/* =========================================================
   HEADER + NAV
   Состояния:
     по умолчанию        — прозрачный поверх hero (белый логотип/ссылки)
     .is-sticky          — фиксированный белый после прокрутки (цветной логотип)
     .is-open            — раскрытое мобильное меню
   ========================================================= */
.site-header {
  position: absolute;
  top: 0;
  left: 0;
  right: 0;
  z-index: 100;
  background: linear-gradient(to bottom, rgba(0, 0, 0, 0.3), rgba(0, 0, 0, 0));
  transition: background-color var(--transition), box-shadow var(--transition);
}

.site-header.is-sticky {
  position: fixed;
  background: var(--color-white);
  box-shadow: var(--shadow-header);
  animation: header-slide-in 0.3s ease-out;
}

@keyframes header-slide-in {
  from { transform: translateY(-100%); }
  to   { transform: translateY(0); }
}

.site-header__inner {
  display: flex;
  align-items: center;
  justify-content: space-between;
  min-height: var(--header-height);
  flex-wrap: wrap;
}

.site-header__logo {
  width: auto;
  height: 60px;
}

.site-header__logo--dark { display: none; }
.site-header.is-sticky .site-header__logo--light,
.site-header.is-open .site-header__logo--light { display: none; }
.site-header.is-sticky .site-header__logo--dark,
.site-header.is-open .site-header__logo--dark { display: block; }

.site-header__toggle {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  width: 40px;
  height: 40px;
  font-size: 22px;
  color: var(--color-white);
  background-color: var(--color-primary);
  border: 0;
  cursor: pointer;
}

/* Nav — мобильная версия */
.site-nav {
  display: none;
  width: 100%;
  padding-bottom: var(--space-md);
}

.site-header.is-open .site-nav {
  display: block;
}

.site-header.is-open {
  background: var(--color-white);
}

.site-nav__link {
  display: block;
  padding: var(--space-sm) 0;
  font-size: 14px;
  font-weight: 700;
  text-transform: uppercase;
  letter-spacing: 0.05em;
  color: var(--color-title);
}

/* Nav — десктоп */
@media (min-width: 768px) {
  .site-header__toggle { display: none; }

  .site-nav {
    display: block;
    width: auto;
    padding: 0;
  }

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

  .site-nav__link {
    padding: 30px 0;
    color: var(--color-white);
    position: relative;
  }

  .site-nav__link::before {
    content: '';
    position: absolute;
    left: 0;
    right: 0;
    top: 0;
    border-top: 3px solid var(--color-primary);
    transform: scaleX(0);
    transition: transform var(--transition);
  }

  .site-nav__link:hover::before,
  .site-nav__link:focus::before {
    transform: scaleX(1);
  }

  .site-header.is-sticky .site-nav__link {
    color: var(--color-title);
  }

  .site-nav__link:hover,
  .site-nav__link:focus,
  .site-header.is-sticky .site-nav__link:hover {
    color: var(--color-primary);
  }
}