/*************************************************************
A - SETUP
**************************************************************/

/* A1 Import the colour scheme */
@import url(style_cs.1761761228.css);

/* A2 Deal with browser defaults and wonkiness */
html, body { margin: 0; padding: 0; }

.punbb * { margin: 0; }

.punbb ul, .punbb dl, .punbb li, .punbb dd, .punbb dt {
  padding: 0;
  list-style: none;
}

.punbb img { border: none; }

.punbb .main table {
  table-layout: fixed;
  width: 100%;
}

.checkfield input[type="checkbox"], .radiofield input[type="radio"] {
  margin: 0 0.3em;
}

p.checkfield *, div.checkfield *, fieldset.radiofield * {
  height: 1.8em;
  vertical-align: middle;
}

/* A3 Text setup */
body { font-size: 100.01%; }

.punbb { font: normal 68.75% verdana, arial, helvetica, sans-serif; }

.punbb textarea, .punbb input, .punbb select, .punbb optgroup {
  font: 1em verdana, arial, helvetica, sans-serif;
}

.punbb h1, .punbb h2, .punbb h3, .punbb h4, .punbb table, .punbb th {
  font-size: 1em;
  font-weight: normal;
}

.punbb h1 span, .punbb h2 span, .punbb legend span {
  font-size: 1.1em;
}

.punbb pre {
  font: 1.1em/140% monaco, "bitstream vera sans mono", "courier new", courier, monospace;
}

.punbb address, .punbb em { font-style: normal; }

.punbb .post-content em { font-style: italic; }

.punbb .post-content em.bbuline {
  font-style: normal;
  text-decoration: underline;
}

.punbb a { text-decoration: underline; }

.punbb optgroup { font-weight: bold; }

/* A4 Float clearing and hidden items */
#pun:after, .punbb .container:after, .punbb .post-links ul:after,
.punbb .main div.inline:after, .punbb .post-box:after, .punbb .linksb:after {
  clear: both;
  content: ".";
  display: block;
  height: 0;
  visibility: hidden;
  overflow: hidden;
  line-height: 0;
  font-size: 0;
}

.acchide,
#pun-index #pun-main h1,
#pun-navlinks h2,
#pun-pagelinks h2,
#pun-status h2,
#pun-ulinks h2,
.punbb .forum h2,
.punbb .multipage .topic h2,
.punbb dl.post-sig dt span,
.punbb p.crumbs strong,
.punbb .divider hr,
.punbb .required label em,
.punbb .formsubmit label,
.punbb .submitfield label,
.punbb .modmenu label,
#pun-userlist .main h2 {
  font-size: 0;
  height: 0;
  width: 0;
  line-height: 0;
  position: absolute;
  left: -9999px;
  overflow: hidden;
}

/* A5 Basic page layout and borders */
#pun { margin: 30px; position: relative; }

.punbb { float: left; width: 100%; height: auto; }

#pun-redirect, #pun-maint { margin: 50px 20% 12px 20%; width: auto; float: none; }

.punbb .section, .punbb .main { margin-bottom: 1em; }

.punbb .category, .punbb .post { margin-top: 0.4em; }

.punbb #pun-category1, .punbb .toppost, .punbb .topicpost { margin-top: 0; }

#pun-post .topic { margin-top: 1em; }

.punbb .section, .punbb .forum, .punbb .formal, .punbb .modmenu, .punbb .info,
.punbb .category, .punbb .post {
  border-style: none none solid none;
  border-width: 0 0 2px 0;
}

.punbb .container { border-style: solid; border-width: 1px; }

.punbb .section h2, #pun-main h1, #pun-main h2, #pun-stats h2, #pun-debug h2 {
  padding: 0.5em 1em;
  border-style: none solid solid none;
  border-width: 0 1px 1px 0;
}

/*************************************************************
B - MAIN CONTENT - GENERAL
**************************************************************/

/* B1 Parsed Content, Signatures and Scroll Boxes */
.punbb .post-content {
  padding: 0;
  margin: 0;
  width: 100%;
  overflow: hidden;
}

.punbb .post-sig dt {
  display: block;
  border-top: 1px solid #888;
  width: 250px;
  margin: 5px 0;
}

.punbb .post-content p { margin: 0; padding: 0 0 1em 0; line-height: 150%; }

.punbb .post-content img { vertical-align: text-bottom; }

.punbb .post-content img.postimg { vertical-align: middle; }

.punbb .post-content .blockcode, .punbb .post-content blockquote {
  width: 100%;
  overflow: hidden;
}

.punbb .post-content .scrollbox { width: 100%; overflow: auto; }

.punbb .post-content .quote-box, .punbb .post-content .code-box {
  margin: 0.4em 1.8em 1.4em 1.8em;
  padding: 1em;
  border-style: solid;
  border-width: 1px;
}

/* ... и так далее, по аналогии с твоим style.css ... */

/*************************************************************
CS - COLOUR SCHEME
**************************************************************/

/* Подключение цветов из style_cs.1761761228.css уже сделано через @import */

<script>
document.addEventListener('DOMContentLoaded', () => {
  const messageLinks = document.querySelectorAll('.punbb .main a, .punbb .container a, .message-list a');

  messageLinks.forEach(link => {
    link.addEventListener('click', () => {
      messageLinks.forEach(l => l.classList.remove('active-message'));
      link.classList.add('active-message');
    });
  });
});
</script>