Update more UI to Bootstrap 4.1

Author: AbrilRBS

Diff for: static/themes/default-theme.css

@@ -66,6 +66,10 @@ body {
     box-shadow: 0 0 0 0.2rem rgba(248, 249, 250, 0.5);
 }
 
+pre.content {
+    background-color: #f5f5f5;
+}
+
 .opcode {
     color: #066;
 }

Diff for: views/popups.pug

@@ -10,9 +10,9 @@
         .card
           .card-header
             ul.nav.nav-tabs.card-header-tabs(role="tablist")
-              li.nav-item.active(role="presentation"): a(href="#load-examples" role="tab" data-toggle="tab") Examples
-              li.nav-item(role="presentation"): a(href="#load-browser-local" role="tab" data-toggle="tab") Browser-local storage
-              li.nav-item(role="presentation"): a(href="#load-file-system" role="tab" data-toggle="tab") File system
+              li.nav-item(role="presentation"): a.nav-link.active(href="#load-examples" role="tab" data-toggle="tab") Examples
+              li.nav-item(role="presentation"): a.nav-link(href="#load-browser-local" role="tab" data-toggle="tab") Browser-local storage
+              li.nav-item(role="presentation"): a.nav-link(href="#load-file-system" role="tab" data-toggle="tab") File system
           .card-body.tab-content
             #load-examples.tab-pane.active(role="tabpanel")
               h4.card-title Load from examples:
@@ -27,9 +27,9 @@
                 button.btn.btn-light.save-button(type="button") Save to browser-local storage
             #load-file-system.tab-pane(role="tabpanel")
               h4.card-title Load/save to your system
-              label.btn.btn-light.btn-file Load from a local file
+              label.btn.btn-outline-secondary.btn-file(role="button") Load from a local file
                 input.local-file(type="file")
-              label.btn.btn-light.btn-file.save-btn Save to file
+              label.btn.btn-outline-secondary.btn-file.save-btn(role="button") Save to file
                 input.save-file(type="button")
       .modal-footer
         button.btn.btn-light(type="button" data-dismiss="modal" aria-label="Close") Close

Diff for: views/templates.pug

@@ -60,7 +60,7 @@
             span 11010
           input.d-none(type="checkbox")
         .button-checkbox
-          button.nav-link-sm.btn.btn-light.btn-sm(type="button" title="Execute the binary" data-bind="execute" aria-pressed="false")
+          button.btn.btn-light.btn-sm(type="button" title="Execute the binary" data-bind="execute" aria-pressed="false")
             span ./a.out
           input.d-none(type="checkbox")
         .button-checkbox
@@ -92,6 +92,7 @@
           span.fas.fa-book(title="Include libs")
           span.hideable  Libraries
           | #[b.caret]
+      .btn-group.btn-group-sm(role="group")
         button.btn.btn-light.btn-sm.dropdown-toggle.add-pane(type="button" title="Add a new pane" data-toggle="dropdown" aria-haspopup="true" aria-expanded="false" aria-label="Add new element for this compiler")
           span.fas.fa-plus
           span.hideable  Add new...