@keyframes shakeRotate {
    0% {
        transform: rotate(-5deg);
        } 25% {
        transform: rotate(5deg);
        } 50% {
        transform: rotate(-3deg);
        } 75% {
        transform: rotate(3deg);
        } 100% {
        transform: rotate(-5deg);
        }
    }
#gameStartUI {
    position: fixed;
    top: 50%;
    left: 50%;
    transform: translate(-50%, -50%);
    max-height: 90vh;
    overflow-y: auto;
    overflow-x: hidden;
    box-sizing: border-box;
    padding: 2em 2.5em;
    background: rgba(255, 255, 255, 0.95);
    border-radius: 16px;
    box-shadow: 0 8px 24px rgba(0, 0, 0, 0.3);
    animation: popIn 0.4s ease-out;
    width: 90vw;
    max-width: 640px;
    z-index: 9999;
}

#amplifySessionInfo {
    color: #111 !important; /* 아주 어두운 회색 or 검정 */
}

#gameStatusMessage {
    margin-top: 1em;
    font-weight: bold;
}
#statusSpinner {
    margin-top: 0.5em;
}

@media (min-width: 768px) {
    #gameStartUI {
        top: 10vh;
        transform: translate(-50%, 0);
        max-height: 80vh;
    }
}

@media (max-width: 480px) {
    #gameStartUI {
        padding: 1.2em 1.5em;
        width: 95vw;
        max-height: 95vh;
    }
}

@keyframes popIn {
    0% {
        opacity: 0;
        transform: translate(-50%, -60%) scale(0.95);
        } 100% {
        opacity: 1;
        transform: translate(-50%, -50%) scale(1);
        }
    }
#gameStartUI {
    animation: popIn 0.4s ease-out
    }
#gameStartUI input, #gameStartUI select {
    background: #fff;
    border: 1px solid #ccc;
    border-radius: 6px;
    color: #000;
    padding: 0.4em 0.7em
    }

@keyframes pulseGlow {
    0% {
        text-shadow: 0 0 5px #fff;
    }
    50% {
        text-shadow: 0 0 15px #00ffcc;
    }
    100% {
        text-shadow: 0 0 5px #fff;
    }
}

.glow {
    animation: pulseGlow 0.8s ease-in-out;
}

#amplifyCardsContainer {
    display: flex;
    justify-content: center;
    gap: 1em;
}

.amplifyCard:hover {
    transform: scale(1.05);
}

.amplifyCard {
    width: 120px;
    height: 180px;
    perspective: 1000px;
    position: relative;
    cursor: pointer;
    transition: transform 0.3s;
}

.amplifyCardInner {
    width: 100%;
    height: 100%;
    transform-style: preserve-3d;
    transition: transform 0.5s;
    position: relative;
}

.cardFront, .cardBack {
    position: absolute;
    width: 100%;
    height: 100%;
    backface-visibility: hidden;
    border-radius: 8px;
}

.cardBack {
    background-size: cover;
    background-position: center;
    background-image: url('../images/card_back.webp');
}

.cardFront {
    background-size: cover;
    background-position: center;
    transform: rotateY(180deg);
}

.amplifyCard.flipped .amplifyCardInner {
    transform: rotateY(180deg);
}

.cardAnswer {
    border: 3px solid limegreen;
}

.cardFail {
    border: 3px solid red;
}