Ghost/ghost/admin/app/styles/components/power-select.css

.ember-power-select-trigger {
    padding: 0 16px 0 8px;
    border: 1px solid color-mod(var(--lightgrey) l(-5%) s(-5%));
    border-radius: var(--border-radius);
    background: transparent;
}

.ember-power-select-trigger:focus, .ember-power-select-trigger--active {
    border: 1px solid color-mod(var(--lightgrey) l(-5%) s(-5%));
}

.ember-power-select-trigger svg {
    height: 4px;
    width: 6.11px;
    margin-left: 2px;
    margin-top: -2px;
    vertical-align: middle;
}

.ember-power-select-trigger svg path {
    stroke: var(--darkgrey);
}

.ember-power-select-search {
    padding: 2px 0 3px 0 !important;
}

.ember-basic-dropdown--opened > .ember-power-select-trigger,
.ember-power-select-trigger[aria-expanded="true"],
.ember-power-select-search input {
    outline: 0;
    border-color: color-mod(var(--whitegrey) a(70%) s(-10%));
}

.ember-power-select-dropdown {
    position: absolute;
    z-index: 1000;
    box-sizing: border-box;
    margin: 0;
    border: 1px solid color-mod(var(--whitegrey) a(70%) s(-10%));
    border-top: 0 none;
    background: #fff;
    border-radius: 0 0 var(--border-radius) var(--border-radius);
    box-shadow: 0 18px 45px -5px rgba(0, 0, 0, 0.15);
}

.ember-power-select-dropdown.ember-basic-dropdown-content--in-place {
    padding: 4px 0;
    border-bottom-color: color-mod(var(--whitegrey) a(70%) s(-10%));
    border-top: 1px solid color-mod(var(--whitegrey) a(70%) s(-10%));
}

.ember-power-select-option {
    margin: 0;
    padding: 6px 14px;
    color: var(--darkgrey);
}

.ember-power-select-option[aria-current="true"] {
    background: color-mod(var(--whitegrey) a(60%) s(-12%));
    color: var(--darkgrey);
}

.ember-power-select-option[aria-selected="true"] {
    color: var(--darkgrey);
    font-weight: 700;
    background: transparent;
}

.ember-power-select-options:not([role="group"]) {
    max-height: 50vh;
}

.ember-power-select-search input {
    display: inline-block !important;
    margin: 0 1px !important;
    padding: 0 !important;
    min-height: 0 !important;
    height: 27px;
    width: calc(100% - 8px) !important;
    max-width: 100% !important;
    max-height: none !important;
    border: 0 none !important;
    background: none !important;
    box-shadow: none !important;
    text-indent: 0 !important;
    font-size: 1.4rem;
    font-weight: 400;
    line-height: inherit !important;
}

.ember-power-select-group {
    float: left;
    box-sizing: border-box;
    width: 100%;
    border-top: 0 none;
}

.ember-power-select-group .ember-power-select-group-name {
    position: relative;
    display: inline-block;
    padding: 7px 12px;
    cursor: default;
    text-transform: uppercase;
    color: var(--midlightgrey);
    white-space: nowrap;
    letter-spacing: 0.1px;
    font-size: 1.2rem;
    font-weight: 500;
}

.ember-power-select-group .ember-power-select-group-name:after {
    content: "";
    position: absolute;
    top: 60%;
    left: calc(100% - 3px);
    display: block;
    width: calc(540px - 100%);
    height: 1px;
    border-bottom: color-mod(var(--lightgrey) l(-5%)) 1px solid;
}

@media (max-width: 900px) {
    .ember-power-select-group .ember-power-select-group-name:after {
        width: calc(524px - 100%);
    }
}

@media (max-width: 600px) {
    .ember-power-select-group .ember-power-select-group-name:after {
        width: calc(80vw - 45px - 100%);
    }
}

.ember-power-select-group:first-of-type .ember-power-select-group-name {
    margin: 8px 0;
    padding-top: 0;
    padding-bottom: 0;
}

.ember-power-select-group:first-of-type .ember-power-select-group-name:after {
    top: 66%;
}

.ember-power-select-group:last-of-type {
    margin-bottom: 4px;
}

.ember-power-select-group .ember-power-select-option {
    overflow: hidden;
    padding: 7px 12px;
    line-height: 1.35em;
    cursor: pointer;
    font-size: 1.4rem;
}

.ember-power-select-group .ember-power-select-option .highlight {
    background: #fff6b8;
    border-radius: 1px;
    color: color-mod(var(--darkgrey) l(-10%));
}

.ember-power-select-group .ember-power-select-option[aria-current="true"] {
    background: color-mod(var(--whitegrey) a(60%) s(-12%));
    color: var(--darkgrey);
}

/*
    HACK: ember-power-select has no separate class for the loading message
    Issue: https://github.com/cibernox/ember-power-select/issues/479
 */
.ember-power-select-option--no-matches-message {
    padding: 7px 8px;
    color: var(--midgrey);
    font-size: 0.9em;
}

.ember-power-select-option[aria-current="true"] {

}

/* Multiple */
.ember-power-select-multiple-trigger {
    background: #fff;
    padding: 4px;
    border: rgb(214, 227, 235) 1px solid;
    border-radius: 3px;
    outline: none;
}

.ember-power-select-multiple-option {
    margin: 2px;
    padding: 2px 6px;
    border: 1px solid #3fb0ef;
    border-radius: 3px;
    font-size: 0.93em;
    font-weight: 500;
    color: white;
    background: #3fb0ef;
}

.ember-power-select-multiple-remove-btn {
    padding: 2px 1px;
}

.ember-power-select-multiple-remove-btn:not(:hover) {
    opacity: 0.75;
}

.ember-power-select-multiple-remove-btn svg {
    width: 9px;
    height: 9px;
}

.ember-power-select-multiple-remove-btn svg path {
    stroke: white;
    fill: white;
}

.ember-power-select-trigger-multiple-input {
    height: 24px;
    margin: 2px;
}

.ember-power-select-status-icon {
    top: -4px;
    right: 13px;
    border: solid var(--midlightgrey);
    border-width: 0 1px 1px 0;
    padding: 3px;
    transform: rotate(45deg);
}

.ember-basic-dropdown-trigger[aria-expanded="true"] .ember-power-select-status-icon {
    transform: rotate(45deg);
}

/* Token input */
.gh-token-input .ember-power-select-options {
    max-height: 172px; /* 5.5 options */
}

/* Tag input */

.tag-token--internal {
    background: color-mod(var(--blue) alpha(0.1));
    color: var(--blue);
}

.tag-token--internal svg path {
    stroke: var(--blue);
    fill: var(--blue);
}

/* Inside settings / Mailgun region */
/* TODO: make these general styles? */

.gh-labs-mailgun-region .ember-power-select-trigger {
    padding: 6px 12px;
}
.gh-labs-mailgun-region .ember-power-select-selected-item {
    margin-left: 0;
}