fix bug

public/content/content.json

@@ -43,8 +43,7 @@
       "youtube": "https://www.youtube.com/watch?v=T5jF20yXcWw",
       "demo": "http://193.196.37.89:8083/visionzero/",
       "publication":"https://doi.org/10.5194/isprs-annals-VI-4-W2-2020-143-2020", 
-      "project":"https://www.hft-stuttgart.de/forschung/i-city", 
-
+      "project":"https://www.hft-stuttgart.de/forschung/i-city"
     },
     "refIndex": 2
   },

public/js/add_content.js

@@ -31,23 +31,23 @@ function addcontent(item) {
     var ExploreHTML = ''
     if ('demo' in item.links) { 
       var ExploreLink = item.links.demo 
-      ExploreHTML = `<a class="btn btn-sm btn-outline-secondary" href="${ExploreLink}" target="_blank"> <i class="fas fa-search"></i> Explore</a>`
+      ExploreHTML = `<a class="btn btn-sm btn-outline-secondary mt-1" href="${ExploreLink}" target="_blank"> <i class="fas fa-search"></i> Explore</a>`
     }
 
     var publicationHTML = ''
     if ('publication' in item.links) {
       var publicationLink = item.links.publication 
-      publicationHTML = `<a class="btn btn-sm btn-outline-primary" href="${publicationLink}" target="_blank"> <i class="fas fa-book"></i> Publication</a>`
+      publicationHTML = `<a class="btn btn-sm btn-outline-primary mt-1" href="${publicationLink}" target="_blank"> <i class="fas fa-book"></i> Publication</a>`
     }
     var projectHTML = ''
     if ('project' in item.links) {
       var projectLink = item.links.project 
-      projectHTML = `<a class="btn btn-sm btn-outline-primary" href="${projectLink}" target="_blank"> <i class="fas fa-project-diagram"></i> Project</a>`
+      projectHTML = `<a class="btn btn-sm btn-outline-success mt-1" href="${projectLink}" target="_blank"> <i class="fas fa-project-diagram"></i> Project</a>`
     }
     var presentationHTML = ''
     if ('presentation' in item.links) {
       var presentationLink = item.links.presentation 
-      presentationHTML = `<a class="btn btn-sm btn-outline-primary" href="${presentationLink}" target="_blank"> <i class="fas fa-file-powerpoint"></i> Presentation</a>`
+      presentationHTML = `<a class="btn btn-sm btn-outline-warning mt-1" href="${presentationLink}" target="_blank"> <i class="fas fa-file-powerpoint"></i> Presentation</a>`
     }
 
     new_row.innerHTML = new_row.innerHTML + '<div class="col-lg-4">' +