body {
    margin: 0;
    min-width: 300px;
}

ul {
    margin: 0;
    padding: 0;
}

ul li {
    cursor: pointer;
    position: relative;
    padding: 10px 8px 10px 50px;
    font-size: 20px;
    transition: 0.5s;
}

ul li:hover {
    background: #e6e6e6;
}

ul li.checked {
    text-decoration: line-through;
}

ul li.checked::before {
    content: '';
    position: absolute;
    border-color: black;
    border-style: solid;
    border-width: 0 2px 2px 0;
    top: 10px;
    left: 16px;
    transform: rotate(45deg);
    height: 10px;
    width: 5px;
}

.addBtn:hover {
    background-color: gray;
}
.addBtn {
    padding: 6px;
    text-align: center;
    cursor: pointer;
    border-radius: 0;
}

.remove {
    position: absolute;
    right: 0;
    top: 0;
    padding 10px 15px 10px 15px;
}

.remove:hover {
    background-color: gray;
    color: white;
}