diff --git a/MMM-ScreenLogic.js b/MMM-ScreenLogic.js
index a0ef46a..c8d29fa 100644
--- a/MMM-ScreenLogic.js
+++ b/MMM-ScreenLogic.js
@@ -86,14 +86,14 @@ Module.register('MMM-ScreenLogic',{
                 let dataStr = poolData.status.pH
                 if (this.config.showPHTankLevel) {
                     let percent = Math.round(((poolData.status.pHTank - 1) / this.config.pHTankLevelMax) * 100)
-                    let cls = ""
+                    let cls = ''
                     if (this.config.colored) {
                         if (percent <= 50 && percent > 33) {
-                            cls = "progress-bar-warning"
+                            cls = 'progress-bar-warning'
                         } else if (percent <= 33) {
-                            cls = "progress-bar-danger"
+                            cls = 'progress-bar-danger'
                         } else {
-                            cls = "progress-bar-success"
+                            cls = 'progress-bar-success'
                         }
                     }
                     let progBarDiv = `<div class="progress vertical">