add `<<imageMain>>`

(cherry picked from commit c7787c4a6ab44ddd4883cb286d078dd68ed7d295)

sugarcube/src/macros/media/image.tw

@@ -39,6 +39,13 @@
     <<image _pathDayNight>>
 <</widget>>
 
+<<widget 'imageMain'>>
+    <<image _args[0] _args[1] _args[2] _args[3]>>
+    <<id 'imageMain'>>
+        <<image _args[0] _args[1] _args[2] _args[3]>>
+    <</id>>
+<</widget>>
+
 <<widget 'imageWithTooltip' container>>
     <<if !$tooltipCounter>><<set $tooltipCounter = 0>><</if>>
     <<set $tooltipCounter = $tooltipCounter % 1000000>>

sugarcube/src/style/images.css

@@ -13,3 +13,15 @@ img, video{
     margin: 0 auto;
     max-width: 100%;
 }
+
+img#imageMain {
+    filter: blur(8px);
+    position: absolute;
+    left: 0;
+    width: 100%;
+    max-height: calc(100vh - 2em);
+    opacity: 0.3;
+    top: 2em;
+    z-index: -1000000;
+    max-width: unset;
+}