/* ==========================================================================
   Header — the logo, the main links, the language switch and one contact
   button (src/partials/header.html). Fixed at the top of every page.
   Over the hero it has no surface of its own, only a soft shade from the top
   edge so it stays legible over the video; once the page scrolls (or on pages
   without a hero) it sits on solid black with a hairline below — no glass, like
   the rest of the site. Below 1024 px the links fold into a menu that covers
   the page (assets/js/site-header.js); without JavaScript they simply wrap.
   ========================================================================== */

:root {
  --header-height: 3.5rem;
  --header-gutter: clamp(1rem, 0.5rem + 1.6vw, 2rem);
}

@media (min-width: 1024px) {
  :root {
    --header-height: 4.25rem;
  }
}

/* links to a section land below the header, not under it */
html {
  scroll-padding-top: calc(var(--header-height) + 1rem);
}

/* ---- Skip link: the first thing a keyboard reaches ------------------------------- */

.skip-link {
  position: fixed;
  top: 0.75rem;
  left: 0.75rem;
  z-index: 100;
  padding: 0.75rem 1.1rem;
  border-radius: 999px;
  background: #fff;
  color: #000;
  font-size: 0.9375rem;
  line-height: 1.2;
  text-decoration: none;
  transform: translateY(calc(-100% - 1.5rem));
}

.skip-link:focus {
  transform: none;
  outline: 2px solid var(--color-accent);
  outline-offset: 2px;
}

main:focus {
  outline: none;
}

/* ---- Bar ------------------------------------------------------------------------- */

.site-header {
  position: fixed;
  inset: 0 0 auto;
  z-index: 50;
  height: var(--header-height);
  border-bottom: 1px solid transparent;
  transition:
    background-color 0.3s ease,
    border-color 0.3s ease;
}

/* over the hero: a shade from the top edge instead of a surface */
.site-header::before {
  content: "";
  position: absolute;
  inset: 0 0 -2.5rem;
  z-index: -1;
  background: linear-gradient(rgb(0 0 0 / 0.72), rgb(0 0 0 / 0.38) 55%, rgb(0 0 0 / 0));
  pointer-events: none;
  transition: opacity 0.3s ease;
}

.site-header.is-scrolled,
.site-header--solid {
  background: rgb(0 0 0 / 0.94);
  border-bottom-color: var(--color-line-soft);
}

.site-header.is-scrolled::before,
.site-header--solid::before {
  opacity: 0;
}

.site-header__bar {
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 1.5rem;
  width: min(100% - 2 * var(--header-gutter), 90rem);
  height: 100%;
  margin-inline: auto;
}

.site-header__brand {
  display: block;
  flex: none;
  border-radius: 0.375rem;
}

/* the owner's logo, at its own proportions (width follows the height) */
.site-header__logo {
  width: auto;
  height: 1.625rem;
}

@media (min-width: 1024px) {
  .site-header__logo {
    height: 1.875rem;
  }
}

.site-header__brand:focus-visible {
  outline: 2px solid var(--color-accent);
  outline-offset: 6px;
}

/* ---- Links ----------------------------------------------------------------------- */

.site-nav {
  display: flex;
  align-items: center;
}

.site-nav__toggle {
  display: none;
}

.site-nav__panel {
  display: flex;
  align-items: center;
  gap: clamp(0.75rem, 1.4vw, 1.5rem);
}

.site-nav__list {
  display: flex;
  align-items: center;
  gap: clamp(0rem, 0.6vw, 0.5rem);
}

.site-nav__link {
  position: relative;
  display: block;
  padding: 0.5rem 0.625rem;
  color: var(--color-text-muted);
  font-size: 0.9375rem;
  line-height: 1.2;
  text-decoration: none;
  white-space: nowrap;
  transition: color 0.2s ease;
}

.site-nav__link:hover,
.site-nav__link.is-current,
.site-nav__link[aria-current="page"] {
  color: var(--color-text);
}

/* the section on screen (or the page you are on): the spark under its link */
.site-nav__link::after {
  content: "";
  position: absolute;
  bottom: 0;
  left: calc(50% - 2px);
  width: 4px;
  height: 4px;
  border-radius: 50%;
  background: var(--color-accent);
  opacity: 0;
  transform: scale(0.4);
  transition:
    opacity 0.25s ease,
    transform 0.25s ease;
}

.site-nav__link.is-current::after,
.site-nav__link[aria-current="page"]::after {
  opacity: 1;
  transform: none;
}

/* "this page is in Polish", next to a link on the English and Russian pages */
.lang-note {
  margin-left: 0.45em;
  padding: 0.15em 0.35em;
  border: 1px solid var(--color-line);
  border-radius: 0.3em;
  font-family: var(--font-mono);
  font-size: 0.6875rem;
  letter-spacing: 0.04em;
  color: var(--color-text-subtle);
  vertical-align: 0.1em;
}

/* the one contact button: an outline that fills on hover, so it never competes with the hero's CTA */
.site-nav__cta {
  display: inline-flex;
  flex: none;
  align-items: center;
  gap: 0.7em;
  height: 2.5rem;
  padding-inline: 1.1em 1em;
  border: 1px solid rgb(255 255 255 / 0.32);
  border-radius: 999px;
  color: var(--color-text);
  font-size: 0.9375rem;
  line-height: 1;
  text-decoration: none;
  white-space: nowrap;
  transition:
    background-color 0.2s ease,
    border-color 0.2s ease,
    color 0.2s ease;
}

.site-nav__cta-arrow {
  flex: none;
  width: 1.15em;
  height: 0.6em;
  fill: none;
  stroke: currentColor;
  stroke-width: 2.6;
  stroke-linecap: round;
  stroke-linejoin: round;
  transition: transform 0.25s ease;
}

.site-nav__cta:hover,
.site-nav__cta.is-current {
  border-color: #fff;
  background: #fff;
  color: #000;
}

.site-nav__cta:hover .site-nav__cta-arrow {
  transform: translateX(0.15em);
}

.site-nav__link:focus-visible,
.site-nav__cta:focus-visible,
.site-nav__toggle:focus-visible {
  outline: 2px solid var(--color-accent);
  outline-offset: 2px;
}

/* ---- Below 1024 px: the menu ------------------------------------------------------- */

@media (max-width: 1023.98px) {
  .site-nav__toggle {
    display: inline-flex;
    align-items: center;
    gap: 0.65rem;
    height: 2.75rem;
    padding-inline: 1rem 0.95rem;
    border: 1px solid rgb(255 255 255 / 0.24);
    border-radius: 999px;
    background: rgb(0 0 0 / 0.35);
    color: var(--color-text);
    font: inherit;
    font-size: 0.9375rem;
    line-height: 1;
    cursor: pointer;
  }

  /* two lines that turn into a cross */
  .site-nav__toggle-icon {
    position: relative;
    width: 1rem;
    height: 0.625rem;
  }

  .site-nav__toggle-icon::before,
  .site-nav__toggle-icon::after {
    content: "";
    position: absolute;
    left: 0;
    right: 0;
    height: 1.5px;
    border-radius: 1px;
    background: currentColor;
    transition:
      top 0.25s ease,
      transform 0.25s ease;
  }

  .site-nav__toggle-icon::before {
    top: 0;
  }

  .site-nav__toggle-icon::after {
    top: calc(100% - 1.5px);
  }

  .site-nav__toggle[aria-expanded="true"] .site-nav__toggle-icon::before {
    top: calc(50% - 0.75px);
    transform: rotate(45deg);
  }

  .site-nav__toggle[aria-expanded="true"] .site-nav__toggle-icon::after {
    top: calc(50% - 0.75px);
    transform: rotate(-45deg);
  }

  /* the open menu covers the page below the bar; closed, it is out of the way for
     the eye, the pointer, the keyboard and screen readers alike (visibility) */
  .site-nav__panel {
    position: fixed;
    inset: var(--header-height) 0 0;
    flex-direction: column;
    align-items: stretch;
    gap: 1.75rem;
    padding: 0.5rem var(--header-gutter) calc(2rem + env(safe-area-inset-bottom, 0px));
    overflow-y: auto;
    overscroll-behavior: contain;
    background: #000;
    visibility: hidden;
    opacity: 0;
    transform: translateY(-0.5rem);
    transition:
      opacity 0.2s ease,
      transform 0.2s ease,
      visibility 0s linear 0.2s;
  }

  .site-header.is-open .site-nav__panel {
    visibility: visible;
    opacity: 1;
    transform: none;
    transition-delay: 0s;
  }

  .site-header.is-open {
    border-bottom-color: var(--color-line-soft);
    background: #000;
  }

  .site-header.is-open::before {
    opacity: 0;
  }

  .site-nav__list {
    flex-direction: column;
    align-items: stretch;
    gap: 0;
  }

  .site-nav__list li {
    border-bottom: 1px solid var(--color-line-soft);
  }

  .site-nav__link {
    padding: 1.1rem 0.25rem;
    color: var(--color-text);
    font-size: 1.375rem;
    font-variation-settings: "opsz" 32;
  }

  .site-nav__link::after {
    top: calc(50% - 2px);
    right: 0.25rem;
    bottom: auto;
    left: auto;
  }

  .site-nav__cta {
    justify-content: center;
    height: 3.25rem;
    border-color: #fff;
    background: #fff;
    color: #000;
    font-size: 1rem;
  }
}

/* while the menu is open, the page underneath stays put */
html.has-open-menu {
  overflow: hidden;
}

/* phones held sideways have little height: there the header scrolls away with the page */
@media (orientation: landscape) and (max-height: 500px) {
  .site-header {
    position: absolute;
  }

  html {
    scroll-padding-top: 1rem;
  }
}

/* without JavaScript there is no menu button: the links wrap under the logo */
@media (scripting: none) and (max-width: 1023.98px) {
  :root {
    --header-height: 6.5rem;
  }

  .site-header {
    position: absolute;
  }

  .site-header__bar {
    flex-wrap: wrap;
    align-content: center;
    row-gap: 0.25rem;
  }

  .site-nav__toggle {
    display: none;
  }

  .site-nav__panel {
    position: static;
    flex-flow: row wrap;
    align-items: center;
    gap: 0.25rem 1rem;
    padding: 0;
    overflow: visible;
    background: none;
    visibility: visible;
    opacity: 1;
    transform: none;
  }

  .site-nav__list {
    flex-flow: row wrap;
  }

  .site-nav__list li {
    border: 0;
  }

  .site-nav__link {
    padding: 0.25rem 0;
    font-size: 0.875rem;
  }

  .site-nav__cta {
    height: 2.25rem;
    border-color: rgb(255 255 255 / 0.32);
    background: none;
    color: var(--color-text);
  }
}

@media (prefers-reduced-motion: reduce) {
  .site-header,
  .site-header::before,
  .site-nav__link,
  .site-nav__link::after,
  .site-nav__cta,
  .site-nav__cta-arrow,
  .site-nav__panel,
  .site-nav__toggle-icon::before,
  .site-nav__toggle-icon::after {
    transition: none;
  }
}

@media print {
  .site-header {
    position: static;
  }

  .site-nav,
  .skip-link {
    display: none;
  }
}