Initiate design system and refactor login page buttons.

frontend/src/app/pages/login/login.component.html

@@ -18,6 +18,6 @@
     </div>
     <div class="actions">
         <button type="submit" i18n>Send</button>
-        <a [routerLink]="['/signin']" i18n>Create an account</a>
+        <a [routerLink]="['/signin']" class="button secondary" i18n>Create an account</a>
     </div>
 </form>