Making an input and two buttons aligned using SCSS - css

Question

I want my two buttons, that are actually <a> tags, stick with my input, and be the same size as input. Image perfectly describes what I want to achieve.
Note that I am just starting to learn SASS and CSS. I have tried with this but no luck
NumberInput.js
<div
className="NumberInput"
data-key={dataKey}>
<div className="numberInputField">
<input
data-key={dataKey}
type="text"
name="number"
value={getValue(datakey)}
onChange={onChange(datakey)}/>
</div>
<div className="buttonsField">
<div className="row">
<ValueChangeButton/>
</div>
<div className="row">
<ValueChangeButton/>
</div>
</div>
</div>
NumberInput.scss
$inputMaxWidth: 450px;
$maxHeight: 80px;
$btnFieldMaxWidth: 150px;
.NumberInput{
max-width: $inputMaxWidth;
max-height: $maxHeight;
.numberInputField{
display: inline-block;
text-align: center;
max-width: inherit;
max-height: inherit;
}
.buttonsField{
display: inline-block;
max-width: $btnFieldMaxWidth;
max-height: $maxHeight;
.button{
width: auto;
height: auto;
}
}
}
The result I get is, buttons are contained in their respective rows, but are not the same size as input, and they are flying all around the page. Also, if I change the className of my input, and set the className of its <div> to "numberInputField", it doesn't change its width and height.

Answer 1

Flexbox is perfect for this:
body {
margin: 1em;
}
.NumberInput {
display: flex;
max-width:450px;
margin:auto;
}
.numberInputField {
flex: 3; /* say 3/4 of width */
display: flex;
flex-direction: column;
}
input {
padding: 1em 4em;
flex: 1;
}
.buttonsField {
flex: 1; /* say 1/4 of width */
display: flex;
flex-direction: column;
}
.row {
flex: 1; /* share width equally */
}
a {
width: 100%;
display: block;
background: rebeccapurple;
text-align:center;
text-decoration: none;
font-size: 1.5em;
color: white;
border:1px solid grey;
}
<div class="NumberInput">
<div class="numberInputField">
<input type="submit" />
</div>
<div class="buttonsField">
<div class="row">
↑
</div>
<div class="row">
↓
</div>
</div>
</div>