document.querySelector(".plus").addEventListener("click", () => {
    const input = document.querySelector(".num-box input");
    const step = Number(input.step) || 1;
    input.value = Number(input.value) + step;
});

document.querySelector(".minus").addEventListener("click", () => {
    const input = document.querySelector(".num-box input");
    const step = Number(input.step) || 1;
    input.value = Math.max(1000, Number(input.value) - step);
});