Marinated Slaw

• 1/2 head Napa cabbage, shredded, salted, and rinsed
• 2 red bell peppers, thinly sliced
• 2 green bell peppers, thinly sliced
• 3/4 cup apple cider vinegar
• 1 tablespoon mustard seed
• 1 teaspoon celery seed
• 1 cup sugar