/* ==========================================================================
 * DSTAIR — Navigation
 * Fixed navbar with scroll effects, mobile slide-out, and hamburger animation.
 * ========================================================================== */


/* --------------------------------------------------------------------------
 * § 1. BASE NAVBAR
 * -------------------------------------------------------------------------- */
#navbar {
    position: fixed;
    top: 0;
    left: 0;
    width: 100%;
    padding: 1.25rem 1.5rem;
    display: flex;
    justify-content: space-between;
    align-items: center;
    z-index: var(--z-sticky);
    transition:
        background 0.4s var(--ease-smooth),
        padding 0.3s var(--ease-smooth),
        box-shadow 0.3s var(--ease-smooth);
}

@media (min-width: 768px) {
    #navbar {
        padding: 1.5rem 2.5rem;
    }
}


/* --------------------------------------------------------------------------
 * § 2. SCROLLED STATE
 * -------------------------------------------------------------------------- */
#navbar.scrolled {
    background: rgba(var(--color-dark-rgb), 0.88);
    backdrop-filter: blur(16px);
    -webkit-backdrop-filter: blur(16px);
    box-shadow: 0 1px 0 var(--white-10), var(--shadow-md);
    padding-top: 0.75rem;
    padding-bottom: 0.75rem;
}


/* --------------------------------------------------------------------------
 * § 3. NAV LINKS
 * -------------------------------------------------------------------------- */
.nav-link {
    position: relative;
    overflow: hidden;
    cursor: pointer;
    transition: color var(--transition-base);
    padding-bottom: 2px;
}

.nav-link:hover,
.nav-link.active {
    color: var(--color-highlight);
}

/* Underline slide-in */
.nav-link span {
    position: absolute;
    bottom: 0;
    left: 0;
    width: 100%;
    height: 2px;
    background: linear-gradient(90deg,
            var(--color-highlight),
            rgba(var(--color-highlight-rgb), 0.4));
    transform: translateX(-101%);
    transition: transform 0.35s var(--ease-out);
    border-radius: var(--radius-pill);
}

.nav-link:hover span,
.nav-link.active span {
    transform: translateX(0);
}


/* --------------------------------------------------------------------------
 * § 4. MOBILE MENU
 * -------------------------------------------------------------------------- */
.mobile-menu {
    position: fixed;
    inset: 0;
    background: rgba(var(--color-dark-rgb), 0.98);
    backdrop-filter: blur(24px);
    -webkit-backdrop-filter: blur(24px);
    z-index: calc(var(--z-sticky) - 1);
    display: flex;
    flex-direction: column;
    align-items: center;
    justify-content: center;
    gap: var(--space-xl);
    transform: translateX(100%);
    transition: transform 0.45s var(--ease-out);
}

.mobile-menu.open {
    transform: translateX(0);
}

/* Stagger mobile links */
.mobile-menu .nav-link {
    opacity: 0;
    transform: translateX(20px);
    transition:
        opacity 0.3s var(--ease-out),
        transform 0.3s var(--ease-out),
        color var(--transition-base);
}

.mobile-menu.open .nav-link {
    opacity: 1;
    transform: translateX(0);
}

.mobile-menu.open .nav-link:nth-child(1) {
    transition-delay: 0.1s;
}

.mobile-menu.open .nav-link:nth-child(2) {
    transition-delay: 0.15s;
}

.mobile-menu.open .nav-link:nth-child(3) {
    transition-delay: 0.2s;
}

.mobile-menu.open .nav-link:nth-child(4) {
    transition-delay: 0.25s;
}

.mobile-menu.open .nav-link:nth-child(5) {
    transition-delay: 0.3s;
}

.mobile-menu.open .nav-link:nth-child(6) {
    transition-delay: 0.35s;
}


/* --------------------------------------------------------------------------
 * § 5. HAMBURGER
 * -------------------------------------------------------------------------- */
.hamburger {
    position: relative;
    z-index: var(--z-sticky);
    width: 28px;
    height: 20px;
    cursor: pointer;
    display: flex;
    flex-direction: column;
    justify-content: space-between;
}

.hamburger span {
    display: block;
    width: 100%;
    height: 2px;
    background: var(--white);
    border-radius: var(--radius-pill);
    transition: all 0.3s var(--ease-smooth);
    transform-origin: center;
}

.hamburger.open span:nth-child(1) {
    transform: rotate(45deg) translate(5px, 6px);
}

.hamburger.open span:nth-child(2) {
    opacity: 0;
    transform: scaleX(0);
}

.hamburger.open span:nth-child(3) {
    transform: rotate(-45deg) translate(5px, -6px);
}