put "[x] as Usercss" option next to "Write new style" button

_locales/en/messages.json

@@ -529,6 +529,10 @@
     "message": "Installed Styles",
     "description": "Heading for the manage page"
   },
+  "manageNewStyleAsUsercss": {
+    "message": "as Usercss",
+    "description": "VERY SHORT label for the checkbox next to the 'Write new style' button in the style manager"
+  },
   "manageOnlyEnabled": {
     "message": "Only enabled styles",
     "description": "Checkbox to show only enabled styles"
@@ -549,6 +553,14 @@
     "message": "(the styles not installed through a userstyles.org page)",
     "description": "Tooltip for the checkbox to show only locally created styles i.e. non-updatable"
   },
+  "manageOnlyNonUsercss": {
+    "message": "Only non-Usercss styles",
+    "description": "Checkbox to show only non-Usercss (standard) styles"
+  },
+  "manageOnlyUsercss": {
+    "message": "Only Usercss styles",
+    "description": "Checkbox to show only Usercss styles"
+  },
   "manageOnlyUpdates": {
     "message": "Only with updates or issues",
     "description": "Checkbox to show only styles that have updates after check-all-styles-for-updates was performed"

manage.html

@@ -207,6 +207,11 @@
   <p>
     <a href="edit.html">
       <button id="add-style-label" i18n-text="addStyleLabel"></button>
+      <label class="nobreak"
+             i18n-text-append="manageNewStyleAsUsercss"
+             i18n-title="optionsAdvancedNewStyleAsUsercss">
+        <input type="checkbox" id="newStyleAsUsercss">
+      </label>
     </a>
   </p>
   <div id="options">

manage/manage.css

@@ -55,6 +55,20 @@ select {
   text-decoration: none;
 }
 
+#add-style-label {
+  margin-right: .25em;
+  margin-bottom: .25em;
+}
+
+.nobreak {
+  white-space: nowrap;
+}
+
+label.nobreak input {
+  vertical-align: middle;
+  margin: 0;
+}
+
 .firefox .chromium-only {
   display: none;
 }

options.html

@@ -125,13 +125,6 @@
         </h1>
       </div>
       <div class="items">
-        <label>
-          <span i18n-text="optionsAdvancedNewStyleAsUsercss"></span>
-          <span class="onoffswitch">
-            <input type="checkbox" id="newStyleAsUsercss">
-            <span></span>
-          </span>
-        </label>
         <label>
           <span i18n-text="optionsAdvancedExposeIframes"> <sup>2</sup></span>
           <span class="onoffswitch">