/* ==========================================================
   HEADER
   Estructura común; la identidad visual se controla por tokens.
========================================================== */

.header {
  position: fixed;
  top: 0;
  left: 0;
  z-index: var(--z-header);
  width: 100%;
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: var(--spacing-xl);
  padding:
    var(--header-padding-block)
    var(--container-padding);
  border-bottom: var(--header-border);
  background: var(--header-background);
  backdrop-filter:
    blur(var(--header-backdrop-blur))
    saturate(1.2);
  -webkit-backdrop-filter:
    blur(var(--header-backdrop-blur))
    saturate(1.2);
  transition:
    background-color var(--transition-base),
    box-shadow var(--transition-base),
    border-color var(--transition-base);
}

.header.scrolled {
  background:
    var(--header-background-scrolled);
  box-shadow:
    var(--header-shadow-scrolled);
}

.header .logo {
  flex-shrink: 0;
  font-size: 1.1rem;
  font-weight: var(--header-logo-weight);
  letter-spacing:
    var(--header-logo-letter-spacing);
}

.header .logo span {
  color: var(--primary);
}

.header nav {
  display: flex;
  align-items: center;
  gap: var(--header-nav-gap);
}

.header nav a {
  position: relative;
  padding: var(--spacing-xs) 0;
  color: var(--header-link-color);
  font-size: 0.875rem;
  font-weight: var(--header-link-weight);
  transition: color var(--transition-base);
}

.header nav a::after {
  content: "";
  position: absolute;
  bottom: -2px;
  left: 0;
  width: 0;
  height: var(--header-link-underline-height);
  border-radius: var(--radius-full);
  background: var(--primary-gradient);
  transition: width var(--transition-base);
}

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

.header nav a:hover::after,
.header nav a.active::after {
  width: 100%;
}

.btn-header {
  flex-shrink: 0;
}

/* ==========================================================
   MENÚ MÓVIL
========================================================== */

.menu-toggle {
  display: none;
  padding: var(--spacing-xs);
  border: 0;
  background: transparent;
  color: var(--color-text);
  font-size: 1.5rem;
  line-height: 1;
  cursor: pointer;
  transition: transform var(--transition-base);
}

.menu-toggle:hover {
  transform: scale(1.1);
}

.menu-toggle:focus-visible {
  outline: 2px solid var(--primary);
  outline-offset: 3px;
  border-radius: var(--radius-sm);
}

/* ==========================================================
   RESPONSIVE
========================================================== */

@media (max-width: 850px) {
  .header {
    flex-wrap: wrap;
    padding:
      14px
      var(--container-padding);
  }

  .menu-toggle {
    display: block;
  }

  .header nav {
    width: 100%;
    display: none;
    flex-direction: column;
    align-items: flex-start;
    gap: var(--spacing-md);
    padding-top: var(--spacing-lg);
    border-top: 1px solid var(--color-border);
  }

  .header nav.open {
    display: flex;
  }

  .header nav a {
    width: 100%;
    padding: var(--spacing-sm) 0;
    font-size: 1rem;
  }

  .header nav a::after {
    display: none;
  }

  .btn-header {
    margin-left: auto;
  }
}

@media (prefers-reduced-motion: reduce) {
  .header,
  .header nav a,
  .header nav a::after,
  .menu-toggle {
    transition: none;
  }
}