function modeTheme() {
   var element = document.body;
   element.classList.toggle("dark-mode");
   document.getElementById("btn1").style.color = "white";
   document.getElementById("btn2").style.color = "white";
   document.getElementById("btn3").style.color = "white";
   document.getElementById("btn4").style.color = "white";
   document.getElementById("btn5").style.color = "white";
   document.getElementById("btn6").style.color = "white";
}