Forms: Use button class directly on buttons for consistent display

Adding the `button` mixin into `input[type="submit"] caused conflicts with the other button classes (`.button-primary`) due to specificity. The button classes should be used on all buttons instead. This also updates which button on the Manage Pledge form is the "primary" action, since it's easy to skip the Update button when it's not primary.

plugins/wporg-5ftf/views/form-pledge-confirm-email.php

@@ -67,6 +67,7 @@ use WP_Post;
 			<p>
 				<input
 					type="submit"
+					class="button"
 					value="Resend Confirmation"
 				/>
 			</p>

plugins/wporg-5ftf/views/form-pledge-manage.php

@@ -29,6 +29,7 @@ require __DIR__ . '/partial-result-messages.php';
 		<div>
 			<input
 				type="submit"
+				class="button button-primary"
 				id="5ftf-pledge-submit"
 				name="action"
 				value="<?php esc_attr_e( 'Update Pledge', 'wporg-5ftf' ); ?>"

plugins/wporg-5ftf/views/form-pledge-new.php

@@ -57,6 +57,7 @@ require __DIR__ . '/partial-result-messages.php';
 		<div>
 			<input
 				type="submit"
+				class="button"
 				id="5ftf-pledge-submit"
 				name="action"
 				value="<?php esc_attr_e( 'Submit Pledge', 'wporg-5ftf' ); ?>"

plugins/wporg-5ftf/views/manage-contributors.php

@@ -102,7 +102,7 @@ use function WordPressDotOrg\FiveForTheFuture\get_views_path;
 		<div id="add-contrib-message" role="alert" aria-atomic="true"></div>
 
 		<button
-			class="button-primary"
+			class="button button-secondary"
 			data-action="add-contributor"
 		>
 			<?php esc_html_e( 'Add new contributors', 'wporg-5ftf' ); ?>

plugins/wporg-5ftf/views/modal-request-manage-link.php

@@ -35,6 +35,7 @@ defined( 'WPINC' ) || die();
 
 			<input
 				type="submit"
+				class="button"
 				name="get_manage_pledge_link"
 				value="<?php esc_attr_e( 'Submit', 'wporg-5ftf' ); ?>"
 			/>

themes/wporg-5ftf/css/objects/_buttons.scss

@@ -1,7 +1,3 @@
-input[type="submit"] {
-	@extend .button;
-}
-
 .wp-block-button {
 	@extend .button;
 

themes/wporg-5ftf/css/objects/_pledge-form.scss

@@ -54,9 +54,8 @@
 			margin-bottom: 0;
 		}
 	}
-	
-	input[type="submit"],
-	.button-primary {
+
+	.button {
 		display: inline-block;
 		height: auto;
 		padding: ms(-3) ms(0);