firefly-iii/resources/views/budgets/available-budgets/create.twig

<div class="modal-dialog">
    <div class="modal-content">
        <div class="modal-header">
            <button type="button" class="close" data-dismiss="modal"><span>&times;</span><span class="sr-only">{{ 'close'|_ }}</span>
            </button>
            <h4 class="modal-title">
                {{ trans('firefly.update_budget_amount_range',
                    {start: start.isoFormat(monthAndDayFormat), end: end.isoFormat(monthAndDayFormat)}) }}
            </h4>
        </div>

        <form style="display: inline;" id="income" action="{{ route('available-budgets.store') }}" method="POST">
            <div class="modal-body">
                <input type="hidden" name="_token" value="{{ csrf_token() }}"/>
                <input type="hidden" name="start" value="{{ start.format('Y-m-d') }}"/>
                <input type="hidden" name="end" value="{{ end.format('Y-m-d') }}"/>
                <input type="hidden" name="page" value="{{ page }}"/>
                <input type="hidden" name="currency_id" value="{{ currency.id }}"/>

                <div class="form-group">
                    <p class="form-control-static">{{ trans('firefly.ab_basic_modal_explain', {currency: currency.name}) }}</p>
                </div>


                <div class="input-group">
                    <div class="input-group-addon">{{ currency.symbol|raw }}</div>
                    <input step="any" required class="form-control" id="amount" value="" autocomplete="off" name="amount" type="number"/>
                </div>
            </div>
            <div class="modal-footer">
                <button type="button" class="btn btn-default" data-dismiss="modal">{{ 'close'|_ }}</button>
                <button type="submit" class="btn btn-primary">{{ 'set_available_amount'|_ }}</button>
            </div>
        </form>
    </div>
</div>