fix smile-png being overlapped

src/features/OnlineExam/OnlineExamHome.vue

@@ -41,7 +41,7 @@ export default {
           render: () => (
             <div class="welcome-modal">
               <div class="smile-png" />
-              <div style="margin-left: 20px">
+              <div style="margin-left: 20px; flex: 1">
                 <div style="margin-bottom: 1.5em">
                   欢迎使用考试系统，祝顺利完成考试！
                 </div>