style.css

/* Styles are taken from https://github.com/monterail/vuelidate */
@import url("http://use.fontawesome.com/releases/v5.0.1/css/all.css");
body {
    width: 40%;
    margin: 0 auto;
    font-family: "Lato", sans-serif;
}
input {
    font-family: "Lato", sans-serif;
    font-size: 0.875rem;
    font-weight: 300;
    color: #374853;
    line-height: 2.375rem;
    min-height: 2.375rem;
    position: relative;
    border: 1px solid #E8E8E8;
    border-radius: 5px;
    background: #fff;
    padding: 0 0.8125rem;
    width: 100%;
    transition: border .1s ease;
    box-sizing: border-box;
}
input.error, input.error:focus {
    border-color: #f79483;
}
input.valid, input.valid:focus {
    border-color: #41B883;
}
input:focus {
    border-color: #a8a8a8;
    outline: none;
}
label {
    font-size: 0.8125rem;
    color: #4b6372;
    margin-bottom: 0.3125rem;
    margin-left: 0.875rem;
    display: block;
}
.form-group {
    margin-bottom: 2rem;
}
.error-message {
    display: block;
    color: #f57f6c;
}
h1 {
    color: #374853;
}
button {
    font-family: "Lato", sans-serif;
    font-size: 0.875rem;
    font-weight: 300;
    color: #fff;
    min-height: 2.5rem;
    line-height: 1.4;
    padding: 0.5rem 1.875rem 0.625rem;
    box-sizing: border-box;
    position: relative;
    display: inline-block;
    background: #41B883;
    border: none;
    border-radius: 5px;
    z-index: 1;
    overflow: hidden;
    outline: none;
    vertical-align: middle;
    transition: 0.1s background ease, 0.1s border-color ease, 0.1s color ease;
    border-bottom: 3px solid #266d4d;
    text-decoration: none;
}
button:hover, button:focus {
    background: #349268;
    cursor: pointer;
}
button:disabled {
    background: #ccc6c6;
    border-bottom: 3px solid #b3b1b1;
    cursor: not-allowed;
}

input[type=checkbox] {
    visibility: hidden;
    font-size: 1.33333333em;
    line-height: .75em;
    vertical-align: -10%;
    position: relative;
    left: 5px;
    color: #555 !important;
    font-weight: 200;
    letter-spacing: 1px;
}


input[type=checkbox]:before {
    font-family: 'Font Awesome 5 Free' !important;
    display: inline-block !important;
    visibility: visible !important;
}

input[type=checkbox]:before {
    font-weight: 400;
    content: "\f0c8";
}

input[type=checkbox]:checked:before {
    font-weight: 900;
    content: "\f14a";
}

.github-username {
    position: relative;
}

.github-username .fa-spinner {
    position: absolute;
    top: 33px;
    right: 10px;
}