--- a/mail/themes/linux/mail/messageHeader.css
+++ b/mail/themes/linux/mail/messageHeader.css
@@ -76,19 +76,21 @@
   -moz-appearance: treetwistyopen;
 }
 
 #attachmentToggle:focus {
   outline: 1px dotted Highlight;
 }
 
 #attachmentIcon {
-  list-style-image: url("chrome://messenger/skin/icons/filterbar.png");
-  -moz-image-region: rect(0px, 80px, 16px, 64px);
+  list-style-image: url("chrome://messenger/skin/icons/attach.svg");
   margin-inline-start: 5px;
+  -moz-context-properties: fill, fill-opacity;
+  fill: currentColor;
+  fill-opacity: var(--toolbarbutton-icon-fill-opacity);
 }
 
 #attachmentName:hover,
 #attachmentName[selected="true"] {
   cursor: pointer;
   color: HighlightText;
   background-color: Highlight;
 }

--- a/mail/themes/osx/mail/messageHeader.css
+++ b/mail/themes/osx/mail/messageHeader.css
@@ -52,18 +52,21 @@
   -moz-appearance: treetwistyopen;
 }
 
 #attachmentToggle:focus {
   outline: 1px dotted Highlight;
 }
 
 #attachmentIcon {
-  list-style-image: url("chrome://messenger/skin/icons/attachment.png");
+  list-style-image: url("chrome://messenger/skin/icons/attach.svg");
   margin-inline-start: 5px;
+  -moz-context-properties: fill, fill-opacity;
+  fill: currentColor;
+  fill-opacity: var(--toolbarbutton-icon-fill-opacity);
 }
 
 #attachmentName:hover,
 #attachmentName[selected="true"] {
   cursor: pointer;
   background: linear-gradient(#F9CE90, #F6A942); /* orange gradient */
 }
 

--- a/mail/themes/windows/mail/messageHeader.css
+++ b/mail/themes/windows/mail/messageHeader.css
@@ -53,20 +53,16 @@
   -moz-user-focus: normal;
   list-style-image: url("chrome://global/skin/tree/twisty.svg#clsd");
 }
 
 #attachmentToggle[checked="true"] {
   list-style-image: url("chrome://global/skin/tree/twisty.svg#open");
 }
 
-#attachmentIcon {
-  margin-inline-start: 5px;
-}
-
 #attachmentName:hover,
 #attachmentName[selected="true"] {
   cursor: pointer;
   color: HighlightText;
   background-color: Highlight;
 }
 
 #attachmentSize {
@@ -288,17 +284,21 @@ mail-emailaddress[selected="true"] .emai
   }
 }
 
 #expandedBoxSpacer {
   height: 6px;
 }
 
 #attachmentIcon {
-  list-style-image: url("chrome://messenger/skin/icons/attachment-col.png");
+  list-style-image: url("chrome://messenger/skin/icons/attach.svg");
+  margin-inline-start: 5px;
+  -moz-context-properties: fill, fill-opacity;
+  fill: currentColor;
+  fill-opacity: var(--toolbarbutton-icon-fill-opacity);
 }
 
 #attachmentToggle:hover {
   list-style-image: url("chrome://global/skin/tree/twisty.svg#clsd-hover");
 }
 
 #attachmentToggle[checked="true"]:hover {
   list-style-image: url("chrome://global/skin/tree/twisty.svg#open-hover");