/*
 * Health Calculators Website - Main Stylesheet
 * Purpose: Provides responsive, accessible, modern styling for all pages
 * Design: Mobile-first, glassmorphism touches, smooth transitions
 * Author: Health Calculators Team
 */

/* ==================== CSS RESET & BASE ==================== */
* {
  margin: 0;
  padding: 0;
  box-sizing: border-box;
}

:root {
  /* Color Palette */
  --primary-color: #4f46e5;
  --primary-dark: #4338ca;
  --primary-light: #818cf8;
  --secondary-color: #06b6d4;
  --success-color: #10b981;
  --warning-color: #f59e0b;
  --danger-color: #ef4444;
  --text-primary: #1f2937;
  --text-secondary: #6b7280;
  --text-light: #9ca3af;
  --bg-primary: #ffffff;
  --bg-secondary: #f9fafb;
  --bg-tertiary: #f3f4f6;
  --border-color: #e5e7eb;
  --shadow-sm: 0 1px 2px 0 rgba(0, 0, 0, 0.05);
  --shadow-md: 0 4px 6px -1px rgba(0, 0, 0, 0.1), 0 2px 4px -1px rgba(0, 0, 0, 0.06);
  --shadow-lg: 0 10px 15px -3px rgba(0, 0, 0, 0.1), 0 4px 6px -2px rgba(0, 0, 0, 0.05);
  --shadow-xl: 0 20px 25px -5px rgba(0, 0, 0, 0.1), 0 10px 10px -5px rgba(0, 0, 0, 0.04);
  
  /* Typography */
  --font-primary: 'Inter', -apple-system, BlinkMacSystemFont, 'Segoe UI', Roboto, sans-serif;
  --font-heading: 'Poppins', -apple-system, BlinkMacSystemFont, 'Segoe UI', Roboto, sans-serif;
  
  /* Spacing */
  --spacing-xs: 0.5rem;
  --spacing-sm: 1rem;
  --spacing-md: 1.5rem;
  --spacing-lg: 2rem;
  --spacing-xl: 3rem;
  --spacing-2xl: 4rem;
  
  /* Border Radius */
  --radius-sm: 0.375rem;
  --radius-md: 0.5rem;
  --radius-lg: 0.75rem;
  --radius-xl: 1rem;
  
  /* Transitions */
  --transition-fast: 150ms ease-in-out;
  --transition-base: 250ms ease-in-out;
  --transition-slow: 350ms ease-in-out;
}

html {
  scroll-behavior: smooth;
  font-size: 16px;
}

body {
  font-family: var(--font-primary);
  color: var(--text-primary);
  background: linear-gradient(135deg, #f5f7fa 0%, #c3cfe2 100%);
  background-attachment: fixed;
  line-height: 1.6;
  min-height: 100vh;
}

/* ==================== TYPOGRAPHY ==================== */
h1, h2, h3, h4, h5, h6 {
  font-family: var(--font-heading);
  font-weight: 700;
  line-height: 1.2;
  margin-bottom: var(--spacing-md);
  color: var(--text-primary);
}

h1 { font-size: 2.5rem; }
h2 { font-size: 2rem; }
h3 { font-size: 1.75rem; }
h4 { font-size: 1.5rem; }
h5 { font-size: 1.25rem; }
h6 { font-size: 1.125rem; }

p {
  margin-bottom: var(--spacing-sm);
  color: var(--text-secondary);
}

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

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

/* ==================== HEADER & NAVIGATION ==================== */
header {
  background: rgba(255, 255, 255, 0.95);
  backdrop-filter: blur(10px);
  box-shadow: var(--shadow-md);
  position: sticky;
  top: 0;
  z-index: 1000;
  border-bottom: 1px solid var(--border-color);
}

nav {
  max-width: 1200px;
  margin: 0 auto;
  padding: var(--spacing-sm) var(--spacing-md);
  display: flex;
  justify-content: space-between;
  align-items: center;
  flex-wrap: wrap;
}

.logo {
  font-family: var(--font-heading);
  font-size: 1.5rem;
  font-weight: 700;
  color: var(--primary-color);
  display: flex;
  align-items: center;
  gap: 0.5rem;
}

.logo svg {
  width: 32px;
  height: 32px;
}

.nav-links {
  display: flex;
  list-style: none;
  gap: var(--spacing-md);
  flex-wrap: wrap;
}

.nav-links a {
  color: var(--text-primary);
  font-weight: 500;
  padding: var(--spacing-xs) var(--spacing-sm);
  border-radius: var(--radius-md);
  transition: all var(--transition-fast);
  text-decoration: none;
}

.nav-links a:hover,
.nav-links a.active {
  background: var(--primary-color);
  color: white;
  text-decoration: none;
}

/* Mobile Navigation Toggle */
.nav-toggle {
  display: none;
  background: none;
  border: none;
  font-size: 1.5rem;
  cursor: pointer;
  color: var(--text-primary);
}

@media (max-width: 768px) {
  .nav-toggle {
    display: block;
  }
  
  .nav-links {
    display: none;
    width: 100%;
    flex-direction: column;
    margin-top: var(--spacing-sm);
  }
  
  .nav-links.active {
    display: flex;
  }
  
  .nav-links a {
    width: 100%;
    text-align: center;
  }
}

/* ==================== MAIN CONTAINER ==================== */
main {
  max-width: 1200px;
  margin: 0 auto;
  padding: var(--spacing-lg) var(--spacing-md);
  min-height: calc(100vh - 200px);
}

/* ==================== HERO SECTION ==================== */
.hero {
  background: linear-gradient(135deg, rgba(79, 70, 229, 0.1) 0%, rgba(6, 182, 212, 0.1) 100%);
  border-radius: var(--radius-xl);
  padding: var(--spacing-2xl) var(--spacing-lg);
  margin-bottom: var(--spacing-xl);
  text-align: center;
  box-shadow: var(--shadow-lg);
  backdrop-filter: blur(10px);
  background-color: rgba(255, 255, 255, 0.8);
  border: 1px solid rgba(255, 255, 255, 0.3);
}

.hero h1 {
  font-size: 3rem;
  background: linear-gradient(135deg, var(--primary-color) 0%, var(--secondary-color) 100%);
  -webkit-background-clip: text;
  -webkit-text-fill-color: transparent;
  background-clip: text;
  margin-bottom: var(--spacing-md);
}

.hero p {
  font-size: 1.25rem;
  color: var(--text-secondary);
  max-width: 700px;
  margin: 0 auto var(--spacing-lg);
}

.hero-cta {
  display: inline-flex;
  gap: var(--spacing-sm);
  flex-wrap: wrap;
  justify-content: center;
}

/* ==================== CARDS ==================== */
.card {
  background: rgba(255, 255, 255, 0.9);
  backdrop-filter: blur(10px);
  border-radius: var(--radius-lg);
  padding: var(--spacing-lg);
  margin-bottom: var(--spacing-lg);
  box-shadow: var(--shadow-md);
  border: 1px solid rgba(255, 255, 255, 0.5);
  transition: all var(--transition-base);
}

.card:hover {
  box-shadow: var(--shadow-xl);
  transform: translateY(-2px);
}

.card h2, .card h3 {
  color: var(--primary-color);
}

.glass-card {
  background: rgba(255, 255, 255, 0.7);
  backdrop-filter: blur(20px);
  border: 1px solid rgba(255, 255, 255, 0.3);
}

/* ==================== BUTTONS ==================== */
button, .btn {
  font-family: var(--font-primary);
  font-weight: 600;
  padding: var(--spacing-sm) var(--spacing-lg);
  border-radius: var(--radius-md);
  border: none;
  cursor: pointer;
  transition: all var(--transition-fast);
  font-size: 1rem;
  display: inline-flex;
  align-items: center;
  gap: var(--spacing-xs);
  text-decoration: none;
}

.btn-primary {
  background: var(--primary-color);
  color: white;
  box-shadow: var(--shadow-md);
}

.btn-primary:hover {
  background: var(--primary-dark);
  box-shadow: var(--shadow-lg);
  transform: translateY(-1px);
}

.btn-secondary {
  background: var(--secondary-color);
  color: white;
  box-shadow: var(--shadow-md);
}

.btn-secondary:hover {
  background: #0891b2;
  box-shadow: var(--shadow-lg);
  transform: translateY(-1px);
}

.btn-outline {
  background: transparent;
  color: var(--primary-color);
  border: 2px solid var(--primary-color);
}

.btn-outline:hover {
  background: var(--primary-color);
  color: white;
}

button:disabled {
  opacity: 0.5;
  cursor: not-allowed;
}

/* ==================== FORMS ==================== */
.form-group {
  margin-bottom: var(--spacing-md);
}

label {
  display: block;
  font-weight: 600;
  margin-bottom: var(--spacing-xs);
  color: var(--text-primary);
}

input[type="text"],
input[type="email"],
input[type="number"],
select,
textarea {
  width: 100%;
  padding: var(--spacing-sm);
  border: 2px solid var(--border-color);
  border-radius: var(--radius-md);
  font-family: var(--font-primary);
  font-size: 1rem;
  transition: all var(--transition-fast);
  background: white;
}

input:focus,
select:focus,
textarea:focus {
  outline: none;
  border-color: var(--primary-color);
  box-shadow: 0 0 0 3px rgba(79, 70, 229, 0.1);
}

input.error,
select.error,
textarea.error {
  border-color: var(--danger-color);
}

.error-message {
  color: var(--danger-color);
  font-size: 0.875rem;
  margin-top: var(--spacing-xs);
  display: none;
}

.error-message.show {
  display: block;
}

textarea {
  min-height: 150px;
  resize: vertical;
}

/* ==================== CALCULATOR SPECIFIC ==================== */
.calculator-container {
  display: grid;
  grid-template-columns: 1fr;
  gap: var(--spacing-lg);
  margin-bottom: var(--spacing-xl);
}

@media (min-width: 768px) {
  .calculator-container {
    grid-template-columns: 1fr 1fr;
  }
}

.calculator-inputs {
  background: rgba(255, 255, 255, 0.9);
  backdrop-filter: blur(10px);
  border-radius: var(--radius-lg);
  padding: var(--spacing-lg);
  box-shadow: var(--shadow-md);
}

.calculator-results {
  background: linear-gradient(135deg, rgba(79, 70, 229, 0.05) 0%, rgba(6, 182, 212, 0.05) 100%);
  backdrop-filter: blur(10px);
  border-radius: var(--radius-lg);
  padding: var(--spacing-lg);
  box-shadow: var(--shadow-md);
  border: 2px solid var(--border-color);
}

.calculator-results.show {
  border-color: var(--primary-color);
  animation: slideIn var(--transition-base);
}

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

.result-value {
  font-size: 3rem;
  font-weight: 700;
  color: var(--primary-color);
  text-align: center;
  margin: var(--spacing-md) 0;
}

.result-classification {
  text-align: center;
  font-size: 1.5rem;
  font-weight: 600;
  margin-bottom: var(--spacing-md);
  padding: var(--spacing-sm);
  border-radius: var(--radius-md);
}

.classification-underweight {
  background: rgba(59, 130, 246, 0.1);
  color: #2563eb;
}

.classification-normal {
  background: rgba(16, 185, 129, 0.1);
  color: #059669;
}

.classification-overweight {
  background: rgba(245, 158, 11, 0.1);
  color: #d97706;
}

.classification-obese {
  background: rgba(239, 68, 68, 0.1);
  color: #dc2626;
}

/* Unit Toggle */
.unit-toggle {
  display: flex;
  gap: var(--spacing-xs);
  margin-bottom: var(--spacing-md);
  background: var(--bg-tertiary);
  padding: 4px;
  border-radius: var(--radius-md);
}

.unit-toggle button {
  flex: 1;
  padding: var(--spacing-xs) var(--spacing-sm);
  background: transparent;
  border: none;
  border-radius: var(--radius-sm);
  font-weight: 600;
  color: var(--text-secondary);
  transition: all var(--transition-fast);
}

.unit-toggle button.active {
  background: white;
  color: var(--primary-color);
  box-shadow: var(--shadow-sm);
}

/* Input Row */
.input-row {
  display: grid;
  grid-template-columns: 1fr 1fr;
  gap: var(--spacing-sm);
}

/* Chart/Gauge */
.bmi-chart {
  margin: var(--spacing-lg) 0;
  padding: var(--spacing-md);
  background: white;
  border-radius: var(--radius-md);
}

.chart-bar {
  height: 30px;
  background: linear-gradient(to right, 
    #3b82f6 0%, 
    #10b981 25%, 
    #10b981 50%, 
    #f59e0b 75%, 
    #ef4444 100%);
  border-radius: var(--radius-md);
  position: relative;
  margin: var(--spacing-sm) 0;
}

.chart-marker {
  position: absolute;
  top: -10px;
  width: 3px;
  height: 50px;
  background: var(--text-primary);
  transition: left var(--transition-base);
}

.chart-marker::after {
  content: '▼';
  position: absolute;
  top: -20px;
  left: 50%;
  transform: translateX(-50%);
  color: var(--text-primary);
  font-size: 1.2rem;
}

.chart-labels {
  display: flex;
  justify-content: space-between;
  font-size: 0.75rem;
  color: var(--text-light);
  margin-top: var(--spacing-xs);
}

/* ==================== ARTICLE CONTENT ==================== */
.article-content {
  background: white;
  padding: var(--spacing-xl) var(--spacing-lg);
  border-radius: var(--radius-lg);
  box-shadow: var(--shadow-md);
  margin-bottom: var(--spacing-xl);
  line-height: 1.8;
}

.article-content h2 {
  margin-top: var(--spacing-xl);
  padding-top: var(--spacing-lg);
  border-top: 2px solid var(--border-color);
}

.article-content h2:first-child {
  margin-top: 0;
  padding-top: 0;
  border-top: none;
}

.article-content h3 {
  margin-top: var(--spacing-lg);
  color: var(--text-primary);
}

.article-content ul, .article-content ol {
  margin-left: var(--spacing-lg);
  margin-bottom: var(--spacing-md);
}

.article-content li {
  margin-bottom: var(--spacing-xs);
  color: var(--text-secondary);
}

.article-content blockquote {
  border-left: 4px solid var(--primary-color);
  padding-left: var(--spacing-md);
  margin: var(--spacing-md) 0;
  font-style: italic;
  color: var(--text-secondary);
  background: var(--bg-secondary);
  padding: var(--spacing-md);
  border-radius: var(--radius-md);
}

.article-content code {
  background: var(--bg-tertiary);
  padding: 2px 6px;
  border-radius: var(--radius-sm);
  font-family: 'Courier New', monospace;
  font-size: 0.9em;
}

/* Insight Card */
.insight-card {
  background: linear-gradient(135deg, rgba(79, 70, 229, 0.1) 0%, rgba(6, 182, 212, 0.1) 100%);
  border-left: 4px solid var(--primary-color);
  padding: var(--spacing-md);
  margin: var(--spacing-lg) 0;
  border-radius: var(--radius-md);
}

.insight-card h4 {
  color: var(--primary-color);
  margin-bottom: var(--spacing-xs);
  display: flex;
  align-items: center;
  gap: var(--spacing-xs);
}

/* ==================== FAQ SECTION ==================== */
.faq-section {
  background: white;
  padding: var(--spacing-xl) var(--spacing-lg);
  border-radius: var(--radius-lg);
  box-shadow: var(--shadow-md);
  margin-bottom: var(--spacing-xl);
}

.faq-item {
  border-bottom: 1px solid var(--border-color);
  padding: var(--spacing-md) 0;
}

.faq-item:last-child {
  border-bottom: none;
}

.faq-question {
  width: 100%;
  text-align: left;
  background: none;
  border: none;
  padding: var(--spacing-sm);
  font-size: 1.125rem;
  font-weight: 600;
  color: var(--text-primary);
  cursor: pointer;
  display: flex;
  justify-content: space-between;
  align-items: center;
  transition: color var(--transition-fast);
  border-radius: var(--radius-md);
}

.faq-question:hover {
  color: var(--primary-color);
  background: var(--bg-secondary);
}

.faq-question::after {
  content: '+';
  font-size: 1.5rem;
  font-weight: 700;
  transition: transform var(--transition-base);
}

.faq-question.active::after {
  transform: rotate(45deg);
}

.faq-answer {
  max-height: 0;
  overflow: hidden;
  transition: max-height var(--transition-base);
  padding: 0 var(--spacing-sm);
}

.faq-answer.show {
  max-height: 500px;
  padding: var(--spacing-sm);
}

.faq-answer p {
  margin-top: var(--spacing-sm);
}

/* ==================== FOOTER ==================== */
footer {
  background: rgba(255, 255, 255, 0.95);
  backdrop-filter: blur(10px);
  border-top: 1px solid var(--border-color);
  padding: var(--spacing-xl) var(--spacing-md);
  margin-top: var(--spacing-2xl);
}

.footer-content {
  max-width: 1200px;
  margin: 0 auto;
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(250px, 1fr));
  gap: var(--spacing-lg);
}

.footer-section h3 {
  font-size: 1.125rem;
  margin-bottom: var(--spacing-sm);
  color: var(--primary-color);
}

.footer-section ul {
  list-style: none;
}

.footer-section li {
  margin-bottom: var(--spacing-xs);
}

.footer-section a {
  color: var(--text-secondary);
  transition: color var(--transition-fast);
}

.footer-section a:hover {
  color: var(--primary-color);
}

.footer-bottom {
  max-width: 1200px;
  margin: var(--spacing-lg) auto 0;
  padding-top: var(--spacing-lg);
  border-top: 1px solid var(--border-color);
  text-align: center;
  color: var(--text-light);
}

/* ==================== CREATOR SECTION ==================== */
.creator-section {
  background: linear-gradient(135deg, var(--primary-color) 0%, var(--secondary-color) 100%);
  color: white;
  padding: var(--spacing-xl) var(--spacing-lg);
  border-radius: var(--radius-lg);
  text-align: center;
  margin: var(--spacing-xl) 0;
  box-shadow: var(--shadow-xl);
}

.creator-section h2 {
  color: white;
}

.creator-section p {
  color: rgba(255, 255, 255, 0.9);
  font-size: 1.125rem;
  max-width: 700px;
  margin: 0 auto var(--spacing-lg);
}

/* ==================== UTILITY CLASSES ==================== */
.text-center { text-align: center; }
.text-left { text-align: left; }
.text-right { text-align: right; }

.mt-sm { margin-top: var(--spacing-sm); }
.mt-md { margin-top: var(--spacing-md); }
.mt-lg { margin-top: var(--spacing-lg); }
.mt-xl { margin-top: var(--spacing-xl); }

.mb-sm { margin-bottom: var(--spacing-sm); }
.mb-md { margin-bottom: var(--spacing-md); }
.mb-lg { margin-bottom: var(--spacing-lg); }
.mb-xl { margin-bottom: var(--spacing-xl); }

.hidden { display: none; }
.show { display: block; }

/* ==================== RESPONSIVE DESIGN ==================== */
@media (max-width: 768px) {
  :root {
    font-size: 14px;
  }
  
  h1 { font-size: 2rem; }
  h2 { font-size: 1.75rem; }
  h3 { font-size: 1.5rem; }
  
  .hero h1 {
    font-size: 2rem;
  }
  
  .hero p {
    font-size: 1rem;
  }
  
  .calculator-container {
    grid-template-columns: 1fr;
  }
  
  .result-value {
    font-size: 2.5rem;
  }
  
  .input-row {
    grid-template-columns: 1fr;
  }
}

@media (max-width: 480px) {
  main {
    padding: var(--spacing-md) var(--spacing-sm);
  }
  
  .card {
    padding: var(--spacing-md);
  }
  
  .article-content {
    padding: var(--spacing-lg) var(--spacing-md);
  }
}

/* ==================== 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-width: 0;
}

/* Focus styles for keyboard navigation */
*:focus-visible {
  outline: 3px solid var(--primary-color);
  outline-offset: 2px;
}

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

/* ==================== PRINT STYLES ==================== */
@media print {
  header, footer, .nav-toggle, .calculator-inputs, .creator-section {
    display: none;
  }
  
  body {
    background: white;
  }
  
  .article-content, .calculator-results {
    box-shadow: none;
    border: 1px solid #000;
  }
}