/* ==========================================================================
   S-001 Header / Nav - NVM Pet Variation A (Heritage Industrial)
   ==========================================================================
   Editorial newspaper-masthead feel: logo left, nav right, uppercase
   letter-spaced labels, slim brass underline on hover, subtle warm
   off-white bg shift after 80px of scroll, thin 1px hamburger lines.
   All tokens via var(--*). No raw hex, no raw px, no raw font-family.
   ========================================================================== */


/* ==========================================================================
   Skip Link (accessibility)
   ========================================================================== */

.skip-link {
    position: absolute;
    top: 0;
    left: 0;
    padding: var(--space-sm) var(--space-md);
    background-color: var(--color-primary);
    color: var(--text-on-dark);
    font-family: var(--font-body);
    font-size: var(--text-body-small);
    font-weight: var(--font-semibold);
    text-transform: uppercase;
    letter-spacing: 0.1em;
    transform: translateY(-110%);
    transition: transform var(--duration-micro) var(--easing-quick);
    z-index: var(--z-max);
}

.skip-link:focus,
.skip-link:focus-visible {
    transform: translateY(0);
    outline: 2px solid var(--color-accent);
    outline-offset: 2px;
}


/* ==========================================================================
   Header Shell
   ========================================================================== */

.site-header {
    position: relative;
    width: 100%;
    background-color: var(--bg-primary);
    border-bottom: 1px solid transparent;
    z-index: var(--z-sticky);
    transition: background-color var(--duration-base) var(--easing-default),
                border-color var(--duration-base) var(--easing-default),
                box-shadow var(--duration-base) var(--easing-default);
}

.site-header--sticky {
    position: sticky;
    top: 0;
    left: 0;
    right: 0;
}

/* Scrolled state: subtle white -> warm off-white shift with hairline border. */
.site-header--scrolled {
    background-color: var(--gray-50);
    border-bottom-color: var(--border-color);
    box-shadow: var(--shadow-raised);
}

.site-header__inner {
    display: flex;
    align-items: center;
    justify-content: space-between;
    gap: var(--space-lg);
    min-height: 88px;
    padding-top: var(--space-md);
    padding-bottom: var(--space-md);
}

/* Slight density reduction on scrolled state for the masthead feel. */
.site-header--scrolled .site-header__inner {
    min-height: 72px;
}


/* ==========================================================================
   Brand / Logo
   ========================================================================== */

.site-header__brand {
    display: flex;
    align-items: center;
    flex-shrink: 0;
}

.site-header__logo-link {
    display: inline-flex;
    align-items: center;
    text-decoration: none;
    color: var(--color-primary);
}

.site-header__logo-link:focus-visible {
    outline: 2px solid var(--color-accent);
    outline-offset: 4px;
}

.site-header__logo {
    display: block;
    width: auto;
    max-height: 56px;
    height: auto;
}

.site-header__wordmark {
    font-family: var(--font-heading);
    font-weight: var(--font-extrabold);
    font-size: 1.5rem;
    line-height: 1;
    letter-spacing: var(--tracking-widest);
    text-transform: uppercase;
    color: var(--color-primary);
}


/* ==========================================================================
   Primary Nav (Desktop)
   ========================================================================== */

.site-header__nav {
    display: flex;
    align-items: center;
    flex: 1 1 auto;
    justify-content: flex-end;
}

.primary-nav {
    display: flex;
    align-items: center;
    gap: var(--space-xl);
    list-style: none;
    margin: 0;
    padding: 0;
}

.primary-nav__item {
    position: relative;
}

.nav-link {
    position: relative;
    display: inline-block;
    padding: var(--space-sm) 0;
    font-family: var(--font-body);
    font-weight: var(--font-semibold);
    font-size: var(--text-body-small);
    letter-spacing: 0.12em;
    text-transform: uppercase;
    color: var(--color-primary);
    text-decoration: none;
    transition: color var(--duration-base) var(--easing-default);
}

/* Brass underline drawn-in on hover/focus. */
.nav-link::after {
    content: '';
    position: absolute;
    left: 0;
    bottom: 0;
    display: block;
    height: 2px;
    width: 0;
    background-color: var(--color-accent);
    transition: width var(--duration-base) var(--easing-default);
}

.nav-link:hover,
.nav-link:focus-visible {
    color: var(--color-primary);
}

.nav-link:hover::after,
.nav-link:focus-visible::after {
    width: 100%;
}

.nav-link:focus-visible {
    outline: 2px solid var(--color-accent);
    outline-offset: 4px;
}

/* Active state (current-page) keeps the brass underline persistently. */
.primary-nav__item.is-active .nav-link::after,
.nav-link[aria-current="page"]::after {
    width: 100%;
    height: 2px;
}


/* ==========================================================================
   Mobile Menu Toggle (Hamburger - thin 1px lines)
   ========================================================================== */

.nav-hamburger {
    display: none;
    align-items: center;
    justify-content: center;
    width: 44px;
    height: 44px;
    padding: 0;
    background: transparent;
    border: none;
    cursor: pointer;
    color: var(--color-primary);
}

.nav-hamburger:focus-visible {
    outline: 2px solid var(--color-accent);
    outline-offset: 2px;
}

.nav-hamburger__lines {
    display: flex;
    flex-direction: column;
    justify-content: space-between;
    width: 24px;
    height: 16px;
}

.nav-hamburger__line {
    display: block;
    width: 100%;
    height: 1px;
    background-color: var(--color-primary);
    transform-origin: center;
    transition: transform var(--duration-base) var(--easing-default),
                opacity var(--duration-micro) var(--easing-quick);
}

/* Morph into an X on open state. */
.nav-hamburger[aria-expanded="true"] .nav-hamburger__line:nth-child(1) {
    transform: translateY(7px) rotate(45deg);
}

.nav-hamburger[aria-expanded="true"] .nav-hamburger__line:nth-child(2) {
    opacity: 0;
}

.nav-hamburger[aria-expanded="true"] .nav-hamburger__line:nth-child(3) {
    transform: translateY(-8px) rotate(-45deg);
}


/* ==========================================================================
   Mobile Menu Overlay
   ========================================================================== */

.mobile-menu {
    position: fixed;
    inset: 0;
    background-color: var(--bg-primary);
    padding: calc(var(--space-3xl) + var(--space-lg)) var(--container-padding) var(--space-2xl);
    opacity: 0;
    visibility: hidden;
    z-index: var(--z-overlay);
    overflow-y: auto;
    transition: opacity var(--duration-base) var(--easing-default),
                visibility 0s linear var(--duration-base);
}

.mobile-menu[aria-hidden="false"] {
    opacity: 1;
    visibility: visible;
    transition: opacity var(--duration-base) var(--easing-default),
                visibility 0s linear 0s;
}

.mobile-menu__close {
    position: absolute;
    top: var(--space-md);
    right: var(--space-md);
    display: inline-flex;
    align-items: center;
    justify-content: center;
    width: 44px;
    height: 44px;
    padding: 0;
    background: transparent;
    border: none;
    color: var(--color-primary);
    cursor: pointer;
    transition: color var(--duration-base) var(--easing-default);
}

.mobile-menu__close:hover,
.mobile-menu__close:focus-visible {
    color: var(--color-accent);
}

.mobile-menu__close:focus-visible {
    outline: 2px solid var(--color-accent);
    outline-offset: 2px;
}

.mobile-menu__nav {
    max-width: var(--container-narrow);
    margin: 0 auto;
}

.mobile-menu__list {
    list-style: none;
    margin: 0;
    padding: 0;
    display: flex;
    flex-direction: column;
    gap: var(--space-md);
}

.mobile-menu__item {
    border-bottom: 1px solid var(--border-color);
}

.mobile-menu__link {
    display: block;
    padding: var(--space-md) 0;
    font-family: var(--font-heading);
    font-weight: var(--font-semibold);
    font-size: var(--text-h3);
    line-height: var(--leading-tight);
    letter-spacing: var(--tracking-tight);
    color: var(--color-primary);
    text-decoration: none;
    transition: color var(--duration-base) var(--easing-default);
}

.mobile-menu__link:hover,
.mobile-menu__link:focus-visible {
    color: var(--color-accent);
}

.mobile-menu__link:focus-visible {
    outline: 2px solid var(--color-accent);
    outline-offset: 2px;
}

/* Lock body scroll when mobile menu is open (paired with body.menu-open in JS). */
body.menu-open {
    overflow: hidden;
}


/* ==========================================================================
   Body offset when sticky header active
   ========================================================================== */

body.has-sticky-header {
    /* sticky uses position: sticky, so no manual offset needed in normal flow.
       Variable kept for any anchor-scroll offsets called by sections. */
}


/* ==========================================================================
   Responsive: mobile / tablet
   ========================================================================== */

@media (max-width: 767.98px) {
    .site-header__inner {
        min-height: 64px;
        gap: var(--space-md);
    }

    .site-header--scrolled .site-header__inner {
        min-height: 56px;
    }

    .site-header__logo {
        max-height: 40px;
    }

    .site-header__wordmark {
        font-size: 1.125rem;
    }

    /* Hide desktop nav, show hamburger. */
    .site-header__nav {
        display: none;
    }

    .nav-hamburger {
        display: inline-flex;
    }
}


/* ==========================================================================
   Reduced motion: kill the underline draw and toggle morph animations
   ========================================================================== */

@media (prefers-reduced-motion: reduce) {
    .site-header,
    .nav-link,
    .nav-link::after,
    .nav-hamburger__line,
    .mobile-menu,
    .mobile-menu__link,
    .skip-link {
        transition: none;
    }
}