Align apartment core validation errors (#43)

frontend/src/app/components/apartment-form/apartment-form.css

@@ -22,6 +22,14 @@
 	font-size: 0.8rem;
 	line-height: 1.6;
 }
+.core-field mat-form-field {
+	width: 100%;
+}
+.field-error {
+	margin: -14px 0 0;
+	color: var(--danger);
+	font-size: 0.75rem;
+}
 @media (min-width: 1180px) {
 	.form-page {
 		max-width: 980px;