style: add classes for different types of notifications

src/styles.css

@@ -1,4 +1,28 @@
-/* You can add global styles to this file, and also import other style files */
+html, body {
+  height: 100%;
+}
 
-html, body { height: 100%; }
+body {
-body { margin: 0; font-family: Roboto, "Helvetica Neue", sans-serif; }
+  margin: 0;
+  font-family: Roboto, "Helvetica Neue", sans-serif;
+}
+
+.green-snackbar, .mat-mdc-snack-bar-container {
+  --mdc-snackbar-container-color: #8CBA51;
+  color: black;
+}
+
+.red-snackbar {
+  --mdc-snackbar-container-color: #E20338;
+  color: white;
+}
+
+.yellow-snackbar {
+  --mdc-snackbar-container-color: #FFD600;
+  color: black;
+}
+
+.snackbar {
+  --mdc-snackbar-container-color: inherit;
+  color: inherit;
+}