fix 多媒体存在多余字段

src/features/mark/MultiMediaMarkBody.vue

@@ -132,6 +132,7 @@ watch(
             questionBody.unionOrder ===
             [v.mainNumber, v.subNumber, v.subIndex]
               .filter((v) => typeof v !== "undefined")
+              .filter((v) => v !== null)
               .join("-")
         ) || {
           mainNumber: +mainNumber,
@@ -170,6 +171,7 @@ watch(
             questionBody.unionOrder ===
             [v.mainNumber, v.subNumber, v.subIndex]
               .filter((v) => typeof v !== "undefined")
+              .filter((v) => v !== null)
               .join("-")
         ) || {
           mainNumber: +mainNumber,

src/styles/cssvar.css

@@ -14,4 +14,6 @@
   --app-main-font-size: 14px;
   --app-secondary-font-size: 12px;
   --app-title-font-size: 16px;
+
+  /* FIXME: z-index 应该用var来代表的 */
 }