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

.ember-power-select-trigger {
    padding: 0 16px 0 8px;
    border: 1px solid #dfe1e3;
    border-radius: var(--border-radius);
}

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

.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: #b1b1b1;
}

.ember-power-select-dropdown {
    position: absolute;
    z-index: 1000;
    box-sizing: border-box;
    margin: -1px 0 0 0;
    border: 1px solid #b1b1b1;
    border-top: 0 none;
    background: #fff;
    border-radius: 0 0 var(--border-radius) var(--border-radius);
    box-shadow: 0 3px 6px rgba(0, 0, 0, 0.1);
}

.ember-power-select-option {
    margin: 0;
    padding: 6px 10px;
    color: color(var(--darkgrey) lightness(+20%));
}

.ember-power-select-option[aria-current="true"] {
    background: color(var(--blue) alpha(-85%));
    color: var(--darkgrey);
}

.ember-power-select-option[aria-selected="true"] {
    color: var(--darkgrey);
    font-weight: 500;
    background: transparent;
}

.ember-power-select-options:not([role="group"]) {
    max-height: 70vh;
}

.ember-power-select-search input {
    display: inline-block !important;
    margin: 0 1px !important;
    padding: 0 !important;
    min-height: 0 !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: 1.3rem;
    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 8px;
    color: var(--midgrey);
    font-size: 0.85em;
    font-weight: normal;
    cursor: default;
}

.ember-power-select-group .ember-power-select-group-name:after {
    content: "";
    position: absolute;
    top: 52%;
    left: calc(100% + 3px);
    display: block;
    width: calc(189px - 100%);
    height: 1px;
    border-bottom: var(--midgrey) 1px solid;
}

@media (max-width: 800px) {
    .ember-power-select-group .ember-power-select-group-name:after {
        width: calc(224px - 100%);
    }
}

@media (max-width: 500px) {
    .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-bottom: 7px;
    padding-top: 0;
    padding-bottom: 0;
}

.ember-power-select-group .ember-power-select-option {
    overflow: hidden;
    padding: 7px 8px;
    line-height: 1.35em;
    cursor: pointer;
}

.ember-power-select-group .ember-power-select-option .highlight {
    background: #fff3b8;
    border-radius: 1px;
}

.ember-power-select-group .ember-power-select-option[aria-current="true"] {
    background: color(var(--blue) alpha(-85%));
    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"] {

}