fix img overflow problem

Signed-off-by: zhangtianli2006 <49156174+zhangtianli2006@users.noreply.github.com>

Author: ZTL-UwU

src/assets/css/basic.css

@@ -63,6 +63,10 @@ h3::before {
     content: "# ";
 }
 
+.markdown-container img {
+    max-width: 100%;
+}
+
 .markdown-container h1,
 .cm-header-1 {
     font-size: 30px;