.htu-module {
    margin-bottom: 25px;
    border: 1px solid #e0e0e0;
    border-radius: var(--border-radius);
    overflow: hidden;
    box-shadow: 0 2px 8px rgba(0,0,0,0.05);
}

.module-header {
    background-color: var(--light-gray);
    padding: 15px 20px;
    cursor: pointer;
    display: flex;
    align-items: center;
    justify-content: space-between;
    transition: var(--transition);
}

.module-header:hover {
    background-color: #e3f2fd;
}

.module-title {
    font-size: 1.3rem;
    font-weight: 600;
    color: var(--secondary);
    display: flex;
    align-items: center;
    gap: 10px;
}

.module-title i {
    font-size: 1rem;
    transition: var(--transition);
}

.module-arrow {
    color: var(--gray);
    transition: var(--transition);
}

.module-content {
    padding: 20px;
    display: grid;
    grid-template-columns: 1fr;
    gap: 30px;
}

.htu-function {
    padding-bottom: 20px;
    margin-bottom: 20px;
    border-bottom: 1px dashed #e0e0e0;
}

.htu-function:last-child {
    border-bottom: none;
    margin-bottom: 0;
    padding-bottom: 0;
}

.function-title {
    font-size: 1.2rem;
    margin-bottom: 15px;
    color: var(--primary-dark);
    display: flex;
    align-items: center;
    gap: 8px;
}

.function-title i {
    font-size: 0.9rem;
    color: var(--primary);
}

.function-content {
    display: flex;
    gap: 25px;
}

.function-img {
    flex: 1;
    min-width: 0;
    border-radius: var(--border-radius);
    overflow: hidden;
    box-shadow: var(--box-shadow);
    background: linear-gradient(45deg, #f5f7fa, #e4edf5);
    height: 300px;
    display: flex;
    align-items: center;
    justify-content: center;
    position: relative;
}

.function-img img {
    width: 100%;
    height: 100%;
    object-fit: contain;
}

.function-img video {
    width: 100%;
    height: 100%;
    object-fit: contain;
    display: block;
    background: linear-gradient(45deg, #f5f7fa, #e4edf5);
}

.function-desc {
    flex: 1;
    min-width: 0;
}

.function-desc p {
    margin-bottom: 12px;
    line-height: 1.7;
}

.function-steps {
    margin-top: 15px;
    padding-left: 20px;
}

.function-steps li {
    margin-bottom: 10px;
    position: relative;
    padding-left: 25px;
    list-style: none;
}

.function-steps li:before {
    content: "";
    position: absolute;
    left: 0;
    top: 8px;
    width: 12px;
    height: 12px;
    border-radius: 50%;
    background-color: var(--primary);
}

.atomic-function {
    background-color: var(--light-gray);
    padding: 12px 15px 12px 25px;
    border-radius: var(--border-radius);
    position: relative;
}

.atomic-function p {
    margin-bottom: 0;
}

.atomic-function:before {
    content: "原子功能";
    position: absolute;
    left: 0;
    top: -8px;
    background-color: var(--primary);
    color: white;
    font-size: 0.75rem;
    padding: 2px 8px;
    border-radius: var(--border-radius) 0 var(--border-radius) 0;
}

.module-open .module-arrow {
    transform: rotate(90deg);
}

.placeholder-text {
    text-align: center;
    color: #95a5a6;
    font-style: italic;
    padding: 30px;
    background-color: var(--light-gray);
    border-radius: var(--border-radius);
}

/* 响应式设计 */
@media (max-width: 768px) {
    .function-content {
        flex-direction: column;
    }

    .function-img {
        height: 200px;
    }

    .section {
        padding: 20px;
    }
}

/* 图片占位符 */
.img-placeholder {
    width: 80%;
    height: 80%;
    display: flex;
    flex-direction: column;
    align-items: center;
    justify-content: center;
    text-align: center;
    color: var(--gray);
    font-size: 0.9rem;
}

.img-placeholder i {
    font-size: 3rem;
    margin-bottom: 15px;
    color: #d1d8e0;
}

.module-breadcrumb {
    font-size: 0.85rem;
    color: var(--gray);
    margin-bottom: 5px;
    display: flex;
    align-items: center;
    gap: 5px;
}

.module-breadcrumb i {
    font-size: 0.7rem;
}