index.css

*{
    margin:0;
    padding:0;
    font-family: 'Poppins',sans-serif;
    box-sizing: border-box;
}
.container{
    width:100%;
    min-height:100vh;
    background: linear-gradient(135deg,#153677,#4e085f);
    padding:10px;
}
.todo-app{
    width:100%;
    max-width:540px;
    background: #fff;
    margin:100px auto 20px;
    padding:40px 30px 70px;
    border-radius:10px
}
.todo-app h2{
    color: #002765;
    display:flex;
    align-items:center;
    margin-bottom:20px;

}
.todo-app h2 img{
    width:30px;
    margin-left: 10px;
}
.row{
    display:flex;
    align-items:center;
    justify-content:space-between;
    background: #edeef0;
    border-radius:30px;
    padding-left:20px;
    margin-bottom: 25px;

}
input{
    flex:1;
    border:none;
    outline: none;
    background: transparent;
    padding:10px;
    font-weight: 14px;
}
button{
    border:none;
    outline: none;
    padding: 16px 50px;
    background: #ff5945;
    color:#fff;
    font-size:16px;
    cursor:pointer;
    border-radius: 40px;


}
ul li{
    list-style: none;
    font-size:17px;
    padding: 12px 8px 12px 50px;
    user-select: none;
    cursor:pointer;
    position:relative;
}
ul li::before{
    content: '';
    position:absolute;
    height:28px;
    width:28px;
    border-radius:50px;
    background-image: url("./To-Do-Img/images/unchecked.png");  /*image link unchecked*/
    background-size:cover;
    background-position: center;
    top:12px;
    left:8px
}
ul li.checked{
    color:#555;
    text-decoration: line-through;
}
ul li.checked::before{  /*image link checked*/
    background-image: url("./To-Do-Img/images/checked.png");
}
ul li span{
    position: absolute;
    right: 0;
    top:5px;
    width: 40px;
    height: 40px;
    font-size:22px;
    color:#555;
    line-height: 40px;
    text-align: center;
    border-radius: 50%;
}
ul li span:hover{
    background: #edeef0;

}