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

:root {
    --primary-color: #2ecc71;
    --secondary-color: #3498db;
    --danger-color: #e74c3c;
    --dark-color: #2c3e50;
    --light-color: #ecf0f1;
    --border-color: #bdc3c7;
    --shadow: 0 2px 8px rgba(0, 0, 0, 0.1);
    --shadow-lg: 0 4px 16px rgba(0, 0, 0, 0.15);
}

body {
    font-family: -apple-system, BlinkMacSystemFont, 'Segoe UI', Roboto, 'Helvetica Neue', Arial, sans-serif;
    background: linear-gradient(135deg, #667eea 0%, #764ba2 100%);
    min-height: 100vh;
    padding: 20px;
    color: var(--dark-color);
}

.container {
    max-width: 1200px;
    margin: 0 auto;
    background: white;
    border-radius: 16px;
    box-shadow: var(--shadow-lg);
    overflow: hidden;
}

header {
    background: linear-gradient(135deg, var(--primary-color), #27ae60);
    color: white;
    padding: 20px 30px;
    text-align: center;
}

header h1 {
    font-size: 1.8em;
    margin-bottom: 5px;
}

header p {
    font-size: 0.95em;
    opacity: 0.95;
}

main {
    padding: 25px;
}

.step {
    display: none;
}

.step.active {
    display: block;
    animation: fadeIn 0.3s ease-in;
}

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

.step-header {
    display: flex;
    align-items: center;
    margin-bottom: 20px;
    padding-bottom: 15px;
    border-bottom: 2px solid var(--light-color);
}

.step-number {
    background: var(--primary-color);
    color: white;
    width: 35px;
    height: 35px;
    border-radius: 50%;
    display: flex;
    align-items: center;
    justify-content: center;
    font-size: 1.2em;
    font-weight: bold;
    margin-right: 15px;
}

.step-header h2 {
    font-size: 1.5em;
    color: var(--dark-color);
}

/* Upload Section */
.upload-area {
    border: 3px dashed var(--border-color);
    border-radius: 12px;
    padding: 40px 30px;
    text-align: center;
    cursor: pointer;
    transition: all 0.3s ease;
    background: var(--light-color);
}

.upload-area:hover {
    border-color: var(--primary-color);
    background: #d5f4e6;
}

.upload-area svg {
    color: var(--primary-color);
    margin-bottom: 20px;
}

.upload-area p {
    font-size: 1.2em;
    color: #7f8c8d;
}

.upload-area.dragging {
    border-color: var(--primary-color);
    background: #d5f4e6;
}

/* Selection Section */
.controls {
    display: flex;
    align-items: center;
    gap: 15px;
    margin-bottom: 20px;
    padding: 15px 20px;
    background: var(--light-color);
    border-radius: 12px;
}

.controls label {
    font-weight: 600;
    color: var(--dark-color);
    white-space: nowrap;
}

.button-group {
    display: flex;
    gap: 10px;
}

.info-box {
    background: #e8f4fd;
    border: 1px solid #b3d9f2;
    border-left: 4px solid #2196f3;
    padding: 12px 16px;
    border-radius: 8px;
    margin-bottom: 15px;
}

.info-box p {
    margin: 0;
    font-size: 0.9em;
    color: #1565c0;
    line-height: 1.5;
}

.info-box strong {
    color: #0d47a1;
    font-weight: 700;
}

.btn {
    padding: 12px 24px;
    border: 2px solid var(--border-color);
    background: white;
    border-radius: 8px;
    cursor: pointer;
    font-size: 1em;
    font-weight: 600;
    transition: all 0.2s ease;
    display: inline-flex;
    align-items: center;
    gap: 8px;
}

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

.btn-active {
    background: var(--primary-color);
    color: white;
    border-color: var(--primary-color);
}

.btn-primary {
    background: var(--primary-color);
    color: white;
    border-color: var(--primary-color);
}

.btn-primary:hover {
    background: #27ae60;
    border-color: #27ae60;
}

.btn-primary:disabled {
    background: var(--border-color);
    border-color: var(--border-color);
    cursor: not-allowed;
    opacity: 0.6;
}

.btn-secondary {
    background: white;
    color: var(--dark-color);
}

.btn-secondary:hover {
    background: var(--light-color);
}

select {
    width: 100%;
    padding: 12px;
    border: 2px solid var(--border-color);
    border-radius: 8px;
    font-size: 1em;
    cursor: pointer;
    background: white;
}

select:focus {
    outline: none;
    border-color: var(--primary-color);
}

.image-container {
    display: flex;
    gap: 15px;
    margin-bottom: 20px;
    align-items: flex-start;
}

#canvas {
    max-width: 68%;
    border: 2px solid var(--border-color);
    border-radius: 8px;
    cursor: crosshair;
    box-shadow: var(--shadow);
    display: block;
}

.point-preview {
    flex: 1;
    background: var(--light-color);
    padding: 15px;
    border-radius: 12px;
    text-align: center;
}

.color-display {
    width: 200px;
    height: 200px;
    border: 2px solid var(--border-color);
    border-radius: 8px;
    margin: 0 auto 10px;
    box-shadow: var(--shadow);
    display: block;
    image-rendering: pixelated;
    image-rendering: -moz-crisp-edges;
    image-rendering: crisp-edges;
}

.point-preview p {
    color: #7f8c8d;
    font-size: 0.85em;
    margin-bottom: 10px;
}

.preview-controls {
    width: 100%;
    background: white;
    padding: 10px;
    border-radius: 8px;
    border: 1px solid var(--border-color);
}

.preview-control-row {
    display: flex;
    align-items: center;
    gap: 8px;
    margin-bottom: 6px;
}

.preview-control-row:last-child {
    margin-bottom: 0;
}

.preview-control-row label {
    min-width: 40px;
    font-size: 0.8em;
    font-weight: 600;
    color: var(--dark-color);
}

.preview-control-row input[type="range"] {
    flex: 1;
    height: 6px;
    border-radius: 3px;
    outline: none;
    -webkit-appearance: none;
    background: var(--border-color);
}

.preview-control-row input[type="range"]::-webkit-slider-thumb {
    -webkit-appearance: none;
    width: 16px;
    height: 16px;
    border-radius: 50%;
    background: var(--primary-color);
    cursor: pointer;
}

.preview-control-row input[type="range"]::-moz-range-thumb {
    width: 16px;
    height: 16px;
    border-radius: 50%;
    background: var(--primary-color);
    cursor: pointer;
    border: none;
}

.preview-control-row span {
    min-width: 35px;
    text-align: right;
    font-weight: 600;
    font-size: 0.75em;
    color: var(--primary-color);
}

.selected-colors {
    display: grid;
    grid-template-columns: 1fr 1fr;
    gap: 15px;
    margin-bottom: 20px;
}

.color-section {
    background: var(--light-color);
    padding: 15px;
    border-radius: 12px;
}

.color-section h4 {
    margin-bottom: 12px;
    color: var(--dark-color);
    font-size: 1em;
}

.color-list {
    display: flex;
    flex-wrap: wrap;
    gap: 8px;
    min-height: 50px;
}

.color-item {
    position: relative;
    width: 40px;
    height: 40px;
    border: 2px solid var(--border-color);
    border-radius: 6px;
    cursor: pointer;
    transition: transform 0.2s;
}

.color-item:hover {
    transform: scale(1.1);
}

.color-item .remove {
    position: absolute;
    top: -8px;
    right: -8px;
    width: 20px;
    height: 20px;
    background: var(--danger-color);
    color: white;
    border-radius: 50%;
    display: flex;
    align-items: center;
    justify-content: center;
    font-size: 12px;
    cursor: pointer;
    opacity: 0;
    transition: opacity 0.2s;
}

.color-item:hover .remove {
    opacity: 1;
}

.action-buttons {
    display: flex;
    gap: 15px;
    justify-content: center;
    padding-top: 15px;
    border-top: 2px solid var(--light-color);
}

/* Results Section */
.results-container {
    display: flex;
    flex-direction: column;
    gap: 20px;
}

.result-header {
    display: flex;
    justify-content: space-between;
    align-items: flex-start;
    gap: 20px;
    padding: 20px 25px;
    background: linear-gradient(135deg, var(--primary-color), #27ae60);
    border-radius: 12px;
    color: white;
}

.result-info {
    display: flex;
    justify-content: center;
    align-items: center;
    flex: 1;
}

.result-percentage-box {
    display: flex;
    flex-direction: column;
    align-items: center;
    gap: 10px;
    text-align: center;
}

.result-percentage-box h3 {
    font-size: 1.4em;
    margin: 0;
    font-weight: 600;
    letter-spacing: 0.5px;
}

.percentage {
    font-size: 4em;
    font-weight: bold;
    text-shadow: 2px 2px 4px rgba(0, 0, 0, 0.2);
    line-height: 1;
}

.transparency-control {
    display: flex;
    align-items: center;
    gap: 12px;
    background: rgba(255, 255, 255, 0.15);
    padding: 10px 15px;
    border-radius: 8px;
}

.transparency-control label {
    font-size: 0.9em;
    white-space: nowrap;
    font-weight: 600;
}

.result-images {
    display: grid;
    grid-template-columns: 1fr 1fr;
    gap: 20px;
}

.result-image-box {
    background: var(--light-color);
    padding: 15px;
    border-radius: 12px;
}

.result-image-box h4 {
    margin-bottom: 12px;
    color: var(--dark-color);
    font-size: 1em;
}

.result-image-box img,
.result-image-box canvas {
    width: 100%;
    min-height: 400px;
    border-radius: 8px;
    border: 2px solid var(--border-color);
    object-fit: contain;
    background: white;
}

.layer-control {
    display: flex;
    flex-direction: row;
    gap: 8px;
    margin-top: 10px;
    padding: 10px;
    background: white;
    border-radius: 6px;
    border: 1px solid var(--border-color);
}

.layer-toggle {
    display: flex;
    align-items: center;
    gap: 8px;
    font-size: 0.85em;
    font-weight: 600;
    color: var(--dark-color);
    cursor: pointer;
    padding: 4px 6px;
    border-radius: 4px;
    transition: background 0.2s;
}

.layer-toggle:hover {
    background: rgba(0, 0, 0, 0.05);
}

.layer-toggle input[type="checkbox"] {
    width: 18px;
    height: 18px;
    cursor: pointer;
    accent-color: var(--primary-color);
}

.layer-toggle span {
    font-size: 1.2em;
    line-height: 1;
    color: var(--primary-color);
}

.transparency-control input[type="range"] {
    flex: 1;
    min-width: 120px;
    height: 6px;
    border-radius: 3px;
    outline: none;
    -webkit-appearance: none;
    background: rgba(255, 255, 255, 0.3);
}

.transparency-control input[type="range"]::-webkit-slider-thumb {
    -webkit-appearance: none;
    width: 16px;
    height: 16px;
    border-radius: 50%;
    background: white;
    cursor: pointer;
}

.transparency-control input[type="range"]::-moz-range-thumb {
    width: 16px;
    height: 16px;
    border-radius: 50%;
    background: white;
    cursor: pointer;
    border: none;
}

.transparency-control span {
    min-width: 35px;
    text-align: right;
    font-weight: 600;
    font-size: 0.9em;
}

.legend-box {
    background: var(--light-color);
    padding: 15px;
    border-radius: 12px;
}

.legend-box h4 {
    margin-bottom: 12px;
    color: var(--dark-color);
    font-size: 1em;
}

.legend-items {
    display: flex;
    flex-direction: column;
    gap: 10px;
}

.legend-item {
    display: flex;
    align-items: center;
    gap: 12px;
}

.legend-color {
    width: 40px;
    height: 30px;
    border: 2px solid var(--border-color);
    border-radius: 6px;
    flex-shrink: 0;
}

.legend-item span {
    font-size: 0.9em;
    color: var(--dark-color);
    line-height: 1.4;
}

.legend-item strong {
    color: var(--primary-color);
}

/* Responsive */
@media (max-width: 768px) {
    header h1 {
        font-size: 1.8em;
    }

    .image-container {
        flex-direction: column;
    }

    #canvas {
        max-width: 100%;
    }

    .selected-colors {
        grid-template-columns: 1fr;
    }

    .result-images {
        grid-template-columns: 1fr;
    }

    .result-header {
        flex-direction: column;
        align-items: flex-start;
    }

    .result-info {
        width: 100%;
    }

    .result-percentage-box {
        width: 100%;
        justify-content: center;
    }

    .transparency-control {
        width: 100%;
    }

    .controls {
        flex-direction: column;
    }

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

    .btn {
        width: 100%;
    }
}