/* ==========================================================================
   layout.css — الهيكل: المسطرة، الترويسة، رأس القسم، الشبكات، التذييل
   Datum rail, header, sheet headers, grids, footer.
   ========================================================================== */

/* --------------------------------------------------------------------------
   1. Shell and bands
   -------------------------------------------------------------------------- */
.shell {
  inline-size: 100%;
  max-inline-size: var(--shell);
  margin-inline: auto;
  padding-inline: var(--pad);
}

.band {
  position: relative;
  padding-block: var(--gap-xl);
  background: var(--surface);
  color: var(--on-surface);
}

.band--tight { padding-block: clamp(3rem, 2rem + 4vw, 5rem); }

.band--dark {
  --surface: var(--graphite);
  --on-surface: var(--paper);
  --on-surface-2: var(--ash-soft);
  --hairline: var(--rule-dark);
  background: var(--graphite);
  color: var(--paper);
}

.band + .band:not(.band--dark) { border-block-start: 1px solid var(--rule); }

/* --------------------------------------------------------------------------
   2. Sheet header — the drawing-sheet strip that opens every section
   -------------------------------------------------------------------------- */
.sheet {
  display: flex;
  align-items: baseline;
  justify-content: space-between;
  gap: 1.5rem;
  padding-block-end: 0.9rem;
  margin-block-end: clamp(2.25rem, 1.8rem + 2.4vw, 4rem);
  border-block-end: 1px solid var(--hairline);
}

.sheet__code { flex: none; }

.sheet__name {
  display: flex;
  align-items: baseline;
  gap: 0.85rem;
  text-align: end;
}

.sheet__name-en { opacity: 0.55; }

@media (max-width: 560px) {
  :root[lang="ar"] .sheet__name-en { display: none; }
}

:root[lang="en"] .sheet__name-ar { display: none; }

/* Section intro: display heading beside a supporting paragraph */
.intro { display: grid; gap: 1.75rem; }

@media (min-width: 900px) {
  .intro {
    grid-template-columns: minmax(0, 1.1fr) minmax(0, 0.9fr);
    align-items: end;
    gap: 3.5rem;
  }
}

.intro__body { padding-block-end: 0.35rem; }

.section-gap { margin-block-start: clamp(2.5rem, 2rem + 3vw, 4.5rem); }

/* --------------------------------------------------------------------------
   3. Datum rail
   -------------------------------------------------------------------------- */
.rail {
  display: none;
  position: fixed;
  inset-block: 0;
  inset-inline-start: 0;
  inline-size: var(--rail);
  z-index: 60;
  background: var(--paper);
  border-inline-end: 1px solid var(--rule);
  pointer-events: none;
}

@media (min-width: 1100px) { .rail { display: block; } }

.rail__ticks {
  position: absolute;
  inset-block: 0;
  inset-inline-end: 0;
  inline-size: 8px;
  background-image: repeating-linear-gradient(
    to bottom, var(--rule) 0 1px, transparent 1px 16px
  );
}

.rail__marker {
  position: absolute;
  inset-inline: 0;
  inset-block-start: 0;
  block-size: 2px;
  background: var(--ink);
  transition: transform 0.12s linear;
  will-change: transform;
}

.rail__label {
  position: absolute;
  inset-block-start: 50%;
  inset-inline-start: 50%;
  transform: translate(-50%, -50%) rotate(-90deg);
  white-space: nowrap;
  font-size: 10px;
  font-weight: 700;
  letter-spacing: 0.24em;
  color: var(--ash);
}

/* --------------------------------------------------------------------------
   4. Header
   -------------------------------------------------------------------------- */
.header {
  position: fixed;
  inset-block-start: 0;
  inset-inline-start: var(--rail);
  inset-inline-end: 0;
  z-index: 80;
  block-size: var(--header-h);
  display: flex;
  align-items: center;
  border-block-end: 1px solid transparent;
  transition: background 0.35s var(--ease), border-color 0.35s var(--ease), color 0.35s var(--ease);
}

.header__inner {
  inline-size: 100%;
  max-inline-size: var(--shell);
  margin-inline: auto;
  padding-inline: var(--pad);
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 1.5rem;
}

.header__logo img { block-size: 28px; inline-size: auto; }

@media (min-width: 1100px) { .header__logo img { block-size: 34px; } }

.header--over { color: var(--paper); }
.header--over .header__logo img { filter: invert(1); }

.header--solid {
  background: rgba(255, 255, 255, 0.95);
  backdrop-filter: blur(12px);
  border-block-end-color: var(--rule);
  color: var(--ink);
}

.header--solid .header__logo img { filter: none; }

.nav { display: none; }

@media (min-width: 1020px) {
  .nav { display: flex; align-items: center; gap: clamp(1.4rem, 2.2vw, 2.5rem); }
}

.nav__link {
  position: relative;
  font-size: var(--step--1);
  font-weight: 400;
  letter-spacing: 0.04em;
  padding-block: 0.4rem;
}

.nav__link::after {
  content: "";
  position: absolute;
  inset-block-end: 0;
  inset-inline-start: 0;
  inline-size: 100%;
  block-size: 1px;
  background: currentColor;
  transform: scaleX(0);
  transition: transform 0.4s var(--ease);
}

[dir="rtl"] .nav__link::after { transform-origin: right; }
[dir="ltr"] .nav__link::after { transform-origin: left; }

.nav__link:hover::after,
.nav__link[aria-current="page"]::after { transform: scaleX(1); }

.header__actions { display: flex; align-items: center; gap: 0.75rem; }

.lang-switch {
  display: inline-flex;
  align-items: center;
  block-size: 38px;
  padding-inline: 0.95rem;
  border: 1px solid currentColor;
  font-size: var(--step--2);
  font-weight: 600;
  letter-spacing: 0.14em;
  transition: background 0.3s var(--ease), color 0.3s var(--ease);
}

.header--solid .lang-switch:hover { background: var(--ink); color: var(--paper); }
.header--over .lang-switch:hover { background: var(--paper); color: var(--ink); }

.menu-btn {
  display: inline-flex;
  flex-direction: column;
  justify-content: center;
  gap: 5px;
  inline-size: 38px;
  block-size: 38px;
  padding-inline: 9px;
  border: 1px solid currentColor;
}

@media (min-width: 1020px) { .menu-btn { display: none; } }

.menu-btn span {
  display: block;
  block-size: 1px;
  background: currentColor;
  transition: transform 0.35s var(--ease), opacity 0.2s linear;
}

.menu-btn[aria-expanded="true"] span:nth-child(1) { transform: translateY(6px) rotate(45deg); }
.menu-btn[aria-expanded="true"] span:nth-child(2) { opacity: 0; }
.menu-btn[aria-expanded="true"] span:nth-child(3) { transform: translateY(-6px) rotate(-45deg); }

/* Mobile drawer */
.drawer {
  position: fixed;
  inset: 0;
  inset-inline-start: var(--rail);
  z-index: 70;
  background: var(--graphite);
  color: var(--paper);
  padding: calc(var(--header-h) + 2.5rem) var(--pad) 2.5rem;
  display: flex;
  flex-direction: column;
  justify-content: space-between;
  gap: 2rem;
  overflow-y: auto;
  transform: translateY(-100%);
  visibility: hidden;
  transition: transform 0.55s var(--ease), visibility 0.55s;
}

.drawer.is-open { transform: translateY(0); visibility: visible; }

.drawer__list { display: grid; }

.drawer__link {
  display: flex;
  align-items: baseline;
  gap: 1.1rem;
  font-size: var(--step-2);
  font-weight: 200;
  padding-block: 0.7rem;
  border-block-end: 1px solid var(--rule-dark);
}

.drawer__link em { font-style: normal; }

.drawer__link span {
  font-size: var(--step--2);
  font-weight: 700;
  letter-spacing: 0.2em;
  color: var(--ash-soft);
}

.drawer__meta {
  display: grid;
  gap: 0.4rem;
  font-size: var(--step--1);
  color: var(--ash-soft);
}

/* --------------------------------------------------------------------------
   5. Page head — inner pages
   -------------------------------------------------------------------------- */
.page-head {
  padding-block-start: calc(var(--header-h) + clamp(3.5rem, 3rem + 5vw, 7.5rem));
  padding-block-end: clamp(3rem, 2.5rem + 3.5vw, 6rem);
}

.page-head__grid { display: grid; gap: 2.25rem; }

@media (min-width: 950px) {
  .page-head__grid {
    grid-template-columns: minmax(0, 1.2fr) minmax(0, 0.8fr);
    align-items: end;
    gap: 4rem;
  }
}

.page-head__title { margin-block-start: 1.1rem; }

/* --------------------------------------------------------------------------
   6. Shared grids
   -------------------------------------------------------------------------- */
.split { display: grid; gap: clamp(2.5rem, 2rem + 4vw, 5.5rem); }

@media (min-width: 950px) {
  .split { grid-template-columns: minmax(0, 1fr) minmax(0, 1fr); align-items: center; }
  .split--wide-start { grid-template-columns: minmax(0, 1.3fr) minmax(0, 0.7fr); }
  .split--wide-end { grid-template-columns: minmax(0, 0.7fr) minmax(0, 1.3fr); }
  .split--top { align-items: start; }
}

/* --------------------------------------------------------------------------
   7. Footer
   -------------------------------------------------------------------------- */
.footer {
  background: var(--graphite);
  color: var(--paper);
  --surface: var(--graphite);
  --on-surface: var(--paper);
  --on-surface-2: var(--ash-soft);
  --hairline: var(--rule-dark);
  padding-block: clamp(3.5rem, 3rem + 4vw, 6rem) 1.75rem;
}

.footer__mark {
  display: block;
  font-size: clamp(2.6rem, 1.4rem + 5.4vw, 6.5rem);
  font-weight: 100;
  line-height: 1;
  letter-spacing: -0.02em;
  padding-block-end: clamp(2rem, 1.5rem + 2vw, 3.5rem);
  border-block-end: 1px solid var(--rule-dark);
}

.footer__top {
  display: grid;
  gap: 2.75rem;
  padding-block: clamp(2.5rem, 2rem + 2vw, 3.5rem);
  border-block-end: 1px solid var(--rule-dark);
}

@media (min-width: 760px) { .footer__top { grid-template-columns: repeat(2, 1fr); } }
@media (min-width: 1020px) { .footer__top { grid-template-columns: 1.4fr repeat(3, 1fr); gap: 3rem; } }

.footer__col h3 { margin-block-end: 1.4rem; }

.footer__tagline {
  font-size: var(--step-1);
  font-weight: 200;
  line-height: 1.7;
  margin-block: 1.25rem 1.75rem;
  max-inline-size: 30ch;
}

.footer__list { display: grid; gap: 0.7rem; font-size: var(--step--1); font-weight: 300; }
.footer__list a { transition: opacity 0.25s var(--ease); }
.footer__list a:hover { opacity: 0.6; }

.footer__bottom {
  display: flex;
  flex-wrap: wrap;
  gap: 0.75rem 2rem;
  justify-content: space-between;
  align-items: center;
  padding-block-start: 1.75rem;
  font-size: var(--step--2);
  letter-spacing: 0.08em;
  color: var(--ash-soft);
}