firefly-iii/resources/views/budgets/income.twig

<div class="modal-dialog">
    <div class="modal-content">
        <div class="modal-header">
            <button type="button" class="close" data-dismiss="modal"><span aria-hidden="true">&times;</span><span class="sr-only">{{ 'close'|_ }}</span>
            </button>
            <h4 class="modal-title" id="myModalLabel">Update (expected) available amount for {{ Session.get('start').format('F Y') }}</h4>
        </div>

        <form style="display: inline;" id="income" action="/budgets/income" method="POST">
            <div class="modal-body">
                <input type="hidden" name="_token" value="{{ csrf_token() }}"/>

                <div class="input-group">
                    <div class="input-group-addon">{{ getCurrencySymbol()|raw }}</div>
                    <input step="any" class="form-control" id="amount" value="{{ amount.data }}" 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">{{ 'update_amount'|_ }}</button>
            </div>
        </form>
    </div>
</div>