/* Site header: sticky, logo + nav + phone + CTA, collapsing to a mobile
   panel below 1024px. Sticky is deliberate, not default: on a long B2B
   homepage the phone number and primary CTA should stay reachable while a
   buyer scrolls through product categories (Development Master Prompt §16). */

.site-header {
    position: sticky;
    top: 0;
    z-index: var(--z-sticky);
    background: var(--color-paper);
    border-bottom: 1px solid transparent;
    transition: border-color var(--duration-base) var(--ease-standard),
                box-shadow var(--duration-base) var(--ease-standard);
}

.site-header.is-scrolled {
    border-bottom-color: var(--color-line);
    box-shadow: var(--shadow-sm);
}

.site-header__row {
    display: flex;
    align-items: center;
    gap: var(--space-6);
    height: var(--header-height);
}

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

.site-header__logo-img {
    width: 9.5rem;
    height: auto;
}

.site-nav {
    flex: 1;
}

.site-nav__list {
    display: flex;
    gap: var(--space-6);
}

.site-nav__link {
    font-size: var(--text-sm);
    font-weight: var(--font-medium);
    color: var(--color-text);
    padding-block: var(--space-2);
    position: relative;
}

.site-nav__link::after {
    content: '';
    position: absolute;
    left: 0;
    right: 0;
    bottom: -1px;
    height: 2px;
    background: var(--color-accent-600);
    transform: scaleX(0);
    transform-origin: left;
    transition: transform var(--duration-base) var(--ease-standard);
}

.site-nav__link:hover::after,
.site-nav__link.is-active::after {
    transform: scaleX(1);
}

.site-header__actions {
    display: flex;
    align-items: center;
    gap: var(--space-5);
    flex-shrink: 0;
}

.site-header__phone {
    font-family: var(--font-mono);
    font-size: var(--text-sm);
    font-weight: var(--font-medium);
    color: var(--color-text);
    white-space: nowrap;
}

.site-header__burger {
    display: none;
    position: relative;
    width: 2.75rem;
    height: 2.75rem;
    align-items: center;
    justify-content: center;
    flex-shrink: 0;
}

.site-header__burger-icon {
    position: absolute;
    width: 1.375rem;
    height: 1.375rem;
    transition: opacity var(--duration-fast) var(--ease-standard), transform var(--duration-fast) var(--ease-standard);
}

.site-header__burger-icon--close { opacity: 0; transform: scale(0.7); }

.site-header__burger[aria-expanded="true"] .site-header__burger-icon--open { opacity: 0; transform: scale(0.7); }
.site-header__burger[aria-expanded="true"] .site-header__burger-icon--close { opacity: 1; transform: scale(1); }

.mobile-nav {
    border-top: 1px solid var(--color-line);
    padding: var(--space-5) var(--container-padding) var(--space-6);
    background: var(--color-paper);
}

.mobile-nav__list {
    display: flex;
    flex-direction: column;
}

.mobile-nav__link {
    display: block;
    padding-block: var(--space-3);
    font-size: var(--text-md);
    font-weight: var(--font-medium);
    border-bottom: 1px solid var(--color-line);
}

.mobile-nav__actions {
    display: flex;
    flex-direction: column;
    align-items: flex-start;
    gap: var(--space-4);
    margin-top: var(--space-5);
}

@media (max-width: 1024px) {
    .site-nav,
    .site-header__actions .site-header__phone,
    .site-header__actions .btn {
        display: none;
    }
    .site-header__burger {
        display: flex;
        margin-left: auto;
    }
}