Keep image small on all screen sizes

Prior to this change, the image would
become full-width on narrow screens,
which looks awful.

src/main/webapp/app/exercise/exercise-details/exercise-details.component.html

@@ -6,7 +6,7 @@
 
                 <!-- Modal Header -->
                 <div class="modal-header">
-                    <img class="card-img-top col-md-3" src="{{exercise.imageURL}}" alt="exercise image"
+                    <img class="card-img-top col-3" src="{{exercise.imageURL}}" alt="exercise image"
                          (error)="correctImageURL($event)"
                         style="height: auto; float: left;">
                     <h4 class="modal-title">{{exercise.title}}</h4>
@@ -83,7 +83,7 @@
                                 </button> -->
                                 <div [ngbTooltip]="helpCommingSoon" placement="bottom">
                                 <button *ngIf="exercise.type == exerciseType.COLLECTION" type="button" class="btn btn-outline-secondary"
-                                    style="display: block; margin-bottom: 5px;" 
+                                    style="display: block; margin-bottom: 5px;"
                                     jhiTranslate="exercise.details.allExercises"
                                     disabled>
                                     >