/* ============================================================
   LAYOUT — Navigation, Containers, Grid Systems
   ============================================================ */

/* --- Container --- */
.container {
  width: 100%;
  max-width: var(--container-max);
  margin: 0 auto;
  padding: 0 var(--space-6);
}

/* --- Navigation --- */
.nav {
  position: fixed;
  top: 0;
  left: 0;
  right: 0;
  z-index: 100;
  height: var(--nav-height);
  background: rgba(10, 10, 15, 0.85);
  backdrop-filter: blur(16px);
  -webkit-backdrop-filter: blur(16px);
  border-bottom: 1px solid var(--color-border);
  transition: background var(--transition-slow), border-color var(--transition-slow);
}

[data-theme="light"] .nav {
  background: rgba(248, 248, 252, 0.85);
}

.nav--scrolled {
  background: rgba(10, 10, 15, 0.95);
}

[data-theme="light"] .nav--scrolled {
  background: rgba(248, 248, 252, 0.95);
}

.nav__container {
  display: flex;
  align-items: center;
  justify-content: space-between;
  height: 100%;
  max-width: var(--container-max);
  margin: 0 auto;
  padding: 0 var(--space-6);
}

.nav__logo {
  display: flex;
  align-items: center;
  gap: var(--space-2);
  color: var(--color-text);
  font-family: var(--font-display);
  font-weight: 800;
  font-size: var(--text-lg);
  text-decoration: none;
}

.nav__logo:hover {
  color: var(--color-text);
}

.nav__logo-icon {
  display: flex;
  align-items: center;
  justify-content: center;
  width: 34px;
  height: 34px;
  background: var(--color-accent);
  color: white;
  border-radius: var(--radius-md);
  font-family: var(--font-mono);
  font-size: var(--text-sm);
  font-weight: 700;
}

.nav__logo-text {
  color: var(--color-text);
}

.nav__links {
  display: flex;
  align-items: center;
  gap: var(--space-1);
}

.nav__link {
  padding: var(--space-2) var(--space-4);
  color: var(--color-text-muted);
  font-size: var(--text-sm);
  font-weight: 500;
  border-radius: var(--radius-md);
  transition: all var(--transition-fast);
  text-decoration: none;
}

.nav__link:hover {
  color: var(--color-text);
  background: var(--color-bg-elevated);
}

.nav__link--active {
  color: var(--color-text);
  background: var(--color-accent-dim);
}

.nav__actions {
  display: flex;
  align-items: center;
  gap: var(--space-2);
}

.nav__hamburger {
  display: none;
  flex-direction: column;
  gap: 5px;
  padding: var(--space-2);
  border-radius: var(--radius-md);
  transition: background var(--transition-fast);
}

.nav__hamburger:hover {
  background: var(--color-bg-elevated);
}

.nav__hamburger span {
  display: block;
  width: 20px;
  height: 2px;
  background: var(--color-text);
  border-radius: var(--radius-full);
  transition: all var(--transition-base);
}

.nav__hamburger.is-open span:nth-child(1) {
  transform: translateY(7px) rotate(45deg);
}

.nav__hamburger.is-open span:nth-child(2) {
  opacity: 0;
}

.nav__hamburger.is-open span:nth-child(3) {
  transform: translateY(-7px) rotate(-45deg);
}

/* --- Sections --- */
.section {
  padding: var(--space-24) 0;
}

.section__header {
  text-align: center;
  margin-bottom: var(--space-16);
}

.section__label {
  display: inline-block;
  font-family: var(--font-mono);
  font-size: var(--text-xs);
  font-weight: 600;
  letter-spacing: 0.12em;
  text-transform: uppercase;
  color: var(--color-accent-light);
  background: var(--color-accent-dim);
  padding: var(--space-1) var(--space-3);
  border-radius: var(--radius-full);
  margin-bottom: var(--space-4);
  border: 1px solid rgba(49, 120, 198, 0.2);
}

.section__title {
  font-size: var(--text-4xl);
  font-weight: 800;
  color: var(--color-text);
  margin-bottom: var(--space-4);
}

.section__subtitle {
  font-size: var(--text-lg);
  color: var(--color-text-muted);
  max-width: 560px;
  margin: 0 auto;
}

/* --- Lesson Layout (Sidebar + Content) --- */
.lesson-layout {
  display: grid;
  grid-template-columns: var(--sidebar-width) 1fr;
  min-height: calc(100vh - var(--nav-height));
  margin-top: var(--nav-height);
}

.lesson-sidebar {
  position: sticky;
  top: var(--nav-height);
  height: calc(100vh - var(--nav-height));
  overflow-y: auto;
  border-right: 1px solid var(--color-border);
  background: var(--color-bg-secondary);
  padding: var(--space-6) 0;
  transition: transform var(--transition-base);
}

.lesson-content {
  padding: var(--space-10) var(--space-8);
  max-width: var(--content-max);
  min-height: 100%;
}

/* --- Footer --- */
.footer {
  border-top: 1px solid var(--color-border);
  padding: var(--space-12) 0;
  margin-top: auto;
}

.footer__content {
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: var(--space-8);
  margin-bottom: var(--space-8);
}

.footer__brand {
  display: flex;
  align-items: center;
  gap: var(--space-3);
  font-family: var(--font-display);
  font-weight: 700;
}

.footer__brand-name {
  color: var(--color-text);
}

.footer__links {
  display: flex;
  gap: var(--space-6);
}

.footer__link {
  color: var(--color-text-muted);
  font-size: var(--text-sm);
  transition: color var(--transition-fast);
}

.footer__link:hover {
  color: var(--color-text);
}

.footer__bottom {
  border-top: 1px solid var(--color-border);
  padding-top: var(--space-6);
  text-align: center;
}

.footer__bottom p {
  font-size: var(--text-sm);
  color: var(--color-text-subtle);
}

/* --- Responsive --- */
@media (max-width: 768px) {
  .nav__links {
    position: fixed;
    top: var(--nav-height);
    left: 0;
    right: 0;
    background: var(--color-bg);
    border-bottom: 1px solid var(--color-border);
    flex-direction: column;
    padding: var(--space-4);
    gap: var(--space-1);
    transform: translateY(-110%);
    transition: transform var(--transition-base);
    z-index: 99;
  }

  .nav__links.is-open {
    transform: translateY(0);
  }

  .nav__link {
    width: 100%;
    text-align: center;
    padding: var(--space-3);
  }

  .nav__hamburger {
    display: flex;
  }

  .lesson-layout {
    grid-template-columns: 1fr;
  }

  .lesson-sidebar {
    position: static;
    height: auto;
    border-right: none;
    border-bottom: 1px solid var(--color-border);
  }

  .lesson-content {
    padding: var(--space-6) var(--space-4);
  }

  .section__title {
    font-size: var(--text-3xl);
  }

  .footer__content {
    flex-direction: column;
    text-align: center;
  }

  .footer__links {
    flex-wrap: wrap;
    justify-content: center;
    gap: var(--space-4);
  }
}

@media (max-width: 480px) {
  .container {
    padding: 0 var(--space-4);
  }
}