Enable the Stylelint declaration-block-no-duplicate-properties rule (issue 16995)

Please refer to https://stylelint.io/user-guide/rules/declaration-block-no-duplicate-properties

.stylelintrc

@@ -7,6 +7,7 @@
     "prettier/prettier": true,
 
     "block-no-empty": true,
+    "declaration-block-no-duplicate-properties": true,
     "declaration-block-no-redundant-longhand-properties": true,
     "declaration-property-value-disallowed-list": {
       "float": ["inline-start", "inline-end"]

web/annotation_editor_layer_builder.css

@@ -717,7 +717,6 @@
 
       & .radioButton {
         display: flex;
-        align-items: flex-start;
         gap: 8px;
         align-self: stretch;
         align-items: center;

web/text_layer_builder.css

@@ -86,7 +86,7 @@
   /*#if !MOZCENTRAL*/
   background: blue;
   /*#endif*/
-  background: AccentColor;
+  background: AccentColor; /* stylelint-disable-line declaration-block-no-duplicate-properties */
 }
 
 /* Avoids https://github.com/mozilla/pdf.js/issues/13840 in Chrome */