/* ==========================================================================
   Layout CSS — Responsive Grid, Navigation, and Structure
   Mobile-first approach with breakpoints:
     - Small:  320px – 767px  (default / base styles)
     - Medium: 768px – 1023px
     - Large:  1024px – 1920px
   All values use CSS custom properties from theme.css.
   ========================================================================== */

/* --- Reset & Base --- */
*,
*::before,
*::after {
  box-sizing: border-box;
  margin: 0;
  padding: 0;
}

html {
  font-size: 100%;
  scroll-behavior: smooth;
}

body {
  font-family: var(--font-body);
  font-size: var(--font-size-base);
  color: var(--color-text);
  background-color: var(--color-background);
  line-height: 1.5;
  min-height: 100vh;
  display: flex;
  flex-direction: column;
}

/* --- Focus Indicators (Requirement 10.4) --- */
:focus-visible {
  outline: 3px solid var(--color-primary);
  outline-offset: 2px;
  border-radius: var(--radius-sm);
}

a:focus-visible,
button:focus-visible,
input:focus-visible,
select:focus-visible,
textarea:focus-visible {
  outline: 3px solid var(--color-primary);
  outline-offset: 2px;
}

/* --- Header & Navigation --- */
header {
  background-color: var(--color-background);
  border-bottom: 1px solid var(--color-border);
  position: sticky;
  top: 0;
  z-index: 100;
}

nav {
  display: flex;
  align-items: center;
  justify-content: space-between;
  flex-wrap: wrap;
  padding: var(--spacing-sm) var(--spacing-md);
  max-width: 1920px;
  margin: 0 auto;
}

.nav-brand {
  font-family: var(--font-heading);
  font-size: var(--font-size-md);
  font-weight: 700;
  color: var(--color-primary);
  text-decoration: none;
}

.nav-brand:hover {
  text-decoration: underline;
}

/* --- Hamburger Toggle (visible below 768px) --- */
.nav-toggle {
  display: flex;
  align-items: center;
  justify-content: center;
  width: 2.5rem;
  height: 2.5rem;
  background: transparent;
  border: none;
  cursor: pointer;
  padding: var(--spacing-xs);
  border-radius: var(--radius-sm);
}

.nav-toggle:hover {
  background-color: rgba(255, 255, 255, 0.1);
}

.nav-toggle-icon,
.nav-toggle-icon::before,
.nav-toggle-icon::after {
  display: block;
  width: 1.25rem;
  height: 2px;
  background-color: var(--color-text);
  border-radius: var(--radius-full);
  transition: transform 0.3s ease, opacity 0.3s ease;
  position: relative;
}

.nav-toggle-icon::before,
.nav-toggle-icon::after {
  content: '';
  position: absolute;
  left: 0;
  width: 100%;
}

.nav-toggle-icon::before {
  top: -6px;
}

.nav-toggle-icon::after {
  top: 6px;
}

/* Hamburger open state animation */
.nav-toggle[aria-expanded="true"] .nav-toggle-icon {
  background-color: transparent;
}

.nav-toggle[aria-expanded="true"] .nav-toggle-icon::before {
  top: 0;
  transform: rotate(45deg);
}

.nav-toggle[aria-expanded="true"] .nav-toggle-icon::after {
  top: 0;
  transform: rotate(-45deg);
}

/* --- Nav Links (mobile: collapsed) --- */
.nav-links {
  list-style: none;
  display: none;
  flex-direction: column;
  width: 100%;
  gap: 0;
  padding-top: var(--spacing-sm);
}

.nav-links.open {
  display: flex;
}

.nav-links li {
  width: 100%;
}

.nav-links a,
.nav-links button {
  display: block;
  width: 100%;
  padding: var(--spacing-sm) var(--spacing-md);
  font-family: var(--font-body);
  font-size: var(--font-size-base);
  color: var(--color-text);
  text-decoration: none;
  border: none;
  background: transparent;
  cursor: pointer;
  text-align: left;
  border-radius: var(--radius-sm);
}

.nav-links a:hover,
.nav-links button:hover {
  background-color: rgba(255, 255, 255, 0.1);
  color: var(--color-primary);
}

.nav-links a[aria-current="page"] {
  color: var(--color-primary);
  font-weight: 600;
}

.nav-logout {
  color: var(--color-error);
}

/* --- Main Content Area --- */
main {
  flex: 1;
  width: 100%;
  max-width: 1920px;
  margin: 0 auto;
  padding: var(--spacing-md);
}

/* --- Footer --- */
footer {
  text-align: center;
  padding: var(--spacing-md);
  font-size: var(--font-size-sm);
  color: var(--color-text-muted);
  border-top: 1px solid var(--color-border);
}

/* --- Grid Layout Utility --- */
.grid {
  display: grid;
  gap: var(--spacing-md);
  grid-template-columns: 1fr;
}

/* --- Container Utility --- */
.container {
  width: 100%;
  padding-left: var(--spacing-md);
  padding-right: var(--spacing-md);
  margin: 0 auto;
}

/* ==========================================================================
   Medium Breakpoint: 768px – 1023px
   ========================================================================== */
@media (min-width: 768px) {
  /* Navigation: show links inline, hide hamburger */
  .nav-toggle {
    display: none;
  }

  .nav-links {
    display: flex;
    flex-direction: row;
    width: auto;
    padding-top: 0;
    gap: var(--spacing-sm);
    align-items: center;
  }

  .nav-links li {
    width: auto;
  }

  .nav-links a,
  .nav-links button {
    width: auto;
    padding: var(--spacing-xs) var(--spacing-sm);
  }

  /* Main content */
  main {
    padding: var(--spacing-lg);
  }

  /* Grid: two-column layout */
  .grid {
    grid-template-columns: repeat(2, 1fr);
  }

  .container {
    max-width: 960px;
  }
}

/* ==========================================================================
   Large Breakpoint: 1024px – 1920px
   ========================================================================== */
@media (min-width: 1024px) {
  nav {
    padding: var(--spacing-md) var(--spacing-lg);
  }

  .nav-brand {
    font-size: var(--font-size-lg);
  }

  .nav-links a,
  .nav-links button {
    padding: var(--spacing-sm) var(--spacing-md);
    font-size: var(--font-size-base);
  }

  /* Main content */
  main {
    padding: var(--spacing-xl);
  }

  /* Grid: three-column layout for large screens */
  .grid {
    grid-template-columns: repeat(3, 1fr);
  }

  .container {
    max-width: 1200px;
  }
}

/* ==========================================================================
   Accessibility: Reduced Motion
   ========================================================================== */
@media (prefers-reduced-motion: reduce) {
  *,
  *::before,
  *::after {
    transition: none !important;
    animation: none !important;
  }

  html {
    scroll-behavior: auto;
  }
}