gallery.accords-library.com/static/css/forms.css

form {
    display: block;
    width: 20em;
}
form fieldset {
    margin: 0;
    padding: 0;
    border: 0;
}
form fieldset legend {
    display: block;
    text-align: center;
    width: 100%;
    font-size: 17pt;
}
form ul {
    list-style-type: none;
    margin: 0;
    padding: 0;
}
form ul li {
    margin-top: 0.5em;
}
form .buttons {
    margin-top: 1em;
}
form .input li:first-child label,
form .input li:first-child {
    padding-top: 0;
    margin-top: 0;
}

form.tabular ul {
    display: table;
    border-spacing: 0.5em;
    margin: 0.5em -0.5em;
    width: 100%;
}
form.tabular ul li {
    display: table-row;
}
form.tabular ul li label {
    display: table-cell;
    width: 33%;
    padding: 0;
}
form.tabular .buttons {
    margin-left: 33%;
}

form:not(.tabular) ul li label {
    display: block;
    padding: 0.5em 0;
}

input[type=radio], input[type=checkbox] {
    float: left;
    display: none;
}

.radio, .checkbox {
    box-sizing: border-box;
    position: relative;
    display: inline-block;
    padding-left: calc(20px + 0.5em) !important;
    vertical-align: middle;
    cursor: pointer;
}
.radio:hover:before, .checkbox:hover:before {
    border-color: var(--main-color);
}
.radio:before, .checkbox:before {
    transition: border-color 0.1s linear;
    position: absolute;
    top: 50%;
    left: 0;
    display: block;
    margin-top: -10px;
    width: 16px;
    height: 16px;
    border: 2px solid var(--input-background-color);
    background: var(--input-border-color);
    content: '';
}
input[type=radio]:checked + .radio:before,
input[type=checkbox]:checked + .checkbox:before {
    border-color: var(--main-color);
}
input[type=radio]:checked + .radio:after,
input[type=checkbox]:checked + .checkbox:after {
    opacity: 1;
}

.radio:after {
    transition: opacity 0.1s linear;
    position: absolute;
    top: 50%;
    left: 5px;
    display: block;
    margin-top: -5px;
    width: 10px;
    height: 10px;
    border-radius: 50%;
    content: '';
    opacity: 0;
}
.checkbox:after {
    transition: opacity 0.1s linear;
    position: absolute;
    top: 50%;
    left: 6px;
    display: block;
    margin-top: -7px;
    width: 5px;
    height: 9px;
    border-right: 3px solid var(--main-color);
    border-bottom: 3px solid var(--main-color);
    content: '';
    opacity: 0;
    transform: rotate(45deg);
}

textarea,
input[type=text],
input[type=email],
input[type=password] {
    transition: border-color 0.1s linear, background-color 0.1s linear;
    font-size: 100%;
    font-family: 'Inconsolata', monospace;
    padding: 0.3em;
    border: 2px solid var(--input-background-color);
    background: var(--input-border-color);
    text-overflow: ellipsis;
    width: 100%;
    box-sizing: border-box;
    box-shadow: none; /* :-moz-submit-invalid on FF */
}

textarea:focus,
input[type=text]:focus,
input[type=email]:focus,
input[type=password]:focus {
    border-color: var(--main-color);
}

form.show-validation fieldset.input input:invalid {
    outline: none;
    border: 2px solid var(--input-bad-border-color);
    background: var(--input-bad-background-color);
}
form.show-validation fieldset.input input:valid {
    outline: none;
    border: 2px solid var(--input-good-border-color);
    background: var(--input-good-background-color);
}

button,
input[type=button],
input[type=submit] {
    cursor: pointer;
    font-size: 100%;
    line-height: 100%;
    padding: 0.3em 0.7em;
    border: 1px solid var(--main-color);
    background: var(--main-color);
    color: white;
}