/* ==========================================================================
   03-header.css
   Site header: brand lockup, desktop + mobile nav, language switcher, hamburger.
   Load order: 3 of 7 - see README.md ("Stylesheet layer order").
   ========================================================================== */

/* --------------------------------------------------------------------------
   6. Header
   -------------------------------------------------------------------------- */
.site-header {
  position: sticky; top: 0; z-index: 100;
  background: rgba(251, 249, 254, .82);
  backdrop-filter: blur(14px) saturate(140%);
  border-bottom: 1px solid transparent;
  transition: background-color .3s var(--ease), border-color .3s var(--ease), box-shadow .3s var(--ease);
}
.site-header.is-stuck {
  background: rgba(251, 249, 254, .96);
  border-bottom-color: var(--line-soft);
  box-shadow: 0 8px 26px -22px rgba(36, 21, 57,.6);
}

.header-inner {
  display: flex; align-items: center; justify-content: space-between; gap: 1.25rem;
  min-height: 76px;
}

.brand { display: inline-flex; align-items: center; gap: .7rem; color: var(--plum-800); }
.brand:hover { color: var(--plum-800); }
.brand-mark { width: 40px; height: 40px; color: var(--plum-600); flex: none; }
.brand-mark svg { width: 100%; height: 100%; }
.brand-text { display: flex; flex-direction: column; line-height: 1.15; }
.brand-name { font-weight: 700; font-size: 1.03rem; letter-spacing: -.015em; white-space: nowrap; }
.brand-tag {
  font-size: .66rem; font-weight: 500; letter-spacing: .07em;
  text-transform: uppercase; color: var(--slate-500);
}
/* The tagline wraps to three lines beside the nav controls on narrow phones,
   so the header keeps the name only until there is room for both. */
@media (max-width: 560px) {
  .site-header .brand-tag { display: none; }
  .site-header .brand-name { font-size: .95rem; }
  .site-header .brand-mark { width: 34px; height: 34px; }
}

.nav-desktop { display: none; gap: clamp(1rem, 2.2vw, 2rem); }
.nav-desktop a {
  position: relative;
  font-size: .9rem; font-weight: 500; color: var(--ink);
  padding-block: .35rem;
}
.nav-desktop a::after {
  content: ''; position: absolute; left: 0; right: 0; bottom: 0;
  height: 2px; background: var(--sun-500);
  transform: scaleX(0); transform-origin: left;
  transition: transform .28s var(--ease);
}
.nav-desktop a:hover, .nav-desktop a[aria-current="page"] { color: var(--plum-700); }
.nav-desktop a:hover::after, .nav-desktop a[aria-current="page"]::after { transform: scaleX(1); }

.header-actions { display: flex; align-items: center; gap: .6rem; }
.header-cta { display: none; }

/* Language switcher */
.lang-switch { position: relative; }
.lang-trigger {
  display: inline-flex; align-items: center; gap: .35rem;
  padding: .5rem .85rem;
  font-size: .82rem; font-weight: 600; color: var(--plum-800);
  background: var(--paper); border: 1px solid var(--line);
  transition: border-color .2s var(--ease), box-shadow .2s var(--ease);
}
.lang-trigger:hover { border-color: var(--plum-300); box-shadow: var(--shadow-sm); }
.lang-trigger .chev { width: 14px; height: 14px; transition: transform .25s var(--ease); }
.lang-trigger[aria-expanded="true"] .chev { transform: rotate(180deg); }

.lang-menu {
  position: absolute; top: calc(100% + .5rem); inset-inline-end: 0;
  min-width: 172px; padding: .4rem;
  background: var(--paper); border: 1px solid var(--line); box-shadow: var(--shadow-lg);
  opacity: 0; visibility: hidden; transform: translateY(-6px);
  transition: opacity .2s var(--ease), transform .2s var(--ease), visibility .2s;
}
.lang-switch.is-open .lang-menu { opacity: 1; visibility: visible; transform: translateY(0); }
.lang-menu a {
  display: flex; align-items: center; gap: .6rem;
  padding: .55rem .75rem;
  font-size: .86rem; font-weight: 500; color: var(--ink);
}
.lang-menu a:hover { background: var(--plum-50); color: var(--plum-700); }
.lang-menu a[aria-current="true"] { background: var(--plum-100); color: var(--plum-800); font-weight: 600; }
.lang-menu .flag { font-size: 1.05rem; line-height: 1; }

/* Hamburger */
.nav-toggle {
  display: inline-flex; flex-direction: column; justify-content: center; gap: 5px;
  width: 42px; height: 42px; padding: 0 10px;
  background: var(--paper); border: 1px solid var(--line);
}
.nav-toggle span {
  display: block; height: 2px; background: var(--plum-800);
  transition: transform .3s var(--ease), opacity .2s var(--ease);
}
.nav-toggle[aria-expanded="true"] span:nth-child(1) { transform: translateY(7px) rotate(45deg); }
.nav-toggle[aria-expanded="true"] span:nth-child(2) { opacity: 0; }
.nav-toggle[aria-expanded="true"] span:nth-child(3) { transform: translateY(-7px) rotate(-45deg); }

.nav-mobile {
  display: flex; flex-direction: column;
  padding: .5rem var(--gutter) 1.5rem;
  background: var(--cream); border-top: 1px solid var(--line-soft);
}
.nav-mobile[hidden] { display: none; }
.nav-mobile a {
  display: flex; align-items: center; justify-content: space-between;
  padding: .95rem .25rem; font-weight: 500; color: var(--ink);
  border-bottom: 1px solid var(--line-soft);
}
.nav-mobile a[aria-current="page"] { color: var(--plum-700); font-weight: 600; }
.nav-mobile a .icon { color: var(--slate-300); }
.nav-mobile-chat { display: flex; flex-wrap: wrap; gap: .5rem; padding-top: 1.15rem; }