[BUGFIX] Fix height of the modal content

Fix height of the modal content to avoid misbehavior in IE11.

Resolves: #81232
Releases: master, 8.7
Change-Id: I302915e1efcd2040f78db8052dc2e09e06f1dfe4
Reviewed-on: https://review.typo3.org/53023


Tested-by: TYPO3com <no-reply@typo3.com>
Reviewed-by: Benjamin Kott <benjamin.kott@outlook.com>
Tested-by: Benjamin Kott <benjamin.kott@outlook.com>
Reviewed-by: Markus Sommer <markussom@posteo.de>
Tested-by: Markus Sommer <markussom@posteo.de>
Reviewed-by: Christian Kuhn <lolli@schwarzbu.ch>
Tested-by: Christian Kuhn <lolli@schwarzbu.ch>

Build/Resources/Public/Sass/component/_modal.scss

@@ -45,7 +45,8 @@ $modal-danger-border: $btn-danger-border;
 
 .modal-dialog {
     display: flex;
-    align-items: center;
+    flex-direction: column;
+    align-items: stretch;
     justify-content: center;
     margin: 0 auto !important;
     height: 100vh;
@@ -55,14 +56,14 @@ $modal-danger-border: $btn-danger-border;
 .modal-content {
     display: flex;
     flex-direction: column;
-    margin-left: 20px;
-    margin-right: 20px;
+    margin: 0 auto;
     max-height: calc(100vh - 40px);
+    max-width: calc(100vw - 40px);
 }
 
 .modal-body {
-    flex: 1;
-    overflow-y: scroll;
+    flex: 1 1 auto;
+    overflow-y: auto;
 }
 
 .modal-header,