/* ============================================
   RESPONSIVE — MOBILE FIRST
   Base styles are for mobile (<480px).
   Progressive enhancement up.
   ============================================ */

/* ============================================
   HIDE / SHOW HELPERS
   ============================================ */
.desktop-only { display: none; }
.mobile-only  { display: flex; }

/* ============================================
   SMALL MOBILE (480px+)
   ============================================ */
@media (min-width: 480px) {
  .hero-title { font-size: var(--font-size-4xl); }

  .hero-stats {
    grid-template-columns: repeat(3, 1fr);
  }

  .result-cards {
    grid-template-columns: 1fr 1fr;
  }
}

/* ============================================
   TABLET PORTRAIT (768px+)
   ============================================ */
@media (min-width: 768px) {
  .desktop-only { display: flex; }
  .mobile-only  { display: none; }

  .hero-title { font-size: var(--font-size-5xl); }

  .feature-grid {
    grid-template-columns: repeat(3, 1fr);
  }

  .result-cards.three-col {
    grid-template-columns: repeat(3, 1fr);
  }

  .regime-comparison {
    grid-template-columns: 1fr 1fr;
  }
}

/* ============================================
   DESKTOP (1024px+) — sidebar appears
   ============================================ */
@media (min-width: 1024px) {
  /* Show sidebar */
  .sidebar {
    transform: translateX(0) !important;
    width: var(--sidebar-width-sm);
  }

  .main-content {
    margin-left: var(--sidebar-width-sm);
  }

  /* Hide hamburger */
  .hamburger { display: none !important; }

  /* Two-column calculator layout */
  .calc-body {
    display: grid;
    grid-template-columns: 380px 1fr;
    gap: var(--space-6);
    align-items: start;
  }

  .calc-results {
    border-left: 1px solid var(--border-color);
    border-top: none;
  }

  .hero-title { font-size: var(--font-size-6xl); }
}

/* ============================================
   LARGE DESKTOP (1280px+)
   ============================================ */
@media (min-width: 1280px) {
  .sidebar {
    width: var(--sidebar-width);
  }

  .main-content {
    margin-left: var(--sidebar-width);
  }

  .calc-body {
    grid-template-columns: 420px 1fr;
  }
}

/* ============================================
   MOBILE LAYOUT OVERRIDES (<1024px)
   ============================================ */
@media (max-width: 1023px) {
  /* Sidebar becomes overlay */
  .sidebar {
    width: min(var(--sidebar-width), 80vw);
    padding-top: var(--topbar-height);
    box-shadow: none;
    z-index: var(--z-sidebar);
  }

  .sidebar-overlay {
    display: none;
    position: fixed;
    inset: 0;
    background: var(--bg-overlay);
    z-index: calc(var(--z-sidebar) - 1);
    backdrop-filter: blur(4px);
    -webkit-backdrop-filter: blur(4px);
    opacity: 0;
    transition: opacity var(--transition-base);
  }

  .hamburger { display: flex !important; }

  .main-content {
    margin-left: 0;
  }

  /* Single column calc layout */
  .calc-body {
    display: flex;
    flex-direction: column;
  }

  .calc-results {
    border-left: none;
    border-top: 1px solid var(--border-color);
  }

  .scroll-progress {
    left: 0;
  }

  /* Top bar desktop links hidden */
  .top-bar-nav { display: none; }
}

/* ============================================
   SMALL MOBILE (<480px)
   ============================================ */
@media (max-width: 479px) {
  :root {
    --content-padding: var(--space-4);
    --topbar-height: 56px;
  }

  .hero-section { padding: var(--space-10) 0 var(--space-8); }

  .hero-badge { font-size: 0.7rem; }

  .hero-title {
    font-size: 1.875rem;
    letter-spacing: -0.02em;
  }

  .hero-subtitle { font-size: var(--font-size-base); }

  .hero-stats {
    grid-template-columns: repeat(3, 1fr);
    gap: var(--space-2);
  }

  .stat-card { padding: var(--space-4) var(--space-3); }
  .stat-value { font-size: var(--font-size-2xl); }

  .hero-cta { flex-direction: column; gap: var(--space-3); }
  .hero-cta .btn { width: 100%; justify-content: center; }

  .feature-grid {
    grid-template-columns: 1fr 1fr;
    gap: var(--space-3);
  }

  .feature-card { padding: var(--space-4); }
  .feature-card-icon { width: 36px; height: 36px; font-size: 1.125rem; }

  .section-title { font-size: var(--font-size-2xl); }

  .section-icon-wrap { width: 44px; height: 44px; font-size: 1.25rem; }

  .result-cards { grid-template-columns: 1fr; }
  .result-cards.three-col { grid-template-columns: 1fr; }
  .result-card.primary { grid-column: 1; }

  .result-value { font-size: var(--font-size-xl); }
  .result-value.large { font-size: var(--font-size-2xl); }

  .chart-container canvas { max-height: 220px; }

  .comparison-grid { grid-template-columns: 1fr; }

  .regime-comparison { grid-template-columns: 1fr; }

  .table-wrapper { font-size: var(--font-size-xs); }

  .calc-inputs { padding: var(--space-5); }
  .calc-results { padding: var(--space-5); }

  .calculator-section { padding: var(--space-8) 0; }

  .top-bar { padding: 0 var(--space-4); }

  .logo-text { font-size: var(--font-size-base); }

  .rate-pills { gap: var(--space-1); }
  .rate-pill { padding: 6px 12px; font-size: 0.75rem; }

  .btn { padding: var(--space-3) var(--space-5); font-size: var(--font-size-sm); }
  .btn-calculate { padding: var(--space-3) var(--space-5); }

  .breakdown-row { padding: var(--space-2) var(--space-3); }
  .breakdown-label { font-size: var(--font-size-xs); }
  .breakdown-value { font-size: var(--font-size-xs); }
}

/* ============================================
   PRINT STYLES
   ============================================ */
@media print {
  .top-bar, .sidebar, .hamburger, .sidebar-overlay, .scroll-progress { display: none !important; }
  .main-content { margin-left: 0; }
  .calc-body { display: block; }
  .calc-results { border: 1px solid #ccc; }
}