style: 更新对话框样式，调整按钮尺寸和间距，增强用户界面一致性

(cherry picked from commit b2395fd3a2)

src/components/signup/SignupModal.vue

@@ -1,7 +1,7 @@
 <template>
   <div v-if="visible">
-    <el-dialog :visible="visible" :title="dialogTitle" width="1200px" top="8vh" append-to-body destroy-on-close
-      class="signup-dialog" @close="handleClose">
+    <el-dialog class="signup-dialog common-course-dialog" :visible="visible" :title="dialogTitle" width="1200px" top="8vh" append-to-body destroy-on-close
+       @close="handleClose">
       <div class="signup-wrap">
         <el-tabs v-model="activeTab">
           <!-- <el-tab-pane v-if="infoType" label="项目内学员" name="project">
@@ -524,28 +524,6 @@ export default {
     background-color: #3b7cff;
   }
 }
-.signup-dialog ::v-deep .el-dialog__footer {
-
-  .el-button {
-    min-width: 120px;
-    height: 40px;
-    font-size: 16px;
-    border-radius: 6px;
-    padding: 0 18px;
-  }
-
-  .el-button--default {
-    color: rgba(0, 0, 0, 0.3);
-    border-color: rgba(0, 0, 0, 0.3);
-    background-color: #ffffff;
-  }
-
-  .el-button--primary {
-    background-color: #3b7cff;
-    border-color: #3b7cff;
-    color: #fff;
-  }
-}
 
 .signup-wrap {
   display: flex;