body {
  padding-top: var(--size-header);
}

.header {
  position: fixed;
  top: 0;
  left: 50%;
  width: 100%;
  max-width: 1920px;
  transform: translateX(-50%);
  z-index: 1000;
  background: rgba(248, 250, 249, .82);
  backdrop-filter: blur(var(--glass-blur));
  -webkit-backdrop-filter: blur(var(--glass-blur));
  border-bottom: 1px solid transparent;
  transition: transform .3s ease, border-color var(--duration-base) ease, background var(--duration-base) ease;
}

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

.header--hidden {
  transform: translateX(-50%) translateY(-100%);
}

.header__inner {
  height: var(--size-header);
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 24px;
}

.header__logo {
  display: flex;
  align-items: center;
  gap: 10px;
  font-size: 27px;
  font-weight: 800;
  letter-spacing: -0.02em;
  color: var(--color-text-primary);
}

.header__logo img {
  width: 34px;
}

.header__nav {
  display: flex;
  gap: 36px;
  font-size: var(--text-nav-size);
  font-weight: var(--text-nav-weight);
  color: var(--color-text-secondary);
}

.header__nav-link {
  color: inherit;
}

.header__nav-link:hover {
  color: var(--color-brand-600);
}

.header__nav-link--active {
  color: var(--color-text-primary);
  font-weight: 700;
  border-bottom: 2px solid var(--color-brand-600);
  padding-bottom: 4px;
}

.header__actions {
  display: flex;
  align-items: center;
  gap: 16px;
}

.header__burger {
  display: none;
  width: 30px;
  height: 18px;
  position: relative;
  background: none;
  border: none;
  padding: 0;
  cursor: pointer;
  flex: none;
}

.header__burger-line {
  position: absolute;
  left: 0;
  right: 0;
  height: 2px;
  border-radius: 2px;
  background: var(--color-brand-600);
  transition: transform var(--duration-fast) var(--ease-out), opacity var(--duration-fast) var(--ease-out), top var(--duration-fast) var(--ease-out);
}

.header__burger-line:nth-child(1) { top: 0; }
.header__burger-line:nth-child(2) { top: 8px; }
.header__burger-line:nth-child(3) { top: 16px; }

.header__burger[aria-expanded="true"] .header__burger-line:nth-child(1) {
  top: 8px;
  transform: rotate(45deg);
}

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

.header__burger[aria-expanded="true"] .header__burger-line:nth-child(3) {
  top: 8px;
  transform: rotate(-45deg);
}

.header__menu {
  position: absolute;
  top: 100%;
  left: 0;
  right: 0;
  display: none;
  flex-direction: column;
  gap: 4px;
  background: var(--color-surface-page);
  padding: 16px var(--gutter) 24px;
  border-radius: 0 0 var(--radius-lg) var(--radius-lg);
  box-shadow: 0 24px 48px rgba(11, 59, 51, .16);
  transform: translateY(-16px);
  opacity: 0;
  visibility: hidden;
  transition: transform var(--duration-fast) var(--ease-out), opacity var(--duration-fast) var(--ease-out), visibility var(--duration-fast);
}

.header__menu--active {
  transform: translateY(0);
  opacity: 1;
  visibility: visible;
}

.header__menu-link {
  padding: 14px 4px;
  font-size: var(--text-m-size);
  color: var(--color-text-primary);
  border-bottom: 1px solid var(--color-border-subtle);
}

.header__menu-cta {
  margin-top: 16px;
}

body.is-menu-open {
  overflow: hidden;
}

body.is-menu-open::after {
  content: "";
  position: fixed;
  inset: 0;
  z-index: 999;
  background: rgba(11, 22, 20, .4);
  animation: header-overlay-fade-in .3s ease both;
}

@keyframes header-overlay-fade-in {
  from { opacity: 0; }
  to { opacity: 1; }
}

@media (max-width: 1100px) {
  .header__nav,
  .header__actions .btn--primary,
  .header__actions .icon-btn {
    display: none;
  }

  .header__burger {
    display: block;
  }

  .header__menu {
    display: flex;
  }

  .header {
    background: var(--color-surface-page);
    backdrop-filter: none;
    -webkit-backdrop-filter: none;
  }
}