* {
    margin: 0;
    padding: 0;
    font-family: 'Poppins', sans-serif;
    box-sizing: border-box;
}

body {
    background: #001e4d;
    display: flex;
    justify-content: center;
    align-items: center;
    min-height: 100vh;
    padding: 20px;
}

.app {
    background: #fff;
    width: 100%;
    max-width: 600px;
    border-radius: 12px;
    padding: 25px;
    box-shadow: 0 0 20px rgba(0,0,0,0.1);
}

.app h1 {
    font-size: 26px;
    color: #001e4d;
    font-weight: 600;
    border-bottom: 2px solid #eee;
    padding-bottom: 20px;
    margin-bottom: 20px;
}

.quiz {
    padding: 10px 0;
}

.quiz h2 {
    font-size: 18px;
    color: #001e4d;
    font-weight: 600;
    margin-bottom: 15px;
}

.btn {
    background-color: #fff;
    color: #222;
    font-weight: 500;
    width: 100%;
    border: 1px solid #222;
    padding: 12px;
    margin: 10px 0;
    text-align: left;
    border-radius: 6px;
    cursor: pointer;
    transition: 0.3s;
    font-size: 16px;
}

.btn:hover:not([disabled]) {
    background: #222;
    color: #fff;
}

.btn:disabled {
    cursor: no-drop;
}

#nextbtn {
    background: #001e4d;
    color: #fff;
    font-weight: 500;
    width: 170px;
    border: 0;
    padding: 12px;
    margin: 20px auto 0;
    border-radius: 6px;
    cursor: pointer;
    display: none;
    font-size: 16px;
}

/* Correct / Incorrect colors */
.correct {
    background: #9aeabc !important;
    color: black;
}

.incorrect {
    background: #ff9393 !important;
    color: black;
}

/* ---------- RESPONSIVE DESIGN ---------- */

/* For tablets */
@media (max-width: 768px) {
    .app {
        padding: 20px;
    }
    .app h1 {
        font-size: 22px;
    }
    .btn {
        font-size: 15px;
        padding: 10px;
    }
}

/* For mobile phones */
@media (max-width: 480px) {
    body {
        padding: 10px;
    }
    .app {
        padding: 15px;
        border-radius: 10px;
    }
    .app h1 {
        font-size: 20px;
        padding-bottom: 15px;
    }
    .quiz h2 {
        font-size: 16px;
    }
    .btn {
        font-size: 14px;
        padding: 10px;
    }
    #nextbtn {
        width: 100%;
        font-size: 15px;
        padding: 12px;
    }
}