/* PK题目推送系统样式 */
.question-card {
    background: linear-gradient(135deg, #667eea 0%, #764ba2 100%);
    border-radius: 15px;
    padding: 20px;
    margin: 15px 0;
    color: white;
    box-shadow: 0 8px 32px rgba(102, 126, 234, 0.3);
    border: 1px solid rgba(255, 255, 255, 0.2);
    backdrop-filter: blur(10px);
    transition: all 0.3s ease;
}

.question-card:hover {
    transform: translateY(-5px);
    box-shadow: 0 12px 40px rgba(102, 126, 234, 0.4);
}

.question-card h5 {
    color: #fff;
    font-weight: 600;
    margin-bottom: 15px;
    text-align: center;
    font-size: 1.2rem;
}

.question-card p {
    margin-bottom: 10px;
    font-size: 1rem;
    line-height: 1.5;
}

.question-card strong {
    color: #ffd700;
    font-weight: 600;
}

.question-card .form-label {
    color: #fff;
    font-weight: 500;
    margin-bottom: 8px;
}

.question-card .form-control {
    background: rgba(255, 255, 255, 0.1);
    border: 1px solid rgba(255, 255, 255, 0.3);
    border-radius: 8px;
    color: #fff;
    padding: 12px 15px;
    font-size: 1rem;
    transition: all 0.3s ease;
}

.question-card .form-control:focus {
    background: rgba(255, 255, 255, 0.2);
    border-color: #ffd700;
    box-shadow: 0 0 0 0.2rem rgba(255, 215, 0, 0.25);
    color: #fff;
}

.question-card .form-control::placeholder {
    color: rgba(255, 255, 255, 0.7);
}

/* 难度标签样式 */
.difficulty-easy {
    background: linear-gradient(135deg, #4facfe 0%, #00f2fe 100%);
}

.difficulty-medium {
    background: linear-gradient(135deg, #43e97b 0%, #38f9d7 100%);
}

.difficulty-hard {
    background: linear-gradient(135deg, #fa709a 0%, #fee140 100%);
}

/* PK状态指示器 */
.pk-status {
    display: inline-block;
    padding: 5px 12px;
    border-radius: 20px;
    font-size: 0.9rem;
    font-weight: 500;
    margin: 5px 0;
}

.pk-status.waiting {
    background: linear-gradient(135deg, #ffecd2 0%, #fcb69f 100%);
    color: #8b4513;
}

.pk-status.active {
    background: linear-gradient(135deg, #a8edea 0%, #fed6e3 100%);
    color: #2c3e50;
}

.pk-status.completed {
    background: linear-gradient(135deg, #d299c2 0%, #fef9d7 100%);
    color: #27ae60;
}

/* 答案提交按钮样式 */
.submit-answer-btn {
    background: linear-gradient(135deg, #667eea 0%, #764ba2 100%);
    border: none;
    border-radius: 25px;
    padding: 12px 30px;
    color: white;
    font-weight: 600;
    font-size: 1rem;
    transition: all 0.3s ease;
    box-shadow: 0 4px 15px rgba(102, 126, 234, 0.3);
}

.submit-answer-btn:hover {
    transform: translateY(-2px);
    box-shadow: 0 6px 20px rgba(102, 126, 234, 0.4);
    background: linear-gradient(135deg, #764ba2 0%, #667eea 100%);
}

.submit-answer-btn:active {
    transform: translateY(0);
}

/* 题目交换动画 */
@keyframes questionExchange {
    0% { opacity: 1; transform: translateX(0); }
    50% { opacity: 0.3; transform: translateX(20px); }
    100% { opacity: 1; transform: translateX(0); }
}

.question-exchange {
    animation: questionExchange 0.8s ease-in-out;
}

/* 响应式设计 */
@media (max-width: 768px) {
    .question-card {
        padding: 15px;
        margin: 10px 0;
    }
    
    .question-card h5 {
        font-size: 1.1rem;
    }
    
    .question-card p {
        font-size: 0.9rem;
    }
    
    .submit-answer-btn {
        padding: 10px 25px;
        font-size: 0.9rem;
    }
}

/* 加载状态 */
.loading-questions {
    text-align: center;
    padding: 40px 20px;
    color: #667eea;
    font-size: 1.1rem;
}

.loading-questions::after {
    content: '';
    display: inline-block;
    width: 20px;
    height: 20px;
    border: 3px solid #667eea;
    border-radius: 50%;
    border-top-color: transparent;
    animation: spin 1s ease-in-out infinite;
    margin-left: 10px;
}

@keyframes spin {
    to { transform: rotate(360deg); }
}