4299e1;
    }
}

/* Responsive Design */
@media (max-width: 640px) {
    .nav-container {
        padding: 0 16px;
    }
    
    .nav-brand .nav-title {
        display: none;
    }
    
    .nav-links {
        gap: 4px;
    }
    
    .nav-link {
        padding: 8px 12px;
        font-size: 13px;
    }
    
    .nav-link span:last-child {
        display: none;
    }
    
    .nav-link-icon {
        font-size: 18px;
    }
    
    .container {
        max-width: 100%;
        padding: 0 16px;
    }
    
    .option-row {
        flex-direction: column;
        align-items: flex-start;
        gap: 12px;
    }
    
    .radio-group {
        gap: 16px;
    }
    
    .inline-options.active {
        width: 100%;
        justify-content: flex-start;
    }
    
    .date-inputs {
        width: 100%;
        justify-content: flex-start;
    }
    
    .select-input {
        flex: 1;
        min-width: auto;
    }
    
    .year-input, .cvv-input {
        width: 80px;
    }
    
    .quantity-section {
        flex-direction: column;
        align-items: flex-start;
        gap: 12px;
    }
    
    .quantity-input {
        width: 100%;
    }
    
    .action-buttons {
        grid-template-columns: 1fr;
        gap: 10px;
    }
    
    .results-controls {
        flex-direction: column;
        gap: 8px;
        align-items: flex-start;
    }
    
    .toast {
        bottom: 10px;
        left: 10px;
        right: 10px;
        transform: translateY(100px);
    }
    
    .toast.show {
        transform: translateY(0);
    }
}

@media (max-width: 480px) {
    .date-inputs {
        flex-direction: column;
        gap: 8px;
        width: 100%;
    }
    
    .date-inputs .select-input,
    .date-inputs .year-input {
        width: 100%;
    }
    
    .cvv-input {
        width: 100%;
    }
}

/* Scrollbar styling */
.cards-display::-webkit-scrollbar {
    width: 6px;
}

.cards-display::-webkit-scrollbar-track {
    background: #f1f5f9;
    border-radius: 3px;
}

.cards-display::-webkit-scrollbar-thumb {
    background: #cbd5e0;
    border-radius: 3px;
}