fix: Mermaid 图表改为宽度固定、高度自适应

- SVG 宽度固定为 100%，适应容器宽度
- SVG 高度自动计算，根据内容自由伸展
- 移除所有高度限制，让图表完整显示

style.css

@@ -919,17 +919,13 @@ article .wp-block-separator {
 	max-width: 100%;
 	opacity: 0;
 	animation: mermaidFadeIn 0.3s ease-in-out forwards;
-	display: flex;
-	justify-content: center;
-	align-items: center;
 }
 
 .mermaid-container svg {
+	width: 100% !important;
+	height: auto !important;
 	max-width: 100%;
-	max-height: 600px;
-	height: auto;
 	display: block;
-	width: auto !important;
 }
 
 /* Mermaid 淡入动画 */
@@ -16636,19 +16632,13 @@ html.darkmode .mermaid-error-container .error-code code {
 	overflow-x: auto;
 	max-width: 100%;
 	transition: opacity 0.3s ease-in;
-	display: flex;
-	justify-content: center;
-	align-items: center;
-	min-height: 100px;
 }
 
 .mermaid-container svg {
+	width: 100% !important;
+	height: auto !important;
 	max-width: 100%;
-	max-height: 600px;
-	height: auto;
-	width: auto !important;
 	display: block;
-	margin: 0 auto;
 }
 
 /* ---------- 卡片内的 Mermaid 图表 ---------- */
@@ -16672,11 +16662,6 @@ html.darkmode .mermaid-container {
 		margin: 15px 0;
 		border-radius: calc(var(--card-radius) * 0.8);
 	}
-	
-	.mermaid-container svg {
-		max-width: 100%;
-		max-height: 500px;
-	}
 }
 
 @media screen and (max-width: 480px) {
@@ -16684,10 +16669,6 @@ html.darkmode .mermaid-container {
 		padding: 10px;
 		margin: 10px 0;
 	}
-	
-	.mermaid-container svg {
-		max-height: 400px;
-	}
 }
 
 /* ---------- Mermaid 错误提示样式 ---------- */