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

body {
    font-family: -apple-system, BlinkMacSystemFont, 'Segoe UI', Roboto, Oxygen, Ubuntu, Cantarell, sans-serif;
    background: linear-gradient(135deg, #1e3c72 0%, #2a5298 50%, #00d2ff 100%);
    min-height: 100vh;
    padding: 20px;
    color: #333;
}

.container {
    max-width: 1200px;
    margin: 0 auto;
    background: white;
    border-radius: 20px;
    box-shadow: 0 25px 70px rgba(0, 0, 0, 0.25);
    overflow: hidden;
}

header {
    background: linear-gradient(135deg, #1e3c72 0%, #2a5298 100%);
    color: white;
    padding: 50px 40px;
    text-align: center;
    position: relative;
    overflow: hidden;
}

header::before {
    content: '';
    position: absolute;
    top: -50%;
    right: -50%;
    width: 200%;
    height: 200%;
    background: radial-gradient(circle, rgba(255,255,255,0.1) 0%, transparent 70%);
    animation: pulse 15s ease-in-out infinite;
}

@keyframes pulse {
    0%, 100% { transform: scale(1); opacity: 0.5; }
    50% { transform: scale(1.1); opacity: 0.8; }
}

header h1 {
    font-size: 2.8rem;
    margin-bottom: 12px;
    font-weight: 800;
    letter-spacing: -0.5px;
    position: relative;
    z-index: 1;
    text-shadow: 0 2px 10px rgba(0, 0, 0, 0.2);
}

header p {
    font-size: 1.15rem;
    opacity: 0.95;
    position: relative;
    z-index: 1;
    font-weight: 300;
}

main {
    padding: 50px 40px;
    background: #fafbfc;
}

.section {
    display: block;
}

.section.hidden {
    display: none;
}

.section h2 {
    font-size: 1.9rem;
    margin-bottom: 35px;
    color: #1e3c72;
    font-weight: 700;
    letter-spacing: -0.3px;
}

/* Drop Zone */
.drop-zone {
    border: 3px dashed #2a5298;
    border-radius: 16px;
    padding: 70px 20px;
    text-align: center;
    background: linear-gradient(135deg, #f0f7ff 0%, #e6f3ff 100%);
    transition: all 0.4s cubic-bezier(0.4, 0, 0.2, 1);
    cursor: pointer;
    position: relative;
    overflow: hidden;
}

.drop-zone::before {
    content: '';
    position: absolute;
    top: 0;
    left: -100%;
    width: 100%;
    height: 100%;
    background: linear-gradient(90deg, transparent, rgba(42, 82, 152, 0.1), transparent);
    transition: left 0.5s;
}

.drop-zone:hover::before {
    left: 100%;
}

.drop-zone:hover,
.drop-zone.dragover {
    border-color: #00d2ff;
    background: linear-gradient(135deg, #e0f2ff 0%, #d4edff 100%);
    transform: translateY(-4px);
    box-shadow: 0 12px 30px rgba(42, 82, 152, 0.2);
}

.drop-zone-content svg {
    color: #2a5298;
    margin-bottom: 24px;
    transition: transform 0.3s ease;
}

.drop-zone:hover .drop-zone-content svg {
    transform: scale(1.1);
}

.drop-text {
    font-size: 1.4rem;
    font-weight: 700;
    color: #1e3c72;
    margin-bottom: 10px;
    letter-spacing: -0.3px;
}

.drop-subtext {
    font-size: 1.05rem;
    color: #64748b;
    margin-bottom: 28px;
    font-weight: 400;
}

/* Buttons */
.btn-primary {
    background: linear-gradient(135deg, #2a5298 0%, #1e3c72 100%);
    color: white;
    border: none;
    padding: 16px 36px;
    font-size: 1.05rem;
    font-weight: 700;
    border-radius: 12px;
    cursor: pointer;
    transition: all 0.3s cubic-bezier(0.4, 0, 0.2, 1);
    margin-top: 24px;
    letter-spacing: 0.3px;
    box-shadow: 0 4px 15px rgba(42, 82, 152, 0.3);
}

.btn-primary:hover:not(:disabled) {
    transform: translateY(-3px);
    box-shadow: 0 12px 30px rgba(42, 82, 152, 0.4);
    background: linear-gradient(135deg, #3573c4 0%, #2a5298 100%);
}

.btn-primary:active:not(:disabled) {
    transform: translateY(-1px);
}

.btn-primary:disabled {
    opacity: 0.5;
    cursor: not-allowed;
    box-shadow: none;
}

.btn-secondary {
    background: #f1f5f9;
    color: #475569;
    border: 2px solid #cbd5e1;
    padding: 14px 32px;
    font-size: 1rem;
    font-weight: 600;
    border-radius: 12px;
    cursor: pointer;
    transition: all 0.3s ease;
    margin-top: 24px;
}

.btn-secondary:hover {
    background: #e2e8f0;
    border-color: #94a3b8;
    transform: translateY(-2px);
    box-shadow: 0 4px 12px rgba(0, 0, 0, 0.1);
}

/* File List */
.file-list {
    margin: 28px 0;
}

.file-item {
    background: white;
    padding: 18px 20px;
    border-radius: 12px;
    margin-bottom: 12px;
    display: flex;
    justify-content: space-between;
    align-items: center;
    border-left: 5px solid #2a5298;
    box-shadow: 0 2px 8px rgba(0, 0, 0, 0.08);
    transition: all 0.3s ease;
}

.file-item:hover {
    box-shadow: 0 4px 16px rgba(42, 82, 152, 0.15);
    transform: translateX(4px);
}

.file-item-info {
    flex: 1;
}

.file-item-name {
    font-weight: 600;
    color: #333;
    margin-bottom: 4px;
}

.file-item-size {
    font-size: 0.9rem;
    color: #666;
}

.file-item-remove {
    background: #ef4444;
    color: white;
    border: none;
    padding: 8px 16px;
    border-radius: 8px;
    cursor: pointer;
    font-size: 0.9rem;
    font-weight: 600;
    transition: all 0.2s ease;
}

.file-item-remove:hover {
    background: #dc2626;
    transform: scale(1.05);
    box-shadow: 0 4px 12px rgba(239, 68, 68, 0.3);
}

/* Progress */
.progress {
    margin-top: 24px;
    padding: 24px;
    background: white;
    border-radius: 12px;
    box-shadow: 0 2px 8px rgba(0, 0, 0, 0.08);
}

.progress-bar {
    width: 100%;
    height: 10px;
    background: #e2e8f0;
    border-radius: 10px;
    overflow: hidden;
    margin-top: 12px;
}

.progress-fill {
    height: 100%;
    background: linear-gradient(90deg, #2a5298 0%, #00d2ff 100%);
    transition: width 0.4s ease;
    width: 0%;
    border-radius: 10px;
}

/* Loading */
.loading {
    text-align: center;
    padding: 80px 20px;
}

.spinner {
    width: 60px;
    height: 60px;
    border: 5px solid #e2e8f0;
    border-top: 5px solid #2a5298;
    border-radius: 50%;
    animation: spin 0.8s linear infinite;
    margin: 0 auto 28px;
}

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

/* Comparison Table */
.info-box {
    background: linear-gradient(135deg, #e0f2ff 0%, #d4edff 100%);
    padding: 24px;
    border-radius: 12px;
    margin-bottom: 35px;
    border-left: 5px solid #2a5298;
    box-shadow: 0 2px 8px rgba(0, 0, 0, 0.08);
}

.info-box strong {
    color: #1e3c72;
    font-weight: 700;
}

.comparison-table {
    overflow-x: auto;
    margin-bottom: 35px;
    border-radius: 12px;
    box-shadow: 0 4px 20px rgba(0, 0, 0, 0.1);
}

table {
    width: 100%;
    border-collapse: collapse;
    background: white;
}

th {
    background: linear-gradient(135deg, #1e3c72 0%, #2a5298 100%);
    color: white;
    padding: 18px 20px;
    text-align: left;
    font-weight: 700;
    font-size: 0.95rem;
    letter-spacing: 0.3px;
    text-transform: uppercase;
    font-size: 0.85rem;
}

td {
    padding: 16px 20px;
    border-bottom: 1px solid #e2e8f0;
    font-size: 0.95rem;
}

tr:hover:not(.section-header) {
    background: #f8faff;
}

.section-header {
    background: linear-gradient(135deg, #cbd5e1 0%, #e2e8f0 100%) !important;
    color: #1e3c72 !important;
    font-weight: 800;
    font-size: 1.05rem;
    letter-spacing: 0.5px;
    text-transform: uppercase;
}

.section-header td {
    padding: 18px 20px;
    border-bottom: 2px solid #94a3b8;
}

.cell-same {
    background: #ffffff;
}

.cell-different {
    background: #fef3c7;
    border-left: 3px solid #f59e0b;
    font-weight: 600;
    color: #92400e;
}

.cell-missing {
    color: #94a3b8;
    font-style: italic;
    background: #f8fafc;
}

/* Export Buttons */
.export-buttons {
    display: flex;
    gap: 16px;
    flex-wrap: wrap;
    margin-top: 35px;
}

.btn-export {
    flex: 1;
    min-width: 160px;
    background: white;
    border: 2.5px solid #2a5298;
    color: #2a5298;
    padding: 16px 28px;
    font-size: 1.05rem;
    font-weight: 700;
    border-radius: 12px;
    cursor: pointer;
    transition: all 0.3s cubic-bezier(0.4, 0, 0.2, 1);
    letter-spacing: 0.2px;
    box-shadow: 0 2px 8px rgba(42, 82, 152, 0.15);
}

.btn-export:hover {
    background: linear-gradient(135deg, #2a5298 0%, #1e3c72 100%);
    color: white;
    transform: translateY(-4px);
    box-shadow: 0 8px 24px rgba(42, 82, 152, 0.35);
    border-color: #2a5298;
}

.btn-export:active {
    transform: translateY(-2px);
}

/* Responsive */
@media (max-width: 768px) {
    header h1 {
        font-size: 2rem;
    }

    main {
        padding: 20px;
    }

    .export-buttons {
        flex-direction: column;
    }

    .btn-export {
        width: 100%;
    }
}