woocommerce/packages/js/components/src/experimental-select-control/combo-box.scss

.woocommerce-experimental-select-control__combo-box-wrapper {
    cursor: text;
    border: 1px solid $studio-gray-20;
    border-radius: 3px;
    background: $studio-white;
    position: relative;
    display: flex;
    flex-wrap: wrap;
    align-items: center;
    padding: $gap-smallest 36px $gap-smallest $gap-smaller;

    > * {
        display: inline-flex;
    }
}

.woocommerce-experimental-select-control__combox-box {
    flex-grow: 1;
    align-items: center;
    flex-basis: 120px;

    input {
        width: 100%;
        margin-top: 2px;
        margin-bottom: 2px;
    }
}

.woocommerce-experimental-select-control__combox-box-icon {
    position: absolute;
    right: 6px;
    top: 50%;
    transform: translateY(-50%);
}