style.css

body{
    background-color: #113f67;
}
#container {
    width: auto;
    /*height: auto;*/
    margin: 0 auto;
    text-align: center;
    background: white;
    height: 900px;
    overflow: auto;
    color: #007065;
   /* border: 5px solid #24edb7;*/
    border-radius: 0px;
}
#container h1 {
    margin-top: 50px;
    margin-bottom: 50px;
    text-transform: capitalize;
    font-family: 'Coda Caption', sans-serif;
    font-family: 'Dancing Script', cursive;


}
#container ul{
    margin-top: 50px;
    padding-left: 0;
}
 #container ul li{
    list-style: none;
   border: 2px solid indigo;
    width: 50%;
    opacity: 0;
    transition: opacity 0.5s ease-in-out;
    height: 30px;
    margin: 5px auto;
    text-align: left;
}
#container ul li label{
    margin: 0 auto;
    vertical-align: middle;
    height: 100%;
    line-height: 30px;
    font-size: 20px;
    font-style: italic;

}

#container ul li #check{
    float: left;
    width: 20px;
    height: 20px;
    margin: 5px;
    -webkit-appearance: none;
   border: 2px solid #db2323;
     border-radius: 50px;
    position: relative;
    outline: 0;
}

#container ul li #check:checked::after {
    content: '\2714';
    font-size: 20px;
    position: absolute;
    top: -6px;
    left: 1px;
    color: black;
}

#container ul li input[type='checkbox']:checked+label{
    text-decoration: line-through;
    color: black
}
#container .controls {
    width: 60%;
    margin: auto;
}

#container .controls #input{
    width: 50%;
    height: 30px;
    font-size: 20px;
    padding-left: 5px;
    box-sizing: border-box;
    margin-bottom: 20px;
    /*border: 2px solid #db2323;*/
    border-radius: 10px;
}
#container .controls #input:focus {
    outline: 0;

}

#container .controls button{
    width: 20%;
    background: white;
    border: none;
    height: 30px;
    margin-top: 2px;
    cursor: pointer;
    color: #f5c181;

}
#container .controls button:focus{
    outline: 0;
}

#container .controls button:hover{
    transform: scale(1.05);
}
#container .controls #add{
    background-color: #113f67;
    border-radius: 10px;
}
#container .controls #remove {
    background-color: #e63946;
    border-radius: 10px;

}
#container .mycheck {
    opacity: 1;
    border-radius: 10px;
}
.visual {
    opacity: 1 !important;
    border-radius: 10px;
}