/* AAEP — Agent Accessibility Event Protocol
 * Minimalist black-and-white technical specification stylesheet.
 * Inspired by W3C, IETF, and the HTML Living Standard.
 */

:root {
  --color-text: #1a1a1a;
  --color-text-muted: #525252;
  --color-bg: #ffffff;
  --color-bg-subtle: #fafafa;
  --color-code-bg: #f4f4f5;
  --color-border: #e5e5e5;
  --color-border-strong: #d4d4d4;
  --color-link: #1d4ed8;
  --color-link-hover: #1e40af;
  --color-accent: #0a0a0a;

  --font-body: "Atkinson Hyperlegible", system-ui, -apple-system, "Segoe UI", Roboto, "Helvetica Neue", Arial, sans-serif;
  --font-mono: ui-monospace, "SF Mono", Menlo, Monaco, "Cascadia Mono", Consolas, "Courier New", monospace;

  --content-max: 48rem;
  --content-max-wide: 72rem;
}

@font-face {
  font-family: "Atkinson Hyperlegible";
  src: url("https://fonts.gstatic.com/s/atkinsonhyperlegible/v11/9Bt23C1KxNDXMspQ1lPyU89-1h6ONRlW45GE5ZgpewSSbQ.woff2") format("woff2");
  font-weight: 400;
  font-style: normal;
  font-display: swap;
}

@font-face {
  font-family: "Atkinson Hyperlegible";
  src: url("https://fonts.gstatic.com/s/atkinsonhyperlegible/v11/9Bt73C1KxNDXMspQ1lPyU89-1h6ONRlW45G055ItWQGCYRk.woff2") format("woff2");
  font-weight: 700;
  font-style: normal;
  font-display: swap;
}

* {
  box-sizing: border-box;
}

html {
  font-size: 100%;
  scroll-behavior: smooth;
}

body {
  margin: 0;
  font-family: var(--font-body);
  font-size: 1rem;
  line-height: 1.65;
  color: var(--color-text);
  background-color: var(--color-bg);
  -webkit-font-smoothing: antialiased;
  -moz-osx-font-smoothing: grayscale;
  text-rendering: optimizeLegibility;
}

/* Skip link */
.skip-link {
  position: absolute;
  top: -100px;
  left: 0;
  padding: 0.75rem 1.25rem;
  background: var(--color-accent);
  color: white;
  text-decoration: none;
  z-index: 100;
}
.skip-link:focus {
  top: 0;
}

/* Header */
.site-header {
  border-bottom: 1px solid var(--color-border);
  background: var(--color-bg);
}

.site-header-inner {
  max-width: var(--content-max-wide);
  margin: 0 auto;
  padding: 1.25rem 1.5rem;
  display: flex;
  align-items: center;
  justify-content: space-between;
  flex-wrap: wrap;
  gap: 1rem;
}

.site-title {
  font-size: 1.125rem;
  font-weight: 700;
  color: var(--color-text);
  text-decoration: none;
  letter-spacing: -0.01em;
}

.site-title-sub {
  color: var(--color-text-muted);
  font-weight: 400;
  margin-left: 0.5rem;
  font-size: 0.95rem;
}

.site-nav {
  display: flex;
  gap: 1.5rem;
  align-items: center;
}

.site-nav a {
  color: var(--color-text);
  text-decoration: none;
  font-size: 0.95rem;
}

.site-nav a:hover,
.site-nav a:focus {
  color: var(--color-link);
  text-decoration: underline;
  text-underline-offset: 3px;
}

/* Breadcrumb */
.breadcrumb {
  max-width: var(--content-max-wide);
  margin: 0 auto;
  padding: 0.75rem 1.5rem;
  font-size: 0.9rem;
  color: var(--color-text-muted);
  border-bottom: 1px solid var(--color-border);
}

.breadcrumb a {
  color: var(--color-text-muted);
  text-decoration: none;
}

.breadcrumb a:hover {
  text-decoration: underline;
  text-underline-offset: 2px;
  color: var(--color-link);
}

/* Main content */
.site-main {
  max-width: var(--content-max);
  margin: 0 auto;
  padding: 3rem 1.5rem 4rem;
}

.site-main.wide {
  max-width: var(--content-max-wide);
}

/* Typography */
h1, h2, h3, h4, h5, h6 {
  font-weight: 700;
  line-height: 1.25;
  margin-top: 2.5rem;
  margin-bottom: 1rem;
  letter-spacing: -0.015em;
  color: var(--color-text);
}

h1 {
  font-size: 2.25rem;
  margin-top: 0;
  margin-bottom: 1.5rem;
  padding-bottom: 0.75rem;
  border-bottom: 2px solid var(--color-border-strong);
}

h2 {
  font-size: 1.625rem;
  margin-top: 3rem;
  padding-bottom: 0.5rem;
  border-bottom: 1px solid var(--color-border);
}

h3 {
  font-size: 1.25rem;
}

h4 {
  font-size: 1.05rem;
}

p {
  margin: 0 0 1.25rem;
}

a {
  color: var(--color-link);
  text-decoration: underline;
  text-underline-offset: 2px;
  text-decoration-thickness: 1px;
}

a:hover, a:focus {
  color: var(--color-link-hover);
  text-decoration-thickness: 2px;
}

/* Lists */
ul, ol {
  margin: 0 0 1.25rem;
  padding-left: 1.75rem;
}

li {
  margin-bottom: 0.4rem;
}

li > ul, li > ol {
  margin-top: 0.4rem;
  margin-bottom: 0.4rem;
}

/* Code */
code, pre, kbd, samp {
  font-family: var(--font-mono);
  font-size: 0.92em;
}

code {
  background-color: var(--color-code-bg);
  padding: 0.15rem 0.4rem;
  border-radius: 3px;
  border: 1px solid var(--color-border);
}

pre {
  background-color: var(--color-code-bg);
  padding: 1rem 1.25rem;
  border-radius: 4px;
  border: 1px solid var(--color-border);
  overflow-x: auto;
  line-height: 1.55;
  margin: 1.5rem 0;
}

pre code {
  background: none;
  padding: 0;
  border: none;
  font-size: 0.9rem;
}

/* Tables */
table {
  border-collapse: collapse;
  margin: 1.5rem 0;
  width: 100%;
  font-size: 0.95rem;
}

th, td {
  text-align: left;
  padding: 0.65rem 0.85rem;
  border: 1px solid var(--color-border);
  vertical-align: top;
}

th {
  background-color: var(--color-bg-subtle);
  font-weight: 700;
}

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

/* Blockquote */
blockquote {
  margin: 1.5rem 0;
  padding: 0.75rem 1.25rem;
  border-left: 4px solid var(--color-border-strong);
  color: var(--color-text-muted);
  background-color: var(--color-bg-subtle);
}

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

/* Horizontal rule */
hr {
  border: 0;
  border-top: 1px solid var(--color-border);
  margin: 2.5rem 0;
}

/* Page index (for section landing pages) */
.page-index {
  list-style: none;
  padding: 0;
  margin: 1.5rem 0;
  border-top: 1px solid var(--color-border);
}

.page-index li {
  padding: 0.85rem 0;
  border-bottom: 1px solid var(--color-border);
  display: flex;
  justify-content: space-between;
  align-items: baseline;
  gap: 1rem;
  margin-bottom: 0;
}

.page-index li a {
  font-weight: 500;
}

.page-index li .path {
  color: var(--color-text-muted);
  font-family: var(--font-mono);
  font-size: 0.85rem;
}

/* Footer */
.site-footer {
  margin-top: 4rem;
  padding: 2rem 1.5rem 3rem;
  border-top: 1px solid var(--color-border);
  background-color: var(--color-bg-subtle);
}

.site-footer-inner {
  max-width: var(--content-max-wide);
  margin: 0 auto;
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(15rem, 1fr));
  gap: 2.5rem;
  color: var(--color-text-muted);
  font-size: 0.9rem;
}

.site-footer h2 {
  font-size: 0.8rem;
  text-transform: uppercase;
  letter-spacing: 0.06em;
  color: var(--color-text);
  margin: 0 0 0.75rem;
  padding: 0;
  border: none;
}

.site-footer ul {
  list-style: none;
  padding: 0;
  margin: 0;
}

.site-footer li {
  margin-bottom: 0.5rem;
}

.site-footer a {
  color: var(--color-text-muted);
}

.site-footer a:hover {
  color: var(--color-link);
}

.site-footer-meta {
  max-width: var(--content-max-wide);
  margin: 2rem auto 0;
  padding-top: 1.5rem;
  border-top: 1px solid var(--color-border-strong);
  color: var(--color-text-muted);
  font-size: 0.85rem;
}

/* Hero on landing page */
.hero {
  padding: 4rem 0 3rem;
  border-bottom: 1px solid var(--color-border);
  margin-bottom: 2rem;
}

.hero-title {
  font-size: 2.75rem;
  margin: 0 0 1rem;
  border: none;
  padding: 0;
  letter-spacing: -0.02em;
}

.hero-tagline {
  font-size: 1.25rem;
  color: var(--color-text-muted);
  margin: 0 0 1.5rem;
  max-width: 36rem;
}

.hero-version {
  font-size: 0.95rem;
  color: var(--color-text-muted);
  margin: 0;
}

.hero-version strong {
  color: var(--color-text);
}

.hero-actions {
  margin-top: 2rem;
  display: flex;
  gap: 1rem;
  flex-wrap: wrap;
}

.btn {
  display: inline-block;
  padding: 0.7rem 1.4rem;
  font-size: 0.95rem;
  font-weight: 500;
  text-decoration: none;
  border-radius: 3px;
  border: 1px solid var(--color-text);
  transition: all 0.15s;
}

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

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

.btn-secondary {
  background: transparent;
  color: var(--color-text);
}

.btn-secondary:hover {
  background: var(--color-bg-subtle);
  text-decoration: none;
}

/* Section cards on landing page */
.section-grid {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(18rem, 1fr));
  gap: 1.5rem;
  margin: 2rem 0 3rem;
}

.section-card {
  padding: 1.5rem;
  border: 1px solid var(--color-border);
  border-radius: 4px;
  text-decoration: none;
  color: inherit;
  transition: border-color 0.15s, transform 0.15s;
}

.section-card:hover {
  border-color: var(--color-text);
  text-decoration: none;
  transform: translateY(-2px);
}

.section-card h3 {
  margin: 0 0 0.5rem;
  font-size: 1.1rem;
  color: var(--color-text);
}

.section-card p {
  margin: 0;
  color: var(--color-text-muted);
  font-size: 0.95rem;
}

/* 404 page */
.error-page {
  text-align: center;
  padding: 4rem 0;
}

.error-code {
  font-size: 5rem;
  font-weight: 700;
  color: var(--color-text-muted);
  margin: 0 0 0.5rem;
  letter-spacing: -0.04em;
}

/* Responsive */
@media (max-width: 640px) {
  .site-header-inner {
    flex-direction: column;
    align-items: flex-start;
  }
  
  .site-nav {
    gap: 1rem;
    flex-wrap: wrap;
  }
  
  .hero-title {
    font-size: 2rem;
  }
  
  h1 {
    font-size: 1.75rem;
  }
  
  h2 {
    font-size: 1.35rem;
  }
}

/* Focus states for keyboard navigation */
*:focus-visible {
  outline: 2px solid var(--color-link);
  outline-offset: 3px;
  border-radius: 2px;
}

/* Print styles */
@media print {
  .site-header, .site-footer, .breadcrumb {
    display: none;
  }
  .site-main {
    max-width: 100%;
  }
}