#cover {
             width: 100%;
             height: 100%;
             background: rgba(128,128,128,0.6);
             position: fixed; 
             top: 0; 
             left: 0; 
             z-index: 100; 
             display: none;
            }
        #cover .form-group:nth-of-type(1) { margin-top: 14%;}
        .cancel_btn { width: 40px; height: 40px;  background-image: url("../img/x.png"); background-size: 40px 40px; 
                      cursor: pointer;
                      position: absolute; right: 20px; top: 20px;
                      transition: 2s;
                  }
        .cancel_btn:hover {
         -webkit-transform:rotate(180deg);
         transition: 2s;
        }
       
       .Index_Form {   
                     position: absolute; 
                     top:50%; 
                     left: 50%; 
                     transform : translate(-50%,-50%);
                     border: 1px solid rgb(224,224,224);
                     border-radius: 4%;  
                     background: rgba(255,255,255,1);
                     display: none;
                 }
       #Login_Form { 
                  width: 360px; 
                  height: 360px;     
                   
                  }
       #Sign_Form {
                    width: 400px; 
                    height: 400px;   
                  }
       .suggestion_area { margin-top: 10px;  color: #FF0000; font-size: 0.4rem;}
       .error { color: #FF0000;}