foo.diff

diff --git a/packages/devtools-modules/client/shared/components/splitter/SplitBox.js b/packages/devtools-modules/client/shared/components/splitter/SplitBox.js
index c046762..25adc95 100644
--- a/packages/devtools-modules/client/shared/components/splitter/SplitBox.js
+++ b/packages/devtools-modules/client/shared/components/splitter/SplitBox.js
@@ -110,6 +110,8 @@ const SplitBox = React.createClass({
     const win = doc.defaultView;
 
     let size;
+    let ratio = win.devicePixelRatio || 1;
+
     let { endPanelControl } = this.props;
 
     if (this.state.vert) {
@@ -120,7 +122,7 @@ const SplitBox = React.createClass({
         endPanelControl = !endPanelControl;
       }
 
-      let innerOffset = x - this.screenX();
+      let innerOffset = (x / ratio) - this.screenX();
       size = endPanelControl ?
         (node.offsetLeft + node.offsetWidth) - innerOffset :
         innerOffset - node.offsetLeft;
@@ -129,7 +131,7 @@ const SplitBox = React.createClass({
         width: size
       });
     } else {
-      let innerOffset = y - this.screenY();
+      let innerOffset = (y / ratio) - this.screenY();
       size = endPanelControl ?
         (node.offsetTop + node.offsetHeight) - innerOffset :
         innerOffset - node.offsetTop;
@@ -186,7 +188,7 @@ const SplitBox = React.createClass({
 
     // Calculate splitter size
     let splitterStyle = {
-      flex: "0 0 " + splitterSize + "px"
+      flex: `0 0 ${ splitterSize }px`
     };
 
     return (