Ghost/ghost/admin/app/components/custom-theme-settings/select.hbs

<div class="gh-stack-item {{if (eq @index 0) "gh-setting-first" "gh-setting"}}">
    <div class="flex-grow-1">
        <label class="gh-setting-title gh-theme-setting-title" for={{this.selectId}}>
            {{humanize-setting-key @setting.key}}
        </label>

        <select class="ember-select" name={{this.selectName}} id={{this.selectId}} {{on "change" this.setSelection}}>
            {{#each @setting.options as |settingOption|}}
                <option value={{settingOption}} selected={{eq settingOption @setting.value}}>
                    {{settingOption}}
                    {{#if (eq settingOption @setting.default)}}(default){{/if}}
                </option>
            {{/each}}
        </select>
    </div>
</div>