/* ============================================
   jim.expert - Complete CSS System
   Mobile-first responsive design
   No external dependencies
   ============================================ */

/* ============================================
   CSS RESET & BASE STYLES
   ============================================ */

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

html {
  font-size: 16px;
  -webkit-text-size-adjust: 100%;
  -ms-text-size-adjust: 100%;
  scroll-behavior: smooth;
}

body {
  min-height: 100vh;
  line-height: 1.5;
  text-rendering: optimizeLegibility;
  -webkit-font-smoothing: antialiased;
  -moz-osx-font-smoothing: grayscale;
}

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

input, button, textarea, select {
  font: inherit;
}

p, h1, h2, h3, h4, h5, h6 {
  overflow-wrap: break-word;
}

a {
  text-decoration: none;
  color: inherit;
}

ul, ol {
  list-style-position: inside;
}

table {
  border-collapse: collapse;
  width: 100%;
}

/* ============================================
   CSS CUSTOM PROPERTIES
   ============================================ */

:root {
  --color-primary: #2563eb;
  --color-primary-dark: #1d4ed8;
  --color-primary-light: #3b82f6;
  --color-success: #059669;
  --color-accent: #f59e0b;
  --color-error: #dc2626;
  --color-warning: #f59e0b;
  --color-info: #0ea5e9;
  --color-text-primary: #1f2937;
  --color-text-secondary: #6b7280;
  --color-text-tertiary: #9ca3af;
  --color-bg-primary: #ffffff;
  --color-bg-secondary: #f9fafb;
  --color-bg-tertiary: #f3f4f6;
  --color-border: #e5e7eb;
  --color-border-dark: #d1d5db;
  --font-base: 'Inter', -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, "Helvetica Neue", Arial, sans-serif;
  --font-heading: 'Inter', -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, "Helvetica Neue", Arial, sans-serif;
  --font-mono: 'JetBrains Mono', 'Courier New', Courier, 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;
  --text-5xl: 3rem;
  --leading-tight: 1.25;
  --leading-normal: 1.5;
  --leading-relaxed: 1.75;
  --space-1: 0.25rem;
  --space-2: 0.5rem;
  --space-3: 0.75rem;
  --space-4: 1rem;
  --space-5: 1.25rem;
  --space-6: 1.5rem;
  --space-8: 2rem;
  --space-10: 2.5rem;
  --space-12: 3rem;
  --space-16: 4rem;
  --space-20: 5rem;
  --shadow-sm: 0 1px 2px 0 rgba(0, 0, 0, 0.05);
  --shadow-md: 0 4px 6px -1px rgba(0, 0, 0, 0.1);
  --shadow-lg: 0 10px 15px -3px rgba(0, 0, 0, 0.1);
  --shadow-xl: 0 20px 25px -5px rgba(0, 0, 0, 0.1);
  --radius-sm: 0.25rem;
  --radius-md: 0.5rem;
  --radius-lg: 0.75rem;
  --radius-xl: 1rem;
  --transition-fast: 150ms ease-in-out;
  --transition-base: 250ms ease-in-out;
  --transition-slow: 350ms ease-in-out;
  --container-max: 1200px;
  --content-max: 65ch;
  --header-height: 64px;
}

body {
  font-family: var(--font-base);
  font-size: var(--text-base);
  line-height: var(--leading-normal);
  color: var(--color-text-primary);
  background-color: var(--color-bg-primary);
}

h1, h2, h3, h4, h5, h6 {
  font-family: var(--font-heading);
  font-weight: 700;
  line-height: var(--leading-tight);
  color: var(--color-text-primary);
  margin-bottom: var(--space-4);
  letter-spacing: -0.02em;
}

h1 { font-size: var(--text-4xl); margin-bottom: var(--space-6); font-weight: 800; }
h2 { font-size: var(--text-3xl); margin-top: var(--space-8); font-weight: 700; }
h3 { font-size: var(--text-2xl); margin-top: var(--space-6); font-weight: 600; }
h4 { font-size: var(--text-xl); font-weight: 600; }
h5 { font-size: var(--text-lg); font-weight: 600; }
h6 { font-size: var(--text-base); font-weight: 600; }

p {
  margin-bottom: var(--space-4);
  line-height: var(--leading-relaxed);
}

a {
  color: var(--color-primary);
  transition: color var(--transition-fast);
}

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

a:focus-visible {
  outline: 2px solid var(--color-primary);
  outline-offset: 2px;
  border-radius: var(--radius-sm);
}

strong, b { font-weight: 700; }
em, i { font-style: italic; }

code {
  font-family: var(--font-mono);
  font-size: 0.9em;
  background-color: var(--color-bg-tertiary);
  padding: 0.125rem 0.25rem;
  border-radius: var(--radius-sm);
}

pre {
  font-family: var(--font-mono);
  font-size: var(--text-sm);
  background-color: var(--color-bg-tertiary);
  padding: var(--space-4);
  border-radius: var(--radius-md);
  overflow-x: auto;
  margin-bottom: var(--space-4);
}

blockquote {
  border-left: 4px solid var(--color-primary);
  padding-left: var(--space-4);
  margin: var(--space-6) 0;
  font-style: italic;
  color: var(--color-text-secondary);
}

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

.content-wrapper {
  max-width: var(--content-max);
  margin: 0 auto;
}

.section { padding: var(--space-12) 0; }
.section-sm { padding: var(--space-8) 0; }
.section-lg { padding: var(--space-16) 0; }

.grid {
  display: grid;
  gap: var(--space-6);
}

.grid-cols-1 { grid-template-columns: 1fr; }

.flex { display: flex; }
.flex-col { flex-direction: column; }
.flex-wrap { flex-wrap: wrap; }
.items-center { align-items: center; }
.items-start { align-items: flex-start; }
.justify-between { justify-content: space-between; }
.justify-center { justify-content: center; }

.gap-2 { gap: var(--space-2); }
.gap-4 { gap: var(--space-4); }
.gap-6 { gap: var(--space-6); }
.gap-8 { gap: var(--space-8); }

.site-header {
  background-color: var(--color-bg-primary);
  border-bottom: 1px solid var(--color-border);
  position: sticky;
  top: 0;
  z-index: 1000;
  height: var(--header-height);
}

.header-container {
  display: flex;
  align-items: center;
  justify-content: space-between;
  height: 100%;
  padding: 0 var(--space-4);
  max-width: var(--container-max);
  margin: 0 auto;
}

.site-logo {
  font-family: var(--font-heading);
  font-size: var(--text-xl);
  font-weight: 800;
  color: var(--color-primary);
  letter-spacing: -0.03em;
}

.site-nav { display: none; }

.nav-list {
  display: flex;
  gap: var(--space-6);
  list-style: none;
}

.nav-link {
  color: var(--color-text-primary);
  font-weight: 600;
  transition: color var(--transition-fast);
  padding: var(--space-2);
  letter-spacing: -0.01em;
}

.nav-link:hover,
.nav-link.active {
  color: var(--color-primary);
}

.mobile-menu-toggle {
  display: flex;
  flex-direction: column;
  justify-content: space-around;
  width: 28px;
  height: 24px;
  background: transparent;
  border: none;
  cursor: pointer;
  padding: 0;
  z-index: 1001;
}

.menu-bar {
  width: 100%;
  height: 3px;
  background-color: var(--color-text-primary);
  transition: all var(--transition-base);
  border-radius: 2px;
}

.mobile-menu-toggle[aria-expanded="true"] .menu-bar:nth-child(1) {
  transform: rotate(45deg) translate(5px, 5px);
}

.mobile-menu-toggle[aria-expanded="true"] .menu-bar:nth-child(2) {
  opacity: 0;
}

.mobile-menu-toggle[aria-expanded="true"] .menu-bar:nth-child(3) {
  transform: rotate(-45deg) translate(7px, -7px);
}

.mobile-nav {
  position: fixed;
  top: var(--header-height);
  left: 0;
  right: 0;
  bottom: 0;
  background-color: var(--color-bg-primary);
  transform: translateX(100%);
  transition: transform var(--transition-base);
  overflow-y: auto;
  padding: var(--space-6) var(--space-4);
}

.mobile-nav.active {
  transform: translateX(0);
}

.mobile-nav-list {
  list-style: none;
  display: flex;
  flex-direction: column;
  gap: var(--space-2);
}

.mobile-nav-link {
  display: block;
  padding: var(--space-3);
  color: var(--color-text-primary);
  font-weight: 600;
  font-size: var(--text-lg);
  border-radius: var(--radius-md);
  transition: background-color var(--transition-fast);
  letter-spacing: -0.01em;
}

.mobile-nav-link:hover,
.mobile-nav-link.active {
  background-color: var(--color-bg-tertiary);
  color: var(--color-primary);
}

.site-footer {
  background-color: var(--color-text-primary);
  color: var(--color-bg-primary);
  padding: var(--space-12) 0 var(--space-6);
  margin-top: var(--space-16);
}

.footer-grid {
  display: grid;
  gap: var(--space-8);
  margin-bottom: var(--space-8);
}

.footer-section h3 {
  color: var(--color-bg-primary);
  font-size: var(--text-lg);
  margin-bottom: var(--space-4);
}

.footer-section p {
  color: var(--color-text-tertiary);
  line-height: var(--leading-relaxed);
}

.footer-links {
  list-style: none;
  display: flex;
  flex-direction: column;
  gap: var(--space-2);
}

.footer-link {
  color: var(--color-text-tertiary);
  transition: color var(--transition-fast);
}

.footer-link:hover {
  color: var(--color-bg-primary);
}

.footer-bottom {
  border-top: 1px solid rgba(255, 255, 255, 0.1);
  padding-top: var(--space-6);
  text-align: center;
  color: var(--color-text-tertiary);
  font-size: var(--text-sm);
}

.article-grid {
  display: grid;
  gap: var(--space-6);
  grid-template-columns: 1fr;
}

.article-card {
  background-color: var(--color-bg-primary);
  border: 1px solid var(--color-border);
  border-radius: var(--radius-lg);
  overflow: hidden;
  transition: transform var(--transition-base), box-shadow var(--transition-base);
}

.article-card:hover {
  transform: translateY(-4px);
  box-shadow: var(--shadow-lg);
}

.article-card-image {
  width: 100%;
  height: 200px;
  object-fit: cover;
  background-color: var(--color-bg-tertiary);
}

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

.article-card-category {
  display: inline-block;
  font-size: var(--text-sm);
  font-weight: 700;
  color: var(--color-primary);
  text-transform: uppercase;
  letter-spacing: 0.08em;
  margin-bottom: var(--space-2);
}

.article-card-title {
  font-size: var(--text-xl);
  margin-bottom: var(--space-3);
  color: var(--color-text-primary);
  font-weight: 700;
  letter-spacing: -0.02em;
  line-height: 1.3;
}

.article-card-excerpt {
  color: var(--color-text-secondary);
  margin-bottom: var(--space-4);
  line-height: var(--leading-relaxed);
}

.article-card-meta {
  display: flex;
  align-items: center;
  gap: var(--space-4);
  font-size: var(--text-sm);
  color: var(--color-text-tertiary);
}

.article-header {
  margin-bottom: var(--space-8);
}

.breadcrumb {
  display: flex;
  align-items: center;
  gap: var(--space-2);
  font-size: var(--text-sm);
  color: var(--color-text-secondary);
  margin-bottom: var(--space-4);
  flex-wrap: wrap;
}

.breadcrumb-separator {
  color: var(--color-text-tertiary);
}

.article-title {
  font-size: var(--text-4xl);
  margin-bottom: var(--space-4);
}

.article-meta {
  display: flex;
  align-items: center;
  gap: var(--space-6);
  color: var(--color-text-secondary);
  font-size: var(--text-base);
  flex-wrap: wrap;
}

.table-of-contents {
  background-color: var(--color-bg-secondary);
  border: 1px solid var(--color-border);
  border-radius: var(--radius-lg);
  padding: var(--space-6);
  margin-bottom: var(--space-8);
}

.table-of-contents h2 {
  font-size: var(--text-xl);
  margin-top: 0;
  margin-bottom: var(--space-4);
}

.toc-list {
  list-style: none;
  display: flex;
  flex-direction: column;
  gap: var(--space-2);
}

.toc-link {
  color: var(--color-text-secondary);
  transition: color var(--transition-fast);
  padding: var(--space-1) 0;
}

.toc-link:hover {
  color: var(--color-primary);
}

.article-content {
  line-height: var(--leading-relaxed);
}

.article-content > * {
  margin-bottom: var(--space-4);
}

.article-content h2,
.article-content h3 {
  scroll-margin-top: calc(var(--header-height) + var(--space-4));
}

.article-content ul,
.article-content ol {
  padding-left: var(--space-6);
  margin-bottom: var(--space-4);
}

.article-content li {
  margin-bottom: var(--space-2);
  line-height: var(--leading-relaxed);
}

.article-content img {
  border-radius: var(--radius-md);
  margin: var(--space-6) 0;
}

.callout {
  padding: var(--space-5);
  border-radius: var(--radius-lg);
  border-left: 4px solid;
  margin: var(--space-6) 0;
}

.callout-title {
  font-weight: 600;
  font-size: var(--text-lg);
  margin-bottom: var(--space-2);
  display: flex;
  align-items: center;
  gap: var(--space-2);
}

.callout-content {
  color: var(--color-text-secondary);
}

.callout-info {
  background-color: #eff6ff;
  border-color: var(--color-info);
}

.callout-info .callout-title {
  color: var(--color-info);
}

.callout-tip {
  background-color: #f0fdf4;
  border-color: var(--color-success);
}

.callout-tip .callout-title {
  color: var(--color-success);
}

.callout-warning {
  background-color: #fffbeb;
  border-color: var(--color-warning);
}

.callout-warning .callout-title {
  color: var(--color-warning);
}

.callout-important {
  background-color: #fef2f2;
  border-color: var(--color-error);
}

.callout-important .callout-title {
  color: var(--color-error);
}

.article-content table {
  width: 100%;
  margin: var(--space-6) 0;
  border: 1px solid var(--color-border);
  border-radius: var(--radius-md);
  overflow: hidden;
}

.article-content th,
.article-content td {
  padding: var(--space-3);
  text-align: left;
  border-bottom: 1px solid var(--color-border);
}

.article-content th {
  background-color: var(--color-bg-secondary);
  font-weight: 600;
  color: var(--color-text-primary);
}

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

.article-content tbody tr:hover {
  background-color: var(--color-bg-secondary);
}

.related-articles {
  margin-top: var(--space-12);
  padding-top: var(--space-8);
  border-top: 2px solid var(--color-border);
}

.related-articles h2 {
  margin-top: 0;
  margin-bottom: var(--space-6);
}

.related-articles-grid {
  display: grid;
  gap: var(--space-4);
  grid-template-columns: 1fr;
}

.reading-progress {
  position: fixed;
  top: var(--header-height);
  left: 0;
  width: 100%;
  height: 3px;
  background-color: var(--color-bg-tertiary);
  z-index: 999;
}

.reading-progress-bar {
  height: 100%;
  background-color: var(--color-primary);
  transition: width 150ms ease-out;
  width: 0%;
}

.social-share {
  display: flex;
  align-items: center;
  gap: var(--space-3);
  margin: var(--space-8) 0;
  padding: var(--space-5);
  background-color: var(--color-bg-secondary);
  border-radius: var(--radius-lg);
  flex-wrap: wrap;
}

.social-share-label {
  font-weight: 600;
  color: var(--color-text-secondary);
  margin-right: var(--space-2);
}

.form-group {
  margin-bottom: var(--space-6);
}

.form-label {
  display: block;
  font-weight: 700;
  margin-bottom: var(--space-2);
  color: var(--color-text-primary);
  letter-spacing: -0.01em;
}

.form-label-required::after {
  content: " *";
  color: var(--color-error);
}

.form-input,
.form-textarea,
.form-select {
  width: 100%;
  padding: var(--space-3);
  border: 1px solid var(--color-border);
  border-radius: var(--radius-md);
  font-size: var(--text-base);
  transition: border-color var(--transition-fast), box-shadow var(--transition-fast);
  background-color: var(--color-bg-primary);
}

.form-input:focus,
.form-textarea:focus,
.form-select:focus {
  outline: none;
  border-color: var(--color-primary);
  box-shadow: 0 0 0 3px rgba(37, 99, 235, 0.1);
}

.form-textarea {
  min-height: 120px;
  resize: vertical;
}

.form-error {
  display: none;
  color: var(--color-error);
  font-size: var(--text-sm);
  margin-top: var(--space-2);
}

.form-group.error .form-error {
  display: block;
}

.form-group.error .form-input,
.form-group.error .form-textarea {
  border-color: var(--color-error);
}

.form-help {
  font-size: var(--text-sm);
  color: var(--color-text-secondary);
  margin-top: var(--space-2);
}

.btn {
  display: inline-block;
  padding: var(--space-3) var(--space-6);
  font-weight: 700;
  font-size: var(--text-base);
  text-align: center;
  border: none;
  border-radius: var(--radius-md);
  cursor: pointer;
  transition: all var(--transition-fast);
  text-decoration: none;
  letter-spacing: -0.01em;
}

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

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

.btn-secondary {
  background-color: var(--color-bg-tertiary);
  color: var(--color-text-primary);
}

.btn-secondary:hover {
  background-color: var(--color-border-dark);
}

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

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

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

.btn-sm {
  padding: var(--space-2) var(--space-4);
  font-size: var(--text-sm);
}

.btn-block {
  width: 100%;
  display: block;
}

.btn:disabled {
  opacity: 0.5;
  cursor: not-allowed;
}

.hero {
  background: linear-gradient(135deg, var(--color-primary-light), var(--color-primary-dark));
  color: white;
  padding: var(--space-16) 0;
  text-align: center;
}

.hero-title {
  font-size: var(--text-5xl);
  color: white;
  margin-bottom: var(--space-4);
  font-weight: 900;
  letter-spacing: -0.03em;
  line-height: 1.1;
}

.hero-description {
  font-size: var(--text-xl);
  color: rgba(255, 255, 255, 0.9);
  max-width: 600px;
  margin: 0 auto var(--space-8);
  line-height: var(--leading-relaxed);
}

.hero-cta {
  display: flex;
  gap: var(--space-4);
  justify-content: center;
  flex-wrap: wrap;
}

.text-center { text-align: center; }
.text-left { text-align: left; }
.text-right { text-align: right; }
.text-primary { color: var(--color-primary); }
.text-secondary { color: var(--color-text-secondary); }
.text-error { color: var(--color-error); }
.text-success { color: var(--color-success); }
.bg-primary { background-color: var(--color-bg-primary); }
.bg-secondary { background-color: var(--color-bg-secondary); }
.bg-tertiary { background-color: var(--color-bg-tertiary); }
.mt-0 { margin-top: 0; }
.mt-2 { margin-top: var(--space-2); }
.mt-4 { margin-top: var(--space-4); }
.mt-6 { margin-top: var(--space-6); }
.mt-8 { margin-top: var(--space-8); }
.mb-0 { margin-bottom: 0; }
.mb-2 { margin-bottom: var(--space-2); }
.mb-4 { margin-bottom: var(--space-4); }
.mb-6 { margin-bottom: var(--space-6); }
.mb-8 { margin-bottom: var(--space-8); }
.p-4 { padding: var(--space-4); }
.p-6 { padding: var(--space-6); }
.p-8 { padding: var(--space-8); }
.hidden { display: none; }

.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;
}

.skip-link {
  position: absolute;
  top: -40px;
  left: 0;
  background: var(--color-primary);
  color: white;
  padding: var(--space-2) var(--space-4);
  z-index: 100;
}

.skip-link:focus {
  top: 0;
}

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

@media (min-width: 768px) {
  .site-nav { display: block; }
  .mobile-menu-toggle { display: none; }
  .mobile-nav { display: none !important; }
  h1 { font-size: var(--text-5xl); }
  h2 { font-size: var(--text-4xl); }
  h3 { font-size: var(--text-3xl); }
  .hero-title { font-size: clamp(3rem, 5vw, 4rem); }
  .footer-grid { grid-template-columns: repeat(2, 1fr); }
}

@media (min-width: 1024px) {
  .grid-cols-3 { grid-template-columns: repeat(3, 1fr); }
  .article-grid { grid-template-columns: repeat(3, 1fr); }
  .footer-grid { grid-template-columns: repeat(4, 1fr); }
}

@media print {
  .site-header,
  .site-footer,
  .mobile-nav,
  .social-share,
  .related-articles,
  .table-of-contents {
    display: none;
  }
  
  body {
    font-size: 12pt;
    line-height: 1.5;
    color: #000;
  }
  
  a {
    color: #000;
    text-decoration: underline;
  }
  
  h1, h2, h3 {
    page-break-after: avoid;
  }
  
  img {
    max-width: 100%;
    page-break-inside: avoid;
  }
}