/* FreeStudyAdda Google Stitch Interactive Logarithm Learning Lab
   Design System & Styling — Clean, standalone CSS without runtime Tailwind CDN */

@import url('https://fonts.googleapis.com/css2?family=Inter:wght@300;400;500;600;700;800&family=Material+Symbols+Outlined:opsz,wght,FILL,GRAD@20..48,100..700,0..1,-50..200&display=swap');

:root {
  --surface: #FAF9F6;
  --surface-ivory: #FAF9F6;
  --surface-white: #FFFFFF;
  --surface-dim: #cbdbf5;
  --surface-bright: #f8f9ff;
  --surface-container-lowest: #ffffff;
  --surface-container-low: #eff4ff;
  --surface-container: #e5eeff;
  --surface-container-high: #dce9ff;
  --surface-container-highest: #d3e4fe;
  --on-surface: #0b1c30;
  --on-surface-variant: #3f4850;
  --deep-navy: #0F172A;
  --outline: #707881;
  --outline-variant: #bfc7d2;
  --primary: #006194;
  --primary-rgb: 0, 97, 148;
  --primary-hover: #0369a1;
  --on-primary: #ffffff;
  --primary-container: #007bb9;
  --primary-fixed: #cce5ff;
  --on-primary-fixed: #001d31;
  --sky-tint: #E0F2FE;
  --secondary: #6b38d4;
  --secondary-container: #8455ef;
  --lavender-tint: #EDE9FE;
  --tertiary: #006947;
  --tertiary-tint: #10B981;
  --mint-tint: #D1FAE5;
  --amber-accent: #F59E0B;
  --amber-tint: #FEF3C7;
  --error: #ba1a1a;
  --error-container: #ffdad6;
  --on-error: #ffffff;
  --font-sans: 'Inter', ui-sans-serif, system-ui, -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, sans-serif;
  --shadow-xs: 0 1px 2px rgba(15, 23, 42, 0.05);
  --shadow-sm: 0 1px 3px rgba(15, 23, 42, 0.08), 0 1px 2px rgba(15, 23, 42, 0.04);
  --shadow-md: 0 4px 6px -1px rgba(15, 23, 42, 0.08), 0 2px 4px -2px rgba(15, 23, 42, 0.04);
  --shadow-lg: 0 10px 15px -3px rgba(15, 23, 42, 0.08), 0 4px 6px -4px rgba(15, 23, 42, 0.04);
  --radius-sm: 0.375rem;
  --radius-md: 0.5rem;
  --radius-lg: 0.75rem;
  --radius-xl: 1rem;
  --radius-full: 9999px;
}

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

html, body {
  margin: 0;
  padding: 0;
  width: 100%;
  min-height: 100vh;
  background-color: var(--surface);
  color: var(--on-surface);
  font-family: var(--font-sans);
  -webkit-font-smoothing: antialiased;
  -moz-osx-font-smoothing: grayscale;
}

body {
  display: flex;
  flex-direction: column;
}

/* Material Symbols Icon Fallbacks & Styling */
.material-symbols-outlined {
  font-family: 'Material Symbols Outlined', sans-serif;
  font-weight: normal;
  font-style: normal;
  font-size: 20px;
  line-height: 1;
  letter-spacing: normal;
  text-transform: none;
  display: inline-block;
  white-space: nowrap;
  word-wrap: normal;
  direction: ltr;
  -webkit-font-feature-settings: 'liga';
  -webkit-font-smoothing: antialiased;
  vertical-align: middle;
  user-select: none;
}

/* Tabular Numerics for High Math Precision */
.font-math-tabular, .tabular-nums {
  font-variant-numeric: tabular-nums;
  font-feature-settings: "tnum" 1, "cv05" 1, "zero" 1;
  letter-spacing: -0.01em;
}

/* Base Utility Classes */
.bg-surface { background-color: var(--surface); }
.bg-surface-white { background-color: var(--surface-white); }
.bg-surface-ivory { background-color: var(--surface-ivory); }
.bg-surface-container-low { background-color: var(--surface-container-low); }
.bg-surface-container { background-color: var(--surface-container); }
.bg-surface-container-high { background-color: var(--surface-container-high); }
.bg-surface-container-highest { background-color: var(--surface-container-highest); }
.bg-primary { background-color: var(--primary); }
.bg-primary-fixed { background-color: var(--primary-fixed); }
.bg-sky-tint { background-color: var(--sky-tint); }
.bg-secondary { background-color: var(--secondary); }
.bg-lavender-tint { background-color: var(--lavender-tint); }
.bg-tertiary { background-color: var(--tertiary); }
.bg-mint-tint { background-color: var(--mint-tint); }
.bg-amber-accent { background-color: var(--amber-accent); }
.bg-amber-tint { background-color: var(--amber-tint); }
.bg-error-container { background-color: var(--error-container); }

.text-on-surface { color: var(--on-surface); }
.text-on-surface-variant { color: var(--on-surface-variant); }
.text-deep-navy { color: var(--deep-navy); }
.text-primary { color: var(--primary); }
.text-on-primary { color: var(--on-primary); }
.text-on-primary-fixed { color: var(--on-primary-fixed); }
.text-secondary { color: var(--secondary); }
.text-tertiary { color: var(--tertiary); }
.text-amber-accent { color: var(--amber-accent); }
.text-outline { color: var(--outline); }
.text-outline-variant { color: var(--outline-variant); }
.text-error { color: var(--error); }

.border-surface-container-high { border-color: var(--surface-container-high); }
.border-outline-variant { border-color: var(--outline-variant); }
.border-primary { border-color: var(--primary); }

.rounded-sm { border-radius: var(--radius-sm); }
.rounded-md, .rounded { border-radius: var(--radius-md); }
.rounded-lg { border-radius: var(--radius-lg); }
.rounded-xl { border-radius: var(--radius-xl); }
.rounded-full { border-radius: var(--radius-full); }

.shadow-xs { box-shadow: var(--shadow-xs); }
.shadow-sm { box-shadow: var(--shadow-sm); }
.shadow-md { box-shadow: var(--shadow-md); }
.shadow-lg { box-shadow: var(--shadow-lg); }

/* Layout Structure */
.lab-header {
  position: fixed;
  top: 0;
  left: 0;
  right: 0;
  z-index: 50;
  background-color: rgba(255, 255, 255, 0.94);
  backdrop-filter: blur(12px);
  -webkit-backdrop-filter: blur(12px);
  border-bottom: 1px solid rgba(226, 232, 240, 0.8);
  box-shadow: 0 1px 8px rgba(0, 0, 0, 0.04);
}

.lab-header-inner {
  max-width: 1200px;
  margin: 0 auto;
  padding: 0.5rem 1rem;
  display: flex;
  flex-direction: column;
  gap: 0.25rem;
}

.lab-header-top {
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 0.75rem;
  height: 48px;
}

.lab-brand {
  display: flex;
  align-items: center;
  gap: 0.625rem;
  text-decoration: none;
  color: inherit;
}

.lab-brand-icon {
  width: 36px;
  height: 36px;
  border-radius: 10px;
  background: linear-gradient(135deg, #006194, #0284c7);
  display: flex;
  align-items: center;
  justify-content: center;
  color: #fff;
  font-weight: 800;
  font-size: 19px;
  box-shadow: 0 2px 6px rgba(0, 97, 148, 0.3);
}

.lab-brand-text {
  display: flex;
  flex-direction: column;
  line-height: 1.1;
}

.lab-brand-title {
  font-size: 0.75rem;
  font-weight: 700;
  color: var(--primary);
  text-transform: uppercase;
  letter-spacing: 0.05em;
}

.lab-brand-sub {
  font-size: 1.125rem;
  font-weight: 700;
  color: var(--deep-navy);
}

.lab-header-tools {
  display: flex;
  align-items: center;
  gap: 0.5rem;
}

.lang-picker {
  display: flex;
  align-items: center;
  background-color: var(--surface-container-low);
  border-radius: var(--radius-full);
  padding: 2px;
  border: 1px solid var(--surface-container-high);
}

.lang-btn {
  padding: 3px 8px;
  border-radius: var(--radius-full);
  font-size: 0.6875rem;
  font-weight: 600;
  border: none;
  background: transparent;
  color: var(--on-surface-variant);
  cursor: pointer;
  transition: all 0.15s ease;
}

.lang-btn.active {
  background-color: var(--primary);
  color: #ffffff;
  box-shadow: 0 1px 3px rgba(0, 0, 0, 0.1);
}

.lab-header-subnav {
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 0.5rem;
  padding-top: 2px;
  border-top: 1px solid rgba(226, 232, 240, 0.6);
}

.lab-breadcrumbs {
  display: flex;
  align-items: center;
  gap: 0.35rem;
  font-size: 0.8125rem;
  color: var(--on-surface-variant);
}

.lab-breadcrumbs a {
  color: inherit;
  text-decoration: none;
}

.lab-breadcrumbs a:hover {
  color: var(--primary);
}

.lab-header-actions {
  display: flex;
  align-items: center;
  gap: 0.35rem;
}

/* Global Content Container */
.lab-main {
  width: 100%;
  max-width: 1200px;
  margin: 0 auto;
  padding: 105px 1rem 80px;
  flex: 1;
  display: flex;
  flex-direction: column;
  gap: 1.25rem;
}

/* Secondary Navigation Bar (Desktop & Mobile Tabs) */
.lab-subnav-bar {
  display: flex;
  align-items: center;
  gap: 0.5rem;
  overflow-x: auto;
  padding-bottom: 2px;
  scrollbar-width: none;
}

.lab-subnav-bar::-webkit-scrollbar {
  display: none;
}

.lab-nav-pill {
  display: inline-flex;
  align-items: center;
  gap: 0.35rem;
  padding: 0.5rem 0.875rem;
  border-radius: var(--radius-full);
  background-color: var(--surface-white);
  border: 1px solid #e2e8f0;
  color: var(--on-surface-variant);
  font-size: 0.8125rem;
  font-weight: 600;
  text-decoration: none;
  white-space: nowrap;
  transition: all 0.15s ease;
  box-shadow: var(--shadow-xs);
}

.lab-nav-pill:hover {
  background-color: var(--sky-tint);
  color: var(--primary);
  border-color: #bae6fd;
}

.lab-nav-pill.active {
  background-color: var(--primary);
  color: #ffffff;
  border-color: var(--primary);
  box-shadow: 0 2px 6px rgba(0, 97, 148, 0.25);
}

/* Bottom Mobile Tab Bar */
.lab-bottom-nav {
  position: fixed;
  bottom: 0;
  left: 0;
  right: 0;
  z-index: 50;
  background-color: rgba(255, 255, 255, 0.96);
  backdrop-filter: blur(12px);
  -webkit-backdrop-filter: blur(12px);
  border-top: 1px solid rgba(226, 232, 240, 0.9);
  box-shadow: 0 -2px 10px rgba(0, 0, 0, 0.04);
}

.lab-bottom-nav-inner {
  max-width: 600px;
  margin: 0 auto;
  display: flex;
  align-items: center;
  justify-content: space-around;
  height: 60px;
  padding: 0 0.5rem;
}

.lab-tab-item {
  display: flex;
  flex-direction: column;
  align-items: center;
  justify-content: center;
  gap: 2px;
  color: var(--on-surface-variant);
  text-decoration: none;
  font-size: 0.6875rem;
  font-weight: 600;
  min-width: 52px;
  padding: 4px;
  border-radius: var(--radius-md);
  transition: color 0.15s ease;
}

.lab-tab-item:hover {
  color: var(--primary);
}

.lab-tab-item.active {
  color: var(--primary);
}

.lab-tab-item.active .material-symbols-outlined {
  color: var(--primary);
  transform: scale(1.1);
}

/* Cards & Panels */
.lab-card {
  background-color: var(--surface-white);
  border-radius: var(--radius-xl);
  padding: 1.25rem;
  box-shadow: var(--shadow-sm);
  border: 1px solid #e2e8f0;
  display: flex;
  flex-direction: column;
  gap: 1rem;
  position: relative;
}

/* Button & Control Classes */
.btn-primary {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  gap: 0.35rem;
  background-color: var(--primary);
  color: #ffffff;
  padding: 0.625rem 1.125rem;
  border-radius: var(--radius-md);
  font-weight: 600;
  font-size: 0.875rem;
  border: none;
  cursor: pointer;
  transition: all 0.15s ease;
  box-shadow: 0 1px 3px rgba(0, 97, 148, 0.2);
  text-decoration: none;
}

.btn-primary:hover {
  background-color: var(--primary-hover);
  box-shadow: 0 2px 6px rgba(0, 97, 148, 0.3);
}

.btn-secondary {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  gap: 0.35rem;
  background-color: var(--sky-tint);
  color: var(--primary);
  padding: 0.625rem 1.125rem;
  border-radius: var(--radius-md);
  font-weight: 600;
  font-size: 0.875rem;
  border: 1px solid #bae6fd;
  cursor: pointer;
  transition: all 0.15s ease;
  text-decoration: none;
}

.btn-secondary:hover {
  background-color: #bae6fd;
}

.btn-pill {
  padding: 0.35rem 0.75rem;
  border-radius: var(--radius-full);
  font-size: 0.75rem;
  font-weight: 600;
  border: 1px solid transparent;
  cursor: pointer;
  transition: all 0.15s ease;
}

/* Interactive Tables */
.table-viewport-container {
  overflow: auto;
  max-height: min(65vh, 600px);
  border: 1px solid #cbd5e1;
  border-radius: var(--radius-lg);
  background-color: #ffffff;
  position: relative;
  scrollbar-width: thin;
}

.log-interactive-table {
  width: 100%;
  border-collapse: separate;
  border-spacing: 0;
  font-size: 0.8125rem;
  font-variant-numeric: tabular-nums;
  font-feature-settings: "tnum" 1, "cv05" 1, "zero" 1;
  text-align: center;
}

.log-interactive-table th, .log-interactive-table td {
  padding: 0.45rem 0.55rem;
  border-right: 1px solid #f1f5f9;
  border-bottom: 1px solid #f1f5f9;
  min-width: 44px;
}

.log-interactive-table thead th {
  position: sticky;
  top: 0;
  z-index: 20;
  background-color: #f8fafc;
  color: var(--on-surface-variant);
  font-size: 0.75rem;
  font-weight: 700;
  border-bottom: 2px solid #cbd5e1;
}

.log-interactive-table th.sticky-col,
.log-interactive-table td.sticky-col {
  position: sticky;
  left: 0;
  z-index: 10;
  background-color: #ffffff;
  font-weight: 700;
  color: var(--primary);
  border-right: 2px solid #cbd5e1;
  box-shadow: 2px 0 4px rgba(0, 0, 0, 0.02);
}

.log-interactive-table thead th.sticky-col {
  z-index: 30;
  background-color: #f8fafc;
}

.log-interactive-table td {
  cursor: pointer;
  user-select: none;
  transition: background-color 0.1s ease;
}

.log-interactive-table td:hover {
  background-color: var(--sky-tint) !important;
}

.log-interactive-table tr.active-row td {
  background-color: rgba(224, 242, 254, 0.35);
}

.log-interactive-table td.active-cell {
  background-color: var(--primary) !important;
  color: #ffffff !important;
  font-weight: 700 !important;
  border-radius: 4px;
  box-shadow: inset 0 0 0 1px #ffffff;
}

.log-interactive-table td.active-diff {
  background-color: var(--mint-tint) !important;
  color: var(--tertiary) !important;
  font-weight: 700 !important;
  outline: 2px solid var(--tertiary);
  outline-offset: -2px;
}

/* Compact Table Density Mode */
.compact-mode .log-interactive-table th,
.compact-mode .log-interactive-table td {
  padding: 0.2rem 0.35rem !important;
  font-size: 0.6875rem !important;
  min-width: 32px !important;
}

/* Mean Difference Columns Highlight */
.md-head {
  background-color: #fef3c7 !important;
  color: #92400e !important;
}

.md-cell {
  background-color: rgba(254, 243, 199, 0.3);
  color: #92400e;
  font-weight: 600;
}

/* Grid Utilities */
.grid-cols-1 { display: grid; grid-template-columns: repeat(1, minmax(0, 1fr)); }
.grid-cols-2 { display: grid; grid-template-columns: repeat(2, minmax(0, 1fr)); }
.grid-cols-3 { display: grid; grid-template-columns: repeat(3, minmax(0, 1fr)); }
.grid-cols-4 { display: grid; grid-template-columns: repeat(4, minmax(0, 1fr)); }
.gap-1 { gap: 0.25rem; }
.gap-2 { gap: 0.5rem; }
.gap-3 { gap: 0.75rem; }
.gap-4 { gap: 1rem; }

/* Responsive adjustments */
@media (max-width: 768px) {
  .lab-main {
    padding-top: 110px;
    padding-bottom: 90px;
  }
  .grid-mobile-1 {
    grid-template-columns: 1fr !important;
  }
  .lab-header-top {
    height: 44px;
  }
}

/* Printable A4 Sheets Styles */
@media print {
  body {
    background-color: #ffffff !important;
    color: #000000 !important;
  }
  .no-print, .lab-header, .lab-bottom-nav, .lab-subnav-bar, .print-hide {
    display: none !important;
  }
  .lab-main {
    padding: 0 !important;
    max-width: 100% !important;
  }
  .table-viewport-container {
    max-height: none !important;
    overflow: visible !important;
    border: 1px solid #000000 !important;
  }
  .page-break {
    page-break-before: always;
    break-before: page;
  }
  @page {
    size: A4 portrait;
    margin: 8mm;
  }
}

/* Grayscale Ink Saver Mode */
.ink-saver-active {
  filter: grayscale(100%) contrast(110%);
}
.ink-saver-active .bg-sky-tint,
.ink-saver-active .bg-lavender-tint,
.ink-saver-active .bg-mint-tint,
.ink-saver-active .bg-amber-tint {
  background-color: #f8fafc !important;
  color: #0f172a !important;
  border-color: #cbd5e1 !important;
}