index.css

*{
    margin: 0;
    padding:0;
    box-sizing: border-box;
}
body{
    height: 100vh;
    display: flex;
    align-items: center;
    justify-content: center;
    background-color: #3C0753;
    font-family:Arial, Helvetica, sans-serif;
}
.container{
    background-color: white;
    padding: 1rem;
    width:30rem;
    min-height:20rem;
    border-radius: 15px;
}
h3{
    color:030637;
    text-align: center;
}
.form{
    background-color: #edeef0;
    display: flex;
    align-items: center;
    justify-content: center;
    border-radius:20px;
    padding: 0;
    margin-top: 2rem;
    height:3rem;
}
#inputTask{
    border-radius: 15px;
    margin:2rem 0;
    width:80%;
    padding:9px;
    border: none;
    outline: none;
    background-color: transparent;
}
#add
{
    background-color:rebeccapurple;
    color: white;
    font-weight: bold;
    width:5.5rem;
    padding:15px;
    border-radius: 40px;
    margin: 0;
    border: none;
    outline: none;
    cursor: pointer;
}
#add:disabled{
    background-color:hsl(282, 49%, 47%);
    cursor:not-allowed;
}
.content{
    display: flex;
    justify-content: space-between;
    align-items: center;
    margin-top: 2rem;
    margin-left: 1rem;
}
ul{
    width: 98%;
}
ul li{
    list-style: none;
    cursor: pointer;
    padding: 12px 8px 12px 50px;
    user-select: none;
    position: relative;
    width: 100%;
    word-wrap: break-word;
}
ul li::before{
    content: '';
    position: absolute;
    background-image:url('https://cdn.iconscout.com/icon/premium/png-512-thumb/radio-9260035-7565719.png?f=webp&w=256');
    height: 20px;
    width: 20px;
    background-size: cover;
    background-position: center;
    top: 12px;
    left:5px;
}
ul li.checked{
    color:#555;
    text-decoration: line-through;
}
ul li.checked::before{
    background-image: url('assets/480px-Eo_circle_purple_white_checkmark.svg.png');
    height:20px;
    width: 20px;
}
ul li span{
    position:absolute;
    right:0;
    top:3px;
    width:40px;
    height:40px;
    font-size: 22px;
    color: #555;
    line-height: 40px;
    text-align: center;
}
ul li span:hover{
    background-color: #edeef0;
    border-radius: 40px;
}