fix(modal): use heading classes (#270)

Author: hellobrian

src/components/modal/modal--nofooter.html

@@ -3,8 +3,8 @@
 <div data-modal id="nofooter" class="bx--modal" tabindex="-1">
   <div class="bx--modal-container">
     <div class="bx--modal-header">
-      <h4 class="bx--modal-header__label">Label (Optional)</h4>
-      <h2 class="bx--modal-header__heading">Modal Title</h2>
+      <p class="bx--modal-header__label bx--type-delta">Label (Optional)</p>
+      <p class="bx--modal-header__heading bx--type-beta">Modal Title</p>
       <button class="bx--modal-close" type="button" data-modal-close data-modal-primary-focus aria-label="close modal">
         <svg class="bx--modal-close__icon" width="10" height="10" viewBox="0 0 10 10" fill-rule="evenodd">
           <title>Close Modal</title>

src/components/modal/modal.html

@@ -3,8 +3,8 @@
 <div data-modal id="modal" class="bx--modal" tabindex="-1">
   <div class="bx--modal-container">
     <div class="bx--modal-header">
-      <h4 class="bx--modal-header__label">Label (Optional)</h4>
-      <h2 class="bx--modal-header__heading">Modal Title</h2>
+      <p class="bx--modal-header__label bx--type-delta">Label (Optional)</p>
+      <p class="bx--modal-header__heading bx--type-beta">Modal Title</p>
       <button class="bx--modal-close" type="button" data-modal-close aria-label="close modal">
         <svg class="bx--modal-close__icon" width="10" height="10" viewBox="0 0 10 10" fill-rule="evenodd">
            <title>Close Modal</title>