[S] Fix margins when there are no unread

src/pages/overall/overall-course/assignment-entry/assignment-entry.scss

@@ -111,6 +111,15 @@
     height: 30px;
 }
 
+// Unread
+.no-unread
+{
+    visibility: hidden !important;
+    width: 0 !important;
+    margin-left: 0 !important;
+    padding: 0 0 0 10px !important;
+}
+
 .unread-entry:first-child
 {
     padding-top: 3px;

src/pages/overall/overall-course/assignment-entry/assignment-entry.vue

@@ -25,8 +25,8 @@
                 <span class="score entry-box">{{assignment.score}}</span>
                 <span class="max entry-box">{{assignment.scoreMax}}</span>
 
-                <el-button class="mark-as-read" :class="unread ? 'unread' : ''"
-                           size="mini" type="text" icon="el-icon-close" 
+                <el-button class="mark-as-read" :class="unread ? 'unread' : 'no-unread'"
+                           size="mini" type="text" icon="el-icon-close"
                            @click="markAsRead">
                 </el-button>
             </el-col>