I want to style the top div and add margin to it, unable to do so

[KaviHarjani]

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[KaviHarjani]

Seems like the top div only has an option to add width in custom style using the data-width property
For example

<div class="dropdown bootstrap-select"><select class="selectpicker" tabindex="-98">
<optgroup label="Picnic">
<option>Mustard</option>
<option>Ketchup</option>
<option>Relish</option>
</optgroup>
<optgroup label="Camping">
<option>Tent</option>
<option>Flashlight</option>
<option>Toilet Paper</option>
</optgroup>
</select><button type="button" class="btn dropdown-toggle btn-light" data-toggle="dropdown" role="combobox" aria-owns="bs-select-2" aria-haspopup="listbox" aria-expanded="false" title="Mustard"><div class="filter-option"><div class="filter-option-inner"><div class="filter-option-inner-inner">Mustard</div></div> </div></button><div class="dropdown-menu "><div class="inner show" role="listbox" id="bs-select-2" tabindex="-1"><ul class="dropdown-menu inner show" role="presentation"></ul></div></div></div>

I want to add style to the first div with class of dropdown bootstrap-select, how to go about that?