.challenge-container {
    max-width: 800px;
    margin: 4rem auto;
    padding: 2rem;
    position: relative;
    overflow: hidden;

    background:
        radial-gradient(
            circle at top left,
            rgba(22,160,133,0.08),
            transparent 40%
        ),
        linear-gradient(
            180deg,
            #0f172a,
            #111827
        );

    border-radius: 20px;

    box-shadow:
        0 15px 35px rgba(0,0,0,0.3);

    color: #f8fafc;
}
.challenge-container::before {
    content: "";

    position: absolute;

    width: 300px;
    height: 300px;

    top: -150px;
    right: -150px;

    border-radius: 50%;

    background:
        radial-gradient(
            rgba(22,160,133,0.15),
            transparent 70%
        );

    pointer-events: none;
}
.challenge-header {
    text-align: center;
    margin-bottom: 2rem;
}

.challenge-header h1 {
    font-size: clamp(2rem, 4vw, 3rem);
    margin-bottom: 0.75rem;
}

.challenge-header p {
    color: #cbd5e1;
    max-width: 60ch;
    margin: auto;
}
#question {
    text-align: center;
    font-size: 1.4rem;
    margin-bottom: 2rem;
    color: #f8fafc;
}
#answers {
    display: grid;
    gap: 1rem;

    grid-template-columns:
        repeat(auto-fit, minmax(220px, 1fr));
}
.answer-btn {
    padding: 1rem;

    border: none;
    border-radius: 12px;

    background: #1e293b;

    color: #f8fafc;

    font-size: 1rem;
    font-weight: 500;

    cursor: pointer;

    transition:
        transform 0.2s ease,
        background 0.3s ease,
        box-shadow 0.3s ease;
}

.answer-btn:hover {
    transform: translateY(-3px);

    background: #16a085;

    box-shadow:
        0 8px 20px rgba(22,160,133,0.35);
}
/* Answer Checking */
.answer-btn.correct {
    background: #16a34a;
}
.answer-btn.wrong {
    background: #dc2626;
}

/* Next Button */
#next-btn {
    display: block;

    margin: 2rem auto 0;

    padding: 0.85rem 1.75rem;

    border: none;
    border-radius: 10px;

    background: var(--accent);

    color: white;

    cursor: pointer;

    font-weight: 600;

    transition: all 0.3s ease;
}
#next-btn:hover {
    transform: translateY(-2px);
}
.category-wrapper {

    display: flex;

    justify-content: center;

    margin-bottom: 1rem;

}
#questionCategory {

    display: inline-block;

    padding: 0.4rem 1rem;

    border-radius: 999px;

    background: var(--accent);

    color: white;

    font-weight: 600;

    margin-bottom: 1rem;

}
.difficultly-wrapper {

    display: flex;

    justify-content: center;

    margin-bottom: 1rem;

}
#difficultyLevel{

    display: inline-block;

    padding: 0.4rem 1rem;

    border-radius: 999px;

    background: #5167a0;

    color: white;

    font-weight: 600;

}
/* Challenge-hub */

.hub-container {
    max-width: 1100px;
    margin: 0 auto;
    padding: 3rem 1.5rem 5rem;
}
/* Hub Intro */ 
.hub-intro {
    text-align: center;
    margin-bottom: 3rem;
}
.hub-intro h2 {
    color: var(--primary);
    margin-bottom: 1rem;
}
.hub-intro p {
    max-width: 700px;
    margin: 0 auto;
    line-height: 1.7;
    color: #444;
}
/* Stats */
.hub-stats {
    display: grid;
    grid-template-columns:
        repeat(auto-fit, minmax(250px, 1fr));
    gap: 1.5rem;
    margin-bottom: 3rem;
}
/* Hub Card */
.hub-card {
    padding: 1.5rem;
    border-radius: 16px;
    text-align: center;
    background: white;
    box-shadow:
        0 10px 25px rgba(0,0,0,0.08);
    border:
        1px solid rgba(31,60,136,0.15);
}
.hub-card h3 {
    color: var(--primary);
    margin-bottom: 0.75rem;
}
/* Options */
.hub-options {
    padding: 2rem;
    border-radius: 16px;
    background: white;
    box-shadow:
        0 10px 25px rgba(0,0,0,0.08);
    margin-bottom: 3rem;
}
.option-group {
    display: flex;
    flex-direction: column;
    margin-bottom: 1.5rem;
}
.option-group label {
    margin-bottom: 0.5rem;
    font-weight: 600;
    color: var(--primary);
}
.option-group select {
    padding: 0.8rem;
    border-radius: 10px;
    border:
        1px solid rgba(31,60,136,0.2);
    font-size: 1rem;
}
/* Launch */
.hub-launch {
    text-align: center;
}
.fact-card {
    padding: 2rem;
    border-radius: 16px;
    background:
        linear-gradient(
            180deg,
            #102040,
            #0a1226
        );
    border:
        1px solid
        rgba(255,215,0,0.35);
    color: white;
    text-align: center;
    box-shadow:
        0 0 20px
        rgba(255,215,0,0.15);
}

.fact-card p {
    margin: 0;
    font-size: 1.2rem;
    line-height: 1.7;
}