#kastengruen { width: 23%;
               background-color: #2F603F;
               height: 400px;
               float: left;
               margin-right: 8px;
               padding: 3px;
             }

#kastengelb { width: 23%;
               background-color: #F09F0F;
               height: 400px;
               float: left;
               margin-right: 8px;
               padding: 3px;
             }

#kastenblau { width: 23%;
               background-color: #403880;
               height: 400px;
               float: left;
               margin-right: 8px;
               padding: 3px;
             }

#kastenrot { width: 23%;
               background-color: #7F082F;
               height: 400px;
               float: left;
               padding: 3px;
             }