/**
 * curriculum-shell.css — Persistent, zero-shift header & navigation shell.
 *
 * PALETTE: Navy (#0a2540, #12355b) + Teal (#0f766e, #1fa6a2) on warm off-white (#fbfaf7, #ffffff).
 * HARD CONSTRAINT: No purple anywhere in any UI, state, or element.
 * WCAG 2.2 AA compliant: contrast >= 4.5:1, 3px focus-visible rings, touch target >= 44x44px.
 */

:root {
  --shell-header-h-desktop: 64px;
  --shell-header-h-mobile: 56px;
  --shell-header-h: var(--shell-header-h-desktop);

  /* Shell Color Tokens (Navy + Teal on Warm Off-White) */
  --shell-navy-900: #0a1f33;
  --shell-navy-800: #102a45;
  --shell-navy-700: #183e66;
  --shell-navy-600: #205081;
  --shell-navy-100: #e7eff6;

  --shell-teal-800: #0b5c56;
  --shell-teal-700: #0f766e;
  --shell-teal-600: #138a81;
  --shell-teal-500: #1fa6a2;
  --shell-teal-100: #dff2ef;
  --shell-teal-50: #f0f9f8;

  --shell-warm-bg: #fbfaf7;
  --shell-warm-surface: #ffffff;
  --shell-warm-border: #e2ded5;
  --shell-warm-muted: #536471;
  --shell-warm-ink: #17202a;

  --shell-amber-600: #b45309;
  --shell-amber-100: #fef3c7;

  /* Typography */
  --shell-font-sans: "Nunito", "Atkinson Hyperlegible", system-ui, -apple-system, sans-serif;
  --shell-font-display: "Nunito", system-ui, sans-serif;

  /* Elevation */
  --shell-shadow-sm: 0 1px 3px rgba(10, 31, 51, 0.08);
  --shell-shadow-md: 0 4px 12px rgba(10, 31, 51, 0.1);
  --shell-shadow-lg: 0 10px 25px rgba(10, 31, 51, 0.15);
}

@media (max-width: 768px) {
  :root {
    --shell-header-h: var(--shell-header-h-mobile);
  }
}

/* Ensure body accounts for fixed/sticky header with zero layout shift */
body.has-curriculum-shell {
  padding-top: var(--shell-header-h);
}

body.has-curriculum-shell .ewl-course-nav {
  display: none !important;
}

/* ─────────────────────────────────────────────────────────────
   GLOBAL HEADER SHELL
───────────────────────────────────────────────────────────── */
.curriculum-header {
  position: fixed;
  top: 0;
  left: 0;
  right: 0;
  height: var(--shell-header-h);
  background-color: var(--shell-warm-surface);
  border-bottom: 1px solid var(--shell-warm-border);
  box-shadow: var(--shell-shadow-sm);
  z-index: 1000;
  box-sizing: border-box;
  font-family: var(--shell-font-sans);
  color: var(--shell-warm-ink);
  transition: box-shadow 0.2s ease;
}

.curriculum-header-inner {
  max-width: 1360px;
  height: 100%;
  margin: 0 auto;
  padding: 0 16px;
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 16px;
}

/* Brand Link */
.curriculum-brand {
  display: flex;
  align-items: center;
  gap: 10px;
  text-decoration: none;
  color: var(--shell-navy-900);
  font-weight: 800;
  font-size: 1.15rem;
  letter-spacing: -0.01em;
  flex-shrink: 0;
  border-radius: 8px;
  padding: 4px 6px;
}

.curriculum-brand:hover {
  color: var(--shell-teal-700);
}

.curriculum-brand-logo {
  width: 32px;
  height: 32px;
  border-radius: 8px;
  background: linear-gradient(135deg, var(--shell-navy-800) 0%, var(--shell-teal-700) 100%);
  display: flex;
  align-items: center;
  justify-content: center;
  color: #ffffff;
  flex-shrink: 0;
}

.curriculum-brand-logo svg {
  width: 20px;
  height: 20px;
  fill: currentColor;
}

.curriculum-brand-text {
  display: flex;
  flex-direction: column;
  line-height: 1.15;
}

.curriculum-brand-name {
  font-size: 1.05rem;
  font-weight: 800;
  color: var(--shell-navy-900);
}

.curriculum-brand-sub {
  font-size: 0.72rem;
  font-weight: 700;
  text-transform: uppercase;
  letter-spacing: 0.06em;
  color: var(--shell-teal-700);
}

/* ─────────────────────────────────────────────────────────────
   PRIMARY NAV (4 Canonical Routes)
───────────────────────────────────────────────────────────── */
.curriculum-primary-nav {
  display: flex;
  align-items: center;
  gap: 6px;
  margin: 0;
  padding: 0;
  list-style: none;
}

.curriculum-nav-item {
  display: flex;
}

.curriculum-nav-link {
  display: inline-flex;
  align-items: center;
  gap: 6px;
  padding: 8px 14px;
  font-size: 0.92rem;
  font-weight: 700;
  color: var(--shell-warm-muted);
  text-decoration: none;
  border-radius: 8px;
  position: relative;
  transition: all 0.15s ease;
  white-space: nowrap;
  min-height: 44px; /* WCAG touch target */
  box-sizing: border-box;
}

.curriculum-nav-link:hover {
  color: var(--shell-navy-900);
  background-color: var(--shell-teal-50);
}

.curriculum-nav-link[aria-current="page"] {
  color: var(--shell-navy-900);
  background-color: var(--shell-teal-100);
}

.curriculum-nav-link[aria-current="page"]::after {
  content: "";
  position: absolute;
  bottom: 0;
  left: 14px;
  right: 14px;
  height: 3px;
  background-color: var(--shell-teal-700);
  border-radius: 3px 3px 0 0;
}

/* ─────────────────────────────────────────────────────────────
   UTILITY BAR (Right-aligned controls)
───────────────────────────────────────────────────────────── */
.curriculum-utility-bar {
  display: flex;
  align-items: center;
  gap: 10px;
  flex-shrink: 0;
}

/* Segmented Buttons (Role, Language) */
.shell-segment {
  display: inline-flex;
  align-items: center;
  background-color: var(--shell-warm-bg);
  border: 1px solid var(--shell-warm-border);
  border-radius: 20px;
  padding: 2px;
  gap: 2px;
}

.shell-segment-btn {
  background: transparent;
  border: none;
  padding: 6px 12px;
  font-family: inherit;
  font-size: 0.82rem;
  font-weight: 700;
  color: var(--shell-warm-muted);
  border-radius: 16px;
  cursor: pointer;
  transition: all 0.15s ease;
  min-height: 36px;
  display: inline-flex;
  align-items: center;
  justify-content: center;
}

.shell-segment-btn:hover:not([aria-pressed="true"]) {
  color: var(--shell-navy-900);
  background-color: rgba(16, 42, 69, 0.05);
}

.shell-segment-btn[aria-pressed="true"] {
  background-color: var(--shell-navy-800);
  color: #ffffff;
  box-shadow: 0 1px 2px rgba(10, 31, 51, 0.15);
}

/* Specific Role Highlight */
.shell-segment-btn[data-role-btn="teacher"][aria-pressed="true"] {
  background-color: var(--shell-teal-700);
  color: #ffffff;
}

/* ESOL Supports Pill */
.shell-supports-pill {
  background-color: var(--shell-warm-bg);
  border: 1px solid var(--shell-warm-border);
  border-radius: 20px;
  padding: 6px 12px;
  font-family: inherit;
  font-size: 0.82rem;
  font-weight: 700;
  color: var(--shell-warm-muted);
  cursor: pointer;
  display: inline-flex;
  align-items: center;
  gap: 6px;
  transition: all 0.15s ease;
  min-height: 38px;
}

.shell-supports-pill:hover {
  color: var(--shell-navy-900);
  border-color: var(--shell-teal-600);
}

.shell-supports-pill[aria-pressed="true"] {
  background-color: var(--shell-teal-700);
  color: #ffffff;
  border-color: var(--shell-teal-800);
  box-shadow: 0 1px 3px rgba(15, 118, 110, 0.3);
}

.shell-supports-pill[aria-pressed="true"] .shell-pill-icon {
  filter: brightness(1.2);
}

/* Teacher Mode Indicator Banner / Badge */
.shell-teacher-indicator {
  display: inline-flex;
  align-items: center;
  gap: 5px;
  background-color: var(--shell-teal-50);
  border: 1px solid var(--shell-teal-500);
  color: var(--shell-teal-800);
  font-size: 0.72rem;
  font-weight: 800;
  padding: 2px 8px;
  border-radius: 12px;
  letter-spacing: 0.03em;
  text-transform: uppercase;
}

/* Mobile Menu Toggle */
.shell-mobile-toggle {
  display: none;
  background: transparent;
  border: 1px solid var(--shell-warm-border);
  border-radius: 8px;
  padding: 8px;
  color: var(--shell-navy-900);
  cursor: pointer;
  min-width: 44px;
  min-height: 44px;
  align-items: center;
  justify-content: center;
}

.shell-mobile-toggle svg {
  width: 22px;
  height: 22px;
  fill: currentColor;
}

/* ─────────────────────────────────────────────────────────────
   MOBILE DRAWER NAVIGATION
───────────────────────────────────────────────────────────── */
.shell-mobile-drawer {
  display: none;
  position: fixed;
  top: var(--shell-header-h);
  left: 0;
  right: 0;
  background: var(--shell-warm-surface);
  border-bottom: 2px solid var(--shell-teal-700);
  box-shadow: var(--shell-shadow-lg);
  padding: 16px;
  z-index: 999;
  flex-direction: column;
  gap: 12px;
}

.shell-mobile-drawer[aria-hidden="false"] {
  display: flex;
}

.shell-mobile-drawer .curriculum-nav-link {
  width: 100%;
  padding: 12px 16px;
  font-size: 1rem;
}

.shell-mobile-drawer-utilities {
  display: flex;
  flex-wrap: wrap;
  align-items: center;
  justify-content: space-between;
  gap: 10px;
  padding-top: 12px;
  border-top: 1px solid var(--shell-warm-border);
}

/* ─────────────────────────────────────────────────────────────
   RESPONSIVE BREAKPOINTS (Optimized for Chromebooks 1366x768)
───────────────────────────────────────────────────────────── */
@media (max-width: 960px) {
  .curriculum-primary-nav {
    display: none;
  }
  .shell-mobile-toggle {
    display: inline-flex;
  }
}

@media (max-width: 600px) {
  .curriculum-brand-sub {
    display: none;
  }
  .curriculum-header-inner { gap: 6px; padding: 0 8px; }
  .curriculum-header .shell-role-group,
  .curriculum-header-inner .shell-supports-pill { display: none; }
  .curriculum-utility-bar .shell-supports-pill span:not(.shell-pill-icon) {
    display: none;
  }
}

@media (max-width: 360px) {
  .curriculum-brand-name { display: none; }
}

/* ─────────────────────────────────────────────────────────────
   ACCESSIBILITY & FOCUS STYLES
───────────────────────────────────────────────────────────── */
.curriculum-header a:focus-visible,
.curriculum-header button:focus-visible {
  outline: 3px solid var(--shell-teal-700) !important;
  outline-offset: 2px !important;
}

/* Screen reader only utility */
.sr-only {
  position: absolute;
  width: 1px;
  height: 1px;
  padding: 0;
  margin: -1px;
  overflow: hidden;
  clip: rect(0, 0, 0, 0);
  white-space: nowrap;
  border: 0;
}