Invalid Style Sheet

Error says,”The author stylesheet specified in tag ‘style amp-custom’ is too long – we saw 51211 bytes whereas the limit is 50000 bytes.”

Here’s my css code in the AMP css customizer. Can anyone tell me where this big css code issue is coming from? Is it from my standard wordpress customizer or somewhere else? Please help me correct this issue since it’s affecting 15 out of 60 pages.

Screenshot from the Google Search Console

/******* Paste your Custom CSS in this Editor *******/

a.buttongreen {
display: inline-block;
margin-top: 10px;
border-radius: 100px;
font-size: 1.3em;
padding: 1em 2em;
background: #ffffff;
color: #61ce70 !important;
border: 8px solid #61ce70;
border-width: 10px 10px;
}
a.buttonblue {
display: inline-block;
margin-top: 10px;
border-radius: 100px;
font-size: 1.3em;
padding: 1em 2em;
background: #ffffff;
color: #0095da !important;
border: 8px solid #0095da;
border-width: 10px 10px;
}
a.buttonred {
display: inline-block;
margin-top: 10px;
border-radius: 100px;
font-size: 1.3em;
padding: 1em 2em;
background: #ffffff;
color: #e53020 !important;
border: 8px solid #e53020;
border-width: 10px 10px;
}
.singlepage-wrapper .post-content p a:hover{
border-bottom:double;
border-top:double;
color:#61ce70;
text-decoration:underline;
}

.su-spoiler-title{
margin-top: 10px;
font-size:1.4em !important;
}
h1{
margin-top: 20px;
font-size:1.4em !important;
}
h2{
margin-top: 20px;
font-size:1.2em !important;
}

.hideamp{
display:none;
}

main > article > div > div > div.page-title{
display:none;
}
main > article > div > div > div.author-info{
display:none;
}
article > div.ampwc-wrapper.amp-wp-content > div.shipping > div.tax-price{
display:none !important;
}
.amp-wp-content .singlepage-wrapper .post-content blockquote > p{
background: #f9f9f9;
font-size: 16px !important;
font:inherit !important;
color:#111;
border-left: 10px solid #0095da;
margin: 1.5em 15px;
padding: 0.5em 10px;
quotes: “\201C””\201D””\2018″”\2019”;
text-align: left;
text-transform:none;
}
.amp-wp-content .singlepage-wrapper .post-content blockquote:before > p{
color: #0095da;
content: open-quote;
font-size: 4em;
line-height: 0.1em;
margin-right: 0.25em;
vertical-align: -0.4em;
text-align: left;
text-transform:none;
}

The page I need help with: [log in to see the link]