app.css

* {
    margin: 0;
    padding: 0;
    box-sizing: border-box;
}
:root {
    --red: #dc3545;
}

/*!         navbar          */
/* .navbar{
    background-color: rgb(124, 139, 139) !important;
} */
.navbar .navbar-nav {
    text-transform: uppercase;
    font-size: 1.2rem;
    font-weight: 600;
}
.navbar .nav-link {
    transition: color 0.5s;
}
.navbar .nav-link:hover {
    color: var(--red);
}

.logo{
    text-shadow: 3px 3px 3px black;
    color: brown;
    font-size: 2rem;
    font-weight: 200%;
}

/*!          CAROUSEL */
.carousel-item {
    max-height: calc(100vh - 88px);
}

.carousel-caption h5 {
    color: var(--red);
    font-size: 2.4rem;
    text-shadow: 3px 3px 3px black;
}
.carousel-caption p {
    text-shadow: 3px 3px 3px black;
    font-weight: 600;
}
.carousel-caption .btn {
    width: 7rem;
}

.carousel-caption {
    bottom: 15rem;
}
.carousel-indicators {
    gap: 0.7rem;
}
.carousel-indicators button {
    background-color: var(--red) !important;
    height: 0.7rem !important;
    width: 3rem !important;
}

/*!   ABOUT US */

/*!   INSTRUCTORS */
section#instructors .card {
    transition: transform 0.4s;
    cursor: pointer;
}

section#instructors .card:hover {
    transform: scale(1.03);
    transition: transform 0.4s;
}

section#instructors i {
    transition: opacity 0.6s;
}

section#instructors i:hover {
    opacity: 0.5;
}

/*! COURSES  */
.nav-pills .nav-link.active {
    background-color: var(--red);
}

.nav-pills .nav-link {
    color: white;
    font-size: 1.1rem;
}

/*! FOOTER */

footer i {
    transition: color 0.8s;
    margin-right: 0.8rem;
    cursor: pointer;
}

footer i:hover {
    color: var(--red);
}

/*! BUTTON UP */
.btn-up {
    position: fixed;
    bottom: 1rem;
    right: 1rem;
    color: white;
    background-color: var(--red);
    width: 50px;
    height: 50px;
    border-radius: 50%;
    display: flex;
    align-items: center;
    justify-content: center;
    font-size: 1.3rem;
    text-decoration: none;
}

.btn-up:hover {
    transform: scale(1.2);
    color: black;
}