🐛 fix https://github.com/siyuan-note/siyuan/issues/6442

app/appearance/themes/daylight/theme.css

@@ -150,13 +150,7 @@
     --b3-pdf-background5: #f5539e;
     --b3-pdf-background6: var(--b3-theme-primary);
     --b3-pdf-background7: #944194;
-}
-
-/* PDF */
-.textLayer,
-.pdf__resize {
-    /* dark 蓝色、紫色背景显示不清楚，文档位于 https://github.com/siyuan-note/siyuan/issues/5351 */
-    mix-blend-mode: multiply;
+    --b3-pdf-dark: #212224;
 }
 
 .b3-typography div.hljs, .protyle-wysiwyg div.hljs {

app/appearance/themes/midnight/theme.css

@@ -150,12 +150,7 @@
     --b3-pdf-background5: #f5539e;
     --b3-pdf-background6: var(--b3-theme-primary);
     --b3-pdf-background7: #944194;
-}
-
-/* PDF */
-.textLayer,
-.pdf__resize {
-    mix-blend-mode: screen;
+    --b3-pdf-dark: #212224;
 }
 
 .b3-text-field::-webkit-calendar-picker-indicator {

app/src/assets/scss/pdf/_pdf.scss

@@ -29,6 +29,12 @@
     width: 100%;
     height: 100%;
     position: relative;
+
+    .textLayer,
+    .pdf__resize {
+      /* dark 蓝色、紫色背景显示不清楚，文档位于 https://github.com/siyuan-note/siyuan/issues/5351 */
+      mix-blend-mode: multiply;
+    }
   }
 
   &__util {
@@ -75,10 +81,22 @@
   }
 }
 
-.pdf__outer--dark .pdfViewer .page canvas,
-.pdf__outer--dark .thumbnailImage {
-  filter: grayscale(0%) invert(100%) contrast(100%) brightness(100%) hue-rotate(180deg);
+.pdf__outer--dark {
+  .pdfViewer .page canvas,
+  .thumbnailImage {
+    filter: grayscale(0%) invert(100%) contrast(100%) brightness(100%) hue-rotate(180deg);
+  }
+
+  .textLayer {
+    background-color: var(--b3-pdf-dark);
+  }
+
+  .textLayer,
+  .pdf__resize {
+    mix-blend-mode: screen;
+  }
 }
+
 .annotationLayer section:not(.linkAnnotation) {
   display: none;
 }

app/src/assets/scss/pdf/text_layer_builder.scss

@@ -22,7 +22,6 @@
   bottom: 0;
   overflow: hidden;
   // NOTE
-  background-color: var(--b3-theme-background);
   line-height: 1;
   text-size-adjust: none;
 }