Код:

/* Меню навигации */
#pun-navlinks .container {
margin: 0;
padding: 8px 10px;
}
#pun-navlinks li {
display: inline;
padding-right: 10px;
}

/* Юзер меню */
#pun-ulinks .container {padding: 8px 10px;}
#pun-ulinks li {
display: inline;
padding-right: 10px;
}

@media screen and (max-width: 540px){
/* Меню навигации */
#pun-navlinks h2 {
  position: fixed;
  bottom: 0;
  left: 0; 
  overflow: initial;
  height: 22px;
  background: var(--text1);
  color: var(--background);
  padding: 7px 0;
  width: calc(50% - 2px);
  border-radius: 0 20px 0 0;
}
#pun-navlinks h2 span {font-size: 0;}
#pun-navlinks h2 span::before {
  font-family: Material Symbols Outlined;
  content: "\e88a";
  color: #ededed;
  font-size: 24px;
  }

#pun-navlinks .container {
  position: fixed;
  left: 0;
  bottom: 36px;
  margin: 0;
  width: calc(50% - 22px);
  padding: 8px 10px;
  background-color: var(--background);
  border-radius: 0 20px 20px 0;
}
#pun-navlinks ul {
  display: none !important;
}
#pun-navlinks:hover ul {
  display: flex !important;
  flex-direction: column;
  align-items: center;
  z-index: 9999;
}
#pun-navlinks li {
  display: block;
  text-align: center;
  padding: 4px;
  margin: 5px;
  width: calc(100% - 10px);
  border: 1px solid var(--background1);
}

/* Юзер меню */
#pun-ulinks h2 {
  position: fixed;
  bottom: 0;
  right: 0; 
  overflow: initial;
  height: 22px;
  background: var(--text1);
  color: var(--background);
  padding: 7px 0;
  width: 50%;
  border-radius: 20px 0 0;
}

#pun-ulinks h2 span {font-size: 0;}
#pun-ulinks h2 span::before {
  font-family: Material Symbols Outlined;
  content: "\e5d2";
  color: #ededed;
  font-size: 24px;
  }
  
#pun-ulinks .container {
  position: fixed;
  right: 0;
  bottom: 36px;
  margin: 0;
  width: calc(50% - 20px);
  padding: 8px 10px;
  background-color: var(--background);
  border-radius: 20px 0 0 20px;
}
#pun-ulinks ul {
  display: none !important;
}
#pun-ulinks:hover ul {
  display: flex !important;
  flex-direction: column;
  align-items: center;
  z-index: 9999;
}
#pun-ulinks li {
  display: block;
  text-align: center;
  padding: 4px;
  margin: 5px;
  width: calc(100% - 10px);
  border: 1px solid var(--background1);
}