/**
 * ==============================================================================
 * EXPERTOS TIC ENGINEERING STANDARD (ETAES)
 * Archivo: public/css/layout.css
 * Propósito: Estructura del layout general, grillas responsivas y encabezado.
 * Responsabilidad: Asegurar arquitectura Mobile First, alineación fluida y orden visual.
 * Dependencias: public/css/variables.css, public/css/base.css
 * Autor: Carlos Londoño – EXPERTOS TIC
 * Proyecto: ViralCTR AI - Generador de Titulares YouTube con Alto CTR
 * ==============================================================================
 */

/* ==============================================================================
 * HEADER / BARRA DE NAVEGACIÓN SUPERIOR
 * ============================================================================== */
.app-header {
  position: sticky;
  top: 0;
  z-index: 100;
  background-color: var(--bg-glass);
  backdrop-filter: blur(12px);
  -webkit-backdrop-filter: blur(12px);
  border-bottom: 1px solid var(--border-subtle);
  padding: 0.85rem 0;
  transition: all var(--transition-normal);
}

.header-inner {
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: var(--space-md);
}

.brand-wrapper {
  display: flex;
  align-items: center;
  gap: var(--space-sm);
  text-decoration: none;
}

.brand-icon {
  width: 2.5rem;
  height: 2.5rem;
  border-radius: var(--radius-md);
  background: linear-gradient(135deg, var(--color-primary), var(--color-secondary));
  display: flex;
  align-items: center;
  justify-content: center;
  color: #ffffff;
  font-size: 1.25rem;
  box-shadow: 0 4px 10px rgba(59, 130, 246, 0.3);
}

.brand-text {
  display: flex;
  flex-direction: column;
}

.brand-title {
  font-family: var(--font-heading);
  font-size: 1.2rem;
  font-weight: 800;
  color: var(--text-primary);
  line-height: 1.1;
  display: flex;
  align-items: center;
  gap: 0.35rem;
}

.brand-subtitle {
  font-size: 0.75rem;
  color: var(--text-muted);
  font-weight: 500;
}

.header-actions {
  display: flex;
  align-items: center;
  gap: var(--space-xs);
}

/* Toggle Switch de Tema Light / Dark */
.theme-toggle-btn {
  width: 2.6rem;
  height: 2.6rem;
  border-radius: var(--radius-full);
  display: flex;
  align-items: center;
  justify-content: center;
  background-color: var(--bg-surface-alt);
  color: var(--text-primary);
  border: 1px solid var(--border-subtle);
  font-size: 1.2rem;
  transition: all var(--transition-fast);
}

.theme-toggle-btn:hover {
  background-color: var(--color-primary-subtle);
  border-color: var(--color-primary-border);
  color: var(--color-primary);
  transform: rotate(15deg);
}

/* ==============================================================================
 * SECCIÓN HERO MINIMALISTA
 * ============================================================================== */
.hero-section {
  padding: clamp(1.25rem, 3.5vw, 2.5rem) 0 clamp(1rem, 2vw, 1.75rem);
  text-align: center;
}

.hero-badge {
  display: inline-flex;
  margin-bottom: var(--space-xs);
}

.hero-title {
  max-width: 780px;
  margin: 0 auto 0.35rem;
  font-size: clamp(1.4rem, 3.2vw + 0.5rem, 2.35rem);
  letter-spacing: -0.03em;
  background: linear-gradient(135deg, var(--text-primary) 30%, var(--color-primary));
  -webkit-background-clip: text;
  -webkit-text-fill-color: transparent;
}

.hero-description {
  max-width: 580px;
  margin: 0 auto var(--space-md);
  font-size: clamp(0.875rem, 1.1vw, 1rem);
  color: var(--text-secondary);
}

/* ==============================================================================
 * PESTAÑAS DE NAVEGACIÓN PRINCIPALES
 * ============================================================================== */
.main-nav-tabs {
  display: flex;
  align-items: center;
  justify-content: center;
  gap: var(--space-xs);
  margin-bottom: var(--space-lg);
  flex-wrap: wrap;
}

.nav-tab {
  padding: 0.55rem 1.15rem;
  border-radius: var(--radius-full);
  font-size: 0.9rem;
  font-weight: 600;
  color: var(--text-secondary);
  background-color: var(--bg-surface);
  border: 1px solid var(--border-subtle);
  transition: all var(--transition-fast);
  display: inline-flex;
  align-items: center;
  gap: 0.5rem;
}

.nav-tab:hover {
  color: var(--text-primary);
  border-color: var(--border-strong);
}

.nav-tab.active {
  background-color: var(--color-primary);
  color: #ffffff;
  border-color: var(--color-primary);
  box-shadow: 0 4px 12px rgba(59, 130, 246, 0.3);
}

/* ==============================================================================
 * GRILLA Y CONTENEDORES PRINCIPALES
 * ============================================================================== */
.app-grid {
  display: grid;
  grid-template-columns: 1fr;
  gap: var(--space-lg);
  margin-bottom: var(--space-3xl);
  width: 100%;
  max-width: 100%;
  min-width: 0;
}

@media (min-width: 1024px) {
  .app-grid {
    grid-template-columns: 440px 1fr;
    align-items: start;
    gap: var(--space-xl);
  }
}

.generator-panel {
  position: relative;
  width: 100%;
  max-width: 100%;
  min-width: 0;
}

@media (min-width: 1024px) {
  .generator-panel.sticky {
    position: sticky;
    top: 5rem;
  }
}

.results-panel {
  min-height: 400px;
  display: flex;
  flex-direction: column;
  gap: var(--space-lg);
}

.results-header {
  display: flex;
  align-items: center;
  justify-content: space-between;
  flex-wrap: wrap;
  gap: var(--space-md);
  padding-bottom: var(--space-sm);
  border-bottom: 1px solid var(--border-subtle);
}

.titles-grid {
  display: grid;
  grid-template-columns: 1fr;
  gap: var(--space-md);
}

@media (min-width: 640px) {
  .titles-grid {
    grid-template-columns: repeat(auto-fill, minmax(320px, 1fr));
  }
}

/* Estado Vacío (Empty State) */
.empty-state {
  display: flex;
  flex-direction: column;
  align-items: center;
  justify-content: center;
  text-align: center;
  padding: clamp(2.5rem, 6vw, 4.5rem) clamp(1rem, 3vw, 2rem);
  background-color: var(--bg-surface);
  border: 2px dashed var(--border-subtle);
  border-radius: var(--radius-xl);
  gap: var(--space-md);
}

.empty-state-icon {
  font-size: 3rem;
  width: 4.5rem;
  height: 4.5rem;
  border-radius: 50%;
  background-color: var(--color-primary-subtle);
  color: var(--color-primary);
  display: flex;
  align-items: center;
  justify-content: center;
}

/* ==============================================================================
 * FOOTER
 * ============================================================================== */
.app-footer {
  margin-top: auto;
  border-top: 1px solid var(--border-subtle);
  background-color: var(--bg-surface);
  padding: var(--space-lg) 0;
  font-size: 0.85rem;
  color: var(--text-muted);
}

.footer-inner {
  display: flex;
  align-items: center;
  justify-content: space-between;
  flex-wrap: wrap;
  gap: var(--space-md);
}

/* ==============================================================================
 * OPTIMIZACIONES ESPECÍFICAS PARA MÓVIL (< 640px y < 420px)
 * ============================================================================== */
@media (max-width: 640px) {
  .hero-section {
    padding: 1.5rem 0 1rem;
  }

  .main-nav-tabs {
    gap: 0.35rem;
    margin-bottom: 1.25rem;
  }

  .nav-tab {
    padding: 0.5rem 0.85rem;
    font-size: 0.85rem;
    flex: 1 1 auto;
    justify-content: center;
  }

  .results-header {
    flex-direction: column;
    align-items: flex-start;
    gap: 0.75rem;
  }

  .results-header > div:last-child {
    width: 100%;
    justify-content: space-between;
  }

  .modal-content {
    padding: 0;
    max-height: 95vh;
  }

  .modal-header, .modal-body, .modal-footer {
    padding: 1rem;
  }
}

@media (max-width: 420px) {
  .brand-title {
    font-size: 1.05rem;
  }

  .brand-title .badge {
    display: none;
  }

  .brand-subtitle {
    display: none;
  }

  .brand-icon {
    width: 2.2rem;
    height: 2.2rem;
    font-size: 1.1rem;
  }

  .theme-toggle-btn {
    width: 2.3rem;
    height: 2.3rem;
    font-size: 1.05rem;
  }

  .chip-group {
    gap: 0.35rem;
  }

  .chip {
    font-size: 0.775rem;
    padding: 0.3rem 0.65rem;
  }
}