how to make automatically resize the aspx page during runtme

I have created project in asp.net

I used ModalPopUpextender.

I have used 3 aspx pages and assign to .<p style="margin: 0px 0px 18px; padding: 0px; border: 0px; outline: 0px; font-size: 13.0080003738403px; vertical-align: baseline; color: #222222; font-family: 'segoe ui', tahoma, arial, helvetica, sans-serif; line-height: 18.2112007141113px; background: #fffbe9;">Popup of all the aspx pages are working<p style="margin: 0px 0px 18px; padding: 0px; border: 0px; outline: 0px; font-size: 13.0080003738403px; vertical-align: baseline; color: #222222; font-family: 'segoe ui', tahoma, arial, helvetica, sans-serif; line-height: 18.2112007141113px; background: #fffbe9;">but the height of page is not adjusted.<p style="margin: 0px 0px 18px; padding: 0px; border: 0px; outline: 0px; font-size: 13.0080003738403px; vertical-align: baseline; color: #222222; font-family: 'segoe ui', tahoma, arial, helvetica, sans-serif; line-height: 18.2112007141113px; background: #fffbe9;">but the resizing of aspx page is not adjusted based on page height<p style="margin: 0px 0px 18px; padding: 0px; border: 0px; outline: 0px; font-size: 13.0080003738403px; vertical-align: baseline; color: #222222; font-family: 'segoe ui', tahoma, arial, helvetica, sans-serif; line-height: 18.2112007141113px; background: #fffbe9;">I have given code below for sing aspx page.<p style="margin: 0px 0px 18px; padding: 0px; border: 0px; outline: 0px; font-size: 13.0080003738403px; vertical-align: baseline; color: #222222; font-family: 'segoe ui', tahoma, arial, helvetica, sans-serif; line-height: 18.2112007141113px; background: #fffbe9;"> <pre class="prettyprint lang-vb prettyprinted" style="margin-top: 18px; margin-bottom: 30px; padding: 5px; border: 1px solid #e1e2e2; outline: 0px; font-size: 13.0080003738403px; vertical-align: baseline; font-family: consolas, monospace; overflow: auto; color: #222222; line-height: 18.2112007141113px; background-image: initial; background-attachment: initial; background-size: initial; background-origin: initial; background-clip: initial; background-position: initial; background-repeat: initial;"><div class="frmrow"> <asp:Button ID="Button3" runat="server" Text="Vat" CssClass="button-simple" /> <ajax:ModalPopupExtender ID="ModalPopupExtender3" runat="server" PopupControlID="Panl1" TargetControlID="Button3" CancelControlID="Button5" BackgroundCssClass="Background"> </ajax:ModalPopupExtender> <asp:Panel ID="Panl1" runat="server" CssClass="Popup" align="center" Style="display: none"> <iframe style="width: 300px; height: 300px;" id="Iframe1" src="party-vat.aspx" runat="server"></iframe> <br /> <asp:Button ID="Button5" CssClass="button-simple" runat="server" Text="close" /> </asp:Panel> </div> </li></pre></div></article><section class="comments" id="replies"><header class="comments-head"><svg xmlns="http://www.w3.org/2000/svg" width="19" height="19" viewBox="0 0 16 16" fill="none" stroke="currentColor" stroke-width="1.5" stroke-linecap="round" stroke-linejoin="round" aria-hidden="true" focusable="false"><path d="M3 3h10a2 2 0 0 1 2 2v4.5a2 2 0 0 1-2 2H7.5L4 14.5V11.5H3a2 2 0 0 1-2-2V5a2 2 0 0 1 2-2z"></path></svg><div><h2 class="comments-title">1 Reply</h2>Know the answer? Post it — somebody with the same question will find it here.</div></header><div class="comment-signin"><svg viewBox="0 0 20 20" fill="none" stroke="currentColor" stroke-width="1.6"><path d="M11.5 3.5h3.2a1 1 0 0 1 1 1v11a1 1 0 0 1-1 1h-3.2" stroke-linecap="round"></path><path d="M4.5 10h7" stroke-linecap="round"></path><path d="M8.8 7.2 11.6 10l-2.8 2.8" stroke-linecap="round" stroke-linejoin="round"></path></svg><div class="comment-signin-body">Sign in to answer this questionIt is the same account you read, post and publish with — and you will come straight back to this page.</div><div class="comment-signin-actions"><a class="btn primary-btn comment-signin-btn" href="/login?returnurl=%2Fforums%2Fhow-to-make-automatically-resize-the-aspx-page-during-runtme">Sign in</a><a class="comment-signin-alt" href="/register?returnurl=%2Fforums%2Fhow-to-make-automatically-resize-the-aspx-page-during-runtme">Create an account</a></div></div><ul class="comment-list"><li class="comment-thread"><article class="comment"><a class="comment-photo-link" href="/members/khargesh-rajput" title="Khargesh Rajput"><img class="comment-photo" src="https://cdn.c-sharpcorner.com/uploadfile/authorimage/c52718.webp" alt="Khargesh Rajput" title="Khargesh Rajput" loading="lazy" data-avatar-name="Khargesh Rajput" referrerPolicy="no-referrer"/></a><div class="comment-main"><div class="comment-head"><a href="/members/khargesh-rajput" class="comment-author">Khargesh Rajput</a><time class="posted-when-value comment-time" dateTime="2015-03-20T02:52:16.657Z">11y ago</time>Posted Mar 20, 2015, 2:52 AM</div><div class="article-body">set height on panel above iframe</div><div class="comment-foot"></div></div></article></li></ul></section></div></div><script>$RS=function(a,b){a=document.getElementById(a);b=document.getElementById(b);for(a.parentNode.removeChild(a);a.firstChild;)b.parentNode.insertBefore(a.firstChild,b);b.parentNode.removeChild(b)};$RS("S:2","P:2")</script><script>$RB=[];$RV=function(a){$RT=performance.now();for(var b=0;b<a.length;b+=2){var c=a[b],e=a[b+1];null!==e.parentNode&&e.parentNode.removeChild(e);var f=c.parentNode;if(f){var g=c.previousSibling,h=0;do{if(c&&8===c.nodeType){var d=c.data;if("/$"===d||"/&"===d)if(0===h)break;else h--;else"$"!==d&&"$?"!==d&&"$~"!==d&&"$!"!==d&&"&"!==d||h++}d=c.nextSibling;f.removeChild(c);c=d}while(c);for(;e.firstChild;)f.insertBefore(e.firstChild,c);g.data="$";g._reactRetry&&requestAnimationFrame(g._reactRetry)}}a.length=0}; $RC=function(a,b){if(b=document.getElementById(b))(a=document.getElementById(a))?(a.previousSibling.data="$~",$RB.push(a,b),2===$RB.length&&("number"!==typeof $RT?requestAnimationFrame($RV.bind(null,$RB)):(a=performance.now(),setTimeout($RV.bind(null,$RB),2300>a&&2E3<a?2300-a:$RT+300-a)))):b.parentNode.removeChild(b)};$RC("B:1","S:1")</script><div style="display:none" id="S:3"></div><script>$RC("B:3","S:3")</script><div style="display:none" id="S:0"></div><script>$RC("B:0","S:0")</script></body></html>