--- a/src/pyams_default_theme/resources/less/pyams-default.less	Tue Nov 20 09:00:46 2018 +0100
+++ b/src/pyams_default_theme/resources/less/pyams-default.less	Tue Nov 20 09:13:12 2018 +0100
@@ -32,7 +32,7 @@
 					position: absolute;
 					top: 10px;
 					left: 10px;
-					max-height: calc(100% - 20px);
+					max-height: ~"calc(100% - 20px)";
 				}
 			}
 		}
@@ -259,4 +259,4 @@
 			margin-top: 0.5em;
 		}
 	}
-}
\ No newline at end of file
+}