/* Styles for the popup window and overlay */ .popup { display: none; /* Hidden by default */ position: fixed; z-index: 1; left: 0; top: 0; width: 100%; height: 100%; overflow: auto; background-color: rgb(0,0,0); background-color: rgba(0,0,0,0.4); padding-top: 15%; } .popup-content { background-color: #fefefe; margin: 5% auto; padding: 20px; border: 1px solid #888; width: 80%; max-width: 600px; } .close-btn { color: #aaa; float: right; font-size: 28px; font-weight: bold; } .close-btn:hover, .close-btn:focus { color: black; text-decoration: none; cursor: pointer; } Pre-shrunk Unisex sizing Coverstitched collar and sleeves Shoulder-to-shoulder taping Side seams cotton/polyester, 32 singles 90/10 Airlume combed and ringspun Size Chart × HOW TO MEASURE WIDTH Measure the shirt from armpit to armpit on a flat surface. Men's Small Medium Large XL XXL XXXL Width (in) 20.5 22 23.5 25 26.5 28.5 Length (in) 28 29 30 31 32 32.5 Sleeve (in) 35.25 36 36.75 37.5 38.25 39 // Get the popup var popup = document.getElementById("popup"); // Get the button that opens the popup var btn = document.getElementById("popupBtn"); // Get the element that closes the popup var span = document.getElementsByClassName("close-btn")[0]; // When the user clicks the button, open the popup btn.onclick = function() { popup.style.display = "block"; } // When the user clicks on (x), close the popup span.onclick = function() { popup.style.display = "none"; } // When the user clicks anywhere outside of the popup, close it window.onclick = function(event) { if (event.target == popup) { popup.style.display = "none"; } }