*, *::before, *::after { box-sizing: border-box; }
html { -webkit-text-size-adjust: 100%; scroll-padding-top: calc(var(--header-h) + env(safe-area-inset-top, 0px)); }
body {
  margin: 0; font-family: var(--font); font-size: var(--fs-md); line-height: 1.6;
  color: var(--text); background: var(--bg-wash), var(--bg); background-attachment: fixed;
  -webkit-font-smoothing: antialiased; text-rendering: optimizeLegibility;
  padding-top: env(safe-area-inset-top, 0px);
  transition: background-color var(--t-med), color var(--t-med);
}
img, svg { display: block; max-width: 100%; }
button, input, select, textarea { font: inherit; color: inherit; }
button { cursor: pointer; }
a { color: var(--accent); }
h1, h2, h3, h4 { line-height: 1.2; margin: 0; font-weight: 700; letter-spacing: -0.01em; }
html[lang="ar"] h1, html[lang="ar"] h2, html[lang="ar"] h3, html[lang="ar"] h4 { letter-spacing: 0; line-height: 1.4; }
p { margin: 0; }
:focus-visible { outline: 2px solid var(--secondary); outline-offset: 2px; border-radius: 4px; }
.visually-hidden { position: absolute !important; width: 1px; height: 1px; overflow: hidden; clip: rect(0 0 0 0); white-space: nowrap; }
::selection { background: var(--accent-soft); }

.skip-link { position: absolute; inset-inline-start: 12px; top: -48px; z-index: 100; background: var(--primary); color: var(--on-primary); padding: 8px 14px; border-radius: var(--r-sm); text-decoration: none; }
.skip-link:focus { top: 12px; }

/* ---------- header ---------- */
.site-header {
  position: sticky; top: env(safe-area-inset-top, 0px); z-index: 50; height: var(--header-h);
  display: flex; align-items: center; gap: 22px; padding: 0 clamp(14px, 3vw, 36px);
  background: var(--header-bg); color: var(--text);
  backdrop-filter: saturate(1.4) blur(14px); -webkit-backdrop-filter: saturate(1.4) blur(14px);
  border-bottom: 1px solid var(--border);
  transition: background var(--t-med), border-color var(--t-med), color var(--t-med);
}
body::before { content: ""; position: fixed; inset: 0 0 auto; height: env(safe-area-inset-top, 0px); z-index: 60; background: var(--bg); }

.brand { display: inline-flex; align-items: center; gap: 10px; text-decoration: none; color: inherit; flex: none; }
.brand-mark { width: 28px; height: 28px; }
.brand-word { font-family: var(--font-en); font-weight: 800; font-size: 0.95rem; letter-spacing: 0.08em; white-space: nowrap; }
.brand-word span { font-weight: 500; opacity: .7; }

.site-nav { display: flex; gap: 2px; margin-inline-start: 6px; min-width: 0; }
.site-nav a {
  text-decoration: none; color: inherit; opacity: .72; white-space: nowrap;
  padding: 7px 12px; border-radius: 999px; font-size: var(--fs-sm); font-weight: 600;
  transition: opacity var(--t-fast), background var(--t-fast), color var(--t-fast);
}
.site-nav a:hover { opacity: 1; background: var(--hover); }
.site-nav a[aria-current="page"] { opacity: 1; background: var(--accent-soft); color: var(--accent); }

.header-end { margin-inline-start: auto; display: flex; align-items: center; gap: 6px; }
.hdr-btn {
  height: 36px; min-width: 36px; display: inline-flex; align-items: center; justify-content: center; gap: 6px;
  border: 1px solid var(--border); background: var(--surface); color: var(--text);
  border-radius: 999px; padding: 0 13px; font-size: var(--fs-sm); font-weight: 600;
  transition: border-color var(--t-fast), background var(--t-fast), color var(--t-fast);
}
.hdr-btn:hover { border-color: var(--secondary); }
.hdr-btn.icon { padding: 0; width: 36px; }
.hdr-btn[lang="en"] { font-family: var(--font-en); }
.hdr-btn[lang="ar"] { font-family: var(--font-ar); }
.theme-toggle .i-sun { display: none; }
:root[data-theme="dark"] .theme-toggle .i-sun { display: block; }
:root[data-theme="dark"] .theme-toggle .i-moon { display: none; }

/* ---------- buttons ---------- */
.btn {
  display: inline-flex; align-items: center; justify-content: center; gap: 10px;
  border-radius: 999px; padding: 13px 24px; font-weight: 700; font-size: var(--fs-md);
  text-decoration: none; border: 1px solid transparent; white-space: nowrap;
  transition: transform var(--t-fast) var(--ease), background var(--t-fast), box-shadow var(--t-fast), border-color var(--t-fast);
}
.btn-primary { background: var(--primary); color: var(--on-primary); box-shadow: 0 12px 26px -16px var(--primary); }
.btn-primary:hover { background: var(--primary-hover); transform: translateY(-1px); }
.btn-quiet { color: var(--text); background: var(--surface); border-color: var(--border); }
.btn-quiet:hover { border-color: var(--secondary); }

/* ---------- boot / errors ---------- */
.boot { min-height: calc(100vh - var(--header-h)); display: grid; place-items: center; align-content: center; gap: 14px; color: var(--muted); font-size: var(--fs-sm); }
.boot-ring { width: 36px; height: 36px; border-radius: 50%; border: 2px solid var(--border); border-top-color: var(--secondary); animation: spin 900ms linear infinite; }
@keyframes spin { to { transform: rotate(360deg); } }
.error-state { max-width: 560px; margin: 12vh auto; padding: 0 20px; }
.error-state h1 { font-size: var(--fs-xl); margin-bottom: 12px; }
.error-state code { background: var(--surface-3); padding: 2px 6px; border-radius: 4px; font-size: .9em; }

/* ---------- toast ---------- */
.toast {
  position: fixed; bottom: calc(24px + env(safe-area-inset-bottom, 0px)); left: 50%; transform: translate(-50%, 12px);
  background: var(--text); color: var(--bg); padding: 10px 18px; border-radius: 999px; font-size: var(--fs-sm); z-index: 200;
  opacity: 0; pointer-events: none; transition: opacity var(--t-med), transform var(--t-med) var(--ease);
  box-shadow: 0 16px 36px -18px var(--shadow);
}
.toast.show { opacity: 1; transform: translate(-50%, 0); }

.lbl-short { display: none; }
@media (max-width: 600px) {
  .lbl-full { display: none; }
  .lbl-short { display: inline; }
}
@media (max-width: 860px) { .nav-extra { display: none; } }
@media (max-width: 720px) {
  .brand-word span { display: none; }
  .site-header { gap: 8px; }
  .site-nav { margin-inline-start: 0; }
  .site-nav a { padding: 7px 9px; }
}
@media (max-width: 460px) {
  .brand-word { display: none; }
  .hdr-btn.lang { padding: 0; width: 36px; }
  .site-nav a { padding: 7px 8px; font-size: 13px; }
}