/* Import IBM Plex Font */
@import url('https://fonts.googleapis.com/css2?family=IBM+Plex+Sans:wght@300;400;500;600;700&family=IBM+Plex+Mono:wght@400;500&display=swap');

/* CSS Variables */
:root {
  --color-primary: #dc143c;
  --color-primary-dark: #a00f2c;
  --color-black: #000000;
  --color-grey-dark: #2a2a2a;
  --color-grey: #4a4a4a;
  --color-grey-light: #8a8a8a;
  --color-grey-lighter: #cccccc;
  --color-white: #ffffff;
  --color-background: #fafafa;
  --color-border: #e0e0e0;
  
  --font-sans: 'IBM Plex Sans', -apple-system, BlinkMacSystemFont, 'Segoe UI', sans-serif;
  --font-mono: 'IBM Plex Mono', 'Courier New', monospace;
  
  --spacing-xs: 0.5rem;
  --spacing-sm: 1rem;
  --spacing-md: 1.5rem;
  --spacing-lg: 2rem;
  --spacing-xl: 3rem;
  --spacing-xxl: 4rem;
  
  --max-width: 1200px;
  --sidebar-width: 280px;
}

/* Reset and Base Styles */
* {
  margin: 0;
  padding: 0;
  box-sizing: border-box;
}

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

body {
  font-family: var(--font-sans);
  line-height: 1.6;
  color: var(--color-grey-dark);
  background-color: var(--color-background);
}

/* Typography */
h1, h2, h3, h4, h5, h6 {
  font-weight: 600;
  line-height: 1.3;
  margin-bottom: var(--spacing-md);
  color: var(--color-black);
}

h1 {
  font-size: 2.5rem;
  font-weight: 700;
}

h2 {
  font-size: 2rem;
  margin-top: var(--spacing-xl);
  padding-bottom: var(--spacing-sm);
  border-bottom: 2px solid var(--color-primary);
}

h3 {
  font-size: 1.5rem;
  margin-top: var(--spacing-lg);
}

h4 {
  font-size: 1.25rem;
  margin-top: var(--spacing-md);
}

p {
  margin-bottom: var(--spacing-md);
}

a {
  color: var(--color-primary);
  text-decoration: none;
  transition: color 0.2s ease;
}

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

code {
  font-family: var(--font-mono);
  background-color: var(--color-grey-lighter);
  padding: 0.2em 0.4em;
  font-size: 0.9em;
  color: var(--color-black);
}

pre {
  background-color: var(--color-grey-dark);
  color: var(--color-white);
  padding: var(--spacing-md);
  overflow-x: auto;
  margin-bottom: var(--spacing-md);
  border-left: 4px solid var(--color-primary);
}

pre code {
  background-color: transparent;
  padding: 0;
  color: var(--color-white);
}

/* Header */
.site-header {
  background-color: var(--color-black);
  color: var(--color-white);
  padding: var(--spacing-lg) 0;
  border-bottom: 3px solid var(--color-primary);
}

.site-header .container {
  max-width: var(--max-width);
  margin: 0 auto;
  padding: 0 var(--spacing-md);
  display: flex;
  justify-content: space-between;
  align-items: center;
}

.header-content {
  flex: 1;
}

.site-title {
  font-size: 1.75rem;
  font-weight: 700;
  margin-bottom: var(--spacing-xs);
  color: var(--color-white);
}

.site-subtitle {
  font-size: 0.95rem;
  color: var(--color-grey-lighter);
  font-weight: 400;
  margin-bottom: 0;
}

/* Mobile Menu Toggle */
.mobile-menu-toggle {
  display: none;
  flex-direction: column;
  background: transparent;
  border: none;
  cursor: pointer;
  padding: var(--spacing-xs);
}

.mobile-menu-toggle span {
  width: 25px;
  height: 3px;
  background-color: var(--color-white);
  margin: 3px 0;
  transition: 0.3s;
}

/* Layout */
.layout {
  display: flex;
  max-width: var(--max-width);
  margin: 0 auto;
  min-height: calc(100vh - 200px);
}

/* Sidebar */
.sidebar {
  width: var(--sidebar-width);
  background-color: var(--color-white);
  border-right: 1px solid var(--color-border);
  padding: var(--spacing-lg) 0;
  position: sticky;
  top: 0;
  height: 100vh;
  overflow-y: auto;
}

.main-nav {
  padding: 0 var(--spacing-md);
}

.nav-list {
  list-style: none;
}

.nav-list li {
  margin-bottom: var(--spacing-xs);
}

.nav-link {
  display: block;
  padding: var(--spacing-sm);
  color: var(--color-grey);
  font-weight: 500;
  transition: all 0.2s ease;
  border-left: 3px solid transparent;
}

.nav-link:hover {
  color: var(--color-primary);
  background-color: var(--color-background);
  border-left-color: var(--color-primary);
  text-decoration: none;
}

.nav-link.active {
  color: var(--color-primary);
  background-color: var(--color-background);
  border-left-color: var(--color-primary);
}

/* Main Content */
.main-content {
  flex: 1;
  padding: var(--spacing-xl) var(--spacing-lg);
  background-color: var(--color-white);
}

.content {
  max-width: 800px;
}

/* Hero Section */
.hero {
  text-align: center;
  padding: var(--spacing-xxl) 0;
  border-bottom: 1px solid var(--color-border);
  margin-bottom: var(--spacing-xl);
}

.hero h1 {
  font-size: 3rem;
  margin-bottom: var(--spacing-md);
}

.hero h2 {
  font-size: 1.5rem;
  font-weight: 400;
  color: var(--color-grey);
  border-bottom: none;
  margin-top: 0;
  margin-bottom: var(--spacing-md);
}

.hero-subtitle {
  font-size: 1.1rem;
  color: var(--color-grey-light);
  max-width: 700px;
  margin: 0 auto;
}

/* Overview Section */
.overview {
  margin-bottom: var(--spacing-xxl);
}

/* Component Cards */
.key-components {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(200px, 1fr));
  gap: var(--spacing-md);
  margin-top: var(--spacing-lg);
}

.component-card {
  background-color: var(--color-background);
  padding: var(--spacing-md);
  border: 1px solid var(--color-border);
  border-top: 3px solid var(--color-primary);
}

.component-card h3 {
  font-size: 1.1rem;
  margin-top: 0;
  margin-bottom: var(--spacing-sm);
  color: var(--color-black);
}

.component-card p {
  font-size: 0.9rem;
  color: var(--color-grey);
  margin-bottom: 0;
}

/* Link Grid */
.link-grid {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(280px, 1fr));
  gap: var(--spacing-md);
  margin-top: var(--spacing-lg);
}

.link-card {
  background-color: var(--color-white);
  padding: var(--spacing-lg);
  border: 2px solid var(--color-border);
  transition: all 0.3s ease;
  display: block;
}

.link-card:hover {
  border-color: var(--color-primary);
  transform: translateY(-2px);
  box-shadow: 0 4px 12px rgba(0, 0, 0, 0.1);
  text-decoration: none;
}

.link-card h3 {
  font-size: 1.25rem;
  margin-top: 0;
  margin-bottom: var(--spacing-sm);
  color: var(--color-black);
}

.link-card p {
  font-size: 0.95rem;
  color: var(--color-grey);
  margin-bottom: 0;
}

/* Tables */
table {
  width: 100%;
  border-collapse: collapse;
  margin: var(--spacing-lg) 0;
  font-size: 0.95rem;
}

thead {
  background-color: var(--color-black);
  color: var(--color-white);
}

th {
  padding: var(--spacing-sm);
  text-align: left;
  font-weight: 600;
  border: 1px solid var(--color-grey-dark);
}

td {
  padding: var(--spacing-sm);
  border: 1px solid var(--color-border);
}

tbody tr:nth-child(even) {
  background-color: var(--color-background);
}

tbody tr:hover {
  background-color: rgba(220, 20, 60, 0.05);
}

/* Lists */
ul, ol {
  margin-bottom: var(--spacing-md);
  padding-left: var(--spacing-lg);
}

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

/* Footer */
.site-footer {
  background-color: var(--color-black);
  color: var(--color-grey-lighter);
  padding: var(--spacing-lg) 0;
  text-align: center;
  border-top: 3px solid var(--color-primary);
}

.site-footer .container {
  max-width: var(--max-width);
  margin: 0 auto;
  padding: 0 var(--spacing-md);
}

.site-footer p {
  margin-bottom: 0;
  font-size: 0.9rem;
}

/* Responsive Design */
@media (max-width: 768px) {
  .mobile-menu-toggle {
    display: flex;
  }
  
  .layout {
    flex-direction: column;
  }
  
  .sidebar {
    width: 100%;
    height: auto;
    position: static;
    border-right: none;
    border-bottom: 1px solid var(--color-border);
    display: none;
  }
  
  .sidebar.active {
    display: block;
  }
  
  .main-content {
    padding: var(--spacing-lg) var(--spacing-md);
  }
  
  .hero h1 {
    font-size: 2rem;
  }
  
  .hero h2 {
    font-size: 1.25rem;
  }
  
  h1 {
    font-size: 2rem;
  }
  
  h2 {
    font-size: 1.5rem;
  }
  
  .key-components {
    grid-template-columns: 1fr;
  }
  
  .link-grid {
    grid-template-columns: 1fr;
  }
}

/* Utility Classes */
.container {
  max-width: var(--max-width);
  margin: 0 auto;
  padding: 0 var(--spacing-md);
}

.text-center {
  text-align: center;
}

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

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

/* Functional Requirements Section */
.functional-requirements-summary {
  margin-bottom: var(--spacing-xxl);
  padding: var(--spacing-xl) 0;
  border-bottom: 1px solid var(--color-border);
}

.section-intro {
  font-size: 1.1rem;
  color: var(--color-grey);
  max-width: 800px;
  margin-bottom: var(--spacing-xl);
}

.requirements-grid {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(320px, 1fr));
  gap: var(--spacing-lg);
  margin-top: var(--spacing-lg);
}

.requirement-card {
  background-color: var(--color-white);
  padding: var(--spacing-lg);
  border: 2px solid var(--color-border);
  border-left: 4px solid var(--color-primary);
  transition: all 0.3s ease;
}

.requirement-card:hover {
  border-left-width: 6px;
  box-shadow: 0 4px 12px rgba(0, 0, 0, 0.08);
}

.requirement-card h3 {
  font-size: 1.25rem;
  margin-top: 0;
  margin-bottom: var(--spacing-sm);
  color: var(--color-black);
}

.requirement-card > p {
  font-size: 0.95rem;
  color: var(--color-grey);
  margin-bottom: var(--spacing-md);
  line-height: 1.6;
}

.requirement-list {
  list-style: none;
  padding-left: 0;
  margin-bottom: 0;
}

.requirement-list li {
  font-size: 0.9rem;
  color: var(--color-grey-dark);
  padding-left: var(--spacing-md);
  margin-bottom: var(--spacing-xs);
  position: relative;
}

.requirement-list li:before {
  content: "▸";
  color: var(--color-primary);
  font-weight: bold;
  position: absolute;
  left: 0;
}

.cta-section {
  text-align: center;
  margin-top: var(--spacing-xl);
  padding-top: var(--spacing-lg);
  border-top: 1px solid var(--color-border);
}

.cta-button {
  display: inline-block;
  background-color: var(--color-primary);
  color: var(--color-white);
  padding: var(--spacing-md) var(--spacing-xl);
  font-size: 1.1rem;
  font-weight: 600;
  border: 2px solid var(--color-primary);
  transition: all 0.3s ease;
  text-decoration: none;
}

.cta-button:hover {
  background-color: var(--color-primary-dark);
  border-color: var(--color-primary-dark);
  transform: translateY(-2px);
  box-shadow: 0 4px 12px rgba(220, 20, 60, 0.3);
  text-decoration: none;
  color: var(--color-white);
}

/* Table of Contents */
.table-of-contents {
  background-color: var(--color-background);
  padding: var(--spacing-lg);
  margin: var(--spacing-xl) 0;
  border-left: 4px solid var(--color-primary);
}

.table-of-contents h3 {
  font-size: 1.1rem;
  margin-top: 0;
  margin-bottom: var(--spacing-md);
}

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

.toc-main {
  margin-bottom: var(--spacing-sm);
}

.toc-sub {
  margin-left: var(--spacing-md);
  margin-bottom: var(--spacing-xs);
  font-size: 0.9rem;
}

.toc-list a {
  color: var(--color-grey-dark);
  text-decoration: none;
}

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

/* Responsive adjustments for functional requirements */
@media (max-width: 768px) {
  .requirements-grid {
    grid-template-columns: 1fr;
  }
  
  .requirement-card {
    padding: var(--spacing-md);
  }
  
  .cta-button {
    padding: var(--spacing-sm) var(--spacing-lg);
    font-size: 1rem;
  }
}