*, *::before, *::after { box-sizing: border-box; }

body {
    font-family: "Microsoft YaHei", "微软雅黑", "Segoe UI", Arial, sans-serif;
    margin: 0;
    padding: 20px;
    background: linear-gradient(135deg, #f5f7fa 0%, #c3cfe2 100%);
    min-height: 100vh;
    color: #333;
}

.container {
    max-width: 1200px;
    margin: 0 auto;
    background: #ffffff;
    border-radius: 16px;
    box-shadow: 0 12px 32px rgba(0, 0, 0, 0.06);
    padding: 30px;
    min-height: 600px;
}

header {
    text-align: center;
    margin-bottom: 30px;
    padding-bottom: 20px;
    border-bottom: 2px solid #f0f0f0;
}

h1 {
    color: #667eea;
    font-size: 2em;
}

.controls {
    margin-bottom: 20px;
}

.control-row {
    display: flex;
    gap: 15px;
    align-items: center;
    margin-bottom: 15px;
    flex-wrap: wrap;
}

.file-button {
    display: inline-block;
    padding: 10px 20px;
    background: #667eea;
    color: white;
    border-radius: 8px;
    cursor: pointer;
    font-weight: 500;
    transition: all 0.3s;
    border: none;
    font-size: 14px;
}

.file-button:hover {
    background: #5568d3;
    transform: translateY(-2px);
    box-shadow: 0 4px 12px rgba(102, 126, 234, 0.4);
}

button {
    padding: 10px 20px;
    background: #667eea;
    color: white;
    border: none;
    border-radius: 8px;
    cursor: pointer;
    font-weight: 500;
    font-size: 14px;
    transition: all 0.3s;
}

button:hover:not(:disabled) {
    background: #5568d3;
    transform: translateY(-2px);
    box-shadow: 0 4px 12px rgba(102, 126, 234, 0.4);
}

button:disabled {
    background: #ccc;
    cursor: not-allowed;
    transform: none;
}

input[type="range"] {
    flex: 1;
    max-width: 300px;
    height: 6px;
    -webkit-appearance: none;
    appearance: none;
    background: #ddd;
    border-radius: 3px;
    outline: none;
}

input[type="range"]::-webkit-slider-thumb {
    -webkit-appearance: none;
    appearance: none;
    width: 18px;
    height: 18px;
    background: #667eea;
    border-radius: 50%;
    cursor: pointer;
    transition: all 0.2s;
}

input[type="range"]::-webkit-slider-thumb:hover {
    background: #5568d3;
    transform: scale(1.2);
}

input[type="range"]::-moz-range-thumb {
    width: 18px;
    height: 18px;
    background: #667eea;
    border-radius: 50%;
    cursor: pointer;
    border: none;
    transition: all 0.2s;
}

input[type="range"]::-moz-range-thumb:hover {
    background: #5568d3;
    transform: scale(1.2);
}

#thresholdValue {
    min-width: 40px;
    font-weight: 600;
    color: #667eea;
}

#selectedCount {
    color: #666;
    font-weight: 500;
    margin-right: auto;
}

.status-message {
    padding: 12px 20px;
    background: #d4edda;
    color: #155724;
    border-radius: 8px;
    margin-bottom: 20px;
    border-left: 4px solid #28a745;
    display: none;
    animation: slideIn 0.3s ease-out;
}

.status-message.show {
    display: block;
}

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

.splits-panel {
    margin-bottom: 20px;
    border: 1px solid #e0e0e0;
    border-radius: 8px;
    padding: 15px;
    background: #f9f9f9;
}

details {
    cursor: pointer;
}

summary {
    font-weight: 600;
    font-size: 1.1em;
    color: #667eea;
    padding: 5px 0;
    user-select: none;
}

summary:hover {
    color: #5568d3;
}

.warning {
    padding: 10px;
    background: #fff3cd;
    color: #856404;
    border-radius: 6px;
    margin: 10px 0;
    border-left: 4px solid #ffc107;
}

.warning button {
    margin-top: 8px;
    background: #ffc107;
    color: #333;
}

.warning button:hover {
    background: #e0a800;
}

.splits-list {
    display: grid;
    grid-template-columns: repeat(auto-fill, minmax(150px, 1fr));
    gap: 10px;
    margin-top: 15px;
}

.split-item {
    display: flex;
    align-items: center;
    gap: 8px;
    padding: 8px 12px;
    background: white;
    border-radius: 6px;
    border: 2px solid transparent;
    transition: all 0.2s;
}

.split-item:hover {
    background: #f0f0f0;
    border-color: #667eea;
}

.split-item input[type="checkbox"] {
    width: 18px;
    height: 18px;
    cursor: pointer;
    accent-color: #667eea;
}

.split-item label {
    cursor: pointer;
    user-select: none;
    flex: 1;
}

.image-container {
    margin-top: 20px;
}

.file-path {
    color: #666;
    font-size: 0.9em;
    margin-bottom: 10px;
    word-break: break-all;
    padding: 8px;
    background: #f5f5f5;
    border-radius: 6px;
    font-family: monospace;
    display: none;
}

.file-path.show {
    display: block;
}

.canvas-wrapper {
    width: 100%;
    overflow: hidden;
    border: 2px solid #e0e0e0;
    border-radius: 8px;
    background: #f9f9f9;
    padding: 20px;
    min-height: 400px;
    display: flex;
    justify-content: center;
    align-items: center;
    position: relative;
    transition: border-color 0.2s, background 0.2s;
    max-width: 100%;
    max-height: 80vh;
}

.canvas-wrapper.dragover {
    border-color: #667eea;
    background: linear-gradient(135deg, #eef1ff 0%, #f7f4ff 100%);
}

.drop-hint {
    position: absolute;
    inset: 20px;
    border: 2px dashed #a6b0f5;
    border-radius: 10px;
    display: flex;
    justify-content: center;
    align-items: center;
    color: #667eea;
    font-weight: 600;
    background: rgba(255, 255, 255, 0.85);
    pointer-events: none;
    text-align: center;
    padding: 10px;
}

.drop-hint.hidden {
    display: none;
}

#canvas {
    max-width: 100%;
    max-height: 76vh;
    width: auto;
    height: auto;
    box-shadow: 0 4px 12px rgba(0, 0, 0, 0.1);
}

.placeholder {
    text-align: center;
    color: #999;
    font-size: 1.1em;
    padding: 40px;
}