todo.css

*{
    margin: 0;
    padding: 0;
    font-family: 'Popins', sans-serif;
    box-sizing: border-box;
}
.container{
    width: 100%;
    min-height: 100vh;
    background:linear-gradient(190deg, #153677, #4e085f,#2939) ;
    padding: 10px;
}
.todo{
    width: 100%;
    max-width: 600px;
    margin: 100px auto 22px;
    padding: 40px 30px 70px;
    background-color: #e1dede;
    border-radius: 10px;
}
.todo h2{
    margin-bottom: 35px;
    display: flex;
    align-items: center;
}
.todo h2 img{
    width: 30px;
    margin-left: 10px;
}
.row{
    display: flex;
    align-items: center;
    justify-content: space-between;
    padding-left: 20px;
    margin-bottom: 25px;
    background-color: #edeef0;
    border-radius: 30px;
}
input{
    flex: 1;
    border: none;
    outline: none;
    background: transparent;
    padding: 10px;
    font-size: 16px;
}
button{
    border: none;
    outline: none;
    background-color: goldenrod;
    font-size: 16px;
    border-radius: 40px;
    cursor: pointer;
    padding: 16px 40px;
}
button:hover{
    background-color: rgb(194, 223, 32);
}
ul li{
    list-style: none;
    font-size: 16px;
    cursor: pointer;
    user-select: none;
    padding: 12px 8px 12px 50px;
    position: relative;
}
ul li::before{
    content: '';
    height: 28px;
    width: 28px;
    position: absolute;
    background-image: url(unchecked.jpg);
    background-position: center;
    background-size: cover;
    border-radius: 50px;
    top: 12px;
    left: 8px;
}
.checked{
    color: #555;
    text-decoration: line-through;
}
.checked::before{
    background-image: url(checked.jpeg);
}
ul li span{
    width: 30px;
    height: 30px;
    font-size: 30px;
    color: #555;
    border-radius: 50%;
    top: 5px;
    right: 0;
    position: absolute;
    line-height: 35px;
    text-align: center;
}
ul li span:hover{
    background: #fff;
}