/* --- BỐ CỤC ĐỒNG QUÊ VIỆT NAM --- */
.vietnam-arena {
    height: 180px;
    background: linear-gradient(180deg, #4fc3f7 0%, #81c784 50%, #4caf50 100%);
    box-shadow: inset 0 0 15px rgba(0,0,0,0.2);
    position: relative;
    overflow: hidden;
    border: 4px solid #388e3c;
    border-radius: 12px;
}

/* Mặt trời */
.sun-bg {
    position: absolute;
    left: 10%; top: 10%;
    font-size: 3rem;
    animation: sun-spin 10s linear infinite;
    z-index: 1;
}
@keyframes sun-spin {
    0% { transform: rotate(0deg); }
    100% { transform: rotate(360deg); }
}

/* Núi non phía xa */
.mountain-bg {
    position: absolute;
    bottom: 30%; right: 10%;
    font-size: 4rem;
    z-index: 2;
    opacity: 0.8;
}

/* Con trâu / Xe đò */
.buffalo-char {
    position: absolute;
    left: 20%;
    bottom: 10%;
    font-size: 4rem;
    z-index: 4;
    transition: all 0.5s ease;
    filter: drop-shadow(0 5px 5px rgba(0,0,0,0.3));
}

/* Hiệu ứng trâu đi tới */
.move-forward {
    animation: walk-fwd 0.8s ease-in-out forwards;
}
@keyframes walk-fwd {
    0% { transform: translateX(0) rotate(0); }
    50% { transform: translateX(30px) rotate(-5deg); }
    100% { transform: translateX(0) rotate(0); }
}

/* Sai số / Trâu lắc đầu */
.shake-error { animation: buffalo-angry 0.4s; }
@keyframes buffalo-angry {
    0% { transform: translateX(0) rotate(0); }
    25% { transform: translateX(-10px) rotate(-10deg); }
    50% { transform: translateX(10px) rotate(10deg); }
    75% { transform: translateX(-10px) rotate(-10deg); }
    100% { transform: translateX(0) rotate(0); }
}

.min-h-75 { min-height: 90px; }
.hl-num { color: #d32f2f; font-weight: 900; font-size: 1.2em; }