script.js

var settingsmenu = document.querySelector(".settings-menu");
var darkBtn = document.getElementById("dark-btn");
function settingsMenuToggle()
{
    settingsmenu.classList.toggle("settings-menu-height");
}
darkBtn.onclick = function()
{
    darkBtn.classList.toggle("dark-btn-on");
    document.body.classList.toggle("dark-theme");

    if(localStorage.getItem("theme") == "light")
    {
        localStorage.setItem("theme","dark");
    }
    else
    {
        localStorage.setItem("theme","light");
    }
}


if(localStorage.getItem("theme") == "light")
{
    darkBtn.classList.remove("dark-btn-on");
    document.body.classList.remove("dark-theme");
}
else if(localStorage.getItem("theme") == "dark")
{
    darkBtn.classList.add("dark-btn-on");
    document.body.classList.add("dark-theme");
}
else
{
    localStorage.setItem("theme","light");
}