/* ============================================================
   Sokogate Construction Materials Calculator
   Modern Design System — Construction Theme
   ============================================================ */

/* ── CSS Custom Properties (Design Tokens) ── */
:root {
  /* Primary Palette: Slate + Amber (Construction Theme) */
  --color-bg: #f1f5f9;
  --color-surface: #ffffff;
  --color-surface-elevated: #ffffff;
  --color-primary: #1e293b;
  --color-primary-light: #334155;
  --color-accent: #f59e0b;
  --color-accent-dark: #d97706;
  --color-accent-soft: #fffbeb;
  --color-secondary: #0ea5e9;
  --color-secondary-soft: #e0f2fe;
  --color-success: #10b981;
  --color-success-soft: #d1fae5;
  --color-warning: #f97316;
  --color-warning-soft: #ffedd5;
  --color-danger: #ef4444;
  --color-danger-soft: #fee2e2;
  --color-info: #6366f1;
  --color-info-soft: #e0e7ff;

  /* Text Colors */
  --text-primary: #0f172a;
  --text-secondary: #475569;
  --text-tertiary: #94a3b8;
  --text-inverse: #ffffff;

  /* Border & Divider */
  --border-color: #e2e8f0;
  --border-color-focus: #f59e0b;
  --divider: #f1f5f9;

  /* Shadows */
  --shadow-sm: 0 1px 2px 0 rgba(15, 23, 42, 0.05);
  --shadow-md: 0 4px 6px -1px rgba(15, 23, 42, 0.07), 0 2px 4px -2px rgba(15, 23, 42, 0.05);
  --shadow-lg: 0 10px 15px -3px rgba(15, 23, 42, 0.08), 0 4px 6px -4px rgba(15, 23, 42, 0.04);
  --shadow-xl: 0 20px 25px -5px rgba(15, 23, 42, 0.1), 0 8px 10px -6px rgba(15, 23, 42, 0.04);
  --shadow-glow: 0 0 20px rgba(245, 158, 11, 0.15);
  --shadow-inner: inset 0 2px 4px 0 rgba(15, 23, 42, 0.03);

  /* Border Radius */
  --radius-sm: 6px;
  --radius-md: 10px;
  --radius-lg: 16px;
  --radius-xl: 24px;
  --radius-full: 9999px;

  /* Spacing Scale */
  --space-1: 4px;
  --space-2: 8px;
  --space-3: 12px;
  --space-4: 16px;
  --space-5: 20px;
  --space-6: 24px;
  --space-8: 32px;
  --space-10: 40px;
  --space-12: 48px;
  --space-16: 64px;

  /* Typography */
  --font-sans: 'Inter', -apple-system, BlinkMacSystemFont, 'Segoe UI', Roboto, 'Helvetica Neue', Arial, sans-serif;
  --font-mono: 'SF Mono', 'Fira Code', 'Cascadia Code', Consolas, monospace;
  --text-xs: 0.75rem;
  --text-sm: 0.875rem;
  --text-base: 1rem;
  --text-lg: 1.125rem;
  --text-xl: 1.25rem;
  --text-2xl: 1.5rem;
  --text-3xl: 1.875rem;
  --text-4xl: 2.25rem;

  /* Transitions */
  --transition-fast: 150ms cubic-bezier(0.4, 0, 0.2, 1);
  --transition-base: 250ms cubic-bezier(0.4, 0, 0.2, 1);
  --transition-slow: 350ms cubic-bezier(0.4, 0, 0.2, 1);

  /* Layout */
  --container-max: 1200px;
  --header-height: 64px;
}

/* ── Dark Mode Support ── */
@media (prefers-color-scheme: dark) {
  :root {
    --color-bg: #0f172a;
    --color-surface: #1e293b;
    --color-surface-elevated: #334155;
    --color-primary: #f8fafc;
    --color-primary-light: #e2e8f0;
    --text-primary: #f8fafc;
    --text-secondary: #cbd5e1;
    --text-tertiary: #64748b;
    --border-color: #334155;
    --divider: #1e293b;
    --shadow-sm: 0 1px 2px 0 rgba(0, 0, 0, 0.2);
    --shadow-md: 0 4px 6px -1px rgba(0, 0, 0, 0.3), 0 2px 4px -2px rgba(0, 0, 0, 0.2);
    --shadow-lg: 0 10px 15px -3px rgba(0, 0, 0, 0.4), 0 4px 6px -4px rgba(0, 0, 0, 0.3);
  }
}

/* ── Base & Reset ── */
*, *::before, *::after {
  margin: 0;
  padding: 0;
  box-sizing: border-box;
}

html {
  scroll-behavior: smooth;
  -webkit-font-smoothing: antialiased;
  -moz-osx-font-smoothing: grayscale;
}

body {
  font-family: var(--font-sans);
  font-size: var(--text-base);
  line-height: 1.6;
  color: var(--text-primary);
  background: var(--color-bg);
  min-height: 100vh;
  overflow-x: hidden;
}

/* ── Typography ── */
h1, h2, h3, h4, h5, h6 {
  font-weight: 700;
  line-height: 1.2;
  letter-spacing: -0.025em;
  color: var(--text-primary);
}

h1 { font-size: var(--text-4xl); }
h2 { font-size: var(--text-3xl); }
h3 { font-size: var(--text-2xl); }
h4 { font-size: var(--text-xl); }

p {
  color: var(--text-secondary);
  line-height: 1.7;
}

a {
  color: var(--color-secondary);
  text-decoration: none;
  transition: color var(--transition-fast);
}

a:hover {
  color: var(--color-accent);
  text-decoration: underline;
}

/* ── Layout Components ── */
.app-wrapper {
  min-height: 100vh;
  display: flex;
  flex-direction: column;
}

.container {
  width: 100%;
  max-width: var(--container-max);
  margin: 0 auto;
  padding: 0 var(--space-4);
}

@media (min-width: 640px) {
  .container { padding: 0 var(--space-6); }
}

@media (min-width: 1024px) {
  .container { padding: 0 var(--space-8); }
}

/* ── Header ── */
.site-header {
  position: sticky;
  top: 0;
  z-index: 100;
  background: rgba(255, 255, 255, 0.85);
  backdrop-filter: blur(12px);
  -webkit-backdrop-filter: blur(12px);
  border-bottom: 1px solid var(--border-color);
  height: var(--header-height);
  display: flex;
  align-items: center;
}

.site-header .container {
  display: flex;
  align-items: center;
  justify-content: space-between;
}

.brand {
  display: flex;
  align-items: center;
  gap: var(--space-3);
  text-decoration: none;
}

.brand-icon {
  width: 40px;
  height: 40px;
  background: linear-gradient(135deg, var(--color-accent) 0%, var(--color-accent-dark) 100%);
  border-radius: var(--radius-md);
  display: flex;
  align-items: center;
  justify-content: center;
  color: white;
  font-weight: 700;
  font-size: var(--text-lg);
  box-shadow: var(--shadow-md);
}

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

.brand-name {
  font-size: var(--text-lg);
  font-weight: 700;
  color: var(--text-primary);
  line-height: 1.2;
  letter-spacing: -0.02em;
}

.brand-tagline {
  font-size: var(--text-xs);
  color: var(--text-tertiary);
  font-weight: 500;
  text-transform: uppercase;
  letter-spacing: 0.08em;
}

.header-actions {
  display: flex;
  align-items: center;
  gap: var(--space-3);
}

.btn-icon {
  width: 40px;
  height: 40px;
  border-radius: var(--radius-full);
  border: 1px solid var(--border-color);
  background: var(--color-surface);
  color: var(--text-secondary);
  cursor: pointer;
  display: flex;
  align-items: center;
  justify-content: center;
  transition: all var(--transition-fast);
}

.btn-icon:hover {
  background: var(--color-accent-soft);
  color: var(--color-accent-dark);
  border-color: var(--color-accent);
  transform: translateY(-1px);
}

/* ── Hero Section ── */
.hero {
  padding: var(--space-10) 0 var(--space-8);
  text-align: center;
  position: relative;
  overflow: hidden;
}

.hero::before {
  content: '';
  position: absolute;
  top: -50%;
  left: 50%;
  transform: translateX(-50%);
  width: 800px;
  height: 800px;
  background: radial-gradient(circle, rgba(245, 158, 11, 0.08) 0%, transparent 70%);
  pointer-events: none;
}

.hero h1 {
  font-size: clamp(var(--text-3xl), 5vw, var(--text-4xl));
  margin-bottom: var(--space-3);
  background: linear-gradient(135deg, var(--color-primary) 0%, var(--color-primary-light) 100%);
  -webkit-background-clip: text;
  -webkit-text-fill-color: transparent;
  background-clip: text;
}

.hero-subtitle {
  font-size: var(--text-lg);
  color: var(--text-secondary);
  max-width: 600px;
  margin: 0 auto var(--space-6);
}

.hero-badge {
  display: inline-flex;
  align-items: center;
  gap: var(--space-2);
  padding: var(--space-2) var(--space-4);
  background: var(--color-accent-soft);
  border: 1px solid rgba(245, 158, 11, 0.2);
  border-radius: var(--radius-full);
  font-size: var(--text-sm);
  font-weight: 600;
  color: var(--color-accent-dark);
}

/* ── Main Layout Grid ── */
.main-grid {
  display: grid;
  gap: var(--space-6);
  padding-bottom: var(--space-12);
}

@media (min-width: 1024px) {
  .main-grid {
    grid-template-columns: 1fr 1fr;
    align-items: start;
  }
}

@media (min-width: 1280px) {
  .main-grid {
    grid-template-columns: 5fr 7fr;
  }
}

/* ── Cards ── */
.card {
  background: var(--color-surface);
  border-radius: var(--radius-lg);
  border: 1px solid var(--border-color);
  box-shadow: var(--shadow-md);
  overflow: hidden;
  transition: box-shadow var(--transition-base), transform var(--transition-base);
}

.card:hover {
  box-shadow: var(--shadow-lg);
}

.card-header {
  padding: var(--space-5) var(--space-6) var(--space-4);
  border-bottom: 1px solid var(--divider);
  display: flex;
  align-items: center;
  gap: var(--space-3);
}

.card-header-icon {
  width: 44px;
  height: 44px;
  border-radius: var(--radius-md);
  display: flex;
  align-items: center;
  justify-content: center;
  flex-shrink: 0;
}

.card-header-icon.accent {
  background: var(--color-accent-soft);
  color: var(--color-accent-dark);
}

.card-header-icon.secondary {
  background: var(--color-secondary-soft);
  color: var(--color-secondary);
}

.card-header-icon.success {
  background: var(--color-success-soft);
  color: var(--color-success);
}

.card-header-title {
  font-size: var(--text-lg);
  font-weight: 700;
  color: var(--text-primary);
}

.card-header-subtitle {
  font-size: var(--text-sm);
  color: var(--text-tertiary);
  margin-top: 2px;
}

.card-body {
  padding: var(--space-6);
}

.card-footer {
  padding: var(--space-4) var(--space-6);
  border-top: 1px solid var(--divider);
  background: rgba(241, 245, 249, 0.5);
}

/* ── Form Elements ── */
.form-group {
  margin-bottom: var(--space-5);
}

.form-group:last-child {
  margin-bottom: 0;
}

.form-label {
  display: flex;
  align-items: center;
  gap: var(--space-2);
  font-size: var(--text-sm);
  font-weight: 600;
  color: var(--text-primary);
  margin-bottom: var(--space-2);
}

.form-label .label-icon {
  color: var(--text-tertiary);
  width: 16px;
  height: 16px;
}

.form-label .label-hint {
  margin-left: auto;
  font-size: var(--text-xs);
  font-weight: 500;
  color: var(--text-tertiary);
  background: var(--divider);
  padding: 2px var(--space-2);
  border-radius: var(--radius-sm);
}

.form-input,
.form-select {
  width: 100%;
  padding: var(--space-3) var(--space-4);
  font-size: var(--text-base);
  font-family: var(--font-sans);
  color: var(--text-primary);
  background: var(--color-surface);
  border: 2px solid var(--border-color);
  border-radius: var(--radius-md);
  transition: all var(--transition-fast);
  appearance: none;
}

.form-input::placeholder {
  color: var(--text-tertiary);
}

.form-input:hover,
.form-select:hover {
  border-color: #cbd5e1;
}

.form-input:focus,
.form-select:focus {
  outline: none;
  border-color: var(--color-accent);
  box-shadow: 0 0 0 4px rgba(245, 158, 11, 0.1), var(--shadow-glow);
}

.form-input:disabled,
.form-select:disabled {
  background: var(--divider);
  cursor: not-allowed;
  opacity: 0.6;
}

.form-input.error {
  border-color: var(--color-danger);
  box-shadow: 0 0 0 4px rgba(239, 68, 68, 0.1);
}

.form-input.success {
  border-color: var(--color-success);
  box-shadow: 0 0 0 4px rgba(16, 185, 129, 0.1);
}

.form-select {
  cursor: pointer;
  background-image: url("data:image/svg+xml,%3Csvg xmlns='http://www.w3.org/2000/svg' width='20' height='20' viewBox='0 0 20 20' fill='none' stroke='%2364748b' stroke-width='2' stroke-linecap='round' stroke-linejoin='round'%3E%3Cpath d='M6 8l4 4 4-4'/%3E%3C/svg%3E");
  background-repeat: no-repeat;
  background-position: right 12px center;
  padding-right: 40px;
}

.form-hint {
  display: flex;
  align-items: center;
  gap: var(--space-1);
  margin-top: var(--space-2);
  font-size: var(--text-xs);
  color: var(--text-tertiary);
}

.form-hint svg {
  width: 14px;
  height: 14px;
  flex-shrink: 0;
}

/* ── Input Groups & Grids ── */
.input-grid {
  display: grid;
  grid-template-columns: repeat(3, 1fr);
  gap: var(--space-3);
}

@media (max-width: 480px) {
  .input-grid {
    grid-template-columns: 1fr;
  }
}

.input-grid .form-group {
  margin-bottom: 0;
}

/* ── Buttons ── */
.btn {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  gap: var(--space-2);
  padding: var(--space-3) var(--space-6);
  font-size: var(--text-base);
  font-weight: 600;
  font-family: var(--font-sans);
  border-radius: var(--radius-md);
  border: none;
  cursor: pointer;
  transition: all var(--transition-fast);
  text-decoration: none;
  position: relative;
  overflow: hidden;
}

.btn::after {
  content: '';
  position: absolute;
  inset: 0;
  background: linear-gradient(to bottom, rgba(255,255,255,0.15), transparent);
  opacity: 0;
  transition: opacity var(--transition-fast);
}

.btn:hover::after {
  opacity: 1;
}

.btn:active {
  transform: translateY(1px);
}

.btn:disabled {
  opacity: 0.6;
  cursor: not-allowed;
  transform: none;
}

.btn-primary {
  background: linear-gradient(135deg, var(--color-accent) 0%, var(--color-accent-dark) 100%);
  color: white;
  box-shadow: 0 4px 14px rgba(245, 158, 11, 0.35);
}

.btn-primary:hover:not(:disabled) {
  transform: translateY(-2px);
  box-shadow: 0 8px 20px rgba(245, 158, 11, 0.45);
}

.btn-secondary {
  background: var(--color-surface);
  color: var(--text-primary);
  border: 2px solid var(--border-color);
  box-shadow: var(--shadow-sm);
}

.btn-secondary:hover:not(:disabled) {
  background: var(--divider);
  border-color: #cbd5e1;
  transform: translateY(-1px);
}

.btn-ghost {
  background: transparent;
  color: var(--text-secondary);
  border: 1px solid transparent;
}

.btn-ghost:hover:not(:disabled) {
  background: var(--divider);
  color: var(--text-primary);
}

.btn-block {
  width: 100%;
}

.btn-lg {
  padding: var(--space-4) var(--space-8);
  font-size: var(--text-lg);
  border-radius: var(--radius-lg);
}

.btn-spinner {
  width: 18px;
  height: 18px;
  border: 2px solid rgba(255, 255, 255, 0.3);
  border-top-color: white;
  border-radius: 50%;
  animation: spin 0.6s linear infinite;
}

/* ── Results Section ── */
.results-section {
  animation: slideUp var(--transition-slow) ease-out;
}

.results-empty {
  text-align: center;
  padding: var(--space-10) var(--space-6);
  color: var(--text-tertiary);
}

.results-empty svg {
  width: 64px;
  height: 64px;
  margin-bottom: var(--space-4);
  opacity: 0.5;
}

.results-empty h3 {
  color: var(--text-secondary);
  font-size: var(--text-xl);
  margin-bottom: var(--space-2);
}

.results-header {
  display: flex;
  align-items: center;
  justify-content: space-between;
  margin-bottom: var(--space-5);
  flex-wrap: wrap;
  gap: var(--space-3);
}

.results-badge {
  display: inline-flex;
  align-items: center;
  gap: var(--space-2);
  padding: var(--space-2) var(--space-4);
  background: linear-gradient(135deg, var(--color-accent-soft) 0%, var(--color-warning-soft) 100%);
  border: 1px solid rgba(245, 158, 11, 0.2);
  border-radius: var(--radius-full);
  font-size: var(--text-sm);
  font-weight: 600;
  color: var(--color-accent-dark);
}

/* Result Cards Grid */
.results-grid {
  display: grid;
  gap: var(--space-4);
}

.result-card {
  background: var(--color-surface);
  border: 1px solid var(--border-color);
  border-radius: var(--radius-lg);
  padding: var(--space-5);
  display: flex;
  align-items: center;
  gap: var(--space-4);
  transition: all var(--transition-base);
  position: relative;
  overflow: hidden;
}

.result-card::before {
  content: '';
  position: absolute;
  left: 0;
  top: 0;
  bottom: 0;
  width: 4px;
  background: var(--color-accent);
  border-radius: var(--radius-lg) 0 0 var(--radius-lg);
  opacity: 0;
  transition: opacity var(--transition-fast);
}

.result-card:hover {
  box-shadow: var(--shadow-md);
  transform: translateY(-2px);
  border-color: var(--color-accent);
}

.result-card:hover::before {
  opacity: 1;
}

.result-card.highlight {
  background: linear-gradient(135deg, var(--color-accent-soft) 0%, var(--color-warning-soft) 100%);
  border-color: rgba(245, 158, 11, 0.3);
}

.result-card.highlight::before {
  opacity: 1;
  background: var(--color-accent);
}

.result-icon {
  width: 48px;
  height: 48px;
  border-radius: var(--radius-md);
  display: flex;
  align-items: center;
  justify-content: center;
  flex-shrink: 0;
  font-size: var(--text-xl);
}

.result-icon.cement { background: #e0f2fe; color: #0284c7; }
.result-icon.sand { background: #fef9c3; color: #a16207; }
.result-icon.bricks { background: #fee2e2; color: #dc2626; }
.result-icon.blocks { background: #e0e7ff; color: #4f46e5; }
.result-icon.concrete { background: #f3f4f6; color: #4b5563; }
.result-icon.steel { background: #dbeafe; color: #2563eb; }
.result-icon.tiles { background: #fce7f3; color: #db2777; }
.result-icon.paint { background: #dcfce7; color: #16a34a; }
.result-icon.gravel { background: #f5f5f4; color: #78716c; }
.result-icon.roofing { background: #ffedd5; color: #ea580c; }
.result-icon.generic { background: var(--color-accent-soft); color: var(--color-accent-dark); }

.result-content {
  flex: 1;
  min-width: 0;
}

.result-label {
  font-size: var(--text-sm);
  font-weight: 500;
  color: var(--text-secondary);
  margin-bottom: 2px;
}

.result-value {
  font-family: var(--font-mono);
  font-size: var(--text-2xl);
  font-weight: 700;
  color: var(--text-primary);
  line-height: 1.2;
}

.result-unit {
  font-size: var(--text-sm);
  font-weight: 500;
  color: var(--text-tertiary);
  margin-left: var(--space-1);
}

/* ── 3D Visualizer Section ── */


/* ── Toast Notifications ── */
.toast-container {
  position: fixed;
  top: calc(var(--header-height) + var(--space-4));
  right: var(--space-4);
  z-index: 1000;
  display: flex;
  flex-direction: column;
  gap: var(--space-3);
  pointer-events: none;
}

.toast {
  pointer-events: all;
  display: flex;
  align-items: center;
  gap: var(--space-3);
  padding: var(--space-4) var(--space-5);
  background: var(--color-surface);
  border-radius: var(--radius-lg);
  box-shadow: var(--shadow-xl);
  border: 1px solid var(--border-color);
  max-width: 400px;
  animation: toastSlideIn var(--transition-base) ease-out;
  position: relative;
  overflow: hidden;
}

.toast::before {
  content: '';
  position: absolute;
  left: 0;
  top: 0;
  bottom: 0;
  width: 4px;
}

.toast.success::before { background: var(--color-success); }
.toast.error::before { background: var(--color-danger); }
.toast.warning::before { background: var(--color-warning); }
.toast.info::before { background: var(--color-secondary); }

.toast-icon {
  width: 24px;
  height: 24px;
  flex-shrink: 0;
}

.toast.success .toast-icon { color: var(--color-success); }
.toast.error .toast-icon { color: var(--color-danger); }
.toast.warning .toast-icon { color: var(--color-warning); }
.toast.info .toast-icon { color: var(--color-secondary); }

.toast-content {
  flex: 1;
}

.toast-title {
  font-weight: 600;
  font-size: var(--text-sm);
  color: var(--text-primary);
  margin-bottom: 2px;
}

.toast-message {
  font-size: var(--text-sm);
  color: var(--text-secondary);
}

.toast-close {
  background: none;
  border: none;
  color: var(--text-tertiary);
  cursor: pointer;
  padding: var(--space-1);
  border-radius: var(--radius-sm);
  transition: all var(--transition-fast);
}

.toast-close:hover {
  background: var(--divider);
  color: var(--text-primary);
}

/* ── Loading States ── */
.skeleton {
  background: linear-gradient(90deg, var(--divider) 25%, #e2e8f0 50%, var(--divider) 75%);
  background-size: 200% 100%;
  animation: skeleton 1.5s ease-in-out infinite;
  border-radius: var(--radius-md);
}

@keyframes skeleton {
  0% { background-position: 200% 0; }
  100% { background-position: -200% 0; }
}

.loading-overlay {
  position: absolute;
  inset: 0;
  background: rgba(255, 255, 255, 0.8);
  backdrop-filter: blur(4px);
  display: flex;
  align-items: center;
  justify-content: center;
  z-index: 10;
  border-radius: inherit;
}

.spinner {
  width: 40px;
  height: 40px;
  border: 3px solid var(--border-color);
  border-top-color: var(--color-accent);
  border-radius: 50%;
  animation: spin 0.8s linear infinite;
}

@keyframes spin {
  to { transform: rotate(360deg); }
}

/* ── Error States ── */
.form-error {
  display: flex;
  align-items: center;
  gap: var(--space-3);
  padding: var(--space-4);
  margin-bottom: var(--space-5);
  background: var(--color-danger-soft);
  border: 1px solid rgba(239, 68, 68, 0.2);
  border-radius: var(--radius-md);
  color: var(--color-danger);
  font-size: var(--text-sm);
  font-weight: 500;
  animation: shake 0.4s ease-in-out;
}

@keyframes shake {
  0%, 100% { transform: translateX(0); }
  20% { transform: translateX(-6px); }
  40% { transform: translateX(6px); }
  60% { transform: translateX(-3px); }
  80% { transform: translateX(3px); }
}

/* ── Animations ── */
@keyframes slideUp {
  from {
    opacity: 0;
    transform: translateY(20px);
  }
  to {
    opacity: 1;
    transform: translateY(0);
  }
}

@keyframes fadeIn {
  from { opacity: 0; }
  to { opacity: 1; }
}

@keyframes toastSlideIn {
  from {
    opacity: 0;
    transform: translateX(100px);
  }
  to {
    opacity: 1;
    transform: translateX(0);
  }
}

@keyframes toastSlideOut {
  from {
    opacity: 1;
    transform: translateX(0);
  }
  to {
    opacity: 0;
    transform: translateX(100px);
  }
}

@keyframes pulse {
  0%, 100% { opacity: 1; }
  50% { opacity: 0.5; }
}

@keyframes countUp {
  from { opacity: 0; transform: translateY(10px); }
  to { opacity: 1; transform: translateY(0); }
}

/* ── Staggered Animation for Result Cards ── */
.result-card {
  opacity: 0;
  animation: slideUp 0.4s ease-out forwards;
}

.result-card:nth-child(1) { animation-delay: 0.05s; }
.result-card:nth-child(2) { animation-delay: 0.1s; }
.result-card:nth-child(3) { animation-delay: 0.15s; }
.result-card:nth-child(4) { animation-delay: 0.2s; }
.result-card:nth-child(5) { animation-delay: 0.25s; }
.result-card:nth-child(6) { animation-delay: 0.3s; }
.result-card:nth-child(7) { animation-delay: 0.35s; }
.result-card:nth-child(8) { animation-delay: 0.4s; }

/* ── Quick Actions Bar ── */
.quick-actions {
  display: flex;
  gap: var(--space-3);
  flex-wrap: wrap;
  margin-top: var(--space-5);
}

/* ── Footer ── */
.site-footer {
  margin-top: auto;
  padding: var(--space-8) 0;
  border-top: 1px solid var(--divider);
  text-align: center;
}

.site-footer p {
  font-size: var(--text-sm);
  color: var(--text-tertiary);
}

/* ── Accessibility ── */
.sr-only {
  position: absolute;
  width: 1px;
  height: 1px;
  padding: 0;
  margin: -1px;
  overflow: hidden;
  clip: rect(0, 0, 0, 0);
  white-space: nowrap;
  border: 0;
}

:focus-visible {
  outline: 2px solid var(--color-accent);
  outline-offset: 2px;
}

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

/* ── Responsive Breakpoints ── */
@media (max-width: 640px) {
  .hero {
    padding: var(--space-8) 0 var(--space-6);
  }

  .hero h1 {
    font-size: var(--text-2xl);
  }

  .card-header,
  .card-body,
  .card-footer {
    padding-left: var(--space-4);
    padding-right: var(--space-4);
  }

  .result-card {
    padding: var(--space-4);
  }

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



  .toast-container {
    left: var(--space-4);
    right: var(--space-4);
  }

  .toast {
    max-width: 100%;
  }
}

@media (min-width: 640px) {
  .sm\\:grid-cols-2 {
    grid-template-columns: repeat(2, 1fr);
  }
}

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

/* ── Print Styles ── */
@media print {
  .site-header,
  .hero,

  .site-footer,
  .btn,
  .toast-container {
    display: none !important;
  }

  .card {
    box-shadow: none;
    border: 1px solid #ccc;
    break-inside: avoid;
  }

  .result-card {
    break-inside: avoid;
  }
}

/* ── Material Select Custom Styling ── */
optgroup {
  font-weight: 600;
  color: var(--text-primary);
  background: var(--divider);
}

optgroup option {
  font-weight: 400;
  color: var(--text-primary);
}