react-day-picker/examples/StylingModifiers.tsx

import React from "react";

import { addDays } from "date-fns";
import { DayPicker } from "react-day-picker";

import customStyles from "./styles/styling-modifiers.module.css";

const today = new Date();
const beforeYesterday = addDays(today, -2);

export function StylingModifiers() {
  return (
    <DayPicker
      mode="single"
      selected={new Date()}
      disabled={beforeYesterday}
      modifiersClassNames={{
        selected: customStyles.purpleToday
      }}
      modifiersStyles={{
        disabled: {
          // Add a line-through style to the disabled days
          textDecoration: "line-through"
        }
      }}
    />
  );
}