/* ==========================================================================
   ScalpelSpace - site styles
   Single stylesheet, no build step, no dependencies.
   ========================================================================== */

/* --- Tokens ------------------------------------------------------------- */

:root {
  --bg: #ffffff;
  --bg-raised: #fafafa;
  --bg-header: rgba(255, 255, 255, 0.8);
  --text: #16161a;
  --text-muted: #5c5c66;
  --text-faint: #85858f;
  --border: #e4e4e9;
  --border-strong: #d0d0d8;
  --accent: #7a00d4;
  --accent-hover: #5c00a8;
  --grad-a: #a800f0;
  --grad-b: #2200cc;
  --shadow-lift: 0 2px 4px rgba(16, 16, 32, 0.06), 0 16px 40px rgba(16, 16, 32, 0.1);

  --font: -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, Helvetica,
    Arial, sans-serif;
  --font-mono: ui-monospace, SFMono-Regular, "SF Mono", Menlo, Consolas,
    "Liberation Mono", monospace;

  --radius: 12px;
  --radius-lg: 16px;
  --container: 1040px;
}

@media (prefers-color-scheme: dark) {
  :root {
    --bg: #0c0c10;
    --bg-raised: #141419;
    --bg-header: rgba(12, 12, 16, 0.8);
    --text: #f2f2f5;
    --text-muted: #a0a0ad;
    --text-faint: #77777f;
    --border: #26262e;
    --border-strong: #35353f;
    --accent: #b46bff;
    --accent-hover: #cb99ff;
    --shadow-lift: 0 2px 4px rgba(0, 0, 0, 0.5), 0 16px 40px rgba(0, 0, 0, 0.45);
  }
}

/* --- Base --------------------------------------------------------------- */

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

html {
  -webkit-text-size-adjust: 100%;
}

body {
  margin: 0;
  background: var(--bg);
  color: var(--text);
  font-family: var(--font);
  font-size: 16px;
  line-height: 1.6;
  -webkit-font-smoothing: antialiased;
  display: flex;
  flex-direction: column;
  min-height: 100vh;
}

h1,
h2,
h3 {
  margin: 0;
  line-height: 1.2;
  letter-spacing: -0.02em;
  font-weight: 650;
}

p {
  margin: 0;
}

a {
  color: var(--accent);
  text-decoration: none;
}

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

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

code {
  font-family: var(--font-mono);
  font-size: 0.875em;
  background: var(--bg-raised);
  border: 1px solid var(--border);
  border-radius: 5px;
  padding: 0.1em 0.4em;
}

:focus-visible {
  outline: 2px solid var(--accent);
  outline-offset: 3px;
  border-radius: 4px;
}

.container {
  width: 100%;
  max-width: var(--container);
  margin: 0 auto;
  padding: 0 24px;
}

.skip-link {
  position: absolute;
  left: -9999px;
}

.skip-link:focus {
  left: 16px;
  top: 16px;
  z-index: 100;
  background: var(--bg);
  border: 1px solid var(--border-strong);
  border-radius: 8px;
  padding: 10px 16px;
}

/* --- Header ------------------------------------------------------------- */

.site-header {
  position: sticky;
  top: 0;
  z-index: 50;
  background: var(--bg-header);
  backdrop-filter: saturate(180%) blur(12px);
  -webkit-backdrop-filter: saturate(180%) blur(12px);
  border-bottom: 1px solid var(--border);
}

.site-header .container {
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 20px;
  min-height: 64px;
  flex-wrap: wrap;
  padding-top: 10px;
  padding-bottom: 10px;
}

.brand {
  display: inline-flex;
  align-items: center;
  gap: 10px;
  color: var(--text);
  font-weight: 650;
  font-size: 1.0625rem;
  letter-spacing: -0.01em;
}

.brand:hover {
  color: var(--text);
  text-decoration: none;
}

.brand img {
  width: 28px;
  height: 28px;
  display: block;
}

.site-nav {
  display: flex;
  align-items: center;
  gap: 4px;
  flex-wrap: wrap;
}

.site-nav a {
  color: var(--text-muted);
  font-size: 0.9375rem;
  font-weight: 500;
  padding: 7px 11px;
  border-radius: 8px;
  white-space: nowrap;
}

.site-nav a:hover {
  color: var(--text);
  background: var(--bg-raised);
  text-decoration: none;
}

.site-nav a[aria-current="page"] {
  color: var(--text);
  background: var(--bg-raised);
}

.site-nav .ext::after {
  content: "\2197";
  font-size: 0.75em;
  margin-left: 4px;
  opacity: 0.6;
  vertical-align: 1px;
}

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

main {
  flex: 1 0 auto;
}

.hero {
  text-align: center;
  padding: clamp(44px, 8vh, 88px) 0 clamp(32px, 5vh, 48px);
}

.hero-mark {
  width: clamp(64px, 9vh, 84px);
  height: auto;
  margin: 0 auto 24px;
  display: block;
}

.hero h1 {
  font-size: clamp(2.25rem, 6vw, 3.5rem);
  font-weight: 700;
  letter-spacing: -0.035em;
}

.hero .tagline {
  margin: 18px auto 0;
  max-width: 46ch;
  font-size: clamp(1.0625rem, 2.2vw, 1.1875rem);
  color: var(--text-muted);
  text-wrap: balance;
}

.page-head {
  padding: clamp(48px, 9vh, 80px) 0 8px;
}

.page-head h1 {
  font-size: clamp(1.875rem, 4.5vw, 2.5rem);
}

.page-head .lede {
  margin-top: 14px;
  max-width: 62ch;
  font-size: 1.0625rem;
  color: var(--text-muted);
}

.section {
  padding: clamp(36px, 6vh, 56px) 0;
}

/*
 * For a section whose prose continues directly from the .page-head lede. The
 * default section padding puts a section break between two paragraphs that
 * are meant to read as one flow. Must stay after .section: equal specificity,
 * so source order decides.
 */
.section-flush {
  padding-top: 20px;
}

.section-title {
  font-size: 0.8125rem;
  font-weight: 600;
  text-transform: uppercase;
  letter-spacing: 0.09em;
  color: var(--text-faint);
  margin-bottom: 20px;
}

/* --- Destination cards (home) ------------------------------------------- */

.cards {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(220px, 1fr));
  gap: 18px;
  /* The footer already contributes its own top margin below this. */
  padding-bottom: clamp(24px, 4vh, 40px);
}

.card {
  position: relative;
  display: flex;
  flex-direction: column;
  gap: 8px;
  padding: 26px 24px 24px;
  background: var(--bg-raised);
  border: 1px solid var(--border);
  border-radius: var(--radius-lg);
  /* Clips the ::before accent bar to the card's own rounded corners. */
  overflow: hidden;
  color: var(--text);
  text-align: left;
  transition: transform 0.18s ease, box-shadow 0.18s ease,
    border-color 0.18s ease;
}

/*
 * No border-radius here on purpose. A 3px tall box cannot hold a 16px corner:
 * the spec scales oversized radii down proportionally, so the bar would end up
 * with ~3px corners and cut straight across the card's 16px curve. The card
 * clips it to the correct shape instead.
 */
.card::before {
  content: "";
  position: absolute;
  inset: 0 0 auto;
  height: 3px;
  background: linear-gradient(90deg, var(--grad-a), var(--grad-b));
  opacity: 0;
  transition: opacity 0.18s ease;
}

.card:hover {
  transform: translateY(-3px);
  box-shadow: var(--shadow-lift);
  border-color: var(--border-strong);
  color: var(--text);
  text-decoration: none;
}

.card:hover::before {
  opacity: 1;
}

.card-name {
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 12px;
  font-size: 1.1875rem;
  font-weight: 650;
  letter-spacing: -0.015em;
}

.card-name .arrow {
  color: var(--text-faint);
  font-size: 1rem;
  transition: transform 0.18s ease, color 0.18s ease;
}

.card:hover .arrow {
  color: var(--accent);
  transform: translate(2px, -2px);
}

.card p {
  color: var(--text-muted);
  font-size: 0.9375rem;
}

/* --- Products banner (home) --------------------------------------------- */

/*
 * Deliberately not a .card and not a grid item. The three cards above are the
 * quick exits to Docs, Shop, and GitHub; this is the "keep reading" surface,
 * so it takes a different shape, its own spacing, and a persistent accent
 * edge rather than the cards' hover-only bar.
 */
.promo {
  padding: clamp(32px, 6vh, 56px) 0 clamp(48px, 8vh, 88px);
}

.promo-banner {
  position: relative;
  display: flex;
  align-items: center;
  justify-content: space-between;
  flex-wrap: wrap;
  gap: 24px 44px;
  padding: 36px 36px 36px 40px;
  background: var(--bg-raised);
  border: 1px solid var(--border);
  border-radius: var(--radius-lg);
  overflow: hidden;
  color: var(--text);
  transition: transform 0.18s ease, box-shadow 0.18s ease,
    border-color 0.18s ease;
}

/* Vertical accent edge, always visible. Clipped by the parent's overflow. */
.promo-banner::before {
  content: "";
  position: absolute;
  inset: 0 auto 0 0;
  width: 4px;
  background: linear-gradient(180deg, var(--grad-a), var(--grad-b));
}

.promo-banner:hover {
  transform: translateY(-3px);
  box-shadow: var(--shadow-lift);
  border-color: var(--border-strong);
  color: var(--text);
  text-decoration: none;
}

.promo-text {
  flex: 1 1 340px;
  min-width: 0;
}

.promo-eyebrow {
  display: block;
  margin-bottom: 8px;
  font-size: 0.75rem;
  font-weight: 600;
  text-transform: uppercase;
  letter-spacing: 0.09em;
  color: var(--text-faint);
}

.promo-title {
  display: block;
  font-size: clamp(1.5rem, 3vw, 1.875rem);
  font-weight: 700;
  line-height: 1.2;
  letter-spacing: -0.025em;
}

.promo-desc {
  display: block;
  margin-top: 10px;
  max-width: 56ch;
  color: var(--text-muted);
  font-size: 0.9375rem;
}

.promo-cta {
  flex: 0 0 auto;
  display: inline-flex;
  align-items: center;
  gap: 8px;
  padding: 13px 24px;
  border-radius: 999px;
  background: linear-gradient(135deg, var(--grad-a), var(--grad-b));
  color: #ffffff;
  font-size: 0.9375rem;
  font-weight: 600;
  white-space: nowrap;
  transition: filter 0.18s ease;
}

.promo-cta .arrow {
  transition: transform 0.18s ease;
}

.promo-banner:hover .promo-cta {
  filter: brightness(1.12);
}

.promo-banner:hover .promo-cta .arrow {
  transform: translateX(3px);
}

@media (max-width: 560px) {
  .promo-banner {
    padding: 28px 24px 28px 28px;
  }

  .promo-cta {
    width: 100%;
    justify-content: center;
  }
}

/* --- Tag filter --------------------------------------------------------- */

/*
 * Pure CSS filtering. Each .product carries a space separated data-tags list;
 * a checked radio inside .filter-scope hides every product that lacks the
 * matching tag. Add a tag by adding one chip, one rule below, and the tag
 * itself to the relevant data-tags attributes.
 */

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

.filter {
  display: flex;
  flex-wrap: wrap;
  align-items: center;
  gap: 8px;
  margin: 0;
  padding: 24px 0 6px;
  border: 0;
  min-width: 0; /* Fieldsets default to min-content, which can overflow. */
}

.chip {
  display: inline-flex;
  align-items: center;
  padding: 7px 15px;
  border: 1px solid var(--border);
  border-radius: 999px;
  background: var(--bg-raised);
  color: var(--text-muted);
  font-size: 0.875rem;
  font-weight: 550;
  white-space: nowrap;
  cursor: pointer;
  -webkit-user-select: none;
  user-select: none;
  transition: border-color 0.15s ease, color 0.15s ease, background 0.15s ease;
}

/* Kept in the accessibility tree and tab order, just not painted. */
.chip input {
  position: absolute;
  width: 1px;
  height: 1px;
  opacity: 0;
  margin: 0;
}

.chip:hover {
  border-color: var(--border-strong);
  color: var(--text);
}

.chip:has(:focus-visible) {
  outline: 2px solid var(--accent);
  outline-offset: 3px;
}

.chip:has(:checked) {
  background: linear-gradient(135deg, var(--grad-a), var(--grad-b));
  border-color: transparent;
  color: #ffffff;
}

/* One rule per tag. "All" needs none: nothing is hidden. */
.filter-scope:has(#tag-sensing:checked) .product:not([data-tags~="sensing"]),
.filter-scope:has(#tag-controller:checked) .product:not([data-tags~="controller"]),
.filter-scope:has(#tag-tools:checked) .product:not([data-tags~="tools"]),
.filter-scope:has(#tag-can:checked) .product:not([data-tags~="can"]),
.filter-scope:has(#tag-arduino:checked) .product:not([data-tags~="arduino"]),
.filter-scope:has(#tag-rpi:checked) .product:not([data-tags~="rpi"]) {
  display: none;
}

/* Without :has() the filter cannot work, so hide it and show every product. */
@supports not selector(:has(*)) {
  .filter {
    display: none;
  }
}

/* --- Product list ------------------------------------------------------- */

/*
 * Every product carries a top border, including the first: it doubles as the
 * rule beneath the filter bar. Exempting the first item would break under
 * filtering, since :first-of-type still counts hidden siblings.
 */
.product {
  padding: 32px 0;
  border-top: 1px solid var(--border);
  display: grid;
  grid-template-columns: minmax(0, 1fr) minmax(0, 1.1fr);
  gap: 12px 48px;
  align-items: start;
}

.product .tags {
  display: flex;
  flex-wrap: wrap;
  gap: 6px;
  list-style: none;
  margin: 14px 0 0;
  padding: 0;
}

.product .tags li {
  margin: 0;
  padding: 2px 10px;
  border: 1px solid var(--border);
  border-radius: 999px;
  font-size: 0.75rem;
  font-weight: 550;
  color: var(--text-faint);
}

.product h2 {
  font-size: 1.375rem;
}

.product .codename {
  margin-top: 8px;
  font-family: var(--font-mono);
  font-size: 0.8125rem;
  color: var(--text-faint);
}

.product .summary {
  color: var(--text-muted);
}

.product ul {
  margin: 14px 0 0;
  padding-left: 18px;
  color: var(--text-muted);
  font-size: 0.9375rem;
}

.product li {
  margin-bottom: 5px;
}

.product li strong {
  color: var(--text);
  font-weight: 600;
}

.links {
  display: flex;
  flex-wrap: wrap;
  gap: 8px;
  margin-top: 18px;
}

.btn {
  display: inline-flex;
  align-items: center;
  gap: 6px;
  padding: 8px 14px;
  border-radius: 9px;
  border: 1px solid var(--border-strong);
  background: var(--bg-raised);
  color: var(--text);
  font-size: 0.875rem;
  font-weight: 550;
  transition: border-color 0.15s ease, background 0.15s ease;
}

.btn:hover {
  border-color: var(--accent);
  color: var(--text);
  text-decoration: none;
}

.btn-primary {
  background: linear-gradient(135deg, var(--grad-a), var(--grad-b));
  border-color: transparent;
  color: #ffffff;
}

.btn-primary:hover {
  color: #ffffff;
  filter: brightness(1.12);
}

/* --- Repo grid ---------------------------------------------------------- */

.repos {
  display: grid;
  grid-template-columns: repeat(auto-fill, minmax(260px, 1fr));
  gap: 12px;
}

.repo {
  display: block;
  padding: 16px 18px;
  border: 1px solid var(--border);
  border-radius: var(--radius);
  color: var(--text);
  transition: border-color 0.15s ease, background 0.15s ease;
}

.repo:hover {
  border-color: var(--border-strong);
  background: var(--bg-raised);
  color: var(--text);
  text-decoration: none;
}

.repo-name {
  font-family: var(--font-mono);
  font-size: 0.875rem;
  font-weight: 600;
  color: var(--accent);
}

.repo p {
  margin-top: 5px;
  font-size: 0.875rem;
  color: var(--text-muted);
}

/* --- Prose (about) ------------------------------------------------------ */

.prose {
  max-width: 68ch;
}

.prose h2 {
  font-size: 1.25rem;
  margin-top: 40px;
  margin-bottom: 12px;
}

.prose p {
  margin-bottom: 14px;
  color: var(--text-muted);
}

.prose p strong {
  color: var(--text);
  font-weight: 600;
}

/*
 * Mission callout. Emphasis comes from scale, colour, and the accent edge
 * rather than bold, echoing the products banner on the home page.
 */
.prose .mission {
  position: relative;
  margin: 26px 0;
  padding-left: 22px;
  color: var(--text);
  font-size: 1.125rem;
  line-height: 1.55;
  letter-spacing: -0.01em;
}

.prose .mission::before {
  content: "";
  position: absolute;
  inset: 3px auto 3px 0;
  width: 3px;
  border-radius: 2px;
  background: linear-gradient(180deg, var(--grad-a), var(--grad-b));
}

.contact {
  margin: 12px 0 0;
}

.contact div {
  display: flex;
  gap: 10px;
  flex-wrap: wrap;
  padding: 9px 0;
  border-bottom: 1px solid var(--border);
  font-size: 0.9375rem;
}

.contact dt {
  min-width: 90px;
  color: var(--text-faint);
  margin: 0;
}

.contact dd {
  margin: 0;
}

/* --- Footer ------------------------------------------------------------- */

.site-footer {
  flex-shrink: 0;
  border-top: 1px solid var(--border);
  margin-top: 40px;
  padding: 28px 0;
  font-size: 0.875rem;
  color: var(--text-faint);
}

.site-footer .container {
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 16px 24px;
  flex-wrap: wrap;
}

.footer-links {
  display: flex;
  gap: 18px;
  flex-wrap: wrap;
}

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

.footer-links a:hover {
  color: var(--text);
}

/* --- Not found ---------------------------------------------------------- */

.notfound {
  text-align: center;
  padding: clamp(72px, 16vh, 140px) 0;
}

.notfound .code {
  font-family: var(--font-mono);
  font-size: 0.875rem;
  color: var(--text-faint);
  letter-spacing: 0.08em;
}

.notfound h1 {
  margin: 12px 0 14px;
  font-size: clamp(1.75rem, 5vw, 2.25rem);
}

.notfound p {
  color: var(--text-muted);
  max-width: 44ch;
  margin: 0 auto;
}

.notfound .links {
  justify-content: center;
}

/* --- Responsive --------------------------------------------------------- */

@media (max-width: 720px) {
  .product {
    grid-template-columns: 1fr;
    gap: 4px;
  }

  /* Let the header scroll away rather than pin a two-row bar to the top. */
  .site-header {
    position: static;
  }

  .site-header .container {
    justify-content: center;
    gap: 10px;
    min-height: 0;
  }

  .site-nav {
    justify-content: center;
    gap: 0;
  }

  .site-nav a {
    font-size: 0.875rem;
    padding: 6px 7px;
  }

  .site-nav .ext::after {
    margin-left: 2px;
  }
}

@media (prefers-reduced-motion: reduce) {
  *,
  *::before,
  *::after {
    transition-duration: 0.01ms !important;
    animation-duration: 0.01ms !important;
  }
}