style.css

@import url('https://fonts.googleapis.com/css2?family=Kalam&display=swap');

*{
    margin: 0;
    padding: 0;
    font-family: 'Kalam', cursive;
    box-sizing: border-box;
}
.container{
  width: 100%;
  min-height: 100vh;
  background: url("assets/ToDo_BG3.jpg");
  background-size: cover;
  background-repeat: no-repeat;
  padding: 10px;
}
.todo-app{
    width: 100%; 
    max-width: 400px;
    background: rgba(255, 255, 255, 0.2);
    box-shadow: 0 4px 30px rgba(0, 0, 0, 0.1);
    backdrop-filter: blur(30.1px);
    border: 2px solid rgba(255, 255, 255, 0.7);
    -webkit-backdrop-filter: blur(3.1px);
    color: #030303;    
    margin: 50px auto 20px;
    padding: 40px 30px 70px;
    border-radius: 10px;
} 
.todo-app h2{
color: #050606;
display: flex;
align-items: center;
justify-content:center;
margin-bottom: 20px;
}
.todo-app img{
    width: 30px;
    margin-left: 10px;
}
.row{
    display: flex;
    align-items:center;
    justify-content: space-between;
    background:#fff;
    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:gray;
    color:#fff;
    font-size: 15px;
    border-radius: 40px;
    cursor: pointer;
}
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(assets/unchecked.png);
    background-size: cover;
    background-position: center;
    top: 8px;
    left: 8px;
}
ul li.checked{
    color: #555;
    text-decoration:line-through;
}
ul li.checked::before{
    background-image: url(assets/checked.png);
}
ul li span{
    position: absolute;
    right: 0;
    top: 4px;
 width: 40px;
 height: 40px;
 font-size: 25px;
 color: #555;
 line-height: 40px;
 text-align:center;
 border-radius: 50%;
}
ul li span:hover{
    background:#fdfcfb;
}