/* ==========================================================================
   Pythagorean Theorem Calculator Design System
   Website: pythagoreantheoremcalculator.online
   ========================================================================== */

:root {
  /* Color Palette - Modern EdTech STEM Theme */
  --primary-900: #0f172a;
  --primary-800: #1e1b4b;
  --primary-700: #334155;
  --primary-600: #475569;
  --primary-500: #64748b;
  --primary-200: #c7d2fe;
  --primary-100: #e0e7ff;
  --primary-50:  #f8fafc;

  /* Accent Colors */
  --accent-indigo: #4f46e5;
  --accent-indigo-hover: #4338ca;
  --accent-blue: #2563eb;
  --accent-blue-hover: #1d4ed8;
  --accent-cyan: #0284c7;
  --accent-cyan-hover: #0369a1;
  --accent-emerald: #0d9488;
  --accent-emerald-hover: #0f766e;
  --accent-amber: #d97706;
  --accent-amber-hover: #b45309;

  /* Geometric Side Colors for Educational Clarity */
  --side-a-color: #4f46e5;
  --side-b-color: #0284c7;
  --side-c-color: #d97706;

  /* State & Alert Colors */
  --color-success: #10b981;
  --color-error: #ef4444;
  --color-warning: #f59e0b;
  --color-info: #3b82f6;

  /* Backgrounds & Cards */
  --bg-main: #f8fafc;
  --bg-card: #ffffff;
  --bg-alt: #f1f5f9;
  --bg-dark-hero: #0f172a;
  
  /* Borders & Shadows */
  --border-light: #e2e8f0;
  --border-focus: #4f46e5;
  --radius-sm: 6px;
  --radius-md: 10px;
  --radius-lg: 16px;
  --radius-xl: 24px;
  
  --shadow-sm: 0 2px 4px 0 rgba(0, 0, 0, 0.05);
  --shadow-md: 0 2px 6px 0 rgba(0, 0, 0, 0.08);
  --shadow-lg: 0 2px 10px 0 rgba(0, 0, 0, 0.1);
  --shadow-xl: 0 2px 16px 0 rgba(0, 0, 0, 0.12);
  --shadow-glow: 0 2px 12px 0 rgba(79, 70, 229, 0.25);

  /* Typography */
  --font-sans: 'Inter', -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, Helvetica, Arial, sans-serif;
  --font-mono: 'Fira Code', 'Consolas', 'Courier New', monospace;

  /* Transitions */
  --transition-fast: 0.15s ease;
  --transition-normal: 0.25s ease;
}

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

html {
  font-family: var(--font-sans);
  font-size: 16px;
  line-height: 1.6;
  color: var(--primary-800);
  background-color: var(--bg-main);
  scroll-behavior: smooth;
  -webkit-text-size-adjust: 100%;
}

body {
  min-height: 100vh;
  display: flex;
  flex-direction: column;
}

main {
  flex: 1;
}

img, svg {
  max-width: 100%;
  height: auto;
  display: block;
}

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

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

/* Typography Hierarchy */
h1, h2, h3, h4, h5, h6 {
  color: var(--primary-900);
  font-weight: 700;
  line-height: 1.25;
  letter-spacing: -0.02em;
}

h1 { font-size: clamp(1.85rem, 4vw, 2.75rem); margin-bottom: 0.75rem; }
h2 { font-size: clamp(1.4rem, 3vw, 2rem); margin-top: 2rem; margin-bottom: 1rem; }
h3 { font-size: clamp(1.15rem, 2vw, 1.4rem); margin-top: 1.5rem; margin-bottom: 0.75rem; }
h4 { font-size: 1.1rem; margin-top: 1.25rem; margin-bottom: 0.5rem; }

p {
  margin-bottom: 1.25rem;
  color: var(--primary-700);
}

p:last-child {
  margin-bottom: 0;
}

ul, ol {
  margin-bottom: 1.25rem;
  padding-left: 1.5rem;
  color: var(--primary-700);
}

li {
  margin-bottom: 0.35rem;
}

code, kbd, pre {
  font-family: var(--font-mono);
  font-size: 0.9em;
}

code {
  background-color: var(--primary-100);
  color: var(--primary-900);
  padding: 0.2em 0.4em;
  border-radius: var(--radius-sm);
}

/* Container & Grid Layout */
.container {
  width: 100%;
  max-width: 1200px;
  margin: 0 auto;
  padding: 0 1.25rem;
}

@media (max-width: 480px) {
  .container {
    padding: 0 1rem;
  }
}

/* Ensure Calculator & Content Sections Share Exact Same Width */
main.container,
#main-calculator .container,
.breadcrumb-container .container {
  max-width: 900px;
  margin-left: auto;
  margin-right: auto;
}

.section-padding {
  padding: 2.25rem 0;
}

@media (min-width: 640px) {
  .section-padding {
    padding: 3rem 0;
  }
}

@media (min-width: 768px) {
  .section-padding {
    padding: 4.5rem 0;
  }
}

/* Grid Layouts - Single Column on Mobile, Responsive Multi-Column on Larger Screens */
.grid-2,
.grid-3,
.grid-4 {
  display: grid;
  grid-template-columns: 1fr;
  gap: 1.25rem;
}

@media (min-width: 640px) {
  .grid-2 {
    grid-template-columns: repeat(2, 1fr);
    gap: 1.5rem;
  }
}

@media (min-width: 768px) {
  .grid-3 {
    grid-template-columns: repeat(3, 1fr);
    gap: 1.5rem;
  }
}

@media (min-width: 1024px) {
  .grid-4 {
    grid-template-columns: repeat(4, 1fr);
    gap: 1.5rem;
  }
}

/* Hero Section - EdTech STEM Gradient */
.hero-section {
  background: linear-gradient(135deg, #0f172a 0%, #1e1b4b 60%, #312e81 100%);
  color: #ffffff;
  padding: 2.5rem 0 3.5rem 0;
  position: relative;
  overflow: hidden;
}

.hero-section::before {
  content: '';
  position: absolute;
  top: -50%;
  right: -20%;
  width: 600px;
  height: 600px;
  background: radial-gradient(circle, rgba(99, 102, 241, 0.22) 0%, rgba(0,0,0,0) 70%);
  pointer-events: none;
}

.hero-grid {
  display: grid;
  grid-template-columns: 1fr;
  gap: 2.5rem;
  align-items: start;
}

.hero-content h1 {
  color: #ffffff;
  line-height: 1.2;
}

.hero-content p {
  color: #cbd5e1;
  font-size: 1.1rem;
}

.tag-list {
  display: flex;
  flex-wrap: wrap;
  gap: 0.5rem;
  margin: 1.25rem 0 1.75rem 0;
}

.tag {
  background-color: rgba(255, 255, 255, 0.1);
  color: #e2e8f0;
  border: 1px solid rgba(255, 255, 255, 0.18);
  padding: 0.25rem 0.75rem;
  border-radius: 9999px;
  font-size: 0.85rem;
  font-weight: 500;
}

.hero-ctas {
  display: flex;
  flex-wrap: wrap;
  gap: 1rem;
}

/* Buttons & Controls */
.btn {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  gap: 0.5rem;
  padding: 0.75rem 1.5rem;
  font-size: 1rem;
  font-weight: 600;
  border-radius: var(--radius-md);
  border: 2px solid transparent;
  cursor: pointer;
  transition: all var(--transition-fast);
  text-decoration: none !important;
  white-space: nowrap;
}

.btn-primary {
  background-color: var(--accent-indigo);
  color: #ffffff;
}

.btn-primary:hover, .btn-primary:focus {
  background-color: var(--accent-indigo-hover);
  color: #ffffff;
  box-shadow: var(--shadow-glow);
}

.btn-amber {
  background-color: var(--accent-amber);
  color: #ffffff;
}

.btn-amber:hover, .btn-amber:focus {
  background-color: var(--accent-amber-hover);
  color: #ffffff;
  box-shadow: 0 2px 8px rgba(217, 119, 6, 0.25);
}

.btn-secondary {
  background-color: rgba(255, 255, 255, 0.12);
  color: #ffffff;
  border-color: rgba(255, 255, 255, 0.25);
}

.btn-secondary:hover, .btn-secondary:focus {
  background-color: rgba(255, 255, 255, 0.22);
  color: #ffffff;
}

.btn-blue {
  background-color: var(--accent-cyan);
  color: #ffffff;
}

.btn-blue:hover, .btn-blue:focus {
  background-color: var(--accent-cyan-hover);
  color: #ffffff;
  box-shadow: 0 2px 8px rgba(2, 132, 199, 0.25);
}

.btn-outline {
  background-color: transparent;
  color: var(--primary-800);
  border-color: var(--border-light);
}

.btn-outline:hover, .btn-outline:focus {
  background-color: var(--primary-100);
  border-color: var(--accent-indigo);
}

.btn-sm {
  padding: 0.4rem 0.85rem;
  font-size: 0.875rem;
}

.btn-block {
  width: 100%;
}

/* Card Styles */
.card, .content-card {
  background-color: var(--bg-card);
  border-radius: var(--radius-lg);
  border: 1px solid var(--border-light);
  padding: 1.75rem 2rem;
  box-shadow: 0 2px 4px rgba(0, 0, 0, 0.05);
  transition: transform var(--transition-fast), box-shadow var(--transition-fast);
}

@media (max-width: 640px) {
  .card, .content-card {
    padding: 1.15rem 1rem;
  }
}

@media (max-width: 480px) {
  .btn {
    white-space: normal;
    text-align: center;
    max-width: 100%;
  }
  .hero-ctas {
    flex-direction: column;
    width: 100%;
  }
  .hero-ctas .btn {
    width: 100%;
  }
}

.card:hover, .content-card:hover {
  box-shadow: 0 2px 8px rgba(0, 0, 0, 0.08);
}

/* Cards inside section cards have 0px box-shadow */
.card .card,
.card .content-card,
.card .example-card,
.card .formula-box,
.card .related-card,
.card .famous-triple-card,
.card .calculator-card,
.card .result-card,
.content-card .card,
.content-card .content-card,
.content-card .example-card,
.content-card .formula-box,
.content-card .related-card,
.content-card .famous-triple-card,
.content-card .calculator-card,
.content-card .result-card,
.section-card .card,
.section-card .content-card,
.section-card .example-card,
.section-card .formula-box,
.section-card .related-card,
.section-card .famous-triple-card,
section.card .card,
section.card .content-card,
section.card .example-card,
section.card .formula-box,
section.card .related-card,
section.card .famous-triple-card,
section.card [class*="card"],
section.content-card [class*="card"],
section [class*="card"] [class*="card"],
section .card,
.card [class*="card"],
.content-card [class*="card"],
[class*="card"] [class*="card"],
[class*="card"] .formula-box {
  box-shadow: 0px 0px 0px 0px transparent !important;
}

.card .card:hover,
.card .content-card:hover,
.card .example-card:hover,
.card .formula-box:hover,
.card .related-card:hover,
.card .famous-triple-card:hover,
.card .calculator-card:hover,
.card .result-card:hover,
.content-card .card:hover,
.content-card .content-card:hover,
.content-card .example-card:hover,
.content-card .formula-box:hover,
.content-card .related-card:hover,
.content-card .famous-triple-card:hover,
.content-card .calculator-card:hover,
.content-card .result-card:hover,
.section-card .card:hover,
.section-card .content-card:hover,
.section-card .example-card:hover,
.section-card .formula-box:hover,
.section-card .related-card:hover,
.section-card .famous-triple-card:hover,
section.card .card:hover,
section.card .content-card:hover,
section.card .example-card:hover,
section.card .formula-box:hover,
section.card .related-card:hover,
section.card .famous-triple-card:hover,
section.card [class*="card"]:hover,
section.content-card [class*="card"]:hover,
section [class*="card"] [class*="card"]:hover,
section .card:hover,
.card [class*="card"]:hover,
.content-card [class*="card"]:hover,
[class*="card"] [class*="card"]:hover,
[class*="card"] .formula-box:hover {
  box-shadow: 0px 0px 0px 0px transparent !important;
}

.card > h2:first-child,
.card > h3:first-child,
.content-card > h2:first-child,
.content-card > h3:first-child {
  margin-top: 0;
}

.card-title {
  font-size: 1.25rem;
  margin-bottom: 0.5rem;
}

/* Formula Box - STEM Academic Accent */
.formula-box {
  background: linear-gradient(135deg, #eef2ff 0%, #e0e7ff 100%);
  border: 1px solid #c7d2fe;
  border-left: 5px solid var(--accent-indigo);
  padding: 1.25rem;
  border-radius: var(--radius-md);
  margin: 1.5rem 0;
  text-align: center;
  box-shadow: 0 2px 4px rgba(79, 70, 229, 0.08);
}

@media (max-width: 640px) {
  .formula-box {
    padding: 1rem 0.75rem;
  }
}

.formula-box .formula-text {
  font-size: clamp(1.15rem, 5vw, 1.75rem);
  font-weight: 700;
  font-family: var(--font-mono);
  color: #3730a3;
  letter-spacing: 0.03em;
  word-break: break-word;
  overflow-x: auto;
}

.formula-box p {
  color: #4338ca;
  font-size: 0.95rem;
  margin-top: 0.35rem;
}

/* Example Box */
.example-card {
  background-color: #ffffff;
  border: 1px solid var(--border-light);
  border-radius: var(--radius-md);
  padding: 1.5rem;
  margin-bottom: 1.5rem;
  box-shadow: 0 2px 4px rgba(0, 0, 0, 0.05);
}

.example-header {
  display: flex;
  align-items: center;
  justify-content: space-between;
  border-bottom: 2px solid var(--primary-100);
  padding-bottom: 0.75rem;
  margin-bottom: 1rem;
}

.example-title {
  font-weight: 700;
  color: var(--primary-900);
  font-size: 1.1rem;
}

.example-badge {
  background-color: #e0e7ff;
  color: #3730a3;
  font-size: 0.8rem;
  font-weight: 600;
  padding: 0.25rem 0.6rem;
  border-radius: 9999px;
}

.step-list {
  list-style: none;
  padding-left: 0;
}

.step-item {
  display: flex;
  gap: 0.75rem;
  margin-bottom: 0.75rem;
}

.step-number {
  background-color: var(--accent-indigo);
  color: #ffffff;
  width: 24px;
  height: 24px;
  border-radius: 50%;
  display: flex;
  align-items: center;
  justify-content: center;
  font-size: 0.75rem;
  font-weight: 700;
  flex-shrink: 0;
  margin-top: 0.2rem;
}

/* Callouts & Alert Boxes */
.callout {
  padding: 1rem 1.25rem;
  border-radius: var(--radius-md);
  border-left: 4px solid;
  margin: 1.5rem 0;
  font-size: 0.95rem;
}

.callout-info {
  background-color: #e0f2fe;
  border-color: #0284c7;
  color: #0369a1;
}

.callout-warning {
  background-color: #fffbeb;
  border-color: #f59e0b;
  color: #92400e;
}

.callout-tip {
  background-color: #f0fdfa;
  border-color: #0d9488;
  color: #0f766e;
}

/* Tables & Definition Lists */
.table-container {
  overflow-x: auto;
  margin: 1.25rem 0;
}

.table {
  width: 100%;
  border-collapse: collapse;
  text-align: left;
  background-color: var(--bg-card);
  border-radius: var(--radius-md);
  overflow: hidden;
  border: 1px solid var(--border-light);
}

.table th, .table td {
  padding: 0.75rem 1rem;
  border-bottom: 1px solid var(--border-light);
}

.table th {
  background-color: var(--primary-50);
  color: var(--primary-900);
  font-weight: 700;
  font-size: 0.9rem;
}

.table td {
  color: var(--primary-700);
  font-size: 0.95rem;
}

.table tr:last-child td {
  border-bottom: none;
}

.def-list {
  display: flex;
  flex-direction: column;
  gap: 0.85rem;
  margin: 1.25rem 0;
}

.def-item {
  background-color: #ffffff;
  border: 1px solid var(--border-light);
  border-radius: var(--radius-md);
  padding: 1rem 1.25rem;
}

.def-term {
  font-weight: 700;
  color: var(--primary-900);
  font-size: 1.05rem;
  margin-bottom: 0.25rem;
}

.def-desc {
  color: var(--primary-700);
  font-size: 0.95rem;
  margin: 0;
}

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

.text-center { text-align: center; }
.text-right { text-align: right; }
.mt-1 { margin-top: 0.25rem; }
.mt-2 { margin-top: 0.5rem; }
.mt-4 { margin-top: 1rem; }
.mb-2 { margin-bottom: 0.5rem; }
.mb-4 { margin-bottom: 1rem; }
.mb-6 { margin-bottom: 1.5rem; }