/* High-contrast, colorblind-safe theme
   WCAG AA+: body ≥4.5:1, large headings ≥3:1 on black.
   Do not rely on red vs green alone. */

:root {
  /* Core palette */
  --bg: #000000;
  --text-primary: #F2F2F2;    /* ~18.4:1 on black */
  --text-secondary: #CCCCCC;  /* ~12:1 on black */
  --text-muted: #999999;      /* ~7:1 on black */
  --text-disabled: #666666;   /* ~4.5:1 on black */

  /* Borders and dividers */
  --border: #444444;
  --border-light: #333333;
  --divider: #222222;

  /* Interactive + headings (amber + cyan: distinguishable with deuteranopia/protanopia) */
  --heading: #FFD60A;         /* amber – ~14:1 on black, not red/green */
  --link: #4CC9F0;            /* cyan – ~10:1 on black */
  --link-hover: #7DDAF5;
  --accent: #FFD60A;
  --accent-hover: #FFE566;
  --focus-ring: #FFFFFF;      /* 3px solid white */

  /* Surfaces / cards */
  --surface: #161616;
  --surface-hover: #1E1E1E;

  /* Buttons */
  --btn-bg: #FFD60A;
  --btn-text: #000000;        /* ~14:1 on amber */

  /* Legacy aliases so leftover var() references stay valid and readable */
  --medium-gray: var(--text-primary);
  --light-text: var(--text-primary);
  --bright-pink: var(--heading);
  --bright-magenta: var(--heading);
  --light-cyan: var(--link);
  --hot-pink: var(--heading);
  --soft-pink: var(--text-primary);
  --pink: var(--heading);
}

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

html {
  color-scheme: dark;
}

body {
  background: var(--bg);
  color: var(--text-primary);
  font-family: 'Courier New', monospace, sans-serif;
  line-height: 1.8;
  min-height: 100vh;
  max-width: 900px;
  margin: 0 auto;
  padding: 2rem 1.5rem;
  position: relative;
}

header {
  margin-bottom: 4rem;
}

.main-nav {
  display: flex;
  flex-wrap: wrap;
  justify-content: space-between;
  align-items: center;
  padding: 1.5rem 0;
  border-bottom: 2px dashed var(--heading);
  gap: 1rem;
}

.nav-left, .nav-right {
  display: flex;
  gap: 2rem;
  flex-wrap: wrap;
  align-items: center;
}

.main-nav a {
  color: var(--link);
  text-decoration: underline;
  font-weight: bold;
  transition: color 0.2s ease, background 0.2s ease;
  padding: 0.4rem 0.8rem;
  border-radius: 4px;
  outline-offset: 2px;
}

.main-nav a:hover,
.main-nav a.active {
  color: var(--btn-text);
  background: var(--heading);
  text-decoration: underline;
  text-shadow: none;
}

.main-nav a:focus,
.main-nav a:focus-visible {
  outline: 3px solid var(--focus-ring);
  background: #222222;
}

.nav-sep {
  color: var(--text-secondary);
}

.buy-cta,
.nav-call-to {
  background: var(--btn-bg) !important;
  color: var(--btn-text) !important;
  padding: 0.8rem 1.6rem !important;
  border-radius: 8px;
  font-weight: bold;
  min-width: 44px;
  min-height: 44px;
  text-decoration: underline;
  transition: background 0.2s ease, color 0.2s ease;
}

.buy-cta:hover,
.nav-call-to:hover {
  background: var(--accent-hover) !important;
  color: var(--btn-text) !important;
  box-shadow: 0 0 0 2px var(--focus-ring);
}

.buy-cta:focus,
.buy-cta:focus-visible,
.nav-call-to:focus,
.nav-call-to:focus-visible {
  outline: 3px solid var(--focus-ring);
  outline-offset: 2px;
}

blockquote {
  font-size: 1.5rem;
  font-style: italic;
  text-align: center;
  margin: 3rem 0;
  padding: 2rem;
  color: var(--text-primary);
  border-left: 6px solid var(--heading);
  background: var(--surface);
  border-radius: 4px;
}

h1, h2, h3, h4, h5, h6 {
  color: var(--heading);
  margin: 2.5rem 0 1.5rem;
  text-shadow: none;
  font-weight: bold;
}

h1 {
  font-size: 2.8rem;
  text-align: center;
  color: var(--heading);
}

h2 {
  font-size: 2rem;
  color: var(--heading);
}

h3 {
  font-size: 1.6rem;
  color: var(--heading);
}

h4, h5, h6 {
  font-size: 1.4rem;
  color: var(--text-primary);
}

p, li {
  margin-bottom: 1.2rem;
  padding: 0 1rem;
  max-width: 900px;
  color: var(--text-primary);
}

ul, ol {
  margin: 1.5rem 0;
  padding-left: 3rem;
}

li {
  margin-bottom: 0.8rem;
  color: var(--text-primary);
}

a {
  color: var(--link);
  text-decoration: underline;
  transition: color 0.2s ease;
}

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

a:focus,
a:focus-visible {
  outline: 3px solid var(--focus-ring);
  outline-offset: 2px;
  border-radius: 2px;
}

input, textarea, select {
  background: var(--surface);
  color: var(--text-primary);
  border: 2px solid var(--border);
  padding: 0.8rem;
  font-family: inherit;
  border-radius: 4px;
  min-height: 44px;
  font-size: 16px;
}

input::placeholder, textarea::placeholder {
  color: var(--text-muted);
  opacity: 1;
}

input:focus, textarea:focus, select:focus {
  outline: 3px solid var(--focus-ring);
  outline-offset: 2px;
  border-color: var(--heading);
}

label {
  margin-bottom: 0.5rem;
  color: var(--text-primary);
  font-weight: bold;
}

table {
  width: 100%;
  border-collapse: collapse;
  margin: 3rem 0;
  background: var(--surface);
  color: var(--text-primary);
  border: 1px solid var(--border);
}

th, td {
  border: 1px solid var(--border);
  padding: 0.75rem 1rem;
  color: var(--text-primary);
}

th {
  color: var(--heading);
  text-align: left;
}

/* Dropdown */
.dropdown {
  position: relative;
  display: inline-block;
}

.dropbtn {
  background: none;
  border: none;
  font-size: 1rem;
  font-weight: 500;
  color: var(--text-primary);
  cursor: pointer;
  padding: 0.5rem 0;
  display: flex;
  align-items: center;
  gap: 0.4rem;
  text-decoration: underline;
}

.dropbtn:focus,
.dropbtn:focus-visible {
  outline: 3px solid var(--focus-ring);
  outline-offset: 2px;
}

.dropdown-content {
  position: absolute;
  color: var(--text-primary);
  background-color: var(--surface);
  min-width: 280px;
  box-shadow: 0 8px 20px rgba(0, 0, 0, 0.6);
  border: 1px solid var(--border);
  border-radius: 8px;
  z-index: 1000;
  top: 100%;
  right: 0;
  padding: 0.8rem 0;
  opacity: 0;
  visibility: hidden;
  transform: translateY(-10px);
  transition: opacity 0.25s ease, transform 0.25s ease, visibility 0.25s ease;
}

.dropdown:hover .dropdown-content,
.dropdown:focus-within .dropdown-content {
  color: var(--text-primary);
  opacity: 1;
  visibility: visible;
  transform: translateY(0);
}

.dropdown-content a {
  color: var(--link);
  padding: 0.7rem 1.2rem;
  text-align: left;
  white-space: nowrap;
  display: block;
  text-decoration: underline;
}

.dropdown-content a:hover {
  background-color: var(--surface-hover);
  color: var(--link-hover);
}

@media (max-width: 900px) {
  .main-nav { flex-direction: column; text-align: center; }
  .nav-left, .nav-right { gap: 1.5rem; justify-content: center; }
  .dropdown-content { right: auto; left: 50%; transform: translateX(-50%); }
  .dropdown:hover .dropdown-content,
  .dropdown:focus-within .dropdown-content { transform: translateX(-50%) translateY(0); }
}

.fade-section {
  opacity: 0;
  transform: translateY(20px);
  transition: opacity 0.5s ease, transform 0.5s ease;
}

.fade-section.visible {
  opacity: 1;
  transform: translateY(0);
}

.logout-btn {
  background: var(--btn-bg);
  color: var(--btn-text);
  border: 2px solid var(--heading);
  padding: 15px 30px;
  font-size: 1rem;
  border-radius: 50px;
  cursor: pointer;
  font-weight: bold;
  transition: background 0.2s ease, color 0.2s ease;
  margin-top: 20px;
}

.logout-btn:hover {
  background: var(--accent-hover);
  color: var(--btn-text);
  transform: none;
}

.logout-btn:focus,
.logout-btn:focus-visible {
  outline: 3px solid var(--focus-ring);
  outline-offset: 2px;
}

/* Riemann / tech article layout */
.project-page.tech-article,
.tech-article {
  color: var(--text-primary);
}

.project-page.tech-article .lead,
.lead {
  font-size: 1.25rem;
  color: var(--text-secondary);
  margin: 1.5rem 0 2rem;
}

.tech-grid {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(220px, 1fr));
  gap: 1.25rem;
  margin: 1.5rem 0 2rem;
}

.tech-card {
  background: var(--surface);
  color: var(--text-primary);
  border: 1px solid var(--border);
  border-radius: 8px;
  padding: 1.25rem 1.4rem;
}

.tech-card h3 {
  margin-top: 0.25rem;
  color: var(--heading);
}

.tech-card p {
  color: var(--text-secondary);
  padding: 0;
  margin-bottom: 0.5rem;
}

.big-o-grid {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(160px, 1fr));
  gap: 0.85rem;
  margin: 1.25rem 0 2rem;
}

.big-o-item {
  background: var(--surface);
  color: var(--text-primary);
  border: 1px solid var(--border);
  border-radius: 6px;
  padding: 0.85rem 1rem;
}

.big-o-item strong {
  color: var(--heading);
}

.math-section {
  background: var(--surface);
  border: 1px solid var(--border);
  border-radius: 8px;
  padding: 1.25rem 1.5rem;
  margin: 2rem 0;
  color: var(--text-primary);
}

.math-section h2 {
  margin-top: 0.5rem;
}

.video-container {
  position: relative;
  width: 100%;
  padding-bottom: 56.25%;
  height: 0;
  overflow: hidden;
  margin: 1.5rem 0;
  background: var(--surface);
  border: 1px solid var(--border);
  border-radius: 8px;
}

.video-container iframe {
  position: absolute;
  top: 0;
  left: 0;
  width: 100%;
  height: 100%;
  border: 0;
}

.tech-link {
  color: var(--link);
  text-decoration: underline;
  font-weight: bold;
  word-break: break-word;
}

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

.download-box {
  background: var(--surface);
  border: 1px solid var(--border);
  border-radius: 8px;
  padding: 1.25rem 1.5rem;
  margin: 1.5rem 0;
}

.download-box a {
  color: var(--link);
  text-decoration: underline;
}

/* MathJax 2.x / CHTML — force light glyphs on black */
.MathJax,
.MathJax_Display,
.mjx-chtml,
.MJXc-display,
.mjx-math,
.mjx-mrow,
.mjx-char,
.mjx-mi,
.mjx-mn,
.mjx-mo,
.mjx-mfrac,
math {
  color: #FFFFFF !important;
}

.menu-toggle {
  background: transparent;
  border: 2px solid var(--heading);
  color: var(--heading);
  min-width: 44px;
  min-height: 44px;
  padding: 0.4rem 0.6rem;
  cursor: pointer;
}

.menu-toggle:focus,
.menu-toggle:focus-visible {
  outline: 3px solid var(--focus-ring);
  outline-offset: 2px;
}

.user-chip {
  color: var(--text-secondary);
}

::selection {
  background: var(--heading);
  color: #000000;
}