Feature/improved signature element (#2489)

# Description

Please provide a summary of the changes, including relevant motivation
and context.

Closes #(issue_number)

## Checklist

- [ ] I have read the [Contribution
Guidelines](https://github.com/Stirling-Tools/Stirling-PDF/blob/main/CONTRIBUTING.md)
- [ ] I have performed a self-review of my own code
- [ ] I have attached images of the change if it is UI based
- [ ] I have commented my code, particularly in hard-to-understand areas
- [ ] If my code has heavily changed functionality I have updated
relevant docs on [Stirling-PDFs doc
repo](https://github.com/Stirling-Tools/Stirling-Tools.github.io/blob/main/docs/)
- [ ] My changes generate no new warnings
- [ ] I have read the section [Add New Translation
Tags](https://github.com/Stirling-Tools/Stirling-PDF/blob/main/HowToAddNewLanguage.md#add-new-translation-tags)
(for new translation tags only)

---------

Co-authored-by: Anthony Stirling <77850077+Frooodle@users.noreply.github.com>
Co-authored-by: Reece Browne <reece@stirling.pdf>

src/main/resources/static/css/fileSelect.css

@@ -118,6 +118,7 @@
   row-gap: 1px;
   height: 60px;
   width: 60px;
+  top:4px;
 }
 
 .file-icon {
@@ -165,8 +166,8 @@
   height: 15px;
   width: 15px;
 
-  right: 10px;
-  top: -5px;
+  right: 0px;
+  top: -17px;
 }
 
 .remove-selected-file * {
@@ -219,3 +220,54 @@
   border-radius: 1rem;
   border: 1px solid rgb(105, 116, 134, 0.5);
 }
+
+.draggable-image-overlay{
+  position: absolute;
+  background: rgba(0, 0, 0, 0.7);
+  display: none;
+  z-index: 10;
+  align-items: center;
+  justify-content: center;
+  color: white;
+  font-size: 16px;
+  font-weight: bold;
+  pointer-events: none;
+  left:0;
+  top:0;
+  height:100%;
+  width:100%;
+  border-radius: 1rem;
+}
+
+.small-file-container:hover .drag-icon {
+  display: flex;
+}
+
+.drag-icon {
+  display: none;
+  position: absolute;
+  top: 5px;
+  width: 20px;
+  height: 20px;
+  background: rgba(0, 0, 0, 0.5);
+  color: white;
+  align-items: center;
+  justify-content: center;
+  border-radius: 50%;
+  font-size: 14px;
+  pointer-events: none;
+  z-index: 1;
+}
+
+#imagePreviewModal {
+  position: fixed;
+  top: 0;
+  left: 0;
+  width: 100vw;
+  height: 100vh;
+  background-color: rgba(0, 0, 0, 0.5);
+  display: none;
+  justify-content: center;
+  align-items: center;
+  z-index: 9999;
+}