:root {
    --primary-color: #007AFF;
    --primary-hover: #0056CC;
    --success-color: #34C759;
    --danger-color: #FF3B30;
    --warning-color: #FF9500;
    --light-bg: #F2F7FF;
    --card-bg: rgba(255, 255, 255, 0.85);
    --border-radius: 1.25rem;
    --shadow-light: 0 4px 20px rgba(0, 122, 255, 0.15);
    --shadow-medium: 0 8px 32px rgba(0, 122, 255, 0.2);
    --shadow-heavy: 0 16px 48px rgba(0, 122, 255, 0.25);
    --text-primary: #1D1D1F;
    --text-secondary: #86868B;
    --backdrop-blur: blur(20px);
}

body {
    font-family: -apple-system, BlinkMacSystemFont, 'SF Pro Display', 'Segoe UI', Roboto, sans-serif;
    background: linear-gradient(135deg, #E3F2FD 0%, #F8FBFF 50%, #E8F4FD 100%);
    min-height: 100vh;
    color: var(--text-primary);
    -webkit-font-smoothing: antialiased;
    -moz-osx-font-smoothing: grayscale;
}

.container-fluid {
    background: transparent;
}

/* Header Styles */
header {
    background: var(--card-bg);
    backdrop-filter: var(--backdrop-blur);
    border-radius: 0 0 var(--border-radius) var(--border-radius);
    box-shadow: var(--shadow-light);
    border: 1px solid rgba(255, 255, 255, 0.3);
}

.text-primary {
    color: var(--primary-color) !important;
}

/* Card Styles */
.card {
    border: 1px solid rgba(255, 255, 255, 0.4) !important;
    backdrop-filter: var(--backdrop-blur);
    background: linear-gradient(145deg, rgba(255, 255, 255, 0.9), rgba(255, 255, 255, 0.7)) !important;
    box-shadow: var(--shadow-medium);
}

.rounded-4 {
    border-radius: var(--border-radius) !important;
}

/* Upload Area Styles */
.upload-area {
    border: 2px dashed rgba(0, 122, 255, 0.3);
    border-radius: var(--border-radius);
    padding: 3rem 2rem;
    text-align: center;
    transition: all 0.3s cubic-bezier(0.25, 0.46, 0.45, 0.94);
    cursor: pointer;
    background: linear-gradient(145deg, rgba(255, 255, 255, 0.6), rgba(242, 247, 255, 0.4));
    box-shadow: inset 0 1px 0 rgba(255, 255, 255, 0.6);
}

.upload-area:hover {
    border-color: var(--primary-color);
    background: linear-gradient(145deg, rgba(0, 122, 255, 0.05), rgba(242, 247, 255, 0.6));
    transform: translateY(-2px);
    box-shadow: var(--shadow-light), inset 0 1px 0 rgba(255, 255, 255, 0.8);
}

.upload-area.dragover {
    border-color: var(--primary-color);
    background: linear-gradient(145deg, rgba(0, 122, 255, 0.1), rgba(242, 247, 255, 0.8));
    transform: translateY(-4px) scale(1.01);
    box-shadow: var(--shadow-medium), inset 0 1px 0 rgba(255, 255, 255, 0.9);
}

.upload-icon i {
    font-size: 4rem;
    color: var(--primary-color);
    margin-bottom: 1rem;
}

.upload-file-icon {
    font-size: 3rem;
    color: var(--text-secondary);
}

/* File Info Styles */
.file-info {
    background: linear-gradient(145deg, rgba(52, 199, 89, 0.08), rgba(52, 199, 89, 0.04));
    border: 1px solid rgba(52, 199, 89, 0.2);
    border-radius: var(--border-radius);
    padding: 1.5rem;
    box-shadow: var(--shadow-light);
}

/* Button Styles */
.btn {
    font-weight: 600;
    transition: all 0.3s cubic-bezier(0.25, 0.46, 0.45, 0.94);
    border: none;
    font-size: 0.95rem;
    letter-spacing: -0.01em;
    position: relative;
    overflow: hidden;
}

.btn-primary {
    background: linear-gradient(135deg, var(--primary-color) 0%, var(--primary-hover) 100%);
    color: white;
    box-shadow: var(--shadow-light);
}

.btn-primary:hover {
    background: linear-gradient(135deg, var(--primary-hover) 0%, #004085 100%);
    transform: translateY(-3px);
    box-shadow: var(--shadow-heavy);
    color: white;
}

.btn-primary:active {
    transform: translateY(-1px);
    box-shadow: var(--shadow-light);
}

.btn-success {
    background: linear-gradient(135deg, var(--success-color) 0%, #28A745 100%);
    color: white;
    box-shadow: var(--shadow-light);
}

.btn-success:hover {
    background: linear-gradient(135deg, #28A745 0%, #1E7E34 100%);
    transform: translateY(-3px);
    box-shadow: var(--shadow-heavy);
    color: white;
}

.btn-outline-primary {
    background: rgba(255, 255, 255, 0.8);
    border: 1px solid rgba(0, 122, 255, 0.3);
    color: var(--primary-color);
    backdrop-filter: var(--backdrop-blur);
}

.btn-outline-primary:hover {
    background: rgba(0, 122, 255, 0.1);
    border-color: var(--primary-color);
    color: var(--primary-color);
    transform: translateY(-2px);
    box-shadow: var(--shadow-light);
}

.btn-outline-secondary {
    background: rgba(255, 255, 255, 0.8);
    border: 1px solid rgba(134, 134, 139, 0.3);
    color: var(--text-secondary);
    backdrop-filter: var(--backdrop-blur);
}

.btn-outline-secondary:hover {
    background: rgba(134, 134, 139, 0.1);
    border-color: var(--text-secondary);
    color: var(--text-secondary);
    transform: translateY(-2px);
}

.btn-check:checked + .btn {
    background: linear-gradient(135deg, var(--primary-color) 0%, var(--primary-hover) 100%);
    border-color: var(--primary-color);
    color: white;
    box-shadow: var(--shadow-medium);
    transform: translateY(-1px);
}

/* Icon Styles */
.processing-spinner i {
    font-size: 4rem;
    color: var(--primary-color);
    filter: drop-shadow(0 4px 8px rgba(0, 122, 255, 0.3));
}

.success-icon i {
    font-size: 4rem;
    color: var(--success-color);
    filter: drop-shadow(0 4px 8px rgba(52, 199, 89, 0.3));
}

.error-icon i {
    font-size: 4rem;
    color: var(--danger-color);
    filter: drop-shadow(0 4px 8px rgba(255, 59, 48, 0.3));
}

.step-icon {
    width: 80px;
    height: 80px;
    margin: 0 auto;
    background: linear-gradient(135deg, var(--primary-color) 0%, var(--primary-hover) 100%);
    border-radius: 50%;
    display: flex;
    align-items: center;
    justify-content: center;
    color: white;
    font-size: 2rem;
    box-shadow: var(--shadow-medium);
    border: 1px solid rgba(255, 255, 255, 0.2);
}

/* Animation Classes */
.fade-in {
    animation: fadeIn 0.5s ease-in;
}

.slide-up {
    animation: slideUp 0.5s ease-out;
}

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

@keyframes slideUp {
    from { 
        opacity: 0;
        transform: translateY(30px);
    }
    to { 
        opacity: 1;
        transform: translateY(0);
    }
}

/* Additional Typography Enhancements */
.display-4 {
    font-weight: 700;
    letter-spacing: -0.02em;
}

.lead {
    color: var(--text-secondary);
    font-weight: 400;
}

.card-title {
    color: var(--text-primary);
    font-weight: 600;
    letter-spacing: -0.01em;
}

.text-muted {
    color: var(--text-secondary) !important;
}

/* "How it Works" Section Enhancement */
.bg-light {
    background: linear-gradient(145deg, rgba(255, 255, 255, 0.7), rgba(242, 247, 255, 0.5)) !important;
    border: 1px solid rgba(255, 255, 255, 0.4);
    box-shadow: var(--shadow-light);
}

/* Responsive Design */
@media (max-width: 768px) {
    .upload-area {
        padding: 2rem 1rem;
    }
    
    .upload-icon i {
        font-size: 3rem;
    }
    
    .step-icon {
        width: 60px;
        height: 60px;
        font-size: 1.5rem;
    }
    
    .card-body {
        padding: 2rem !important;
    }
    
    .display-4 {
        font-size: 2.5rem !important;
    }
    
    header {
        border-radius: 0 0 1rem 1rem;
    }
    
    footer {
        border-radius: 1rem 1rem 0 0;
    }
}

/* Loading Animation */
@keyframes spin {
    from { transform: rotate(0deg); }
    to { transform: rotate(360deg); }
}

.fa-spin {
    animation: spin 2s linear infinite;
}

/* Smooth Transitions */
* {
    transition: all 0.3s ease;
}

/* Footer Styles */
footer {
    background: var(--card-bg);
    backdrop-filter: var(--backdrop-blur);
    border-radius: var(--border-radius) var(--border-radius) 0 0;
    border: 1px solid rgba(255, 255, 255, 0.3);
    border-bottom: none;
    box-shadow: var(--shadow-light);
}

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

::-webkit-scrollbar-track {
    background: rgba(255, 255, 255, 0.1);
}

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

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

/* MCEasyLink Branding */
.powered-by {
    color: var(--text-secondary);
    font-size: 0.875rem;
    font-weight: 400;
}

.brand-name {
    color: var(--primary-color);
    font-weight: 600;
    font-size: 0.875rem;
    text-decoration: none;
    transition: all 0.3s cubic-bezier(0.25, 0.46, 0.45, 0.94);
    background: linear-gradient(135deg, var(--primary-color), var(--primary-hover));
    -webkit-background-clip: text;
    -webkit-text-fill-color: transparent;
    background-clip: text;
}

.brand-name:hover {
    transform: translateY(-1px);
    filter: brightness(1.1);
}

/* Performance Optimizations */
.card {
    will-change: transform;
    backface-visibility: hidden;
}

.upload-area {
    will-change: transform, background-color;
}

/* Reduced motion for better performance */
@media (prefers-reduced-motion: reduce) {
    * {
        animation-duration: 0.01ms !important;
        animation-iteration-count: 1 !important;
        transition-duration: 0.01ms !important;
    }
}