Added light & dark theme. Basic theme applied on dialogs/modals. Attempt to apply uniformity to the website.

src/app/twitch-users/twitch-user-item-add/twitch-user-item-add.component.html

@@ -15,12 +15,18 @@
   </mat-card-content>
 
   <mat-card-actions class="actions">
-    <button mat-raised-button
+    <button mat-button
+            class="neutral"
             disabled="{{waitForResponse}}"
-            (click)="dialogRef.close()">Cancel</button>
-    <button mat-raised-button
+            (click)="dialogRef.close()">
+      <mat-icon>cancel</mat-icon>Cancel
+    </button>
+    <button mat-button
+            class="confirm"
             disabled="{{!usernameControl.dirty || usernameControl.invalid || waitForResponse}}"
-            (click)="submit()">Add</button>
+            (click)="submit()">
+      <mat-icon>add</mat-icon>Add
+    </button>
   </mat-card-actions>
 
   @if (responseError) {