main.css

body {
    background: #fff;
    color: black;
    font-family: sans-serif;
}

.container {
   float: left;
    margin-top: -10px;
    padding-bottom: 100px;
}

ul {
    margin: 5px 0;
    padding: 0;
}

li * {
    float: left;
}

li, h3 {
    clear: both;
    list-style: none;
}

input, button {
    outline: none;
}

button {
    background: none;
    border: 0px;
    color: #888;
    font-size: 15px;
    font-family: sans-serif;
    cursor: pointer;
    float: right;
    margin: 8px auto;
}

button:hover {
    color: black;
}

#add:hover {
    border-radius: 14px;
    border: 1px solid #ddd;
}

#add {
    float: right;
    padding: 10px;
    margin-top: 0;
    border: 1px solid #000000;
    border-radius: 50px;
}

h3 {
    color: black;
    font-weight: bold;
    font-size: 15px;
    border-bottom: 2px solid black;
    padding: 10px 250px;
    margin: 0 0 10px;
    text-transform: uppercase;
    /* background: #4a76a8; */
    border-radius: 50px;
}

input[type="text"] {
    margin: 1px 0;
    font-size: 18px;
    line-height: 18px;
    height: 18px;
    padding: 10px;
    border: 1px solid #ddd;
    background: #fff;
    border-radius: 6px;
    font-family: sans-serif;
    color: #888;
}

input[type="text"]:focus {
    color: black;
}

label[for='new-task'] {
    display: block;
    margin: 0 0 20px;
}

input#new-task {
    float: left;
    width: 487px;
}

p > button:hover {
    color: #0FC57C;
}

li {
    overflow: hidden;
    border-bottom: 1px solid #eee;
}

li > input[type="checkbox"] {
    margin: 0 10px;
    position: relative;
    top: 15px;
    transform: scale(1.5);
}

li > label {
    font-size: 18px;
    line-height: 40px;
    width: 237px;
    padding: 1px 0 0 11px
}

li > input[type="text"] {
    width: 457px;
}

li > .delete:hover {
    color: #CF2323;
}

#finished-tasks label, #finished-tasks button {
    text-decoration: line-through;
    color: lightgray;
}

ul li input[type=text] {
    display: none;
}

ul li.editMode input[type=text] {
    display: block;
}

ul li.editMode label {
    display: none;
}

button.checkbox {
    float: left;
}