.w-100 {
    width: 100%;
}

.h-100 {
    height: 100%;
}

.text-decoration-underline {
    text-decoration: underline;
}

.bold {
    font-weight: bold;
}

.italic {
    font-style: italic;
}

.smooth-video {
    width: 100%;
    transition: opacity 0.5s ease-in-out; /* 控制淡入的速度 */
}

.video-hidden {
    opacity: 0;
}