.captcha-container {
    margin: 20px 0;
}

.captcha-message {
    text-align: center;
    margin-bottom: 15px;
    font-weight: 500;
    color: #fff;
    font-size: 16px;
}

.captcha-images {
    display: grid;
    grid-template-columns: repeat(4, 1fr);
    gap: 10px;
    margin-bottom: 15px;
}

.captcha-image {
    width: 100%;
    height: 60px;
    background-color: rgba(255, 255, 255, 0.15);
    border: 2px solid transparent;
    border-radius: 8px;
    display: flex;
    align-items: center;
    justify-content: center;
    cursor: pointer;
    transition: all 0.3s ease;
    position: relative;
    overflow: hidden;
    box-sizing: border-box;
}

.captcha-image:hover {
    background-color: rgba(255, 255, 255, 0.25);
}

.captcha-image.selected {
    background-color: rgba(46, 204, 113, 0.6); /* 更明显的绿色背景 */
    border: 2px solid #2ecc71; /* 更明显的绿色边框 */
    transform: scale(0.95);
    box-shadow: 0 0 0 3px rgba(46, 204, 113, 0.8), /* 添加更强的发光效果 */
                inset 0 0 15px rgba(46, 204, 113, 0.7);
}

.captcha-image.selected::after {
    content: "✓";
    position: absolute;
    top: 50%;
    left: 50%;
    background-color: #2ecc71;
    color: white;
    width: 35px; /* 增大到35px */
    height: 35px; /* 增大到35px */
    border-radius: 50%;
    display: flex;
    align-items: center;
    justify-content: center;
    font-weight: bold;
    font-size: 24px; /* 增大到24px */
    box-shadow: 0 2px 8px rgba(0,0,0,0.4); /* 加强阴影效果 */
    transform: translate(-50%, -50%);
    z-index: 10;
    border: 2px solid white; /* 添加白色边框使勾选更明显 */
}

.captcha-image img {
    max-width: 80%;
    max-height: 80%;
    object-fit: contain;
    display: block;
}

.captcha-image .placeholder {
    font-size: 24px;
    color: rgba(255, 255, 255, 0.5);
    font-weight: bold;
}

.captcha-refresh {
    background: rgba(255, 255, 255, 0.1);
    color: white;
    border: none;
    padding: 10px 20px;
    border-radius: 4px;
    cursor: pointer;
    font-size: 14px;
    margin: 10px auto;
    display: block;
    transition: background 0.3s;
}

.captcha-refresh:hover {
    background: rgba(255, 255, 255, 0.2);
}

@media (max-width: 768px) {
    .captcha-images {
        grid-template-columns: repeat(3, 1fr);
    }
    
    .captcha-image {
        height: 50px;
    }
}

@media (max-width: 480px) {
    .captcha-images {
        grid-template-columns: repeat(2, 1fr);
    }
    
    .captcha-image {
        height: 60px;
    }
    
    .captcha-message {
        font-size: 14px;
    }
}