/* 轮播图占位样式 */
.carousel-placeholder {
    height: 400px;
    background-color: #e9ecef;
    display: flex;
    align-items: center;
    justify-content: center;
    color: #6c757d;
    font-size: 1.5rem;
    text-align: center;
}

.carousel-color-1 {
    background-color: #4285f4;
    color: white;
}

.carousel-color-2 {
    background-color: #34a853;
    color: white;
}

.carousel-color-3 {
    background-color: #ea4335;
    color: white;
}

/* 学科卡片占位样式 */
.subject-placeholder {
    height: 150px;
    background-color: #e9ecef;
    display: flex;
    align-items: center;
    justify-content: center;
    color: #6c757d;
    font-size: 1.2rem;
    margin-bottom: 1rem;
}

.subject-color-1 {
    background-color: #4285f4;
    color: white;
}

.subject-color-2 {
    background-color: #34a853;
    color: white;
}

.subject-color-3 {
    background-color: #ea4335;
    color: white;
}

.subject-color-4 {
    background-color: #fbbc05;
    color: white;
}

.subject-color-5 {
    background-color: #673ab7;
    color: white;
}

.subject-color-6 {
    background-color: #3f51b5;
    color: white;
}

.subject-color-7 {
    background-color: #009688;
    color: white;
}

.subject-color-8 {
    background-color: #ff5722;
    color: white;
}