a.nav-link[href="https://kenoko.pl/pl/info/ergorewolucja-51"] {
    background-color: #e1ddcd;
    color: #000000;
    border-radius: 20px;
    padding: 6px 14px;
    display: inline-block;
    text-align: center;
    text-decoration: none;
    font-weight: 500;
    transition: all 0.3s ease;
}

a.nav-link[href="https://kenoko.pl/pl/info/ergorewolucja-51"]:hover {
    background-color: #edecbc;
    color: #2b2a2a;
    box-shadow: 0 2px 6px rgba(0,0,0,0.15);
    transform: translateY(-1px);
}

a.nav-link[href="https://kenoko.pl/pl/info/ergorewolucja-51"]:active {
    transform: translateY(0);
    box-shadow: 0 1px 3px rgba(0,0,0,0.1);
}
div#menu_blog_rss {
display: none !IMPORTANT;
}

#projector_amount,
.projector_status__info_amount {
    display: none !important;
}
<style>
#blackweeks-tab {
  position: fixed;
  top: 40%;
  right: 0;
  background: linear-gradient(180deg, #2b2a2a 0%, #b30000 100%);
  color: #fff;
  font-family: "Poppins", "Montserrat", sans-serif;
  font-weight: 800;
  font-size: 18px;
  letter-spacing: 1px;
  padding: 14px 24px;
  border-radius: 12px 0 0 12px;
  box-shadow: 0 4px 15px rgba(0,0,0,0.3);
  z-index: 9999;
  cursor: pointer;
  transform: translateX(120px);
  transition: transform 0.6s ease;
  writing-mode: vertical-rl;
  text-orientation: mixed;
  text-align: center;
}

#blackweeks-tab.show {
  transform: translateX(0);
}

#blackweeks-tab:hover {
  background: linear-gradient(180deg, #b30000 0%, #2b2a2a 100%);
}
</style>

<div id="blackweeks-tab" onclick="window.open('https://twoj-link.pl', '_blank')">
  BLACK WEEKS
</div>

<script>
document.addEventListener("DOMContentLoaded", function() {
  const tab = document.getElementById("blackweeks-tab");
  setTimeout(() => tab.classList.add("show"), 1500); // pojawia się po 1.5 s
});
</script>