/* ── Navigation Bar ── */
.navbar {
    position: fixed;
    top: 0; left: 0;
    width: 100%;
    z-index: 1000;
    display: flex;
    align-items: center;
    justify-content: center;
    padding: 0 40px;
    height: 80px;
    background: rgba(0,0,0,0.75);
    backdrop-filter: blur(6px);
    -webkit-backdrop-filter: blur(6px);
    transition: background 0.4s ease;
}
.navbar.scrolled {
    background: rgba(0,0,0,0.92);
    backdrop-filter: blur(14px);
    -webkit-backdrop-filter: blur(14px);
}

/* Center nav links */
.nav-center {
    display: flex;
    align-items: center;
    gap: 48px;
    list-style: none;
}
.nav-center a {
    color: #fff;
    text-decoration: none;
    font-size: 1.05rem;
    font-weight: 700;
    letter-spacing: 0.16em;
    text-transform: uppercase;
    opacity: 0.7;
    transition: opacity 0.25s;
    white-space: nowrap;
}
.nav-center a:hover {
    opacity: 1;
}

.nav-lang {
    position: absolute;
    left: 40px;
    top: 50%;
    transform: translateY(-50%);
}
.lang-switch {
    display: inline-flex;
    align-items: center;
    gap: 4px;
    padding: 4px 10px;
    color: #fff;
    background: none;
    border: 1px solid rgba(255,255,255,0.25);
    border-radius: 4px;
    cursor: pointer;
    font-family: inherit;
    font-size: 0.85rem;
    font-weight: 700;
    letter-spacing: 0.06em;
    opacity: 0.7;
    transition: opacity 0.25s, border-color 0.25s;
}
.lang-switch:hover {
    opacity: 1;
    border-color: rgba(255,255,255,0.6);
}

/* Right side circular social icons */
.nav-icons {
    position: absolute;
    right: 40px;
    display: flex;
    align-items: center;
    gap: 10px;
}
.nav-icons a,
.nav-icons button {
    display: inline-flex;
    align-items: center;
    justify-content: center;
    width: 42px;
    height: 42px;
    color: #111;
    font-size: 1.15rem;
    text-decoration: none;
    background: #fff;
    border: none;
    border-radius: 50%;
    font-family: inherit;
    transition: background 0.25s, color 0.25s, transform 0.25s;
    cursor: pointer;
}
.nav-icons a:hover,
.nav-icons button:hover {
    background: #ddd;
    color: #000;
    transform: translateY(-2px);
}
.nav-icons-en,
.nav-icons-zh {
    display: flex;
    align-items: center;
    gap: 10px;
}
body.lang-zh .nav-icons-en {
    display: none;
}
body.lang-en .nav-icons-zh {
    display: none;
}
.social-text-icon {
    font-size: 0.82rem;
    font-weight: 700;
    letter-spacing: 0.02em;
}
.social-logo-icon {
    width: 24px;
    height: 24px;
    object-fit: contain;
    border-radius: 4px;
}
.social-logo-bili {
    width: 24px;
    height: 24px;
    border-radius: 0;
    object-fit: contain;
}