Fix CSS

www/assets/css/app.css

@@ -36,7 +36,7 @@ file, You can obtain one at http://mozilla.org/MPL/2.0/.
     line-height: var(--f7-line-height);
 }
 
-.button .fas, .button .far, .button .fal, .button .fad {
+.button .fa-solid, .button .fa-regular, .button .fa-duotone {
     margin-right: 0.3rem;
 }