Improve frontend and add "How to use" (#3)

style.css

@@ -9,7 +9,8 @@ html {
        
 .dragndrop { 
         margin: 20%;
-        margin-top: 10%;
+        margin-top: 5%;
+        margin-bottom: 3%;
         background-color: #a3a3a3;
         padding: 1px;
         padding-top: 5%;
@@ -20,8 +21,30 @@ html {
         border-radius: 20px;
         
 }
-.dragndrop:hover { 
-
+.dragover {
         background-color: #888888;
+}
+.dragndrop:hover { 
+        background-color: #888888;
+}
 
-}
+.infobox {
+        text-align: left;
+        background: #eeeeee;
+        margin-left: 20%;
+        margin-right:20%;
+        height: 20%;
+        border-radius: 20px;
+        border: 4px solid #a3a3a3;
+        padding: 10px;
+}
+
+.footer {
+        position: fixed;
+        padding: 1%;
+        bottom: 0;
+        left: 0;
+        width: 100%;
+        text-align: center;
+        background-color: #eeeeee;
+}