body {
    margin: 0;
    padding: 0;
    font-family: Arial, sans-serif;
    background: #f2f2f2;
}

.container {
    width: 90%;
    max-width: 1000px;
    margin: 40px auto;
}

h1 {
    text-align: center;
    font-size: 50px;
    margin-bottom: 30px;
}

#unitSelect {
    width: 100%;
    padding: 15px;
    font-size: 18px;
    border: 1px solid #ccc;
    border-radius: 8px;
    margin-bottom: 30px;
    background: white;
}

.question-box {
    background: white;
    padding: 25px;
    border-radius: 15px;
    margin-bottom: 25px;
    box-shadow: 0 2px 10px rgba(0, 0, 0, 0.1);
}

.question-box h3 {
    margin-bottom: 20px;
    font-size: 28px;
}

/* OPTION DESIGN */

.option {
    display: block;
    padding: 15px;
    margin-top: 12px;
    background: #ececec;
    border-radius: 8px;
    cursor: pointer;
    transition: 0.3s;
    font-size: 20px;
}

.option:hover {
    background: #dcdcdc;
}

/* CORRECT ANSWER */

.correct {
    background: #28a745 !important;
    color: white;
    font-weight: bold;
}

/* WRONG ANSWER */

.wrong {
    background: #dc3545 !important;
    color: white;
    font-weight: bold;
}

/* EXPLANATION */

.explanation {
    margin-top: 20px;
    padding: 15px;
    background: #f7f7f7;
    border-left: 5px solid blue;
    border-radius: 5px;
    font-size: 18px;
    display: none;
}

/* MOBILE */

@media(max-width:768px) {

    h1 {
        font-size: 35px;
    }

    .question-box h3 {
        font-size: 22px;
    }

    .option {
        font-size: 16px;
    }

}