/* ============================================================
   Unboxing Software — global stylesheet
   Plain CSS, no build step. Mobile-first, then tablet/desktop.
   Colour palette chosen for WCAG AA contrast and colour-blind safety
   (no information conveyed by hue alone; blue/orange pairing is
   distinguishable across all common colour-vision deficiencies).
   ============================================================ */

:root {
  --color-bg: #ffffff;
  --color-bg-alt: #f4f6f9;
  --color-text: #16202a;
  --color-text-muted: #45525f;
  --color-primary: #1a4d7a;      /* deep blue - headings, links */
  --color-primary-dark: #0f3452;
  --color-accent: #c9631a;       /* burnt orange - CTAs, focus accents */
  --color-accent-dark: #9c4b12;
  --color-border: #d7dde3;
  --color-focus: #c9631a;
  --max-width: 72rem;
  --radius: 0.5rem;
  --font-base: -apple-system, "Segoe UI", Roboto, Helvetica, Arial, sans-serif;
}

/* Reset */
*, *::before, *::after { box-sizing: border-box; }
html { -webkit-text-size-adjust: 100%; }
body, h1, h2, h3, h4, p, ul, ol, figure { margin: 0; }
ul, ol { padding: 0; }
img { max-width: 100%; height: auto; display: block; }

body {
  font-family: var(--font-base);
  color: var(--color-text);
  background: var(--color-bg);
  line-height: 1.6;
  font-size: 1.0625rem;
}

/* Respect reduced-motion preference */
@media (prefers-reduced-motion: reduce) {
  * { animation-duration: 0.001ms !important; animation-iteration-count: 1 !important; transition-duration: 0.001ms !important; scroll-behavior: auto !important; }
}

/* Visible, high-contrast focus for keyboard and switch-device users */
a:focus-visible,
button:focus-visible,
summary:focus-visible {
  outline: 3px solid var(--color-focus);
  outline-offset: 2px;
  border-radius: 2px;
}

/* Skip link */
.skip-link {
  position: absolute;
  left: -999px;
  top: auto;
  background: var(--color-primary-dark);
  color: #fff;
  padding: 0.75rem 1.25rem;
  z-index: 100;
  border-radius: 0 0 var(--radius) 0;
}
.skip-link:focus {
  left: 0;
  top: 0;
}

/* Layout helpers */
.container {
  max-width: var(--max-width);
  margin-inline: auto;
  padding-inline: 1.25rem;
}

/* ---------- Header ---------- */
.site-header {
  border-bottom: 1px solid var(--color-border);
  background: var(--color-bg);
  position: sticky;
  top: 0;
  z-index: 20;
}

.header-inner {
  display: flex;
  flex-wrap: wrap;
  align-items: center;
  justify-content: space-between;
  padding-block: 0.9rem;
}

.site-logo {
  display: flex;
  align-items: center;
  gap: 0.6rem;
  font-weight: 700;
  font-size: 1.25rem;
  color: var(--color-primary-dark);
  text-decoration: none;
}
.site-logo:hover,
.site-logo:focus-visible { text-decoration: underline; }
.site-logo svg { flex-shrink: 0; }

.nav-toggle {
  display: inline-flex;
  align-items: center;
  gap: 0.5rem;
  background: var(--color-bg);
  border: 1px solid var(--color-border);
  border-radius: var(--radius);
  padding: 0.5rem 0.75rem;
  font-size: 1rem;
  color: var(--color-text);
  cursor: pointer;
}
.nav-toggle .icon-bar { display: block; width: 20px; height: 2px; background: currentColor; position: relative; }
.nav-toggle .icon-bar::before,
.nav-toggle .icon-bar::after {
  content: "";
  position: absolute;
  left: 0;
  width: 20px;
  height: 2px;
  background: currentColor;
}
.nav-toggle .icon-bar::before { top: -6px; }
.nav-toggle .icon-bar::after { top: 6px; }

.primary-nav {
  flex-basis: 100%;
  width: 100%;
  margin-top: 0.75rem;
  padding-top: 0.5rem;
  border-top: 1px solid var(--color-border);
}
.primary-nav ul {
  list-style: none;
  display: flex;
  flex-direction: column;
  gap: 0.25rem;
}
.primary-nav[data-open="false"] { display: none; }
.primary-nav a {
  display: block;
  padding: 0.6rem 0.25rem;
  color: var(--color-text);
  text-decoration: none;
  font-weight: 600;
  border-bottom: 1px solid var(--color-border);
}
.primary-nav a:hover,
.primary-nav a[aria-current="page"] {
  color: var(--color-primary);
}
.primary-nav a[aria-current="page"] {
  text-decoration: underline;
  text-decoration-color: var(--color-accent);
  text-decoration-thickness: 3px;
  text-underline-offset: 4px;
}
.primary-nav .nav-external {
  display: inline-flex;
  align-items: center;
  gap: 0.35rem;
}

@media (min-width: 56rem) {
  .nav-toggle { display: none; }
  .header-inner { flex-wrap: nowrap; }
  .primary-nav {
    flex-basis: auto;
    width: auto;
    margin-top: 0;
    padding-top: 0;
    border-top: none;
  }
  .primary-nav[data-open="false"] { display: block; }
  .primary-nav ul { flex-direction: row; gap: 1.75rem; }
  .primary-nav a { border-bottom: none; padding: 0.25rem 0; }
}

/* ---------- Hero ---------- */
.hero {
  background: linear-gradient(180deg, var(--color-bg-alt) 0%, var(--color-bg) 100%);
  padding-block: 3rem 2.5rem;
  border-bottom: 1px solid var(--color-border);
}
.hero h1 {
  font-size: clamp(1.9rem, 4vw, 2.75rem);
  color: var(--color-primary-dark);
  line-height: 1.2;
  max-width: 40ch;
}
.hero .lede {
  margin-top: 1rem;
  font-size: 1.2rem;
  color: var(--color-text-muted);
  max-width: 60ch;
}
.hero-actions {
  margin-top: 1.75rem;
  display: flex;
  flex-wrap: wrap;
  gap: 0.9rem;
}

/* ---------- Buttons ---------- */
.btn {
  display: inline-flex;
  align-items: center;
  gap: 0.5rem;
  padding: 0.75rem 1.25rem;
  border-radius: var(--radius);
  font-weight: 700;
  text-decoration: none;
  border: 2px solid transparent;
  font-size: 1rem;
  cursor: pointer;
}
.btn-primary {
  background: var(--color-primary);
  color: #fff;
}
.btn-primary:hover { background: var(--color-primary-dark); }
.btn-secondary {
  background: transparent;
  color: var(--color-primary-dark);
  border-color: var(--color-primary-dark);
}
.btn-secondary:hover { background: var(--color-bg-alt); }

/* ---------- Main content sections ---------- */
main { display: block; }

.section {
  padding-block: 3rem;
}
.section + .section { border-top: 1px solid var(--color-border); }
.section h2 {
  font-size: 1.75rem;
  color: var(--color-primary-dark);
}
.section .section-intro {
  margin-top: 0.75rem;
  color: var(--color-text-muted);
  max-width: 65ch;
  font-size: 1.05rem;
}

.about-content p { margin-top: 1rem; max-width: 68ch; }

/* ---------- Track cards ---------- */
.track-grid {
  margin-top: 2rem;
  display: grid;
  gap: 1.5rem;
  grid-template-columns: 1fr;
}
@media (min-width: 40rem) {
  .track-grid { grid-template-columns: repeat(3, 1fr); }
}

.track-card {
  border: 1px solid var(--color-border);
  border-radius: var(--radius);
  padding: 1.5rem;
  background: var(--color-bg-alt);
  display: flex;
  flex-direction: column;
  gap: 0.75rem;
  text-decoration: none;
  color: inherit;
  border-top: 4px solid var(--color-primary);
}
.track-card:hover,
.track-card:focus-visible {
  border-top-color: var(--color-accent);
  background: #eef2f7;
}
.track-card .track-label {
  font-size: 0.8rem;
  font-weight: 700;
  letter-spacing: 0.04em;
  text-transform: uppercase;
  color: var(--color-accent-dark);
}
.track-card h3 {
  font-size: 1.3rem;
  color: var(--color-primary-dark);
}
.track-card p {
  color: var(--color-text-muted);
  flex-grow: 1;
}
.track-card .track-cta {
  font-weight: 700;
  color: var(--color-primary);
}

/* ---------- Breadcrumbs ---------- */
.breadcrumbs {
  padding-block: 1rem;
  font-size: 0.95rem;
  color: var(--color-text-muted);
}
.breadcrumbs ol {
  list-style: none;
  display: flex;
  flex-wrap: wrap;
  gap: 0.4rem;
}
.breadcrumbs a { color: var(--color-primary); }
.breadcrumbs li:not(:last-child)::after {
  content: "/";
  margin-left: 0.4rem;
  color: var(--color-border);
}
.breadcrumbs [aria-current="page"] { color: var(--color-text); }

/* ---------- Article list (track pages) ---------- */
.article-list {
  margin-top: 2rem;
  list-style: none;
  display: flex;
  flex-direction: column;
  gap: 1rem;
}
.article-list li {
  border: 1px solid var(--color-border);
  border-radius: var(--radius);
  padding: 1.25rem 1.5rem;
}
.article-list a {
  font-weight: 700;
  font-size: 1.1rem;
  color: var(--color-primary-dark);
}
.article-list p {
  margin-top: 0.4rem;
  color: var(--color-text-muted);
}

.empty-state {
  margin-top: 2rem;
  padding: 1.75rem;
  border: 1px dashed var(--color-border);
  border-radius: var(--radius);
  color: var(--color-text-muted);
  background: var(--color-bg-alt);
}

/* ---------- Article page ---------- */
.article-header h1 {
  font-size: clamp(1.6rem, 3.5vw, 2.25rem);
  color: var(--color-primary-dark);
}
.article-meta {
  margin-top: 0.6rem;
  color: var(--color-text-muted);
  font-size: 0.95rem;
}
.article-body {
  margin-top: 1.75rem;
  max-width: 68ch;
}
.article-body h2 { margin-top: 2rem; font-size: 1.4rem; color: var(--color-primary-dark); }
.article-body h3 { margin-top: 1.5rem; font-size: 1.15rem; color: var(--color-primary-dark); }
.article-body h4 { margin-top: 1.25rem; font-size: 1.02rem; color: var(--color-primary-dark); }
.article-body p { margin-top: 1rem; }
.article-body ul,
.article-body ol { margin-top: 1rem; padding-left: 1.5rem; }
.article-body li > ul,
.article-body li > ol { margin-top: 0.5rem; }

.article-body ul.triangle-examples {
  list-style: none;
  padding-left: 0;
}
.article-body ul.triangle-examples li {
  display: flex;
  align-items: center;
  gap: 1.25rem;
  margin-top: 1rem;
}
.tri-icon {
  flex-shrink: 0;
  height: 56px;
  width: auto;
}

.article-body code {
  font-family: ui-monospace, SFMono-Regular, Menlo, Consolas, monospace;
  background: var(--color-bg-alt);
  padding: 0.15em 0.4em;
  border-radius: 4px;
  font-size: 0.9em;
}
.article-body pre {
  margin-top: 1rem;
  padding: 1rem 1.25rem;
  background: var(--color-bg-alt);
  border: 1px solid var(--color-border);
  border-radius: var(--radius);
  overflow-x: auto;
}
.article-body pre code {
  background: none;
  padding: 0;
}

.code-block {
  margin-top: 1.25rem;
}
.code-block .code-label {
  margin-top: 0;
  font-size: 0.8rem;
  font-weight: 700;
  letter-spacing: 0.03em;
  text-transform: uppercase;
  color: var(--color-text-muted);
}
.code-block pre {
  margin-top: 0.4rem;
}

/* Syntax-highlight tokens (applied by js/syntax-highlight.js). Each category
   is distinguished by weight/style as well as hue, not color alone. */
.tok-kw { color: #6c3fa8; font-weight: 700; }
.tok-str { color: #1f7a52; }
.tok-num { color: #b3521e; }
.tok-com { color: #5c6773; font-style: italic; }
.tok-fn { color: var(--color-primary); }

.article-body blockquote {
  margin-top: 1rem;
  padding: 0.25rem 1.25rem;
  border-left: 4px solid var(--color-accent);
  color: var(--color-text-muted);
  font-style: italic;
}

.article-body figure {
  margin: 1.5rem 0 0;
}
.article-body figcaption {
  margin-top: 0.5rem;
  font-size: 0.9rem;
  color: var(--color-text-muted);
  text-align: center;
}
.article-body .flowchart-wrap {
  overflow-x: auto;
  padding: 0.5rem 0;
}
.article-body .flowchart-wrap svg {
  display: block;
  margin: 0 auto;
  max-width: 460px;
  width: 100%;
  height: auto;
}

.article-body .table-scroll {
  margin-top: 1rem;
  overflow-x: auto;
}
.article-body table {
  border-collapse: collapse;
  width: 100%;
  min-width: 480px;
}
.article-body th,
.article-body td {
  border: 1px solid var(--color-border);
  padding: 0.6rem 0.9rem;
  text-align: left;
  vertical-align: top;
}
.article-body th {
  background: var(--color-bg-alt);
  color: var(--color-primary-dark);
}
.shape-cell {
  display: flex;
  align-items: center;
  gap: 0.75rem;
  white-space: nowrap;
}
.shape-icon {
  flex-shrink: 0;
  height: 30px;
  width: auto;
}

.article-body ul.file-tree {
  list-style: none;
  margin-top: 1rem;
  padding: 1rem 1.25rem;
  background: var(--color-bg-alt);
  border: 1px solid var(--color-border);
  border-radius: var(--radius);
  overflow-x: auto;
}
.article-body ul.file-tree ul {
  list-style: none;
  margin-top: 0;
  padding-left: 1.4rem;
}
.article-body ul.file-tree li {
  padding: 0.15rem 0;
}
.tree-label {
  display: inline-flex;
  align-items: center;
  gap: 0.45rem;
  font-family: ui-monospace, SFMono-Regular, Menlo, Consolas, monospace;
  font-size: 0.9rem;
  white-space: nowrap;
}
.tree-comment {
  margin-left: 0.6rem;
  color: var(--color-text-muted);
  font-style: italic;
}
.tree-icon {
  flex-shrink: 0;
  width: 16px;
  height: 14px;
}

.video-callout {
  margin-top: 2.5rem;
  padding: 1.5rem;
  border: 1px solid var(--color-border);
  border-radius: var(--radius);
  background: var(--color-bg-alt);
  display: flex;
  flex-wrap: wrap;
  gap: 1rem;
  align-items: center;
  justify-content: space-between;
}
.video-callout p { color: var(--color-text-muted); max-width: 40ch; }

.article-nav {
  margin-top: 2.5rem;
  padding-top: 1.5rem;
  border-top: 1px solid var(--color-border);
  display: flex;
  justify-content: flex-end;
}

/* ---------- Footer ---------- */
.site-footer {
  border-top: 1px solid var(--color-border);
  background: var(--color-bg-alt);
  padding-block: 2.5rem;
  margin-top: 3rem;
}
.footer-inner {
  display: flex;
  flex-direction: column;
  gap: 1.25rem;
}
@media (min-width: 40rem) {
  .footer-inner { flex-direction: row; justify-content: space-between; align-items: flex-start; }
}
.footer-nav ul {
  list-style: none;
  display: flex;
  flex-wrap: wrap;
  gap: 1rem 1.5rem;
}
.footer-nav a { color: var(--color-primary-dark); text-decoration: none; }
.footer-nav a:hover { text-decoration: underline; }
.footer-copy {
  color: var(--color-text-muted);
  font-size: 0.9rem;
}

/* ---------- Cookie consent banner ---------- */
.cookie-banner {
  display: none;
  position: fixed;
  left: 0;
  right: 0;
  bottom: 0;
  z-index: 100;
  background: var(--color-primary-dark);
  color: #ffffff;
  border-top: 3px solid var(--color-accent);
  padding-block: 1rem;
  padding-bottom: calc(1rem + env(safe-area-inset-bottom, 0px));
}
.cookie-banner.is-visible {
  display: block;
}
.cookie-banner-inner {
  display: flex;
  flex-wrap: wrap;
  align-items: center;
  justify-content: space-between;
  gap: 1rem;
}
.cookie-banner p {
  margin: 0;
  flex: 1 1 320px;
  font-size: 0.95rem;
}
.cookie-banner-actions {
  display: flex;
  gap: 0.75rem;
  flex-wrap: wrap;
  flex-shrink: 0;
}
.cookie-banner .btn-primary {
  background: var(--color-accent-dark);
  color: #ffffff;
}
.cookie-banner .btn-primary:hover {
  box-shadow: 0 0 0 2px rgba(255, 255, 255, 0.5);
}
.cookie-banner .btn-secondary {
  background: transparent;
  color: #ffffff;
  border-color: #ffffff;
}
.cookie-banner .btn-secondary:hover {
  background: rgba(255, 255, 255, 0.12);
}

/* Visually-hidden but screen-reader accessible text */
.visually-hidden {
  position: absolute;
  width: 1px; height: 1px;
  padding: 0; margin: -1px;
  overflow: hidden;
  clip: rect(0,0,0,0);
  white-space: nowrap;
  border: 0;
}