/**
 * Radiology Conference - Layout & Responsive
 * Mobile-first approach
 */

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

@media (min-width: 576px) {
  .container { padding: 0 var(--spacing-lg); }
}

@media (min-width: 768px) {
  .container { padding: 0 var(--spacing-xl); }
}

/* Header */
.site-header {
  position: sticky;
  top: 0;
  z-index: 1000;
  height: var(--header-height);
  background: rgba(255, 255, 255, 0.95);
  backdrop-filter: blur(12px);
  -webkit-backdrop-filter: blur(12px);
  box-shadow: 0 1px 3px rgba(0, 0, 0, 0.06);
}

.header-inner {
  display: flex;
  align-items: center;
  justify-content: space-between;
  height: 100%;
  max-width: var(--max-width);
  margin: 0 auto;
  padding: 0 var(--spacing-md);
}

.logo:hover {
  color: inherit;
}

.logo:hover .logo-text > span:first-child {
  color: var(--color-primary-dark);
}

/* Navigation */
.nav-toggle {
  display: flex;
  flex-direction: column;
  justify-content: center;
  gap: 5px;
  width: 44px;
  height: 44px;
  padding: 10px;
  background: none;
  border: none;
  cursor: pointer;
  touch-action: manipulation;
}

.nav-toggle span {
  display: block;
  width: 24px;
  height: 2px;
  background: var(--color-neutral-dark);
  transition: transform 0.3s ease, opacity 0.3s ease;
}

.nav-toggle[aria-expanded="true"] span:nth-child(1) {
  transform: translateY(7px) rotate(45deg);
}

.nav-toggle[aria-expanded="true"] span:nth-child(2) {
  opacity: 0;
}

.nav-toggle[aria-expanded="true"] span:nth-child(3) {
  transform: translateY(-7px) rotate(-45deg);
}

.main-nav {
  display: none;
  position: absolute;
  top: var(--header-height);
  left: 0;
  right: 0;
  background: var(--color-white);
  box-shadow: var(--shadow-md);
  padding: var(--spacing-md);
}

.main-nav.is-open {
  display: block;
}

.main-nav ul {
  list-style: none;
  margin: 0;
  padding: 0;
}

.main-nav li {
  border-bottom: 1px solid var(--color-neutral-light);
}

.main-nav li:last-child {
  border-bottom: none;
}

.main-nav a {
  display: block;
  padding: var(--spacing-md);
  color: var(--color-neutral-dark);
  font-weight: 500;
}

.main-nav a:hover {
  color: var(--color-primary);
  background: var(--color-neutral-light);
}

.main-nav a.active {
  color: var(--color-primary);
  font-weight: 600;
}

.main-nav .btn-nav {
  margin: var(--spacing-sm);
  padding: var(--spacing-sm) var(--spacing-md);
  font-size: 0.9375rem;
}

.main-nav .btn-nav.active {
  background: var(--color-button);
  color: var(--color-white);
}

@media (min-width: 768px) {
  .nav-toggle {
    display: none;
  }

  .main-nav {
    display: block;
    position: static;
    box-shadow: none;
    padding: 0;
  }

  .main-nav ul {
    display: flex;
    gap: var(--spacing-xs);
  }

  .main-nav li {
    border-bottom: none;
  }

  .main-nav a {
    padding: var(--spacing-sm) var(--spacing-md);
    border-radius: var(--radius-sm);
  }
}

/* Main content */
.main-content {
  min-height: calc(100vh - var(--header-height) - 180px);
  padding: 0;
}

.main-content .section:first-of-type {
  padding-top: 0;
}

@media (min-width: 768px) {
  .main-content {
    padding: var(--spacing-2xl) 0;
  }
}

/* Footer */
.site-footer {
  background: var(--color-neutral-dark);
  color: var(--color-neutral-light);
  padding: var(--spacing-xl) 0 var(--spacing-lg);
  margin-top: auto;
}

.site-footer a {
  color: var(--color-accent-light);
}

.site-footer a:hover {
  color: var(--color-white);
}

.footer-inner h4 {
  margin: 0 0 var(--spacing-sm);
  font-size: 1rem;
}

.footer-inner {
  display: grid;
  gap: var(--spacing-lg);
  text-align: center;
}

@media (min-width: 576px) {
  .footer-inner {
    grid-template-columns: repeat(2, 1fr);
    text-align: left;
  }
}

@media (min-width: 768px) {
  .footer-inner {
    grid-template-columns: repeat(3, 1fr);
  }
}

.footer-bottom {
  margin-top: var(--spacing-xl);
  padding-top: var(--spacing-lg);
  border-top: 1px solid rgba(255, 255, 255, 0.1);
  text-align: center;
  font-size: 0.875rem;
}

/* Grid utilities */
.grid {
  display: grid;
  gap: var(--spacing-lg);
}

.grid-2 { grid-template-columns: 1fr; }
.grid-3 { grid-template-columns: 1fr; }
.grid-4 { grid-template-columns: 1fr; }

@media (min-width: 576px) {
  .grid-2 { grid-template-columns: repeat(2, 1fr); }
  .grid-3 { grid-template-columns: repeat(2, 1fr); }
  .grid-4 { grid-template-columns: repeat(2, 1fr); }
}

@media (min-width: 768px) {
  .grid-3 { grid-template-columns: repeat(3, 1fr); }
  .grid-4 { grid-template-columns: repeat(3, 1fr); }
}

@media (min-width: 992px) {
  .grid-4 { grid-template-columns: repeat(4, 1fr); }
}

/* Section spacing */
.section {
  padding: var(--spacing-xl) 0;
}

.section-title {
  text-align: center;
  margin-bottom: var(--spacing-2xl);
}

.section-title h2 {
  margin-bottom: var(--spacing-sm);
  font-size: clamp(1.5rem, 4vw, 2rem);
  font-weight: 800;
  letter-spacing: -0.02em;
}

.section-title p {
  color: var(--color-neutral);
  max-width: 600px;
  margin-left: auto;
  margin-right: auto;
  font-size: 1.0625rem;
}