Currently, there is no gap between the "-" button and the quantity field. It shows up when I apply display: inline; for .qib-container div.quantity but inline has one downside that I found out and possibly more. I expected both gaps to show up with inline-block.
I would like to know why this happens and how to make this gap appear.
As far as aesthetics go, I prefer no gaps at all, but I already have a working solution for this, "with gaps" is just an alternate option.
https://jsfiddle.net/Lybwro64/
.qib-button {
    line-height: 1.2;
    display: inline-block;
    margin: 0;
    padding: 0;
    box-sizing: border-box;
    height: 35px;
    width: 30px;
    color: #000;
    background: #e2e2e2;
    border-color: #cac9c9;
    vertical-align: top;
    font-size: 16px;
    letter-spacing: 0;
    border-style: solid;
    border-width: 1px;
    transition: none;
    border-radius: 2px;
 }
.qib-container div.quantity {
    float: none;
    display: inline-block;
    margin: 0;
    padding: 0;
    border: none;
    width: auto;
 }
 .qib-container .quantity input.qty {
    line-height: 1.2;
    margin: 0;
    padding: 0;
    box-sizing: border-box;
    height: 35px;
    width: 45px;
    min-height: unset;
    min-width: unset;
    box-shadow: none;
    font-size: 15px;
    border-style: solid;
    border-color: #cac9c9;
    border-width: 1px;
    border-radius: 2px;
    text-align: center
}
  .screen-reader-text {
    border: 0;
    clip: rect(1px,1px,1px,1px);
    -webkit-clip-path: inset(50%);
    clip-path: inset(50%);
    height: 1px;
    margin: -1px;
    overflow: hidden;
    padding: 0;
    position: absolute;
    width: 1px;
    word-wrap: normal !important;
} 
<div class="qib-container">
<button type="button" class="minus qib-button">-</button><div class="quantity">
<label class="screen-reader-text" for="quantity_5d33c50739412">Stainless steel standoff - satin finish quantity</label>  <input type="number" id="quantity_5d33c50739412" class="input-text qty text" step="1" min="1" max="" name="quantity" value="1" title="Qty" size="4" inputmode="numeric"></div>
<button type="button" class="plus qib-button">+</button></div>
