Enhance/pdf enhancements (#8616)

- Improve interactions about the popup modal from the PDF viewer toolbar
- Persist highlights data with multiple-lines text format (for friendly Git diff)
- Blink the text highlight when scrolling to position
- Open the PDF viewer in the system Window

src/main/frontend/extensions/pdf/pdf.css

@@ -56,7 +56,7 @@ input::-webkit-inner-spin-button {
     position: relative;
   }
 
-&-header {
+  &-header {
     display: flex;
     justify-content: flex-end;
     position: absolute;
@@ -721,7 +721,7 @@ input::-webkit-inner-spin-button {
   }
 }
 
-#pdf-layout-container {
+.extensions__pdf-container {
   background-color: transparent;
 
   .extensions__pdf-toolbar .buttons {
@@ -980,6 +980,17 @@ body.is-pdf-active {
   }
 }
 
+html.is-system-window {
+  .extensions__pdf-container {
+    width: 100vw;
+    height: 100vh;
+  }
+
+  .extensions__pdf-loader {
+    @apply w-full;
+  }
+}
+
 /* overrides for pdf_viewer.css from PDF.JS web viewer */
 
 .textLayer {
@@ -1016,3 +1027,21 @@ body.is-pdf-active {
     border: 2px dashed #ff3434;
   }
 }
+
+.hl-flash {
+  animation-name: hl-flash;
+  animation-duration: 0.3s;
+  animation-timing-function: ease;
+  animation-iteration-count: 2;
+  animation-direction: alternate;
+  animation-play-state: running;
+}
+
+@keyframes hl-flash {
+  from {
+    opacity: 0;
+  }
+  to {
+    opacity: 1;
+  }
+}