[HTML, JavaScript] Tworzenie menu rozwijalnego

function pokaz_postac(){
var a = document.getElementById('postacbutton');
a.style.display = "block";
}
function schowaj_postac(){
var a = document.getElementById('postacbutton');
a.style.display = "none";
}
function pokaz_eq(){
var a = document.getElementById('eqbutton');
a.style.display = "block";
}
function schowaj_eq(){
var a = document.getElementById('eqbutton');
a.style.display = "none";
}
function pokaz_kraina(){
var a = document.getElementById('krainabutton');
a.style.display = "block";
var b = document.getElementById('postacbutton');
b.style.display = "none";
}
function schowaj_kraina(){
var a = document.getElementById('krainabutton');
a.style.display = "none";
}
function pokaz_mapa(){
var a = document.getElementById('mapabutton');
a.style.display = "block";
}
function schowaj_mapa(){
var a = document.getElementById('mapabutton');
a.style.display = "none";
}
function pokaz_um(){
var a = document.getElementById('umbutton');
a.style.display = "block";
}
function schowaj_um(){
var a = document.getElementById('umbutton');
a.style.display = "none";
}
function pokaz_ranking(){
var a = document.getElementById('rankingbutton');
a.style.display = "block";

}
function schowaj_ranking(){
var a = document.getElementById('rankingbutton');
a.style.display = "none";
}
function pokaz_przyjaciele(){
var a = document.getElementById('przyjacielebutton');
a.style.display = "block";
}
function schowaj_przyjaciele(){
var a = document.getElementById('przyjacielebutton');
a.style.display = "none";
}
function pokaz_gildia(){
var a = document.getElementById('gildiabutton');
a.style.display = "block";
}
function schowaj_gildia(){
var a = document.getElementById('gildiabutton');
a.style.display = "none";
}
function pokaz_poczta(){
var a = document.getElementById('pocztabutton');
a.style.display = "block";

}
function schowaj_poczta(){
var a = document.getElementById('pocztabutton');
a.style.display = "none";
}
function pokaz_konfig(){
var a = document.getElementById('konfigbutton');
a.style.display = "block";
}
function schowaj_konfig(){
var a = document.getElementById('konfigbutton');
a.style.display = "none";
}

BODY{
 background:black;
 }
 
 #calosc{
background:red;
width:900px;
height:500px;
position:relative;
top:35px;
left:50px;
 }
 #play{
background:yellow;
width:750px;
height:475px;
float:left;
 }
 
 #information{
background:white;
height:25px;
 }
/*------------------------------*/
/*             MENU             */
/*------------------------------*/
 #menu{
background:yellow;
width:150px;
height:475px;
float:left;
 }
 
 #menu_1,#menu_3,#menu_5,#menu_7,#menu_9{
background:pink;
width:150px;
height:47.5px;
 }
  #menu_2,#menu_4,#menu_6,#menu_8,#menu_10{
background:purple;
width:150px;
height:47.5px;
 }
 
 #menu_1:hover,#menu_3:hover,#menu_5:hover,#menu_7:hover,#menu_9:hover
 ,#menu_2:hover,#menu_4:hover,#menu_6:hover,#menu_8:hover,#menu_10:hover{
  background:maroon;
width:150px;
height:47.5px;
 }
 
 #krainabutton{
background:red;
width:750px;
height:475px;
float:left;
position:absolute;
top:25px;
left:150px;
 }
  #postacbutton{
background:white;
width:750px;
height:475px;
float:left;
position:absolute;
top:25px;
left:150px;
 }
  #eqbutton{
background:black;
width:750px;
height:475px;
float:left;
position:absolute;
top:25px;
left:150px;
 }
  #umbutton{
background:blue;
width:750px;
height:475px;
float:left;
position:absolute;
top:25px;
left:150px;
 }
  #przyjacielebutton{
background:purple;
width:750px;
height:475px;
float:left;
position:absolute;
top:25px;
left:150px;
 }
  #gildiabutton{
background:maroon;
width:750px;
height:475px;
float:left;
position:absolute;
top:25px;
left:150px;
 }
  #rankingbutton{
background:yellow;
width:750px;
height:475px;
float:left;
position:absolute;
top:25px;
left:150px;
 }
  #konfigbutton{
background:brown;
width:750px;
height:475px;
float:left;
position:absolute;
top:25px;
left:150px;
 }
  #pocztabutton{
background:green;
width:750px;
height:475px;
float:left;
position:absolute;
top:25px;
left:150px;
 }
  #mapabutton{
background:gray;
width:750px;
height:475px;
float:left;
position:absolute;
top:25px;
left:150px;
 }