Setup flow for cross-signing on login / registration

Still outstanding:
 * Keep password from login / registration
 * Confirmation on skip button

Fixes https://github.com/vector-im/riot-web/issues/11902

res/css/views/auth/_AuthBody.scss

@@ -15,13 +15,10 @@ limitations under the License.
 */
 
 .mx_AuthBody {
-    width: 500px;
     background-color: $authpage-body-bg-color;
     border-radius: 0 4px 4px 0;
     padding: 25px 60px;
     box-sizing: border-box;
-    font-size: 12px;
-    color: $authpage-secondary-color;
 
     h2 {
         font-size: 24px;
@@ -99,6 +96,12 @@ limitations under the License.
     border-radius: 4px;
 }
 
+.mx_AuthBody_loginRegister {
+    width: 500px;
+    font-size: 12px;
+    color: $authpage-secondary-color;
+}
+
 .mx_AuthBody_editServerDetails {
     padding-left: 1em;
     font-size: 12px;

res/css/views/dialogs/secretstorage/_CreateSecretStorageDialog.scss

@@ -78,6 +78,10 @@ limitations under the License.
     align-items: center;
 }
 
+.mx_CreateSecretStorageDialog_recoveryKeyButtons .mx_AccessibleButton {
+    margin-right: 10px;
+}
+
 .mx_CreateSecretStorageDialog_recoveryKeyButtons button {
     flex: 1;
     white-space: nowrap;