add text superposition base layout

src/assets/scss/_variables.scss

@@ -26,3 +26,5 @@ $families: (
 @function setColorFromId($id) {
   @return map-get($families, $id);
 }
+
+$text-card-header-height: 4rem;

src/assets/scss/main.scss

@@ -3,8 +3,11 @@
 @import 'bootstrap';
 
 
-html, body, #app {
+html,
+body,
+#app {
   height: 100%;
+  overflow: hidden;
 }
 
 #app {
@@ -13,7 +16,8 @@ html, body, #app {
 }
 
 main {
-  height: 100%;
+  flex: 1;
+  overflow-y: auto;
 }
 
 // Layouts
@@ -24,15 +28,6 @@ main {
   height: 100%;
 }
 
-.split-screen {
-  display: flex;
-  height: 100%;
-
-  & > * {
-    flex-basis: 50%;
-  }
-}
-
 .container-fill {
   display: flex;
   flex-direction: column;