function correct() {
    const quiz = document.getElementById('quiz');
    const judge = document.getElementById("judge");
    document.getElementById('judge').setAttribute('class', 'correct');
    judge.innerHTML = "正解!!";
}

function incorrect() {
    const quiz = document.getElementById('quiz');
    const judge = document.getElementById("judge");
    document.getElementById('judge').setAttribute('class', 'incorrect');
    judge.innerHTML = "不正解…";
}