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

body {
    font-family: 'Times New Roman', Times, serif;
    background: linear-gradient(135deg, #f5f7fa 0%, #c3cfe2 100%);
    min-height: 100vh;
}

/* 导航栏样式 */
.navbar {
    background: linear-gradient(135deg, #667eea 0%, #764ba2 100%);
    color: white;
    padding: 1rem 0;
    box-shadow: 0 2px 10px rgba(0,0,0,0.1);
}

.navbar .container {
    max-width: 1400px;
    margin: 0 auto;
    padding: 0 20px;
}

.navbar h1 {
    font-size: 1.8rem;
    font-weight: 600;
    text-align: center;
}

/* 主内容区 */
.main-content {
    padding: 20px;
}

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

/* 主布局 */
.main-layout {
    display: flex;
    gap: 20px;
}

/* 左侧面板 */
.left-panel {
    flex: 2;
    display: flex;
    flex-direction: column;
    gap: 15px;
    min-width: 0;
}

/* 右侧面板 */
.right-panel {
    flex: 1;
    display: flex;
    flex-direction: column;
    gap: 20px;
    min-width: 0;
    overflow: hidden;
}

/* 右侧上方：受力分析 + F-h 上下排列 */
.right-top {
    display: flex;
    flex-direction: column;
    gap: 16px;
}

.right-top > div {
    flex: 1;
    min-width: 0;
}

/* Canvas 包装器（主画布） */
.canvas-wrapper {
    background: white;
    border-radius: 12px;
    padding: 20px;
    box-shadow: 0 4px 20px rgba(0,0,0,0.1);
    position: relative;
}

#mainCanvas {
    display: block;
    margin: 0 auto;
    border: 2px solid #e0e0e0;
    border-radius: 8px;
    background: #fafafa;
    max-width: 100%;
    height: auto;
}

/* 迷你 Canvas 包装器（受力分析 + F-h 图） */
.mini-canvas-wrapper {
    padding: 0 14px 14px 14px;
}

.mini-canvas-wrapper canvas {
    display: block;
    margin: 0 auto;
    border: 2px solid #e8e8e8;
    border-radius: 8px;
    background: #fcfcfc;
}

/* 通用隐藏 */
.hidden {
    display: none !important;
}

/* 受力分析面板（右侧） */
.force-panel {
    background: white;
    border-radius: 12px;
    box-shadow: 0 4px 20px rgba(0,0,0,0.1);
    overflow: hidden;
    min-width: 0;
}

.force-header {
    display: flex;
    align-items: center;
    justify-content: space-between;
    padding: 12px 14px 8px 14px;
}

.force-title {
    font-size: 1.1rem;
    font-weight: 600;
    color: #444;
    position: relative;
    padding-left: 14px;
}

.force-title::before {
    content: '';
    position: absolute;
    left: 0;
    top: 2px;
    bottom: 2px;
    width: 4px;
    background: linear-gradient(180deg, #667eea, #764ba2);
    border-radius: 2px;
}

/* 参数调节面板 */
.controls-overlay {
    display: flex;
    flex-wrap: wrap;
    gap: 15px;
    justify-content: center;
    align-items: center;
    padding: 12px 20px;
    background: linear-gradient(145deg, #ffffff, #f8f9fa);
    border-radius: 10px;
    box-shadow: 0 4px 15px rgba(0, 0, 0, 0.08);
    border: 1px solid rgba(0, 0, 0, 0.05);
}

.reset-btn {
    padding: 6px 16px;
    background: linear-gradient(135deg, #667eea 0%, #764ba2 100%);
    color: white;
    border: none;
    border-radius: 5px;
    font-size: 12px;
    font-weight: 500;
    cursor: pointer;
    transition: all 0.2s ease;
    box-shadow: 0 2px 8px rgba(102, 126, 234, 0.3);
}

.reset-btn:hover {
    transform: translateY(-1px);
    box-shadow: 0 4px 12px rgba(102, 126, 234, 0.4);
}

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

.checkbox-group {
    display: flex;
    gap: 12px;
    padding: 6px 10px;
    background: rgba(255, 255, 255, 0.8);
    border-radius: 6px;
    border: 1px solid rgba(0, 0, 0, 0.06);
}

.force-checkbox {
    display: flex;
    align-items: center;
    gap: 4px;
    font-size: 11px;
    color: #4a5568;
    cursor: pointer;
}

.force-checkbox input[type="checkbox"] {
    width: 14px;
    height: 14px;
    cursor: pointer;
    accent-color: #667eea;
}

.force-checkbox span {
    user-select: none;
}

/* 参数显示面板 */
.params-panel {
    background: white;
    border-radius: 12px;
    padding: 14px 16px;
    box-shadow: 0 4px 20px rgba(0,0,0,0.1);
}

.params-panel h3 {
    color: #333;
    margin-bottom: 10px;
    font-size: 1rem;
}

.params-groups {
    display: grid;
    grid-template-columns: repeat(3, 1fr);
    gap: 10px;
}

.param-group {
    background: #f8f9fa;
    border-radius: 8px;
    padding: 8px 10px;
}

.param-group-title {
    font-size: 0.78rem;
    font-weight: 700;
    color: #667eea;
    margin-bottom: 5px;
    padding-bottom: 4px;
    border-bottom: 2px solid #e8ecf4;
}

.param-item {
    display: flex;
    justify-content: space-between;
    align-items: center;
    padding: 3px 0;
}

.param-item + .param-item {
    border-top: 1px solid #eee;
}

.param-label {
    font-weight: 500;
    color: #666;
    font-style: italic;
    font-size: 0.85rem;
}

.param-value {
    font-weight: 600;
    color: #667eea;
    font-size: 0.85rem;
}

.param-input {
    font-weight: 600;
    color: #667eea;
    font-size: 0.85rem;
    border: 1px solid #ddd;
    border-radius: 4px;
    padding: 2px 6px;
    width: 60px;
    text-align: right;
    outline: none;
}

.param-input:focus {
    border-color: #667eea;
    box-shadow: 0 0 0 2px rgba(102, 126, 234, 0.2);
}

/* F-h 关系图像 */
.graph-panel {
    background: white;
    border-radius: 12px;
    padding: 14px 16px;
    box-shadow: 0 4px 20px rgba(0,0,0,0.1);
    min-width: 0;
}

.graph-panel h3 {
    color: #333;
    margin-bottom: 8px;
    font-size: 1rem;
}

.graph-h-controls {
    display: flex;
    gap: 8px;
    align-items: center;
    padding: 0 14px 10px 14px;
}

.graph-h-controls label {
    font-weight: 500;
    color: #555;
    font-size: 0.9rem;
    font-style: italic;
}

.graph-h-controls select {
    padding: 3px 6px;
    border: 1px solid #ddd;
    border-radius: 4px;
    outline: none;
    font-size: 0.85rem;
    font-family: 'Times New Roman', Times, serif;
}

/* 响应式设计 */
@media (max-width: 1200px) {
    .params-groups {
        grid-template-columns: repeat(2, 1fr);
    }
}

@media (max-width: 1024px) {
    .main-layout {
        flex-direction: column;
    }
    .left-panel {
        flex: 1;
    }
}

@media (max-width: 768px) {
    .params-groups {
        grid-template-columns: 1fr;
    }
}

/* 手机小屏适配 */
@media (max-width: 480px) {
    .navbar h1 {
        font-size: 1.2rem;
    }
    .main-content {
        padding: 10px;
    }
    .main-content .container {
        padding: 0;
    }
    .left-panel {
        flex: 0 0 auto;
    }
    .canvas-wrapper {
        padding: 10px;
        border-radius: 8px;
    }
    #mainCanvas {
        max-width: 100%;
        height: auto;
    }
    .mini-canvas-wrapper {
        padding: 0 8px 8px 8px;
        overflow: hidden;
    }
    .mini-canvas-wrapper canvas {
        max-width: 100%;
        height: auto;
    }
    .controls-overlay {
        padding: 10px;
        gap: 10px;
        flex-direction: column;
    }
    .checkbox-group {
        width: 100%;
        justify-content: center;
    }
    .params-panel {
        padding: 12px;
    }
    .params-panel h3 {
        font-size: 1rem;
    }
    .param-group {
        padding: 10px;
    }
    .force-header {
        padding: 10px 10px 6px 10px;
    }
    .force-title {
        font-size: 0.95rem;
    }
    .graph-panel {
        padding: 12px;
    }
    .graph-panel h3 {
        font-size: 0.95rem;
    }
    .right-top {
        gap: 12px;
    }
}

/* 极小屏适配 */
@media (max-width: 360px) {
    .navbar h1 {
        font-size: 1rem;
    }
    .param-item {
        font-size: 0.85rem;
    }
    .params-groups {
        gap: 8px;
    }
}

/* 物理量斜体样式 */
i {
    font-style: italic;
}

.subscript {
    font-size: 0.7em;
    vertical-align: sub;
}