Unity C# hide tool bar and menu bar for light panel in dark mode

HideTitleMenuBar.cs

#if UNITY_EDITOR
using System;
using System.Runtime.InteropServices;
using System.Text;
using UnityEditor;
using UnityEngine;

public static class HideTitleMenuBar
{
	[DllImport("user32.dll")]
	static extern IntPtr GetActiveWindow();

	[DllImport("user32.dll")]
	static extern IntPtr GetMenu(IntPtr hwnd);

	[DllImport("user32.dll")]
	static extern IntPtr SetMenu(IntPtr hwnd, IntPtr hMenu);
	
	[DllImport("user32.dll", CharSet=CharSet.Unicode, SetLastError=true)]
	static extern int GetWindowText(IntPtr hWnd, StringBuilder lpString,  int nMaxCount);
	
	[DllImport("user32.dll")]
	static extern int GetWindowTextLength(IntPtr hWnd);

	[DllImport("user32.dll")]
	private static extern IntPtr GetWindowLongPtr(IntPtr hWnd, int nIndex);
	
	[DllImport("user32.dll")]
	private static extern IntPtr SetWindowLongPtr(IntPtr hWnd, int nIndex, IntPtr dwNewLong);
	
	const string idLastMenuPtr = "ks_toggleTitleBar_lastMenuPtr";
	const long titlebarStyle = 0x00C00000;
	
	[MenuItem("Tools/Kamyker/Toggle title bar _1")]
	static void ToggleTitleBar()
	{
		var unity = GetActiveWindow();
		if(unity == IntPtr.Zero)
			return;
		
		int titleLength = GetWindowTextLength(unity);
		var title = new StringBuilder(titleLength);
		GetWindowText(unity, title, titleLength);

		if(!title.ToString().Contains("unity", StringComparison.InvariantCultureIgnoreCase))
		{
			Debug.LogError($"Can't hide title bar of {title.ToString()}, change 'unity' in the code if it's translated differently");
			return;
		}

		var menu = GetMenu(unity);
		var style = GetWindowLongPtr(unity, -16);
		
		if(menu != IntPtr.Zero)
		{
			PlayerPrefs.SetString(idLastMenuPtr, menu.ToString());
			SetWindowLongPtr(unity, -16, new IntPtr(style.ToInt64() - titlebarStyle));
			SetMenu(unity, IntPtr.Zero);
		}
		else
		{
			var lastMenuPtr = long.Parse(PlayerPrefs.GetString(idLastMenuPtr));
			SetWindowLongPtr(unity, -16, new IntPtr(style.ToInt64() + titlebarStyle));
			SetMenu(unity, new IntPtr(lastMenuPtr));
		}
	}
}
#endif

Set to shortcut '1'. You can change it at the end of "Tools/Kamyker/Toggle title bar _1".