:root {
  --bg-primary: #0b0f19;
  --bg-card: #111827;
  --bg-card-hover: #1f2937;
  --border-color: #1f2937;
  --text-main: #f9fafb;
  --text-muted: #9ca3af;
  
  --accent-cyan: #06b6d4;
  --accent-blue: #3b82f6;

  /* Severity Badge & Grade Colors - High Contrast WCAG AA Standards */
  --color-pass: #10b981;
  --color-warn: #f59e0b;
  --color-fail: #ef4444;
  --color-critical: #dc2626;
  --color-error: #94a3b8;
  --color-high: #ef4444;
  --color-medium: #f59e0b;
  --color-low: #3b82f6;
  --color-info: #60a5fa;

  --font-family: 'Inter', system-ui, -apple-system, BlinkMacSystemFont, 'Segoe UI', Roboto, sans-serif;
  --radius: 12px;
  --focus-ring: 0 0 0 3px #06b6d4, 0 0 0 5px rgba(6, 182, 212, 0.4);
}

*, *::before, *::after {
  box-sizing: border-box;
  margin: 0;
  padding: 0;
}

html {
  overflow-x: hidden;
  scroll-behavior: smooth;
}

body {
  background-color: var(--bg-primary);
  color: var(--text-main);
  font-family: var(--font-family);
  line-height: 1.6;
  min-height: 100vh;
  display: flex;
  flex-direction: column;
  overflow-x: hidden;
  text-rendering: optimizeLegibility;
  -webkit-font-smoothing: antialiased;
}

/* Accessibility Utilities & High-Contrast Focus States */
.sr-only {
  position: absolute !important;
  width: 1px !important;
  height: 1px !important;
  padding: 0 !important;
  margin: -1px !important;
  overflow: hidden !important;
  clip: rect(0, 0, 0, 0) !important;
  white-space: nowrap !important;
  border: 0 !important;
}

/* Accessibility Skip Link */
.skip-link {
  position: absolute;
  top: -100px;
  left: 1rem;
  background: var(--accent-cyan);
  color: #000;
  padding: 0.5rem 1rem;
  font-weight: 700;
  z-index: 9999;
  border-radius: 4px;
  text-decoration: none;
  transition: top 0.2s ease;
}
.skip-link:focus {
  top: 1rem;
  outline: none;
  box-shadow: var(--focus-ring);
}

/* Navbar */
.navbar {
  border-bottom: 1px solid var(--border-color);
  background: rgba(17, 24, 39, 0.92);
  backdrop-filter: blur(12px);
  position: sticky;
  top: 0;
  z-index: 100;
}
.nav-container {
  max-width: 1200px;
  margin: 0 auto;
  padding: 1rem 1.5rem;
  display: flex;
  justify-content: space-between;
  align-items: center;
}
.logo {
  display: flex;
  align-items: center;
  gap: 0.75rem;
  text-decoration: none;
  color: var(--text-main);
  font-weight: 800;
  font-size: 1.35rem;
  letter-spacing: -0.02em;
}
.logo:focus-visible {
  outline: none;
  box-shadow: var(--focus-ring);
  border-radius: 6px;
}
.logo-icon {
  width: 28px;
  height: 28px;
  background: linear-gradient(135deg, var(--accent-cyan), var(--accent-blue));
  border-radius: 8px;
  display: inline-block;
  flex-shrink: 0;
}
.nav-links {
  display: flex;
  gap: 1rem;
  list-style: none;
  align-items: center;
}
.nav-links a {
  color: var(--text-muted);
  text-decoration: none;
  font-size: 0.95rem;
  font-weight: 500;
  transition: color 0.2s ease, background-color 0.2s ease;
  padding: 0.4rem 0.75rem;
  border-radius: 6px;
  display: inline-block;
}
.nav-links a:hover {
  color: var(--text-main);
  background: rgba(255,255,255,0.05);
}
.nav-links a:focus-visible {
  outline: none;
  box-shadow: var(--focus-ring);
}

/* Main Container */
main {
  flex: 1;
  max-width: 1200px;
  width: 100%;
  margin: 0 auto;
  padding: 2.5rem 1.5rem;
}

/* Typography & Word Break Safety */
h1, h2, h3, h4, h5, h6 {
  overflow-wrap: break-word;
  word-break: break-word;
}

/* Hero Section */
.hero {
  text-align: center;
  max-width: 750px;
  margin: 2rem auto 3rem;
}
.hero h1 {
  font-size: clamp(2rem, 5vw, 2.8rem);
  font-weight: 800;
  letter-spacing: -0.03em;
  margin-bottom: 1rem;
  line-height: 1.2;
  background: linear-gradient(180deg, #ffffff 0%, #9ca3af 100%);
  -webkit-background-clip: text;
  -webkit-text-fill-color: transparent;
}
.hero p {
  color: var(--text-muted);
  font-size: clamp(1rem, 2.5vw, 1.15rem);
  margin-bottom: 2rem;
}

/* Scanner Form */
.scanner-form-box {
  background: var(--bg-card);
  border: 1px solid var(--border-color);
  padding: 1.5rem;
  border-radius: var(--radius);
  box-shadow: 0 20px 40px rgba(0,0,0,0.3);
}
.scanner-form {
  display: flex;
  gap: 0.75rem;
  flex-wrap: wrap;
  align-items: flex-end;
}
.input-group {
  flex: 1;
  min-width: min(100%, 280px);
  position: relative;
}
.scanner-input {
  width: 100%;
  padding: 0.9rem 1.25rem;
  background: #0b0f19;
  border: 1px solid var(--border-color);
  border-radius: 8px;
  color: var(--text-main);
  font-size: 1rem;
  transition: border-color 0.2s ease, box-shadow 0.2s ease;
}
.scanner-input:focus {
  outline: none;
  border-color: var(--accent-cyan);
  box-shadow: var(--focus-ring);
}
.btn-primary {
  background: linear-gradient(135deg, var(--accent-cyan), var(--accent-blue));
  color: #fff;
  border: none;
  padding: 0.9rem 1.75rem;
  border-radius: 8px;
  font-weight: 600;
  font-size: 1rem;
  cursor: pointer;
  transition: transform 0.15s ease, opacity 0.2s ease;
  display: inline-flex;
  align-items: center;
  justify-content: center;
  gap: 0.5rem;
  min-height: 48px;
}
.btn-primary:hover {
  opacity: 0.92;
}
.btn-primary:active {
  transform: scale(0.98);
}
.btn-primary:focus-visible {
  outline: none;
  box-shadow: var(--focus-ring);
}

/* Cards & Grid Layout */
.grid-2 {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(min(100%, 300px), 1fr));
  gap: 1.5rem;
  margin-top: 2rem;
}
.card {
  background: var(--bg-card);
  border: 1px solid var(--border-color);
  border-radius: var(--radius);
  padding: 1.5rem;
  transition: border-color 0.2s ease;
  overflow-wrap: break-word;
  word-break: break-word;
}
.card:focus-visible {
  outline: none;
  box-shadow: var(--focus-ring);
  border-color: var(--accent-cyan);
}

/* Comparison Grid */
.compare-grid {
  display: grid;
  grid-template-columns: 1fr;
  gap: 1.5rem;
  margin-top: 2rem;
}
@media (min-width: 768px) {
  .compare-grid {
    grid-template-columns: 1fr 1fr;
    gap: 2rem;
  }
}

/* Grade Display Badge */
.grade-badge {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  width: 80px;
  height: 80px;
  border-radius: 50%;
  font-size: 2.5rem;
  font-weight: 900;
  color: #fff;
  flex-shrink: 0;
  box-shadow: 0 10px 25px rgba(0,0,0,0.4);
}
.grade-A { background: linear-gradient(135deg, #10b981, #059669); }
.grade-B { background: linear-gradient(135deg, #3b82f6, #2563eb); }
.grade-C { background: linear-gradient(135deg, #f59e0b, #d97706); }
.grade-D { background: linear-gradient(135deg, #f97316, #ea580c); }
.grade-F { background: linear-gradient(135deg, #ef4444, #dc2626); }
.grade-NA { background: linear-gradient(135deg, #64748b, #475569); }

/* Status & Severity Badges */
.badge {
  padding: 0.25rem 0.75rem;
  border-radius: 999px;
  font-size: 0.8rem;
  font-weight: 700;
  text-transform: uppercase;
  letter-spacing: 0.05em;
  display: inline-block;
  white-space: nowrap;
}
.badge-pass { background: rgba(16, 185, 129, 0.2); color: #34d399; border: 1px solid rgba(16, 185, 129, 0.4); }
.badge-warn { background: rgba(245, 158, 11, 0.2); color: #fbbf24; border: 1px solid rgba(245, 158, 11, 0.4); }
.badge-fail { background: rgba(239, 68, 68, 0.2); color: #f87171; border: 1px solid rgba(239, 68, 68, 0.4); }
.badge-critical { background: rgba(220, 38, 38, 0.3); color: #fca5a5; border: 1px solid rgba(220, 38, 38, 0.6); }
.badge-high { background: rgba(239, 68, 68, 0.25); color: #f87171; border: 1px solid rgba(239, 68, 68, 0.5); }
.badge-medium { background: rgba(245, 158, 11, 0.25); color: #fbbf24; border: 1px solid rgba(245, 158, 11, 0.5); }
.badge-low { background: rgba(59, 130, 246, 0.25); color: #60a5fa; border: 1px solid rgba(59, 130, 246, 0.5); }
.badge-error { background: rgba(148, 163, 184, 0.2); color: #cbd5e1; border: 1px solid rgba(148, 163, 184, 0.4); }
.badge-info { background: rgba(96, 165, 250, 0.2); color: #93c5fd; border: 1px solid rgba(96, 165, 250, 0.4); }

/* Report Header & Audio Card Responsive Containers */
.report-header {
  display: flex;
  justify-content: space-between;
  align-items: center;
  flex-wrap: wrap;
  gap: 1.5rem;
  border-bottom: 1px solid var(--border-color);
  padding-bottom: 2rem;
  margin-bottom: 2.5rem;
}
.report-header-title {
  font-size: clamp(1.6rem, 4vw, 2.2rem);
  font-weight: 800;
  letter-spacing: -0.02em;
  word-break: break-word;
  overflow-wrap: anywhere;
}
.report-header-score {
  display: flex;
  align-items: center;
  gap: 1.5rem;
}

.audio-card-inner {
  display: flex;
  align-items: center;
  justify-content: space-between;
  flex-wrap: wrap;
  gap: 1.25rem;
}
.audio-card-actions {
  display: flex;
  gap: 0.75rem;
  flex-wrap: wrap;
}

/* Footer */
footer {
  border-top: 1px solid var(--border-color);
  padding: 2rem 1.5rem;
  text-align: center;
  color: var(--text-muted);
  font-size: 0.9rem;
}

/* Comprehensive Mobile & Small Screen Media Queries (< 640px) */
@media (max-width: 640px) {
  .nav-container {
    flex-direction: column;
    gap: 0.85rem;
    padding: 0.85rem 1rem;
    text-align: center;
  }
  .nav-links {
    width: 100%;
    justify-content: center;
    gap: 0.5rem;
    flex-wrap: wrap;
  }
  .nav-links a {
    padding: 0.4rem 0.6rem;
    font-size: 0.85rem;
  }

  main {
    padding: 1.5rem 1rem;
  }

  .hero {
    margin: 1rem auto 2rem;
  }

  .scanner-form-box {
    padding: 1.15rem;
  }
  .scanner-form {
    flex-direction: column;
    gap: 0.85rem;
  }
  .input-group {
    width: 100%;
    min-width: 100%;
  }
  .btn-primary {
    width: 100%;
    justify-content: center;
  }

  .report-header {
    flex-direction: column;
    align-items: flex-start;
    gap: 1.25rem;
  }
  .report-header-score {
    width: 100%;
    justify-content: space-between;
    background: rgba(0,0,0,0.2);
    padding: 1rem;
    border-radius: var(--radius);
    border: 1px solid var(--border-color);
  }

  .audio-card-inner {
    flex-direction: column;
    align-items: flex-start;
  }
  .audio-card-actions {
    width: 100%;
    flex-direction: column;
  }
  .audio-card-actions button,
  .audio-card-actions a {
    width: 100%;
    justify-content: center;
  }

  .card {
    padding: 1.15rem;
  }
}