:root {
    --primary-color: #6c5ce7;
    --primary-hover: #5b4cc4;
    --bg-color: #f5f6fa;
    --card-bg: #ffffff;
    --text-color: #2d3436;
    --border-color: #dfe6e9;
    --error-color: #ff7675;
}

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

body {
    font-family: -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, Helvetica, Arial, sans-serif;
    background-color: var(--bg-color);
    color: var(--text-color);
    line-height: 1.6;
}

.container {
    max-width: 800px;
    margin: 0 auto;
    padding: 20px;
    min-height: 100vh;
    display: flex;
    flex-direction: column;
}

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

header h1 {
    font-size: 2rem;
    color: var(--primary-color);
    margin-bottom: 0.5rem;
}

header p {
    color: #636e72;
}

main {
    flex: 1;
    background: var(--card-bg);
    border-radius: 12px;
    padding: 24px;
    box-shadow: 0 4px 6px rgba(0, 0, 0, 0.05);
}

/* Upload Section */
.upload-section {
    border: 2px dashed var(--border-color);
    border-radius: 8px;
    padding: 40px 20px;
    text-align: center;
    cursor: pointer;
    transition: all 0.3s ease;
}

.upload-section:hover, .upload-section.drag-over {
    border-color: var(--primary-color);
    background-color: rgba(108, 92, 231, 0.05);
}

.upload-icon {
    color: #b2bec3;
    margin-bottom: 10px;
}

.file-hint {
    display: block;
    font-size: 0.85rem;
    color: #b2bec3;
    margin-top: 5px;
}

.tools-bar {
    display: flex;
    gap: 10px;
    margin-bottom: 20px;
    align-items: center;
}

.tool-btn {
    display: flex;
    align-items: center;
    gap: 6px;
    padding: 8px 12px;
    border: 1px solid var(--border-color);
    background: white;
    border-radius: 6px;
    cursor: pointer;
    font-size: 0.9rem;
    transition: all 0.2s;
}

.tool-btn:hover {
    background: #f1f2f6;
}

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

.tool-hint {
    font-size: 0.85rem;
    color: var(--primary-color);
    animation: fadeIn 0.3s ease;
}

@keyframes fadeIn {
    from { opacity: 0; transform: translateY(5px); }
    to { opacity: 1; transform: translateY(0); }
}
.controls-section {
    margin-top: 24px;
    padding-top: 24px;
    border-top: 1px solid var(--border-color);
}

.view-controls {
    display: flex;
    justify-content: space-between;
    align-items: center;
    margin-bottom: 20px;
    padding-bottom: 15px;
    border-bottom: 1px dashed var(--border-color);
}

.toggle-switch {
    display: flex;
    align-items: center;
    cursor: pointer;
    gap: 10px;
}

.toggle-switch input {
    display: none;
}

.toggle-switch .slider {
    position: relative;
    width: 40px;
    height: 20px;
    background-color: #ccc;
    border-radius: 20px;
    transition: .4s;
}

.toggle-switch .slider:before {
    position: absolute;
    content: "";
    height: 16px;
    width: 16px;
    left: 2px;
    bottom: 2px;
    background-color: white;
    transition: .4s;
    border-radius: 50%;
}

.toggle-switch input:checked + .slider {
    background-color: var(--primary-color);
}

.toggle-switch input:checked + .slider:before {
    transform: translateX(20px);
}

.toggle-switch .label-text {
    font-weight: 600;
    color: var(--text-color);
}

.hint-text {
    color: #636e72;
    background: #dfe6e9;
    padding: 4px 8px;
    border-radius: 4px;
}

.control-group {
    margin-bottom: 20px;
}

.control-group label {
    display: block;
    margin-bottom: 8px;
    font-weight: 600;
}

input[type="range"] {
    width: 100%;
    height: 6px;
    background: #dfe6e9;
    border-radius: 5px;
    outline: none;
    -webkit-appearance: none;
}

input[type="range"]::-webkit-slider-thumb {
    -webkit-appearance: none;
    width: 20px;
    height: 20px;
    background: var(--primary-color);
    border-radius: 50%;
    cursor: pointer;
    transition: background .15s ease-in-out;
}

select {
    width: 100%;
    padding: 10px;
    font-size: 14px;
    border: 2px solid var(--border-color);
    border-radius: 8px;
    background-color: #fff;
    cursor: pointer;
    transition: border-color 0.2s;
}

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

.guide-text {
    font-size: 0.9rem;
    color: #636e72;
}

/* Preview */
.preview-section {
    margin-top: 24px;
    text-align: center;
}

.canvas-container {
    position: relative; /* 确保 tooltip 可以绝对定位 */
    overflow: hidden; /* 防止 tooltip 溢出 */
    max-width: 100%;
    border: 1px solid var(--border-color);
    border-radius: 4px;
    background-image: 
        linear-gradient(45deg, #eee 25%, transparent 25%), 
        linear-gradient(-45deg, #eee 25%, transparent 25%), 
        linear-gradient(45deg, transparent 75%, #eee 75%), 
        linear-gradient(-45deg, transparent 75%, #eee 75%);
    background-size: 20px 20px;
    background-position: 0 0, 0 10px, 10px -10px, -10px 0px;
}

.bead-tooltip {
    position: absolute;
    background: rgba(0, 0, 0, 0.8);
    color: white;
    padding: 8px 12px;
    border-radius: 4px;
    font-size: 0.85rem;
    pointer-events: none;
    z-index: 10;
    white-space: nowrap;
    box-shadow: 0 2px 4px rgba(0,0,0,0.2);
    transform: translate(-50%, -100%); /* 居中并在上方显示 */
    margin-top: -10px;
}

.bead-tooltip::after {
    content: '';
    position: absolute;
    top: 100%;
    left: 50%;
    margin-left: -5px;
    border-width: 5px;
    border-style: solid;
    border-color: rgba(0, 0, 0, 0.8) transparent transparent transparent;
}

canvas {
    max-width: 100%;
    height: auto;
    display: block;
    margin: 0 auto;
}

/* Actions */
.action-section {
    margin-top: 30px;
    text-align: center;
}

.button-group {
    display: flex;
    gap: 12px;
    justify-content: center;
    flex-wrap: wrap;
}

.btn {
    padding: 12px 24px;
    border: none;
    border-radius: 6px;
    font-size: 1rem;
    font-weight: 600;
    cursor: pointer;
    transition: background 0.3s ease;
}

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

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

.btn.secondary {
    background-color: #dfe6e9;
    color: var(--text-color);
}

.btn.secondary:hover {
    background-color: #b2bec3;
}

.pdf-options {
    margin-top: 15px;
    font-size: 0.9rem;
}

.pdf-options label {
    margin: 0 10px;
    cursor: pointer;
}

.error-message {
    margin-top: 15px;
    padding: 10px;
    background-color: #ffeaa7;
    border-left: 4px solid var(--error-color);
    color: #d63031;
    border-radius: 4px;
}

footer {
    text-align: center;
    margin-top: 40px;
    color: #b2bec3;
    font-size: 0.8rem;
}

/* Mobile Responsiveness */
@media (max-width: 600px) {
    .container {
        padding: 10px;
    }
    
    header h1 {
        font-size: 1.5rem;
    }

    .button-group {
        flex-direction: column;
    }

    .btn {
        width: 100%;
    }
}