diff --git a/src/perfect-scrollbar.css b/src/perfect-scrollbar.css
index aa98c54..ea39d37 100644
--- a/src/perfect-scrollbar.css
+++ b/src/perfect-scrollbar.css
@@ -6,7 +6,7 @@
     -moz-border-radius: 4px;
     border-radius: 4px;
     opacity: 0;
-    filter: alpha(opacity = 0);
+    filter: alpha(opacity=0);
     -o-transition: background-color .2s linear, opacity .2s linear;
     -webkit-transition: background-color .2s linear, opacity .2s linear;
     -moz-transition: background-color .2s linear, opacity .2s linear;
@@ -16,20 +16,20 @@
 .ps-container:hover .ps-scrollbar-x-rail,
 .ps-container.hover .ps-scrollbar-x-rail {
     opacity: 0.6;
-    filter: alpha(opacity = 60);
+    filter: alpha(opacity=60);
 }
 
 .ps-container .ps-scrollbar-x-rail:hover,
 .ps-container .ps-scrollbar-x-rail.hover {
     background-color: #eee;
     opacity: 0.9;
-    filter: alpha(opacity = 90);
+    filter: alpha(opacity=90);
 }
 
 .ps-container .ps-scrollbar-x-rail.in-scrolling {
     background-color: #eee;
     opacity: 0.9;
-    filter: alpha(opacity = 90);
+    filter: alpha(opacity=90);
 }
 
 .ps-container .ps-scrollbar-y-rail {
@@ -50,20 +50,20 @@
 .ps-container:hover .ps-scrollbar-y-rail,
 .ps-container.hover .ps-scrollbar-y-rail {
     opacity: 0.6;
-    filter: alpha(opacity = 60);
+    filter: alpha(opacity=60);
 }
 
 .ps-container .ps-scrollbar-y-rail:hover,
 .ps-container .ps-scrollbar-y-rail.hover {
     background-color: #eee;
     opacity: 0.9;
-    filter: alpha(opacity = 90);
+    filter: alpha(opacity=90);
 }
 
 .ps-container .ps-scrollbar-y-rail.in-scrolling {
     background-color: #eee;
     opacity: 0.9;
-    filter: alpha(opacity = 90);
+    filter: alpha(opacity=90);
 }
 
 .ps-container .ps-scrollbar-x {