body {
    font-family: Arial, sans-serif;
    margin: 40px;
}
h1 {
    color: #333;
}
form {
    margin-bottom: 20px;
}
input {
    padding: 5px;
    font-size: 14px;
}
button {
    padding: 6px 10px;
}
ul {
    list-style-type: none;
    padding: 0;
}
li {
    margin-bottom: 10px;
}
.completed {
    text-decoration: line-through;
    color: gray;
}
a {
    margin-left: 10px;
    cursor: pointer;
    color: blue;
    text-decoration: none;
}