/**
 * RedNoteHub — Global Design System & Main Stylesheet
 * Layered Architecture: Tokens -> Base -> Components -> Utilities -> Media
 */

/* ==========================================================================
   1. DESIGN TOKENS & CSS CUSTOM PROPERTIES
   ========================================================================== */
:root {
  /* Brand Palette */
  --brand-red: #FF2442;
  --brand-coral: #FF526E;
  --brand-coral-light: #FFA3B5;
  --brand-dark: #0B0D11;
  --brand-dark-surface: #10131A;
  --brand-dark-surface-elevated: #161A24;

  /* Typography & Surfaces */
  --text-primary: #F3F4F6;
  --text-secondary: #D1D5DB;
  --text-muted: #9CA3AF;
  --card-bg: rgba(18, 22, 30, 0.75);
  --card-border: rgba(255, 255, 255, 0.08);
  --card-border-hover: rgba(255, 36, 66, 0.4);

  /* Elevation & Glow Effects */
  --glow-red: 0 10px 28px -6px rgba(255, 36, 66, 0.35);
  --glow-card: 0 16px 36px -10px rgba(0, 0, 0, 0.5), 0 0 20px -3px rgba(255, 36, 66, 0.15);
  --shadow-subtle: 0 4px 20px -2px rgba(0, 0, 0, 0.4);

  /* Transitions */
  --transition-fast: 0.15s ease;
  --transition-normal: 0.25s cubic-bezier(0.16, 1, 0.3, 1);
}

/* ==========================================================================
   2. BASE & TYPOGRAPHY
   ========================================================================== */
html {
  scroll-behavior: smooth;
  scroll-padding-top: 5.5rem;
  -webkit-tap-highlight-color: transparent;
}

body {
  font-family: -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, "Helvetica Neue", Arial, sans-serif;
  background-color: var(--brand-dark);
  color: var(--text-primary);
  overflow-x: hidden;
  -webkit-font-smoothing: antialiased;
  -moz-osx-font-smoothing: grayscale;
}

::selection {
  background-color: var(--brand-red);
  color: #FFFFFF;
}

:focus-visible {
  outline: 2px solid var(--brand-coral);
  outline-offset: 3px;
  border-radius: 4px;
}

.skip-link {
  position: absolute;
  top: -5rem;
  left: 1rem;
  z-index: 100;
  background: var(--brand-dark);
  color: #FFFFFF;
  padding: 0.75rem 1.25rem;
  border-radius: 0.5rem;
  border: 1px solid var(--brand-red);
  font-weight: 600;
  transition: top var(--transition-fast);
}

.skip-link:focus {
  top: 1rem;
}

/* ==========================================================================
   3. REUSABLE COMPONENT STYLES & GLASSMORPHISM
   ========================================================================== */
.red-gradient {
  background: linear-gradient(135deg, #FF2442 0%, #FF526E 100%);
}

.red-glow {
  box-shadow: var(--glow-red);
}

.glass-card {
  background: var(--card-bg);
  backdrop-filter: blur(16px);
  -webkit-backdrop-filter: blur(16px);
  border: 1px solid var(--card-border);
  transition: transform var(--transition-normal), border-color var(--transition-normal), box-shadow var(--transition-normal);
}

.glass-card:hover {
  border-color: var(--card-border-hover);
  box-shadow: var(--glow-card);
}

/* Slang Filter Chips */
.chip-btn {
  transition: background-color var(--transition-fast), color var(--transition-fast), border-color var(--transition-fast), box-shadow var(--transition-fast);
}

.chip-btn.active {
  background-color: var(--brand-red);
  color: #FFFFFF;
  border-color: var(--brand-red);
  box-shadow: 0 4px 14px -2px rgba(255, 36, 66, 0.4);
}

/* Native Details/Summary FAQ Styling */
details summary::-webkit-details-marker {
  display: none;
}

details summary {
  list-style: none;
}

details[open] summary .faq-icon {
  transform: rotate(180deg);
  color: var(--brand-coral);
}

/* ROI Estimator Preset Buttons */
.est-budget-btn {
  transition: all var(--transition-fast);
}

.est-budget-btn.active {
  background-color: var(--brand-red);
  border-color: var(--brand-red);
  color: #FFFFFF;
  box-shadow: 0 4px 12px rgba(255, 36, 66, 0.35);
}

/* ==========================================================================
   4. MOBILE ERGONOMICS & SAFE AREAS
   ========================================================================== */
.pb-safe {
  padding-bottom: calc(4.5rem + env(safe-area-inset-bottom, 0px));
}

.bottom-safe {
  padding-bottom: env(safe-area-inset-bottom, 12px);
}

/* Reduced Motion */
@media (prefers-reduced-motion: reduce) {
  html {
    scroll-behavior: auto;
  }
  *, *::before, *::after {
    animation-duration: 0.01ms !important;
    animation-iteration-count: 1 !important;
    transition-duration: 0.01ms !important;
  }
}