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

:root {
    --primary-color: #3f51b5;
    --secondary-color: #f50057;
    --background-color: #f5f5f5;
    --sidebar-width: 280px;
    --code-panel-width: 350px;
    --header-height: 60px;
    --status-height: 30px;
}

body {
    font-family: 'Segoe UI', Tahoma, Geneva, Verdana, sans-serif;
    background: var(--background-color);
    overflow: hidden;
    height: 100vh;
}

.app-container {
    display: flex;
    flex-direction: column;
    height: 100vh;
}

/* 头部样式 */
.app-header {
    background: linear-gradient(135deg, var(--primary-color), #5c6bc0);
    color: white;
    padding: 0 20px;
    height: var(--header-height);
    display: flex;
    justify-content: space-between;
    align-items: center;
    box-shadow: 0 2px 10px rgba(0,0,0,0.2);
    z-index: 100;
}

.app-header h1 {
    font-size: 1.5rem;
    font-weight: 500;
    display: flex;
    align-items: center;
    gap: 10px;
}

.header-actions {
    display: flex;
    gap: 10px;
}

.header-actions button {
    background: rgba(255,255,255,0.1);
    border: 1px solid rgba(255,255,255,0.3);
    color: white;
    padding: 8px 16px;
    border-radius: 4px;
    cursor: pointer;
    display: flex;
    align-items: center;
    gap: 5px;
    transition: all 0.2s;
}

.header-actions button:hover {
    background: rgba(255,255,255,0.2);
    transform: translateY(-1px);
}

/* 主要内容区域 */
.main-content {
    display: flex;
    flex: 1;
    overflow: hidden;
}

/* 侧边栏样式 */
.sidebar {
    width: var(--sidebar-width);
    background: white;
    border-right: 1px solid #ddd;
    padding: 20px;
    overflow-y: auto;
    display: flex;
    flex-direction: column;
    gap: 20px;
}

.tool-category h3 {
    color: var(--primary-color);
    margin-bottom: 10px;
    font-size: 0.9rem;
    display: flex;
    align-items: center;
    gap: 8px;
}

.tool-buttons {
    display: grid;
    grid-template-columns: repeat(3, 1fr);
    gap: 8px;
    margin-bottom: 20px;
}

.tool-btn {
    padding: 10px;
    border: 1px solid #ddd;
    background: white;
    border-radius: 4px;
    cursor: pointer;
    display: flex;
    flex-direction: column;
    align-items: center;
    gap: 5px;
    transition: all 0.2s;
    font-size: 0.8rem;
}

.tool-btn:hover {
    border-color: var(--primary-color);
    background: #f0f4ff;
}

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

.property-panel {
    display: flex;
    flex-direction: column;
    gap: 12px;
}

.property-group {
    display: flex;
    flex-direction: column;
    gap: 5px;
}

.property-group label {
    font-size: 0.8rem;
    color: #666;
}

.property-group select,
.property-group input[type="range"],
.property-group input[type="color"] {
    padding: 5px;
    border: 1px solid #ddd;
    border-radius: 4px;
    width: 100%;
}

/* 画布区域 */
.canvas-area {
    flex: 1;
    display: flex;
    flex-direction: column;
    padding: 20px;
    background: #f8f9fa;
    position: relative;
}

.canvas-container {
    flex: 1;
    border: 1px solid #ddd;
    background: white;
    position: relative;
    overflow: hidden;
    border-radius: 8px;
    box-shadow: 0 2px 10px rgba(0,0,0,0.1);
}

#feynmanCanvas {
    width: 100%;
    height: 100%;
    cursor: crosshair;
}

.canvas-grid {
    position: absolute;
    top: 0;
    left: 0;
    right: 0;
    bottom: 0;
    background-image: 
        linear-gradient(#e0e0e0 1px, transparent 1px),
        linear-gradient(90deg, #e0e0e0 1px, transparent 1px);
    background-size: 20px 20px;
    pointer-events: none;
    opacity: 0.3;
}

.canvas-controls {
    position: absolute;
    bottom: 30px;
    right: 30px;
    display: flex;
    flex-direction: column;
    gap: 8px;
    background: white;
    padding: 10px;
    border-radius: 8px;
    box-shadow: 0 2px 10px rgba(0,0,0,0.1);
}

.canvas-controls button {
    width: 40px;
    height: 40px;
    border: 1px solid #ddd;
    background: white;
    border-radius: 4px;
    cursor: pointer;
    display: flex;
    align-items: center;
    justify-content: center;
    transition: all 0.2s;
}

.canvas-controls button:hover {
    background: #f5f5f5;
    border-color: var(--primary-color);
}

.canvas-controls button.active {
    background: var(--primary-color);
    color: white;
    border-color: var(--primary-color);
}

/* 代码面板 */
.code-panel {
    width: var(--code-panel-width);
    background: white;
    border-left: 1px solid #ddd;
    display: flex;
    flex-direction: column;
    overflow: hidden;
}

.panel-header {
    padding: 15px 20px;
    border-bottom: 1px solid #ddd;
    display: flex;
    justify-content: space-between;
    align-items: center;
    background: #f8f9fa;
}

.panel-header h3 {
    color: var(--primary-color);
    font-size: 1rem;
    display: flex;
    align-items: center;
    gap: 8px;
}

.panel-actions {
    display: flex;
    gap: 8px;
}

.panel-actions button {
    background: white;
    border: 1px solid #ddd;
    width: 32px;
    height: 32px;
    border-radius: 4px;
    cursor: pointer;
    display: flex;
    align-items: center;
    justify-content: center;
}

.code-container {
    flex: 1;
    padding: 20px;
    overflow-y: auto;
    background: #1e1e1e;
    color: #d4d4d4;
    font-family: 'Consolas', 'Monaco', monospace;
    font-size: 0.9rem;
    line-height: 1.4;
}

#tikzCode {
    margin: 0;
    white-space: pre-wrap;
    word-wrap: break-word;
}

.code-actions {
    padding: 15px 20px;
    border-top: 1px solid #ddd;
    display: flex;
    gap: 10px;
}

.btn-primary, .btn-secondary {
    flex: 1;
    padding: 10px;
    border: none;
    border-radius: 4px;
    cursor: pointer;
    font-size: 0.9rem;
    display: flex;
    align-items: center;
    justify-content: center;
    gap: 8px;
    transition: all 0.2s;
}

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

.btn-secondary {
    background: #6c757d;
    color: white;
}

.btn-primary:hover {
    background: #303f9f;
}

.btn-secondary:hover {
    background: #5a6268;
}

.history-panel {
    border-top: 1px solid #ddd;
    padding: 15px 20px;
    max-height: 200px;
    overflow-y: auto;
}

.history-panel h3 {
    color: var(--primary-color);
    font-size: 0.9rem;
    margin-bottom: 10px;
    display: flex;
    align-items: center;
    gap: 8px;
}

.history-list {
    display: flex;
    flex-direction: column;
    gap: 5px;
}

.history-item {
    padding: 8px 10px;
    background: #f8f9fa;
    border: 1px solid #ddd;
    border-radius: 4px;
    font-size: 0.8rem;
    cursor: pointer;
    transition: all 0.2s;
}

.history-item:hover {
    background: #e9ecef;
    border-color: var(--primary-color);
}

/* 状态栏 */
.status-bar {
    height: var(--status-height);
    background: white;
    border-top: 1px solid #ddd;
    padding: 0 20px;
    display: flex;
    justify-content: space-between;
    align-items: center;
    font-size: 0.8rem;
    color: #666;
}

.status-info {
    display: flex;
    gap: 20px;
}

.offline-status {
    display: flex;
    align-items: center;
    gap: 5px;
}

.offline-status.offline {
    color: #dc3545;
}

.offline-status.online {
    color: #28a745;
}

/* 模态框 */
.modal {
    display: none;
    position: fixed;
    top: 0;
    left: 0;
    width: 100%;
    height: 100%;
    background: rgba(0,0,0,0.5);
    z-index: 1000;
    align-items: center;
    justify-content: center;
}

.modal.active {
    display: flex;
}

.modal-content {
    background: white;
    width: 600px;
    max-width: 90%;
    border-radius: 8px;
    overflow: hidden;
    box-shadow: 0 4px 20px rgba(0,0,0,0.2);
}

.modal-header {
    padding: 20px;
    background: var(--primary-color);
    color: white;
    display: flex;
    justify-content: space-between;
    align-items: center;
}

.modal-header .close-btn {
    background: none;
    border: none;
    color: white;
    font-size: 1.5rem;
    cursor: pointer;
    line-height: 1;
}

.modal-body {
    padding: 20px;
}

#exportedCode {
    width: 100%;
    height: 300px;
    padding: 10px;
    border: 1px solid #ddd;
    border-radius: 4px;
    font-family: 'Consolas', monospace;
    font-size: 0.9rem;
    resize: vertical;
    margin-bottom: 20px;
}

.modal-actions {
    display: flex;
    gap: 10px;
    justify-content: flex-end;
}

/* 响应式设计 */
@media (max-width: 1200px) {
    .sidebar {
        width: 240px;
    }
    .code-panel {
        width: 300px;
    }
}

@media (max-width: 768px) {
    .main-content {
        flex-direction: column;
    }
    .sidebar, .code-panel {
        width: 100%;
        max-height: 200px;
    }
    .canvas-controls {
        bottom: 10px;
        right: 10px;
    }
}

/* 工具提示 */
[title] {
    position: relative;
}

[title]:hover::after {
    content: attr(title);
    position: absolute;
    bottom: 100%;
    left: 50%;
    transform: translateX(-50%);
    background: #333;
    color: white;
    padding: 5px 10px;
    border-radius: 4px;
    font-size: 0.8rem;
    white-space: nowrap;
    z-index: 1000;
    margin-bottom: 5px;
}

/* 滚动条样式 */
::-webkit-scrollbar {
    width: 8px;
    height: 8px;
}

::-webkit-scrollbar-track {
    background: #f1f1f1;
    border-radius: 4px;
}

::-webkit-scrollbar-thumb {
    background: #c1c1c1;
    border-radius: 4px;
}

::-webkit-scrollbar-thumb:hover {
    background: #a8a8a8;
}

/* --- KaTeX DOM label overlay layer --- */
.canvas-container { position: relative; }

.label-layer{
  position:absolute;
  left:0; top:0; right:0; bottom:0;
  pointer-events:none; /* 默认不拦截鼠标，避免影响画线/选择 */
  z-index: 20;         /* 高于 canvas */
}

/* 单个标签：可拖拽、可双击 */
.latex-label{
  position:absolute;
  pointer-events:auto;
  cursor: move;
  user-select: none;
  transform: translate(-50%, -50%); /* 以中心点定位 */
  color: #000;
  background: transparent;
  padding: 2px 4px;
  border-radius: 4px;
}

.latex-label.dragging{
  outline: 1px dashed rgba(63,81,181,0.8);
  background: rgba(63,81,181,0.06);
}

/* KaTeX 默认大小可稍微调一下 */
.latex-label .katex { font-size: 1.1em; }

.latex-label.selected{
  outline: 2px solid rgba(63,81,181,0.8);
  background: rgba(63,81,181,0.06);
}

/* hand 工具时禁用标签交互，避免标签挡住拖动画布 */
.label-layer.labels-disabled .latex-label{
  pointer-events: none !important;
}