How to make these div elements responsive?

Question

I have a marketplace type of page im working on but I can't seem to get the products(div elements) to be responsive. It looks terrible when resizing the window or looking at it on mobile. What am I doing wrong here?

<div class="productlayout">
        <div class="products">
            <div id="col-1">
                <img src="originallogo.png">
                    <hr class="lineunderproduct">
                    <h3 class="title1">Official Mens T-Shirt</h3>
                    <h4 class="price1">$49.99</h4>
                <button class="btn btn-5 btn-5a glyphicon glyphicon-shopping-cart"><span>Purchase</span></button>
            </div>

            <div id="col-2">
                <img src="originallogo.png">
                    <hr class="lineunderproduct">
                <h3 class="title2">Mens Tank</h3>
                    <h4 class="price2">$29.99</h4>
                <button class="btn btn-5 btn-5a glyphicon glyphicon-shopping-cart"><span>Purchase</span></button>
            </div>

            <div id="col-3">
                <img src="originallogo.png">
                    <hr class="lineunderproduct">
                <h3 class="title3">Mens Sweatpants</h3>
                    <h4 class="price3">$49.99</h4>
                <button class="btn btn-5 btn-5a glyphicon glyphicon-shopping-cart"><span>Purchase</span></button>
            </div>
        </div>
    </div>

CSS

.productlayout {
    display: flex;
    flex-direction: row;
    height: 500px; 
}


.products {
    display: flex;
    flex-grow: 1;
    background-color: #c7c4c4;
    margin: 0px 40px;
    justify-content: space-around;
    padding: 30px 0px;

}

#col-1 {
    background: #1d1d1d;
    width: 320px;
    order: 1;
    box-shadow: 0px 0px 1px 1px #000;
}

#col-1 img {        /*Product Image placement settings */
    width: 75%;
    display: block;
    margin: 20px auto 0 auto;
}


#col-2 {
    background: #1d1d1d;
    width: 320px;
    order: 2;
    box-shadow: 0px 0px 1px 1px #000;
}

#col-2 img {        /*Product Image placement settings */
    width: 75%;
    display: block;
    margin: 20px auto 0 auto;
}

#col-3 {
    background: #1d1d1d;
    width: 320px;
    order: 3;
    box-shadow: 0px 0px 1px 1px #000;
}

#col-3 img {        /*Product Image placement settings */
    width: 75%;
    display: block;
    margin: 20px auto 0 auto;
}

.lineunderproduct {
    width: 75%;
    margin: 0 auto;
    margin-top: 20px;
}

.title1 {
    color: #e0dcdc;
    text-align: center;
    font-size: 20px;
    font-family: 'Droid Serif', serif;
}

.title2 {
    color: #e0dcdc;
    text-align: center;
    font-size: 20px;
    font-family: 'Droid Serif', serif;
}

.title3 {
    color: #e0dcdc;
    text-align: center;
    font-size: 20px;
    font-family: 'Droid Serif', serif;
}

.price1 {
    color: #959393;
    font-family: 'Droid Serif', serif;
    font-size: 15px;
    text-align: center;
    font-style: italic;
}

.price2 {
    color: #959393;
    font-family: 'Droid Serif', serif;
    font-size: 15px;
    text-align: center;
    font-style: italic;
}

.price3 {
    color: #959393;
    font-family: 'Droid Serif', serif;
    font-size: 15px;
    text-align: center;
    font-style: italic;
}


/* Add to Cart Buttons */

.btn {
    border: none;
    font-family: 'Droid Serif', serif;
    font-size: 20px;
    color: #1d1d1d;
    background: none;
    cursor: pointer;
    padding: 20px 80px;
    display: inline-block;
    margin: 15px 30px;
    text-transform: uppercase;
    letter-spacing: none;
    outline: none;
    position: relative;
    box-shadow: 0px 0px 0px 3px #D4AF37;
    -webkit-transition: all 0.3s;
    -moz-transition: all 0.3s;
    transition: all 0.3s;
}

.btn:after {
    content: '';
    position: absolute;
    z-index: -1;
    -webkit-transition: all 0.3s;
    -moz-transition: all 0.3s;
    transition: all 0.3s;
}

.btn-5 {
    background: #fff;
    color: #1d1d1d;
    height: 40px;
    min-width: 260px;
    line-height: 30px;
    font-size: 20px;
    overflow: hidden;
    -webkit-backface-visibility: hidden;
    -moz-backface-visibility: hidden;
    backface-visibility: hidden;
}

.btn-5:active {
    background: #9053a9;
    top: 2px;
}

.btn-5 span {
    display: inline-block;
    letter-spacing: 0.1px;
    width: 100%;
    height: 100%;
    -webkit-transition: all 0.3s;
    -webkit-backface-visibility: hidden;
    -moz-transition: all 0.3s;
    -moz-backface-visibility: hidden;
    transition: all 0.3s;
    backface-visibility: hidden;
}

.btn-5:before {
    position: absolute;
    height: 100%;
    width: 100%;
    line-height: 1.5;
    font-size: 180%;
    -webkit-transition: all 0.3s;
    -moz-transition: all 0.3s;
    transition: all 0.3s;
}

.btn-5:active:before {
    color: #703b87;
}

/* Button 5a */
.btn-5a:hover span {
    -webkit-transform: translateY(300%);
    -moz-transform: translateY(300%);
    -ms-transform: translateY(300%);
    transform: translateY(300%);
}

.btn-5a:before {
    left: 0;
    top: -100%;
}

.btn-5a:hover:before {
    top: 0;
    /* Hover backgorund change background-color: #308014; */
}

@media (max-width: 800px) {
    .products {
        flex-direction: column;
    }

Answer 1

You need to add media queries for your design to be responsive and also always try to use % to provide width for responsive design

an example of media query for screen smaller that 768 px will be

 @media only screen and (max-width: 768px) {

    .products {
        display:block;
    }

    #col-1 {width: 100%;}
    #col-2 {width: 100%;}
    #col-3 {width: 100%;}

    }

Check the below example on expanded and small view to see the impact.

 .productlayout { display: flex; flex-direction: row; height: 500px; } .products { display: flex; flex-grow: 1; background-color: #c7c4c4; margin: 0px 40px; justify-content: space-around; padding: 30px 0px; } #col-1 { background: #1d1d1d; width: 33%; order: 1; box-shadow: 0px 0px 1px 1px #000; } #col-2 { background: #1d1d1d; width: 33%; order: 2; box-shadow: 0px 0px 1px 1px #000; } #col-3 { background: #1d1d1d; width: 33%; order: 2; box-shadow: 0px 0px 1px 1px #000; } @media only screen and (max-width: 768px) { .products { display:block; } #col-1 {width: 100%;} #col-2 {width: 100%;} #col-3 {width: 100%;} } You need to write media queries for different view ports to make your design responsive. for smaller screen you can make add this css.

 <div class="productlayout"> <div class="products"> <div id="col-1"> <img src="originallogo.png"> <hr class="lineunderproduct"> <h3 class="title1">Official Mens T-Shirt</h3> <h4 class="price1">$49.99</h4> <button class="btn btn-5 btn-5a glyphicon glyphicon-shopping-cart"><span>Purchase</span></button> </div> <div id="col-2"> <img src="originallogo.png"> <hr class="lineunderproduct"> <h3 class="title2">Mens Tank</h3> <h4 class="price2">$29.99</h4> <button class="btn btn-5 btn-5a glyphicon glyphicon-shopping-cart"><span>Purchase</span></button> </div> <div id="col-3"> <img src="originallogo.png"> <hr class="lineunderproduct"> <h3 class="title3">Mens Sweatpants</h3> <h4 class="price3">$49.99</h4> <button class="btn btn-5 btn-5a glyphicon glyphicon-shopping-cart"><span>Purchase</span></button> </div> </div> </div>