optionsUI: add a post-import update hint

_locales/en/messages.json

@@ -663,6 +663,9 @@
   "optionsUpdateIntervalNote": {
     "message": "To disable the automatic userstyle update checks, set interval to 0"
   },
+  "optionsUpdateImportNote": {
+    "message": "When importing style backups from old version or from Stylish, do a one-time check for updates manually in the styles manager to ensure all styles are updated."
+  },
   "optionsCustomizeBadge": {
     "message": "Badge on the toolbar icon"
   },

options/index.css

@@ -99,6 +99,11 @@ input[type=number]:invalid {
   color: darkred;
 }
 
+input[type="color"] {
+  box-sizing: border-box;
+  height: 2em;
+}
+
 [data-cmd="check-updates"] button {
   position: relative;
 }
@@ -152,11 +157,6 @@ input[type=number]:invalid {
   margin-bottom: 1ex;
 }
 
-input[type="color"] {
-  box-sizing: border-box;
-  height: 2em;
-}
-
 #notes a {
   color: inherit;
 }
@@ -165,6 +165,12 @@ input[type="color"] {
   color: black;
 }
 
+#notes p {
+  line-height: 1.25;
+  margin-top: 1ex;
+  margin-bottom: 1ex;
+}
+
 @keyframes fadeinout {
   0%   { opacity: 0 }
   10%  { opacity: 1 }

options/index.html

@@ -79,7 +79,10 @@
 
   <div id="notes">
     <ol>
-      <li i18n-text="optionsUpdateIntervalNote"></li>
+      <li>
+        <p i18n-text="optionsUpdateIntervalNote"></p>
+        <p i18n-text="optionsUpdateImportNote"></p>
+      </li>
       <li class="chromium-only">
         <a data-cmd="open-keyboard"
            i18n-text="optionsOpenManagerNote"