use a typical OS order for #help-popup buttons

* horizontally centered in Windows
* right-aligned otherwise

edit/edit.css

@@ -564,10 +564,11 @@ body[data-match-highlight="selection"] .CodeMirror-selection-highlight-scrollbar
   top: .5em;
 }
 #help-popup .saved-message {
-  display: none;
+  /* display: none; */
   color: #090;
-  margin-left: 10px;
+  /* margin-left: 10px; */
   font-weight: bold;
+  position: absolute;
 }
 #help-popup .saved-message.show {
   display: inline-block;
@@ -590,13 +591,19 @@ body[data-match-highlight="selection"] .CodeMirror-selection-highlight-scrollbar
   padding-right: 0.5rem;
 }
 
+#help-popup .buttons {
+  text-align: center;
+}
+.non-windows #help-popup .buttons {
+  direction: rtl;
+  text-align: right;
+}
 #help-popup button[name^="import"] {
   line-height: 1.5rem;
   padding: 0 0.5rem;
   margin: 0.5rem 0 0 0.5rem;
   pointer-events: none;
   opacity: 0.5;
-  float: right;
 }
 #help-popup.ready button[name^="import"] {
   pointer-events: all;

edit/edit.js

@@ -427,19 +427,19 @@ function toMozillaFormat() {
 
 function fromMozillaFormat() {
   const popup = showCodeMirrorPopup(t('styleFromMozillaFormatPrompt'),
-    $create([
-      $create('button', {
-        name: 'import-append',
-        textContent: t('importAppendLabel'),
-        title: 'Ctrl-Enter:\n' + t('importAppendTooltip'),
-        onclick: doImport,
-      }),
+    $create('.buttons', [
       $create('button', {
         name: 'import-replace',
         textContent: t('importReplaceLabel'),
         title: 'Ctrl-Shift-Enter:\n' + t('importReplaceTooltip'),
         onclick: () => doImport({replaceOldStyle: true}),
       }),
+      $create('button', {
+        name: 'import-append',
+        textContent: t('importAppendLabel'),
+        title: 'Ctrl-Enter:\n' + t('importAppendTooltip'),
+        onclick: doImport,
+      }),
     ]));
   const contents = $('.contents', popup);
   contents.insertBefore(popup.codebox.display.wrapper, contents.firstElementChild);

edit/lint.js

@@ -448,10 +448,12 @@ function setupLinterPopup(config) {
           t('linterRulesLink')),
         linter === 'csslint' ? ' ' + t('linterCSSLintSettings') : '',
       ]),
+      $create('.buttons', [
         $create('button.save', {onclick: save, title: 'Ctrl-Enter'}, t('styleSaveLabel')),
         $create('button.cancel', {onclick: cancel}, t('confirmClose')),
         $create('button.reset', {onclick: reset, title: t('linterResetMessage')}, t('genericResetLabel')),
         $create('span.saved-message', t('genericSavedMessage')),
+      ]),
     ]);
   }