修改

src/styles/index.scss

@@ -591,6 +591,10 @@ li {
   background-color: #eaeef9;
 }
 
+.el-avatar>img{
+  max-width: 100%;
+}
+
 /*二级弹框背景*/
 .ej-dialog-bg {
   background: #f5f7fa !important;

src/views/login/index.vue

@@ -2,7 +2,7 @@
   <div class="login-container">
     <el-form ref="loginForm" :model="loginForm" :rules="loginRules" class="login-form" auto-complete="on" label-position="left">
       <div class="title-container flex-wrap">
-        <el-avatar :size="36" :src="imgSrc" @error="errorHandler">
+        <el-avatar :size="40" shape="square" :src="imgSrc" @error="errorHandler">
           <img src="@/assets/logo/error.png">
         </el-avatar>
         <!-- <el-divider direction="vertical"></el-divider> -->