/* pkgs.rsquaredacademy.com - hand-written stylesheet, no frameworks.
   Design ported from aravindhebbali.com/packages/ (tokens, listing cards).
   Dark mode: data-theme on <html>, set pre-paint by js/theme-init.js. */

:root {
  color-scheme: light;

  --ink: #0f172a;
  --body: #334155;
  --muted: #64748b;
  --line: #e2e8f0;
  --line-soft: #f1f5f9;
  --line-strong: #cbd5e1;
  --accent: #2563eb;
  --accent-dk: #1d4ed8;
  --surface: #ffffff;
  --canvas: #fbfcfd;
  --note-bg: #f0f9ff;
  --note-line: #e0f2fe;
  --note-ink: #075985;
  --arch-bg: #fee2e2;
  --arch-ink: #991b1b;
  --on-ink: #ffffff;
  --ink-hover: #1e293b;
  --accent-ring: rgba(37, 99, 235, 0.28);
  --shadow-md: rgba(2, 6, 23, 0.12);

  --sans: -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, Helvetica, Arial, sans-serif;
  --serif: Georgia, "Times New Roman", serif;
  --mono: ui-monospace, SFMono-Regular, Menlo, Consolas, monospace;
}

:root[data-theme="dark"] {
  color-scheme: dark;

  --ink: #f8fafc;
  --body: #e2e8f0;
  --muted: #a8b6c8;
  --line: #24334a;
  --line-soft: #182338;
  --line-strong: #3d4d66;
  --accent: #7cc0ff;
  --accent-dk: #a8d3ff;
  --surface: #0f172a;
  --canvas: #020617;
  --note-bg: #0c2436;
  --note-line: #123a52;
  --note-ink: #8fdcff;
  --arch-bg: #331318;
  --arch-ink: #ffb3b3;
  --on-ink: #0f172a;
  --ink-hover: #e2e8f0;
  --accent-ring: rgba(124, 192, 255, 0.34);
  --shadow-md: rgba(2, 6, 23, 0.6);
}

/* ---------- base ---------- */

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

body {
  margin: 0;
  font-family: var(--sans);
  font-size: 1rem;
  line-height: 1.6;
  color: var(--body);
  background: var(--canvas);
  -webkit-font-smoothing: antialiased;
  text-align: left;
}

h1,
h2,
h3 {
  font-family: var(--serif);
  color: var(--ink);
  font-weight: 600;
  letter-spacing: -0.015em;
  line-height: 1.25;
  margin: 0;
}

p {
  margin: 0 0 1.1rem;
}

a {
  color: var(--accent);
  text-decoration: none;
  border-bottom: 1px solid var(--accent-ring);
}

a:hover {
  color: var(--accent-dk);
  border-bottom-color: var(--accent-dk);
}

a:focus-visible,
button:focus-visible,
summary:focus-visible {
  outline: 2px solid var(--accent);
  outline-offset: 2px;
  border-radius: 4px;
}

code {
  font-family: var(--mono);
  font-size: 0.875em;
  color: var(--ink);
  background: var(--line-soft);
  padding: 0.1em 0.35em;
  border-radius: 3px;
}

img {
  max-width: 100%;
  height: auto;
}

.container {
  max-width: 1060px;
  margin: 0 auto;
  padding: 0 1.25rem;
}

.visually-hidden {
  position: absolute;
  width: 1px;
  height: 1px;
  margin: -1px;
  padding: 0;
  overflow: hidden;
  clip: rect(0 0 0 0);
  white-space: nowrap;
  border: 0;
}

.skip-link {
  position: absolute;
  left: -9999px;
  top: 0;
  background: var(--surface);
  color: var(--ink);
  padding: 0.5rem 0.9rem;
  z-index: 100;
  border: 1px solid var(--line);
}

.skip-link:focus {
  left: 0.5rem;
  top: 0.5rem;
}

/* ---------- header / nav ---------- */

.site-header {
  position: sticky;
  top: 0;
  z-index: 50;
  background: var(--surface);
  border-bottom: 1px solid var(--line);
}

.site-nav {
  display: flex;
  align-items: center;
  gap: 1.25rem;
  min-height: 3.5rem;
  flex-wrap: wrap;
}

.brand {
  font-family: var(--serif);
  font-weight: 700;
  font-size: 1.05rem;
  color: var(--ink);
  border-bottom: 0;
}

.brand:hover {
  color: var(--accent);
}

.nav-links {
  display: flex;
  align-items: center;
  gap: 1.1rem;
  list-style: none;
  margin: 0;
  padding: 0;
  font-size: 0.9375rem;
  flex-wrap: wrap;
}

.nav-links a {
  color: var(--body);
  border-bottom: 0;
}

.nav-links a:hover,
.nav-links a[aria-current="page"] {
  color: var(--accent);
}

.nav-right {
  margin-left: auto;
  display: flex;
  align-items: center;
  gap: 0.9rem;
}

.nav-icon {
  display: inline-flex;
  color: var(--body);
  border-bottom: 0;
}

.nav-icon:hover {
  color: var(--accent);
}

.nav-icon svg,
.theme-toggle svg {
  width: 1.15rem;
  height: 1.15rem;
  display: block;
}

.theme-toggle {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  width: 2.25rem;
  height: 2.25rem;
  padding: 0;
  background: var(--surface);
  color: var(--body);
  border: 1px solid var(--line-strong);
  border-radius: 9px;
  cursor: pointer;
}

.theme-toggle:hover {
  background: var(--line-soft);
  color: var(--ink);
}

.theme-toggle .icon-sun {
  display: none;
}

:root[data-theme="dark"] .theme-toggle .icon-sun {
  display: block;
}

:root[data-theme="dark"] .theme-toggle .icon-moon {
  display: none;
}

/* ---------- hero ---------- */

.hero {
  padding: 3rem 0 1.5rem;
}

.hero h1 {
  font-size: 2.25rem;
  font-weight: 700;
  margin-bottom: 0.9rem;
}

.hero .lede {
  font-size: 1.0625rem;
  color: var(--ink);
  max-width: 68ch;
}

.hero p {
  max-width: 68ch;
}

.hero .lede {
  color: var(--muted);
}

/* ---------- sections ---------- */

.listing {
  padding-bottom: 1rem;
}

.listing h2 {
  font-size: 1.5rem;
  margin: 3.5rem 0 1.25rem;
  padding-bottom: 0.6rem;
  border-bottom: 1px solid var(--line);
}

.lgrid {
  display: grid;
  grid-template-columns: repeat(3, 1fr);
  gap: 18px;
  margin: 0 0 2rem;
}

.lgrid-h {
  grid-template-columns: repeat(2, 1fr);
}

/* ---------- cards ---------- */

.lcard {
  background: var(--surface);
  border: 1px solid var(--line);
  border-radius: 14px;
  overflow: hidden;
  display: flex;
  flex-direction: column;
  transition: transform 0.15s ease, box-shadow 0.15s ease;
}

.lcard:hover {
  transform: translateY(-3px);
  box-shadow: 0 14px 34px var(--shadow-md);
}

.lcard-h {
  flex-direction: row;
  align-items: flex-start;
  padding: 1rem 1.15rem;
}

.lside {
  flex: 0 0 auto;
  width: 108px;
  display: flex;
  flex-direction: column;
  align-items: center;
  gap: 0.55rem;
  margin-right: 1.15rem;
}

.lside > p {
  margin: 0;
  line-height: 0;
}

.lcover-hex {
  max-height: 100px;
  width: auto;
  display: block;
  margin: 0;
}

.lbody {
  padding: 0.9rem 1rem 1rem;
  display: flex;
  flex-direction: column;
  gap: 0.5rem;
  flex: 1;
  min-width: 0;
}

.lcard-h .lbody {
  padding: 0;
  gap: 0.75rem;
}

.lbody h3 {
  font-family: var(--serif);
  font-size: 1.15rem;
  margin: 0;
  line-height: 1.25;
}

.lbody h3 a {
  color: var(--ink);
  border-bottom: 0;
}

.lbody h3 a:hover {
  color: var(--accent);
}

.lbody ul {
  padding-left: 1.05rem;
  margin: 0;
}

.lbody li {
  margin-bottom: 0.15rem;
}

.ltrack {
  font-family: var(--mono);
  font-size: 0.6875rem;
  font-weight: 700;
  letter-spacing: 0.14em;
  text-transform: uppercase;
  color: var(--accent);
  margin: 0;
}

.ltrack.util {
  color: var(--muted);
}

.ltrack.arch {
  color: var(--arch-ink);
}

.lout {
  color: var(--muted);
  font-size: 0.875rem;
  line-height: 1.5;
  margin: 0;
}

.lcard-h .lbody .lout {
  margin-top: 0.25rem;
}

.lmeta {
  font-size: 0.78125rem;
  color: var(--muted);
  margin: 0;
}

.lpill {
  display: inline-block;
  font-size: 0.6875rem;
  font-weight: 700;
  border-radius: 999px;
  padding: 0.1rem 0.55rem;
  background: var(--note-bg);
  color: var(--note-ink);
  margin-right: 5px;
}

.lpill.arch {
  background: var(--arch-bg);
  color: var(--arch-ink);
}

.lprereq {
  font-size: 0.78125rem;
  line-height: 1.5;
  color: var(--note-ink);
  background: var(--note-bg);
  border: 1px solid var(--note-line);
  border-radius: 8px;
  padding: 0.35rem 0.5rem;
  margin: 0;
}

.lcard-h .lbody .lprereq {
  margin-top: 0.4rem;
}

/* ---------- actions (link buttons) ---------- */

.lactions {
  display: flex;
  flex-wrap: wrap;
  gap: 8px;
  margin-top: 0.15rem;
  width: 100%;
}

.lcard-h .lactions > .lactions-row,
.lactions-row {
  display: flex;
  flex-wrap: wrap;
  gap: 8px;
  margin: 0;
  width: 100%;
}

.lcard-h .lactions {
  flex-direction: column;
}

.lcard-h .lactions .lactions-row {
  flex-direction: column;
  align-items: stretch;
  gap: 5px;
}

.lbtn {
  display: inline-block;
  font-size: 0.8125rem;
  font-weight: 700;
  line-height: 1.3;
  text-decoration: none;
  padding: 0.4rem 0.7rem;
  border: 1px solid var(--line-strong);
  border-radius: 9px;
  color: var(--ink);
  background: var(--surface);
  text-align: center;
}

.lbtn:hover {
  color: var(--ink);
  background: var(--line-soft);
}

.lbtn.primary {
  background: var(--ink);
  border-color: var(--ink);
  color: var(--on-ink);
}

.lbtn.primary:hover {
  background: var(--ink-hover);
  border-color: var(--ink-hover);
  color: var(--on-ink);
}

/* ---------- details ("What's inside") ---------- */

.lbody details {
  font-size: 0.8125rem;
  color: var(--body);
  background: var(--canvas);
  border: 1px solid var(--line);
  border-radius: 9px;
  padding: 0.4rem 0.55rem;
  margin-top: 0.2rem;
}

.lcard-h .lbody details {
  margin-top: 0.5rem;
}

.lbody details summary {
  cursor: pointer;
  font-weight: 600;
  color: var(--ink);
}

.lbody details ul {
  margin: 0.5rem 0 0;
}

/* ---------- footer ---------- */

.site-footer {
  border-top: 1px solid var(--line);
  margin-top: 3rem;
  padding: 1.75rem 0 2.5rem;
  font-size: 0.875rem;
  color: var(--muted);
}

.site-footer p {
  margin: 0 0 0.75rem;
}

.social {
  display: flex;
  flex-wrap: wrap;
  gap: 1.1rem;
  list-style: none;
  margin: 0;
  padding: 0;
}

.social a {
  display: inline-flex;
  align-items: center;
  gap: 0.4rem;
  color: var(--muted);
  border-bottom: 0;
}

.social a:hover {
  color: var(--accent);
}

.social svg {
  width: 1.05rem;
  height: 1.05rem;
}

/* ---------- responsive ---------- */

@media (max-width: 900px) {
  .lgrid,
  .lgrid-h {
    grid-template-columns: 1fr;
  }

  .lcard-h {
    flex-direction: column;
    align-items: center;
    text-align: left;
  }

  .lside {
    width: 100%;
    margin-right: 0;
    margin-bottom: 0.9rem;
  }

  .lcard-h .lactions {
    flex-direction: row;
    justify-content: center;
  }

  .lcard-h .lactions .lactions-row {
    flex-direction: row;
    justify-content: center;
    flex-wrap: wrap;
  }
}

@media (max-width: 560px) {
  .hero {
    padding-top: 2rem;
  }

  .hero h1 {
    font-size: 1.75rem;
  }

  .listing h2 {
    font-size: 1.3rem;
  }
}

@media (prefers-reduced-motion: reduce) {
  .lcard {
    transition: none;
  }

  .lcard:hover {
    transform: none;
  }
}