Updated start page layout

frontend/src/pages/reviewer/ReviewerStartPage.vue

 <template>
-  <div v-if="dataLoaded">
+  <v-container v-if="dataLoaded">
     <v-row>
       <v-col
-        lg="5"
-        md="9"
-        cols="12"
+        lg="6"
+        md="12"
       >
-        <change-log class="ma-4" />
+        <change-log />
       </v-col>
       <v-col
-        lg="5"
-        md="9"
-        cols="12"
+        lg="6"
+        md="12"
       >
-        <correction-statistics class="ma-4" />
+        <correction-statistics />
+      </v-col>
+      <v-col>
+        <SubmissionTypesOverview />
       </v-col>
     </v-row>
-    <SubmissionTypesOverview class="ma-4" />
-  </div>
+  </v-container>
   <v-row
     v-else
     justify="center"

frontend/src/pages/tutor/TutorStartPage.vue

 <template>
-  <div>
+  <v-container>
     <v-row>
       <v-col
-        lg="5"
-        md="9"
-        cols="12"
+        lg="6"
+        md="12"
       >
-        <change-log class="ma-4" />
+        <change-log />
       </v-col>
       <v-col
-        lg="5"
-        md="9"
-        cols="12"
+        lg="6"
+        md="12"
       >
-        <correction-statistics class="ma-4" />
+        <correction-statistics />
+      </v-col>
+      <v-col>
+        <SubmissionTypesOverview />
       </v-col>
     </v-row>
-    <SubmissionTypesOverview class="ma-4" />
-  </div>
+  </v-container>
 </template>
 
 <script>