Website is not responsive in Tablets

Let's try excluding the sub-menu as well. :)

ul:not(.menu):not(.sub-menu) {
    list-style: none;
}

ul:not(.menu):not(.sub-menu) li::before {
  content: "\2022";  /* Add content: \2022 is the CSS Code/unicode for a bullet */
  color: red; /* Change the color */
  font-size: 20px;
  font-weight: bold; /* If you want it to be bold */
  display: inline-block; /* Needed to add space between the bullet and the text */
  width: 1em; /* Also needed for space (tweak if needed) */
  margin-left: -1em; /* Also needed for space (tweak if needed) */
}