fix web端判断封面图片高度

@@ -10,8 +10,9 @@
     <van-image
       v-if="PHeader.type === '单张图'"
       width="100%"
-      height="200"
+      :height="PHeaderHeight"
       :src="PHeader.cover"
+      fit="cover"
     />
     <template v-if="PHeader.type === '轮播图'">
       <van-swipe class="my-swipe" lazy-render indicator-color="white">
@@ -50,7 +51,16 @@ import { useRoute } from "vue-router";
 import { queryFormAPI } from "@/api/form.js";
 import { addFormDataAPI } from "@/api/data.js";
 import { showSuccessToast, showFailToast } from "vant";
-
+import { wxInfo } from "@/utils/tools";
+// web端判断封面图片高度
+const is_pc = computed(() => wxInfo().isPC);
+const PHeaderHeight = computed(() => {
+  if (is_pc.value) {
+    return "35vh";
+  } else {
+    return "20vh";
+  }
+});
 // TAG: 自定义主题颜色
 const themeVars = {
   buttonPrimaryBackground: "#c2915f",