align div horizontally after screen resize using css - html

Question

I'm trying to align div horizontally as the browser resizes, currently, I have 3 divs. As per the requirement, I can add an additional div. My problem is as soon I increase the window size above 2500, the right side of the screen becomes empty & all the divs are floating to left. As I cannot set the div width to 30-33% as per the requirement. Below is my code. kindly help.
div.box-container {
mc-grid-row: true;
margin-left: auto;
margin-right: auto;
float: left;
display: flex;
width: 100%
}
div.box {
float: left;
background-color: #ffffff;
position: relative;
padding: 10px;
box-sizing: border-box;
height: 326px;
margin-left: 20px;
margin-bottom: 0;
top: 55px;
border-top-right-radius: 0px;
width: 30%;
border: 1px solid #cccccc;
}
<div class="box-container">
<div class="box">
<p>jfn,mnfngf,mn,mgfnbgnkjdkjgkdg</p>
</div>
<div class="box">
<p>jfn,mnfngf,mn,mgfnbgnkjdkjgkdg</p>
</div>
<div class="box">
<p>jfn,mnfngf,mn,mgfnbgnkjdkjgkdg</p>
</div>
</div>

Answer 1

As #Arman Ebrahimi had already mentioned correctly. Use flex box only. The issue of responsibility can be handled well with media queries.
Working example
* {
box-sizing: border-box;
}
div.box-container {
display: flex;
flex-wrap: wrap;
font-size: 30px;
text-align: center;
gap: 10px;
width: 80%;
margin: 0 auto;
/* or use justify-content: center; */
}
.box {
background-color: #f1f1f1;
padding: 10px;
flex: 30%;
border: 1px solid #cccccc;
word-break: break-word;
height: 326px;
}
#media (max-width: 800px) {
.box {
flex: 100%;
}
}
<div class="box-container">
<div class="box">1</div>
<div class="box">2</div>
<div class="box">3</div>
<div class="box">4</div>
<div class="box">5</div>
<div class="box">6</div>
</div>

Answer 2

Remove float and only use flex:
* {
box-sizing: border-box;
}
body,
html {
margin: auto;
}
div.box-container {
mc-grid-row: true;
margin-left: auto;
margin-right: auto;
display: flex;
width: 100%;
}
div.box {
background-color: #ffffff;
padding: 10px;
height: 326px;
margin-left: 20px;
margin-bottom: 0;
top: 55px;
border-top-right-radius: 0px;
width: calc(100vw / 3);
/*calc(100vw / number of div)*/
border: 1px solid #cccccc;
word-break: break-word;
}
<div class="box-container">
<div class="box">
<p>jfn,mnfngf,mn,mgfnbgnkjdkjgkdg</p>
</div>
<div class="box">
<p>jfn,mnfngf,mn,mgfnbgnkjdkjgkdg</p>
</div>
<div class="box">
<p>jfn,mnfngf,mn,mgfnbgnkjdkjgkdg</p>
</div>
</div>

Answer 3

Use justify-content: center; when you are using flex. This means the flexed contents will always be centered on all screen types.
div.box-container {
mc-grid-row: true;
margin-left: auto;
margin-right: auto;
display: flex;
gap: 10px;
justify-content: center;
width: 100%
}
div.box {
background-color: #ffffff;
position: relative;
padding: 10px;
box-sizing: border-box;
height: 326px;
margin-bottom: 0;
top: 55px;
border-top-right-radius: 0px;
width: 33.33%;
border: 1px solid #cccccc;
}
body {
margin: 0;
}
<div class="box-container">
<div class="box">
<p>jfn,mnfngf,mn,mgfnbgnkjdkjgkdg</p>
</div>
<div class="box">
<p>jfn,mnfngf,mn,mgfnbgnkjdkjgkdg</p>
</div>
<div class="box">
<p>jfn,mnfngf,mn,mgfnbgnkjdkjgkdg</p>
</div>
</div>
Edit ~ add another div, reduce the % the div covers. Demonstrate min-width responsiveness.
div.box-container {
mc-grid-row: true;
margin-left: auto;
margin-right: auto;
display: flex;
flex-wrap: wrap;
gap: 10px;
justify-content: center;
width: 100%
}
div.box {
background-color: #ffffff;
position: relative;
padding: 10px;
box-sizing: border-box;
height: 326px;
margin-bottom: 0;
top: 55px;
border-top-right-radius: 0px;
width: 24%;
min-width: 300px;
border: 1px solid #cccccc;
}
body {
margin: 0;
}
<div class="box-container">
<div class="box">
<p>jfn,mnfngf,mn,mgfnbgnkjdkjgkdg</p>
</div>
<div class="box">
<p>jfn,mnfngf,mn,mgfnbgnkjdkjgkdg</p>
</div>
<div class="box">
<p>jfn,mnfngf,mn,mgfnbgnkjdkjgkdg</p>
</div>
<div class="box">
<p>jfn,mnfngf,mn,mgfnbgnkjdkjgkdg</p>
</div>
</div>