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

body {
    font-family: 'Segoe UI', Tahoma, Geneva, Verdana, sans-serif;
    background: linear-gradient(135deg, #667eea 0%, #764ba2 100%);
    min-height: 100vh;
    padding: 20px;
}

.main-container {
    max-width: 1400px;
    margin: 0 auto;
}

.header {
    text-align: center;
    margin-bottom: 30px;
    color: white;
}

.header h1 {
    font-size: 2.5rem;
    font-weight: 300;
    margin-bottom: 10px;
    text-shadow: 0 2px 4px rgba(0,0,0,0.3);
}

.header p {
    font-size: 1.1rem;
    opacity: 0.9;
}

.container {
    background: white;
    border-radius: 20px;
    box-shadow: 0 20px 60px rgba(0,0,0,0.15);
    overflow: hidden;
    backdrop-filter: blur(10px);
}

.tab-header {
    display: flex;
    background: linear-gradient(90deg, #f8f9fa, #e9ecef);
    border-bottom: 1px solid rgba(0,0,0,0.1);
}

.tab-button {
    flex: 1;
    padding: 20px;
    border: none;
    background: transparent;
    cursor: pointer;
    font-size: 16px;
    font-weight: 500;
    color: #6c757d;
    transition: all 0.3s ease;
    position: relative;
}

.tab-button::after {
    content: '';
    position: absolute;
    bottom: 0;
    left: 50%;
    width: 0;
    height: 3px;
    background: linear-gradient(90deg, #667eea, #764ba2);
    transition: all 0.3s ease;
    transform: translateX(-50%);
}

.tab-button.active {
    color: #495057;
    background: white;
}

.tab-button.active::after {
    width: 80%;
}

.tab-button:hover {
    color: #495057;
    background: rgba(255,255,255,0.8);
}

.tab-content {
    display: none;
    padding: 30px;
}

.tab-content.active {
    display: block;
}

.section-title {
    font-size: 1.8rem;
    font-weight: 300;
    color: #2c3e50;
    margin-bottom: 25px;
    text-align: center;
}

.upload-area {
    border: 3px dashed #667eea;
    border-radius: 15px;
    padding: 50px 20px;
    text-align: center;
    margin-bottom: 30px;
    background: linear-gradient(135deg, #f8f9ff 0%, #e6f0ff 100%);
    cursor: pointer;
    transition: all 0.3s ease;
    position: relative;
    overflow: hidden;
}

.upload-area::before {
    content: '';
    position: absolute;
    top: 0;
    left: -100%;
    width: 100%;
    height: 100%;
    background: linear-gradient(90deg, transparent, rgba(255,255,255,0.4), transparent);
    transition: left 0.5s;
}

.upload-area:hover::before {
    left: 100%;
}

.upload-area:hover {
    border-color: #5a67d8;
    background: linear-gradient(135deg, #e6f0ff 0%, #cce7ff 100%);
    transform: translateY(-2px);
    box-shadow: 0 8px 25px rgba(102, 126, 234, 0.15);
}

.upload-area.dragover {
    border-color: #4c51bf;
    background: linear-gradient(135deg, #cce7ff 0%, #b3d9ff 100%);
    transform: scale(1.02);
}

.upload-icon {
    font-size: 3rem;
    color: #667eea;
    margin-bottom: 15px;
}

.upload-text {
    font-size: 1.2rem;
    color: #4a5568;
    font-weight: 500;
}

.controls {
    display: flex;
    gap: 20px;
    margin-bottom: 30px;
    align-items: center;
    flex-wrap: wrap;
    justify-content: center;
    padding: 25px;
    background: linear-gradient(135deg, #f7fafc, #edf2f7);
    border-radius: 15px;
    border: 1px solid rgba(0,0,0,0.05);
}

.control-group {
    display: flex;
    align-items: center;
    gap: 10px;
    background: white;
    padding: 15px 20px;
    border-radius: 10px;
    box-shadow: 0 4px 12px rgba(0,0,0,0.05);
    transition: all 0.3s ease;
}

.control-group:hover {
    transform: translateY(-2px);
    box-shadow: 0 6px 20px rgba(0,0,0,0.1);
}

.control-group label {
    font-weight: 600;
    color: #2d3748;
    font-size: 0.95rem;
}

input[type="number"], input[type="range"] {
    padding: 10px 15px;
    border: 2px solid #e2e8f0;
    border-radius: 8px;
    font-size: 14px;
    transition: all 0.3s ease;
    background: white;
}

input[type="number"]:focus, input[type="range"]:focus {
    outline: none;
    border-color: #667eea;
    box-shadow: 0 0 0 3px rgba(102, 126, 234, 0.1);
}

.checkbox-label {
    display: flex;
    align-items: center;
    cursor: pointer;
    font-weight: 600;
    color: #2d3748;
    font-size: 0.95rem;
    position: relative;
    padding-left: 35px;
    user-select: none;
}

.checkbox-label input[type="checkbox"] {
    position: absolute;
    opacity: 0;
    cursor: pointer;
    height: 0;
    width: 0;
}

.checkmark {
    position: absolute;
    left: 0;
    top: 50%;
    transform: translateY(-50%);
    height: 20px;
    width: 20px;
    background: white;
    border: 2px solid #e2e8f0;
    border-radius: 4px;
    transition: all 0.3s ease;
}

.checkbox-label:hover .checkmark {
    border-color: #667eea;
    box-shadow: 0 0 0 3px rgba(102, 126, 234, 0.1);
}

.checkbox-label input[type="checkbox"]:checked ~ .checkmark {
    background: linear-gradient(135deg, #667eea, #764ba2);
    border-color: #667eea;
}

.checkmark::after {
    content: "";
    position: absolute;
    display: none;
}

.checkbox-label input[type="checkbox"]:checked ~ .checkmark::after {
    display: block;
    left: 6px;
    top: 2px;
    width: 6px;
    height: 12px;
    border: solid white;
    border-width: 0 2px 2px 0;
    transform: rotate(45deg);
}

input[type="range"] {
    width: 150px;
    height: 6px;
    background: #e2e8f0;
    border-radius: 3px;
    appearance: none;
}

input[type="range"]::-webkit-slider-thumb {
    appearance: none;
    width: 20px;
    height: 20px;
    border-radius: 50%;
    background: linear-gradient(135deg, #667eea, #764ba2);
    cursor: pointer;
    box-shadow: 0 2px 8px rgba(0,0,0,0.2);
}

.btn {
    padding: 12px 30px;
    border: none;
    border-radius: 10px;
    cursor: pointer;
    font-size: 15px;
    font-weight: 600;
    transition: all 0.3s ease;
    text-transform: uppercase;
    letter-spacing: 0.5px;
    position: relative;
    overflow: hidden;
}

.btn-primary {
    background: linear-gradient(135deg, #667eea 0%, #764ba2 100%);
    color: white;
    box-shadow: 0 4px 15px rgba(102, 126, 234, 0.3);
}

.btn-primary:hover {
    transform: translateY(-2px);
    box-shadow: 0 8px 25px rgba(102, 126, 234, 0.4);
}

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

.btn:disabled {
    background: #a0aec0;
    cursor: not-allowed;
    transform: none;
    box-shadow: none;
}

.progress {
    width: 100%;
    height: 8px;
    background: #f1f5f9;
    border-radius: 4px;
    overflow: hidden;
    margin: 20px 0;
    display: none;
    box-shadow: inset 0 2px 4px rgba(0,0,0,0.1);
}

.progress-bar {
    height: 100%;
    background: linear-gradient(90deg, #667eea, #764ba2);
    width: 0%;
    transition: width 0.3s ease;
    border-radius: 4px;
    position: relative;
}

.progress-bar::after {
    content: '';
    position: absolute;
    top: 0;
    left: 0;
    bottom: 0;
    right: 0;
    background: linear-gradient(
        -45deg,
        rgba(255,255,255,.2) 25%,
        transparent 25%,
        transparent 50%,
        rgba(255,255,255,.2) 50%,
        rgba(255,255,255,.2) 75%,
        transparent 75%,
        transparent
    );
    background-size: 50px 50px;
    animation: move 2s linear infinite;
}

@keyframes move {
    0% { background-position: 0 0; }
    100% { background-position: 50px 50px; }
}

.image-preview {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(300px, 1fr));
    gap: 30px;
    margin-top: 30px;
}

.preview-container {
    background: white;
    border-radius: 15px;
    padding: 25px;
    text-align: center;
    box-shadow: 0 10px 30px rgba(0,0,0,0.08);
    border: 1px solid rgba(0,0,0,0.05);
    transition: all 0.3s ease;
}

.preview-container:hover {
    transform: translateY(-5px);
    box-shadow: 0 15px 40px rgba(0,0,0,0.12);
}

.preview-container h3 {
    margin-bottom: 20px;
    color: #2d3748;
    font-weight: 600;
    font-size: 1.2rem;
}

.image-container {
    position: relative;
    display: inline-block;
    border-radius: 10px;
    overflow: hidden;
    box-shadow: 0 8px 25px rgba(0,0,0,0.1);
    margin-bottom: 15px;
}

.preview-container img {
    max-width: 100%;
    max-height: 300px;
    display: block;
    image-rendering: pixelated;
}

.image-info {
    margin-top: 15px;
    padding: 15px;
    background: linear-gradient(135deg, #f7fafc, #edf2f7);
    border-radius: 10px;
    font-size: 14px;
    color: #4a5568;
    font-weight: 500;
}

.download-link {
    display: inline-block;
    margin-top: 20px;
    padding: 12px 25px;
    background: linear-gradient(135deg, #48bb78, #38a169);
    color: white;
    text-decoration: none;
    border-radius: 10px;
    font-weight: 600;
    transition: all 0.3s ease;
    text-transform: uppercase;
    letter-spacing: 0.5px;
    box-shadow: 0 4px 15px rgba(72, 187, 120, 0.3);
}

.download-link:hover {
    transform: translateY(-2px);
    box-shadow: 0 8px 25px rgba(72, 187, 120, 0.4);
    background: linear-gradient(135deg, #38a169, #2f855a);
}

.threshold-display {
    font-weight: bold;
    color: #667eea;
    min-width: 40px;
    text-align: center;
}

@media (max-width: 768px) {
    .header h1 {
        font-size: 2rem;
    }
    
    .controls {
        flex-direction: column;
        align-items: stretch;
    }
    
    .control-group {
        justify-content: space-between;
    }
    
    .image-preview {
        grid-template-columns: 1fr;
    }
    
    .tab-button {
        padding: 15px;
        font-size: 14px;
    }
}

.checkerboard {
    background-image: 
        linear-gradient(45deg, #f0f0f0 25%, transparent 25%), 
        linear-gradient(-45deg, #f0f0f0 25%, transparent 25%), 
        linear-gradient(45deg, transparent 75%, #f0f0f0 75%), 
        linear-gradient(-45deg, transparent 75%, #f0f0f0 75%);
    background-size: 20px 20px;
    background-position: 0 0, 0 10px, 10px -10px, -10px 0px;
}

.preview-note {
    margin-top: 15px;
    padding: 12px 15px;
    background: linear-gradient(135deg, #e6f3ff, #cce7ff);
    border: 1px solid #b3d9ff;
    border-radius: 8px;
    font-size: 13px;
    color: #2c5aa0;
    font-weight: 500;
    text-align: center;
}

.canvas-container {
    position: relative;
    display: inline-block;
    border-radius: 10px;
    overflow: hidden;
    box-shadow: 0 8px 25px rgba(0,0,0,0.1);
    margin-bottom: 15px;
}

.processed-canvas {
    display: block;
    max-width: 100%;
    max-height: 400px;
    border-radius: 10px;
}

.canvas-controls {
    display: flex;
    align-items: center;
    justify-content: center;
    margin: 20px 0;
    padding: 15px;
    background: linear-gradient(135deg, #f7fafc, #edf2f7);
    border-radius: 12px;
    border: 1px solid rgba(0,0,0,0.05);
}

.btn-secondary {
    background: linear-gradient(135deg, #718096, #4a5568);
    color: white;
    padding: 10px 20px;
    border: none;
    border-radius: 8px;
    cursor: pointer;
    font-size: 14px;
    font-weight: 600;
    transition: all 0.3s ease;
    text-transform: uppercase;
    letter-spacing: 0.5px;
    box-shadow: 0 4px 12px rgba(113, 128, 150, 0.3);
}

.btn-secondary:hover {
    transform: translateY(-2px);
    box-shadow: 0 6px 20px rgba(113, 128, 150, 0.4);
    background: linear-gradient(135deg, #4a5568, #2d3748);
}


.zoom-controls {
    display: flex;
    align-items: center;
    gap: 12px;
    background: white;
    padding: 12px 18px;
    border-radius: 10px;
    box-shadow: 0 4px 12px rgba(0,0,0,0.05);
    transition: all 0.3s ease;
}

.zoom-controls:hover {
    transform: translateY(-1px);
    box-shadow: 0 6px 18px rgba(0,0,0,0.1);
}

.zoom-level {
    background: linear-gradient(135deg, #e6f3ff, #cce7ff);
    padding: 8px 12px;
    border-radius: 6px;
    font-weight: 600;
    color: #667eea;
    min-width: 50px;
    text-align: center;
    font-size: 0.85rem;
    border: 1px solid #b3d9ff;
}

.processed-canvas {
    transition: cursor 0.2s ease;
}

@media (max-width: 768px) {
    .canvas-controls {
        flex-direction: column;
        gap: 12px;
    }
    
    .zoom-controls {
        width: 100%;
        justify-content: center;
        flex-wrap: wrap;
    }
    
    .processed-canvas {
        max-height: 300px;
    }
}

@media (max-width: 400px) {
    body {
        padding: 10px;
    }
    
    .header h1 {
        font-size: 1.5rem;
    }
    
    .tab-button {
        padding: 12px 8px;
        font-size: 12px;
        text-align: center;
    }
    
    .tab-content {
        padding: 20px 15px;
    }
    
    .section-title {
        font-size: 1.4rem;
        margin-bottom: 20px;
    }
    
    .upload-area {
        padding: 30px 15px;
        margin-bottom: 20px;
    }
    
    .upload-text {
        font-size: 1rem;
    }
    
    .controls {
        padding: 15px;
        gap: 15px;
    }
    
    .control-group {
        padding: 10px 15px;
        flex-direction: column;
        text-align: center;
        gap: 8px;
    }
    
    .checkbox-label {
        font-size: 0.9rem;
        justify-content: center;
    }
    
    .btn {
        padding: 10px 15px;
        font-size: 12px;
        width: 100%;
        max-width: 200px;
    }
    
    .btn-secondary {
        padding: 8px 12px;
        font-size: 11px;
    }
    
    .canvas-controls {
        padding: 15px;
        gap: 10px;
    }
    
    
    .zoom-controls {
        padding: 10px 12px;
        gap: 8px;
        justify-content: center;
    }
    
    .zoom-controls .btn-secondary {
        flex: 1;
        min-width: 60px;
        padding: 6px 8px;
        font-size: 10px;
    }
    
    .zoom-level {
        padding: 6px 10px;
        font-size: 0.8rem;
        min-width: 45px;
    }
    
    .processed-canvas {
        max-height: 250px;
        width: 100%;
    }
    
    .image-preview {
        gap: 20px;
    }
    
    .preview-container {
        padding: 15px;
    }
    
    .preview-container h3 {
        font-size: 1rem;
        margin-bottom: 15px;
    }
    
    .image-info {
        font-size: 12px;
        padding: 10px;
    }
    
    .download-link {
        padding: 10px 20px;
        font-size: 12px;
    }
    
    .preview-note {
        padding: 10px 12px;
        font-size: 12px;
    }
    
    .threshold-display {
        min-width: 35px;
        font-size: 0.8rem;
    }
}

@media (max-width: 320px) {
    .header h1 {
        font-size: 1.3rem;
    }
    
    .tab-button {
        padding: 10px 4px;
        font-size: 10px;
        letter-spacing: 0;
    }
    
    .upload-area {
        padding: 20px 10px;
    }
    
    .upload-icon {
        font-size: 2rem;
        margin-bottom: 10px;
    }
    
    .upload-text {
        font-size: 0.9rem;
    }
    
    .controls {
        padding: 10px;
    }
    
    .btn {
        font-size: 11px;
        padding: 8px 12px;
    }
    
    .checkbox-label {
        font-size: 0.8rem;
    }
    
    .zoom-controls .btn-secondary {
        font-size: 9px;
        padding: 5px 6px;
        min-width: 50px;
    }
    
    .zoom-level {
        font-size: 0.75rem;
        padding: 5px 8px;
        min-width: 40px;
    }
    
    
    .processed-canvas {
        max-height: 200px;
    }
    
    .image-container {
        margin-bottom: 10px;
    }
    
    .preview-container img {
        max-height: 200px;
    }
}