I can't alter the width of an item through CSS - html

Question

I'm a beginner in front-end development and I'm working on a survey website. My website has a lot of input fields and I want to alter their width per their nature but I'm not able to do it for some reason. The item is not in a flex container and yet changing the value in the width attribute makes no difference.
I'm trying to change the width of my input field in my customerAge div to make it small enough to just hold 2 digits.
This is my codepen link: https://codepen.io/omaroz92/full/VBWbae/
I'd appreciate a detailed explanation on why changing the value in the width attribute made no difference.
body {
background-color: #98AFC7;
}
#title {
text-align: center;
font-family: Arial, Times, serif;
font-style: oblique;
color: white;
}
#screen-belly {
background-color: rgb(250, 250, 250);
margin: 0 auto;
border-radius: 4px;
width: 75%;
max-width: 1000px;
padding: 10px;
padding-top: 20px;
}
p {
text-align: center;
font-family: monospace, serif;
font-size: 15px;
}
.container {
width: 75%;
max-width: 600px;
margin: 0 auto;
}
.row {
display: flex;
}
.customerAge {
width: 100px;
}
input {
flex: 1;
height: 20px;
min-width: 0;
padding: 5px;
margin: 10px;
border: 1px solid #c0c0c0;
border-radius: 2px;
}
<h1 id="title">Survey Form</h1>
<div id="screen-belly">
<p>Please take the short Survey to hep us improve our services</p>
<div class="container">
<div class="row">
<input autofocus type="text" name="name" id="name" placeholder="First name" required>
<input type="text" name="name" id="name" placeholder="Last Name" required>
</div>
<div class="row">
<input type="text" name="email" id="email" placeholder="e-Mail address" required>
</div>
<div class="customerAge">
<input type="number" name="age" id="Age" placeholder="age" required>
</div>
</div>
</div>

Answer 1

You've wrapped the Age input in customerAge div. But you've applied the width property to the parent, not to the input.
You can try this in your css code:
.customerAge input#Age {
width: 31px;
}
And you can change 31px to the value you want.
If you are confused, the input#Age after .customerAge, means: the input field with Age id that is inside of the customerAge class.