JSFiddle - React, Tailwind, and code Playground

HTML

<blockquote class="postMessage">
    <div class="none">&gt;&gt;-----Цитата----&gt;&gt;</div>
    <div class="quote"><!-- hello -->
        <p>Системный администратор <b>LINUX</b><br/>на основе Windows Server 2008<br/></p>
    </div>
    <div class="none">&lt;&lt;-----Цитата----&lt;&lt;</div>
    <p>почем нынче работа осьмирука в Казане?</p>
</blockquote>

CSS

.quote { color: green; }
.none { display: none; }

JavaScript

// MutationObserver-Shim v0.2.7 (github.com/megawac/MutationObserver.js)
// Authors: Graeme Yeates (github.com/megawac) 
this.MutationObserver=this.MutationObserver||this.WebKitMutationObserver||function(v){function m(b){var a=this;a.g=[];a.k=function(){var c=a.takeRecords();c.length&&b.call(a,c,a);a.f=setTimeout(a.k,m._period)}}function r(b){var a={type:null,target:null,addedNodes:[],removedNodes:[],previousSibling:null,nextSibling:null,attributeName:null,attributeNamespace:null,oldValue:null},c;for(c in b)a[c]!==v&&b[c]!==v&&(a[c]=b[c]);return a}function F(b,a){var c=A(b,a);return function(d){var g=d.length;a.a&&
c.a&&z(d,b,c.a,a.d);(a.c||a.e)&&G(d,b,c,a);d.length!==g&&(c=A(b,a))}}function z(b,a,c,d){for(var g={},u=a.attributes,w,h,n=u.length;n--;)w=u[n],h=w.name,d&&d[h]===v||(w.value!==c[h]&&b.push(r({type:"attributes",target:a,attributeName:h,oldValue:c[h],attributeNamespace:w.namespaceURI})),g[h]=!0);for(h in c)g[h]||b.push(r({target:a,type:"attributes",attributeName:h,oldValue:c[h]}))}function G(b,a,c,d){function g(a,c,g,p,x){var m=a.length-1;x=-~((m-x)/2);for(var f,k,e;e=a.pop();)f=g[e.h],k=p[e.i],d.c&&
x&&Math.abs(e.h-e.i)>=m&&(b.push(r({type:"childList",target:c,addedNodes:[f],removedNodes:[f],nextSibling:f.nextSibling,previousSibling:f.previousSibling})),x--),d.a&&k.a&&z(b,f,k.a,d.d),d.b&&3===f.nodeType&&f.nodeValue!==k.b&&b.push(r({type:"characterData",target:f,oldValue:k.b})),d.e&&u(f,k)}function u(a,c){for(var...