/* 主布局 */
#app {
    --panel-width: 0px;
    display: grid;
    grid-template-areas:
        "toolbar header header"
        "toolbar canvas panel"
        "toolbar footer footer";
    grid-template-columns: 220px 1fr var(--panel-width);
    grid-template-rows: 60px 1fr 40px;
    height: 100vh;
    height: 100dvh;
    width: 100vw;
}

#app.panel-open {
    --panel-width: 320px;
}

/* 头部 */
#header {
    grid-area: header;
    background: var(--bg-tertiary);
    border-bottom: 1px solid var(--border-color);
    display: flex;
    align-items: center;
    justify-content: space-between;
    gap: var(--spacing-md);
    padding: 0 var(--spacing-lg);
}

#header h1 {
    font-size: 18px;
    font-weight: 600;
    color: var(--text-primary);
    flex: 0 1 auto;
    min-width: 0;
    overflow: hidden;
    text-overflow: ellipsis;
    white-space: nowrap;
}

.header-controls {
    display: flex;
    align-items: center;
    gap: var(--spacing-md);
    flex: 1 1 auto;
    min-width: 0;
    justify-content: flex-end;
    overflow-x: auto;
    overflow-y: hidden;
    white-space: nowrap;
    scrollbar-width: thin;
}

.header-controls::-webkit-scrollbar {
    height: 6px;
}

.control-label {
    display: flex;
    align-items: center;
    gap: var(--spacing-sm);
    font-size: 13px;
    color: var(--text-secondary);
}

#timestep-slider {
    width: 100px;
}

#timestep-value {
    min-width: 40px;
    color: var(--info-blue);
    font-weight: 500;
}

/* 工具栏 */
#toolbar {
    grid-area: toolbar;
    background: var(--bg-secondary);
    border-right: 1px solid var(--border-color);
    overflow-y: auto;
    padding: var(--spacing-md);
}

#toolbar h2 {
    font-size: 16px;
    margin-bottom: var(--spacing-md);
    color: var(--text-primary);
}

.tool-section {
    margin-bottom: var(--spacing-lg);
}

.tool-section h3 {
    font-size: 13px;
    color: var(--text-secondary);
    margin-bottom: var(--spacing-sm);
    text-transform: uppercase;
    letter-spacing: 0.5px;
}

.tool-item {
    display: flex;
    align-items: center;
    gap: var(--spacing-sm);
    padding: var(--spacing-sm);
    margin-bottom: var(--spacing-xs);
    background: var(--bg-tertiary);
    border: 1px solid var(--border-color);
    border-radius: var(--radius-sm);
    cursor: grab;
    transition: all var(--transition-fast);
    user-select: none;
}

.tool-item:hover {
    background: var(--bg-hover);
    border-color: var(--accent-blue);
    box-shadow: var(--shadow-sm);
}

.tool-item.active {
    background: var(--bg-hover);
    border-color: var(--accent-blue);
    box-shadow: var(--shadow-sm);
}

.tool-item:active {
    cursor: grabbing;
    transform: scale(0.98);
}

.tool-item svg {
    color: var(--info-blue);
}

.tool-item span {
    font-size: 13px;
    color: var(--text-primary);
}

.preset-btn {
    width: 100%;
    padding: var(--spacing-sm);
    margin-bottom: var(--spacing-xs);
    background: var(--bg-tertiary);
    border: 1px solid var(--border-color);
    border-radius: var(--radius-sm);
    color: var(--text-primary);
    font-size: 13px;
    cursor: pointer;
    transition: all var(--transition-fast);
}

.preset-btn:hover {
    background: var(--accent-blue);
    border-color: var(--accent-blue);
}

.preset-btn:focus-visible {
    outline: 2px solid var(--border-focus);
    outline-offset: 2px;
}

/* 画布区域 */
#canvas-area {
    grid-area: canvas;
    background: var(--bg-primary);
    position: relative;
    overflow: hidden;
}

#canvas-container {
    width: 100%;
    height: 100%;
    position: relative;
}

#canvas-container canvas {
    position: absolute;
    top: 0;
    left: 0;
    width: 100%;
    height: 100%;
    touch-action: none;
}

#bg-canvas {
    z-index: 1;
}

#field-canvas {
    z-index: 2;
}

#particle-canvas {
    z-index: 3;
}

#fps-counter {
    position: absolute;
    top: 10px;
    left: 10px;
    background: rgba(0, 0, 0, 0.7);
    color: var(--success-green);
    padding: var(--spacing-xs) var(--spacing-sm);
    border-radius: var(--radius-sm);
    font-family: 'Courier New', monospace;
    font-size: 12px;
    z-index: 10;
}

/* 属性面板 */
.panel {
    grid-area: panel;
    background: var(--bg-secondary);
    border-left: 1px solid var(--border-color);
    display: flex;
    flex-direction: column;
}

.panel-header {
    display: flex;
    align-items: center;
    justify-content: space-between;
    padding: var(--spacing-md);
    border-bottom: 1px solid var(--border-color);
}

.panel-header h3 {
    font-size: 14px;
    font-weight: 600;
}

.panel-content {
    flex: 1;
    overflow-y: auto;
    padding: var(--spacing-md);
}

/* 底部状态栏 */
#footer {
    grid-area: footer;
    background: var(--bg-tertiary);
    border-top: 1px solid var(--border-color);
    display: flex;
    align-items: center;
    justify-content: space-between;
    padding: 0 var(--spacing-lg);
    font-size: 12px;
    color: var(--text-secondary);
}

#footer span {
    margin-right: var(--spacing-lg);
}

/* 响应式布局 */
@media (max-width: 1200px) {
    #app {
        grid-template-columns: 60px 1fr;
        grid-template-areas:
            "toolbar header"
            "toolbar canvas"
            "toolbar footer";
    }
    
    #property-panel {
        position: fixed;
        right: -320px;
        top: 60px;
        bottom: 40px;
        width: 320px;
        transition: right var(--transition-slow);
        z-index: 100;
        box-shadow: var(--shadow-lg);
    }
    
    #property-panel.open {
        right: 0;
    }
    
    #toolbar .tool-item span,
    #toolbar h2,
    #toolbar h3 {
        display: none;
    }
    
    #toolbar {
        padding: var(--spacing-sm);
    }
}

@media (max-width: 768px) {
    #app {
        grid-template-columns: 52px 1fr;
    }

    #header {
        padding: 0 var(--spacing-md);
    }

    #header h1 {
        font-size: 14px;
    }

    #timestep-slider {
        width: 80px;
    }

    #property-panel {
        width: 100vw;
        right: -100vw;
    }
}