pygame issue with the following code help me resolve it please

I am trying to build a checkerboard where the squares underneath my cursor light up. I managed to create the checkerboard, but when I tried to implement the tiles lighting up under my cursor everything went wild. All the code does is that it alternate between light green and dark green and draw a rectangle and if the cursor position is equal to the rectangle about to be written I switch the light and dark greens to lighter greens named: LIGH_LIGHT_GREEN and LIGHT_DARK_GREEN.

# Setup
import pygame,sys
pygame.init()
WIDTH = 500
HEIGHT = 500
cell_size = 50
screen=pygame.display.set_mode((WIDTH,HEIGHT))
pygame.display.set_caption('HELP')
FPS=pygame.time.Clock()

DARK_GREEN = (76,175,79)
LIGHT_DARK_GREEN = (126,225,129)
LIGHT_GREEN = (139,195,74)
LIGHT_LIGHT_GREEN = (189,245,124)

def mouse_pos():
    mx,my = pygame.mouse.get_pos()
    mx = int(mx / cell_size)
    my = int(my / cell_size)
    print(mx,my)
    return mx,my

while True:
    for event in pygame.event.get():
        if event.type == pygame.QUIT:
            pygame.quit()
            sys.exit()
    
    # Colors
    BLACK=(0,0,0)

    gameOver=False
    while not gameOver:
        for event in pygame.event.get():
            if event.type == pygame.QUIT:
                pygame.quit()
                sys.exit()
    

        mx,my = mouse_pos()
        LIGHT = LIGHT_GREEN
        DARK = DARK_GREEN
        COLOR = DARK
        for x in range(0,10):
            for y in range(0,10):
                if mx == x and my == y:
                    LIGHT = LIGHT_LIGHT_GREEN
                    DARK = LIGHT_DARK_GREEN
                else:
                    LIGHT = LIGHT_GREEN
                    DARK = DARK_GREEN
                if COLOR == LIGHT:
                    COLOR = DARK
                else:
                    COLOR = LIGHT
                pygame.draw.rect(screen,COLOR,(x*cell_size,y*cell_size,cell_size,cell_size))
            if COLOR == LIGHT:
                COLOR = DARK
            else:
                COLOR = LIGHT

        pygame.display.update()
        FPS.tick(60)

Pleas help.

>Solution :

When you reach your cursor square, you don’t want to interrupt your alternating COLOR toggling. So, keep your alternating stuff static, and use a separate variable to set "what do I draw for this particular square", which can either come from COLOR, or from your altered colors:

        mx,my = mouse_pos()
        LIGHT = LIGHT_GREEN
        DARK = DARK_GREEN
        COLOR = DARK
        for x in range(10):
            for y in range(10):
                draw = COLOR
                if mx == x and my == y:
                    if draw == LIGHT_GREEN:
                        draw = LIGHT_LIGHT_GREEN
                    else:
                        draw = LIGHT_DARK_GREEN
                if COLOR == LIGHT:
                    COLOR = DARK
                else:
                    COLOR = LIGHT
                pygame.draw.rect(screen,draw,(x*cell_size,y*cell_size,cell_size,cell_size))
            if COLOR == LIGHT:
                COLOR = DARK
            else:
                COLOR = LIGHT