Images are overlapping the header in AMP (CSS problem) - wordpress

Question

I want to ask you for help with adapting AMP version of website: https://imperiumromanum.pl/en/roman-society/amp/
I am able to make fixed HEADER bar by adding css code
nav.amphtml-title {
position: fixed;
width: 100%;
}
but once I am scrolling down I can see images are overlapping the header. Below screen:
I see that guilty is position: absolute; in below code
.i-amphtml-layout-size-defined .i-amphtml-fill-content {
position: absolute;
top: 0;
left: 0;
bottom: 0;
right: 0;
}
But do not know what to change to appear the image + have it under the header bar.
Do you know what change I need to do in CSS for elements to be able to correct it?
Below if part of code from AMP version where is located headr
<div class="wrapper">
<nav class="amphtml-title" style="position: fixed;width: 100%;">
<div class="header">
<div class="logo">
<a href="https://imperiumromanum.pl/en/amp/">
<amp-img src="https://imperiumromanum.pl/wp-content/uploads/2015/01/logo-2.png" width="32" height="32" alt="logo" class="amphtml-site-icon i-amphtml-element i-amphtml-layout-fixed i-amphtml-layout-size-defined i-amphtml-built i-amphtml-layout" style="width: 32px; height: 32px; --loader-delay-offset: 47ms !important;" i-amphtml-layout="fixed"><img decoding="async" alt="logo" src="https://imperiumromanum.pl/wp-content/uploads/2015/01/logo-2.png" class="i-amphtml-fill-content i-amphtml-replaced-content"></amp-img>
IMPERIUM ROMANUM </a>
</div>
<div class="sidebar-header">
<section class="icon-button-section">
<button id="menu-search" class="amp-menu-sidebar hamburger icon-button" on="tap:search-lightbox"><amp-img src="https://imperiumromanum.pl/wp-content/themes/romanum/wp-amp/icons/amp-search.png" width="68" height="68" alt="Search" class="amphtml-site-icon i-amphtml-element i-amphtml-layout-fixed i-amphtml-layout-size-defined i-amphtml-built i-amphtml-layout" style="width: 68px; height: 68px; --loader-delay-offset: 47ms !important;" i-amphtml-layout="fixed"><img decoding="async" alt="Search" src="https://imperiumromanum.pl/wp-content/themes/romanum/wp-amp/icons/amp-search.png" class="i-amphtml-fill-content i-amphtml-replaced-content"></amp-img>
</button>
<button class="amp-menu-sidebar hamburger icon-button" on="tap:amp-sidebar.toggle"> <amp-img src="https://imperiumromanum.pl/wp-content/themes/romanum/wp-amp/icons/amp-menu.png" width="68" height="68" alt="Menu" class="amphtml-site-icon i-amphtml-element i-amphtml-layout-fixed i-amphtml-layout-size-defined i-amphtml-built i-amphtml-layout" style="width: 68px; height: 68px; --loader-delay-offset: 47ms !important;" i-amphtml-layout="fixed"><img decoding="async" alt="Menu" src="https://imperiumromanum.pl/wp-content/themes/romanum/wp-amp/icons/amp-menu.png" class="i-amphtml-fill-content i-amphtml-replaced-content"></amp-img>
</button>
</section>
</div>
</div>
<div>
<amp-lightbox id="search-lightbox" layout="nodisplay" class="i-amphtml-element i-amphtml-layout-nodisplay i-amphtml-overlay i-amphtml-built" i-amphtml-layout="nodisplay" hidden="">
<div class="lightbox-menu" tabindex="0">
<button class="lightbox-close" on="tap:search-lightbox.close">
<amp-img src="https://imperiumromanum.pl/wp-content/themes/romanum/wp-amp/icons/amp-close.png" width="68" height="68" alt="Close" class="amphtml-site-icon i-amphtml-element i-amphtml-layout-fixed i-amphtml-layout-size-defined i-amphtml-built" style="width: 68px; height: 68px;" i-amphtml-layout="fixed"></amp-img>
</button>
</div>
<div class="lightbox-search" tabindex="0">
<form role="search" method="get" class="search-form i-amphtml-form" action="https://imperiumromanum.pl/en/amp/" target="_top" novalidate="">
<label>
<input type="search" class="search-field" placeholder="Search …" value="" name="s">
<input type="hidden" name="is_amp" value="1">
</label>
<input type="submit" class="search-submit" value="Search">
</form> </div>
</amp-lightbox>
<amp-lightbox id="n-lightbox" layout="nodisplay" class="i-amphtml-element i-amphtml-layout-nodisplay i-amphtml-overlay i-amphtml-built" i-amphtml-layout="nodisplay" hidden="">
<div class="lightbox-menu" tabindex="0">
<button class="lightbox-close" on="tap:n-lightbox.close">
<amp-img src="https://imperiumromanum.pl/wp-content/themes/romanum/wp-amp/icons/amp-close.png" width="68" height="68" alt="Close" class="amphtml-site-icon i-amphtml-element i-amphtml-layout-fixed i-amphtml-layout-size-defined i-amphtml-built" style="width: 68px; height: 68px;" i-amphtml-layout="fixed"></amp-img>
</button>
</div>
<div class="lightbox-search" tabindex="0">
<div class="newsletter-wrapper">
<form id="pop_newsletter" name="submit" method="post" action-xhr="//imperiumromanum.pl/wp-content/themes/romanum/wp-amp/includes/mailchimp-pop.php" target="_top" novalidate="" class="i-amphtml-form amp-form-dirty">
<h2>Subscribe to the newsletter!</h2>
<p>Do you want to be up to date with news, curiosities and discoveries from the world of ancient Romans? Subscribe to the newsletter! The newsletter will be sent every Saturday.</p>
<input type="email" name="pop_email" placeholder="Enter your email address" required="">
<label for="pop_lang"><span>Language</span>
<select name="pop_lang" required="">
<option value="2">English</option>
<option value="1">Polish</option>
</select></label>
<input type="submit" value="Subscribe">
<div submit-success="">
<template type="amp-mustache">
Thank you! Check {{email_address}} to confirm your subscription. </template>
</div>
<div submit-error="">
<template type="amp-mustache">
Ooops... Something went wrong. Please try again later. </template>
</div>
</form>
</div> </div>
</amp-lightbox> </div></nav>
<div id="main">
<div class="target">
<a class="target-anchor" id="top"></a>
<amp-position-observer on="enter:hideAnim.start; exit:showAnim.start" layout="nodisplay" class="i-amphtml-element i-amphtml-layout-nodisplay i-amphtml-built" i-amphtml-layout="nodisplay" hidden=""></amp-position-observer>
</div>
<amp-animation id="showAnim" layout="nodisplay" class="i-amphtml-element i-amphtml-layout-nodisplay i-amphtml-built" i-amphtml-layout="nodisplay" hidden="">
<script type="application/json">
{
"duration": "200ms",
"fill": "both",
"iterations": "1",
"direction": "alternate",
"animations": [{
"selector": "#scrollToTopButton",
"keyframes": [{
"opacity": "0.9",
"visibility": "visible"
}]
}]
}
</script>
</amp-animation>
<amp-animation id="hideAnim" layout="nodisplay" class="i-amphtml-element i-amphtml-layout-nodisplay i-amphtml-built" i-amphtml-layout="nodisplay" hidden="">
<script type="application/json">
{
"duration": "200ms",
"fill": "both",
"iterations": "1",
"direction": "alternate",
"animations": [{
"selector": "#scrollToTopButton",
"keyframes": [{
"opacity": "0",
"visibility": "hidden"
}]
}]
}
</script>
</amp-animation>
<div class="inner">
<div class="amp-ad"><amp-ad width="0" height="320" type="adsense" data-ad-client="ca-pub-1752121314293437" data-ad-slot="5827352308" class="i-amphtml-element i-amphtml-layout-fixed i-amphtml-layout-size-defined i-amphtml-built" style="width: 100%; height: 320px;" i-amphtml-layout="fixed" data-amp-slot-index="0" data-a4a-upgrade-type="amp-ad-network-adsense-impl">
<div overflow=""></div>
<div fallback=""><div class="i-amphtml-ad-default-holder" data-ad-holder-text="Ad"></div></div><amp-analytics sandbox="true" trigger="immediate" class="i-amphtml-element i-amphtml-layout-fixed i-amphtml-layout-size-defined i-amphtml-built" style="width: 1px; height: 1px;" i-amphtml-layout="fixed" aria-hidden="true" hidden=""><script type="application/json">{"requests":{"csi":"https://csi.gstatic.com/csi?"},"transport":{"xhrpost":false},"triggers":{"adRequestStart":{"on":"ad-request-start","request":"csi","sampleSpec":{"sampleOn":"a4a-csi-${pageViewId}","threshold":1},"selector":"amp-ad","selectionMethod":"closest","extraUrlParams":{"met.a4a":"afs_lvt.${viewerLastVisibleTime}~afs.${time}"}},"adResponseEnd":{"on":"ad-response-end","request":"csi","sampleSpec":{"sampleOn":"a4a-csi-${pageViewId}","threshold":1},"selector":"amp-ad","selectionMethod":"closest","extraUrlParams":{"met.a4a":"afe.${time}"}},"adRenderStart":{"on":"ad-render-start","request":"csi","sampleSpec":{"sampleOn":"a4a-csi-${pageViewId}","threshold":1},"selector":"amp-ad","selectionMethod":"closest","extraUrlParams":{"met.a4a":"ast.${scheduleTime}~ars_lvt.${viewerLastVisibleTime}~ars.${time}","qqid":"${qqid}"}},"adIframeLoaded":{"on":"ad-iframe-loaded","request":"csi","sampleSpec":{"sampleOn":"a4a-csi-${pageViewId}","threshold":1},"selector":"amp-ad","selectionMethod":"closest","extraUrlParams":{"met.a4a":"ail.${time}"}}},"extraUrlParams":{"s":"ampad","ctx":"2","c":"${correlator}","slotId":"${slotId}","puid":"${requestCount}~${timestamp}"}}</script></amp-analytics></amp-ad></div>
<div class="amphtml-content amphtml-single-page single-content">
<div class="okruszki">
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<span><a rel="v:url" property="v:title" title="Go to IMPERIUM ROMANUM." href="https://imperiumromanum.pl/en/" class="home">Home</a></span> » <span><a rel="v:url" property="v:title" title="Idź do Roman society." href="https://imperiumromanum.pl/en/roman-society/" class="post post-page current-item">Roman society</a></span></div> <div class="titlediv">
<h1 class="amphtml-title">Roman society</h1>
<p class="lang_sel">This post is also available in: <strong>Polish</strong> (polski)</p></div> <amp-img lightbox="" src="https://imperiumromanum.pl/wp-content/uploads/2014/10/Pompeii-couple-e1664121350864-600x582.jpg" layout="responsive" width="600" height="582" alt="Fresco showing a Roman couple" class="i-amphtml-element i-amphtml-layout-responsive i-amphtml-layout-size-defined i-amphtml-built i-amphtml-layout" i-amphtml-layout="responsive" on="tap:amp-lightbox-gallery.activate" style="--loader-delay-offset: 47ms !important;"><i-amphtml-sizer slot="i-amphtml-svc" style="padding-top: 97%;"></i-amphtml-sizer>
<img decoding="async" alt="Fresco showing a Roman couple" src="https://imperiumromanum.pl/wp-content/uploads/2014/10/Pompeii-couple-e1664121350864-600x582.jpg" class="i-amphtml-fill-content i-amphtml-replaced-content"></amp-img>
<div class="chmurka_feat"><p class="opis_feat">Fresco showing a Roman couple</p></div>
Thank you.
Regards,
Jakub