/* UPDATED NAV SECTION */
nav {
    display: flex;             /* Keeps items in a flexible row */
    justify-content: center;   /* Centers them */
    flex-wrap: wrap;           /* Lets them stack cleanly if screen is tiny */
    gap: 15px;                 /* Adds guaranteed space between buttons */
    padding: 40px 20px;
    background: #000000;
}

nav a {
    color: #ffffff;
    text-decoration: none;
    font-weight: 700;
    font-size: 16px;
    opacity: 0.5;
    text-transform: uppercase;
    transition: opacity 0.2s;
    letter-spacing: 1px;
    padding-bottom: 5px;       /* Room for the underline */
    border-bottom: 2px solid transparent; /* Invisible border prevents "jump" */
}

nav a:hover, nav a.active {
    opacity: 1;
}

nav a.active {
    border-bottom: 2px solid white; /* The white line */
}