/* ==========================================================================
   article.css — unified design layer for white-paper / article pages
   ==========================================================================

   These 201 pages each ship their own inline <style> block (25 variants,
   ~2.1 MB duplicated site-wide). Those blocks are written entirely against
   CSS custom properties, and originally declared an off-brand set:

       --primary  3157f6 (violet-blue)   Robo Lab is #007DD1
       --ink      0b1527                 Midnight Blue is #20305B
       font-family: Inter                superseded — the brand face is Roboto / Noto Sans JP
       --radius   28 / 20 / 14           RDS scale is 4 / 8 / 16 / 24
       --max      1180px                 RDS wide container is 1300px

   This file MUST be linked AFTER the inline block. Redeclaring the same
   tokens re-themes every article onto the Robo Lab brand without touching
   a single layout rule. Values below come from the Robo Design System
   (tokens/brands/robo-lab.json); prefer the --rds-* tokens directly in new
   work and treat these as the compatibility shim they are.
   ========================================================================== */

:root {
  /* ink & surfaces -------------------------------------------------------- */
  --ink: #20305B;
  --ink-soft: #1B3A5C;
  --muted: #636E8C;
  --line: rgba(24, 49, 105, 0.14);
  --surface: #F8FCFE;
  --surface-soft: #EAF5FD;
  --surface-blue: #D0E8FA;
  --fade-bg: #EAF5FD;

  /* brand ----------------------------------------------------------------- */
  --primary: #007DD1;
  --primary-dark: #006FBA;
  --teal: #1EB2A9;
  --amber: #F75326;

  /* geometry — Robo Design System scale ------------------------------------ */
  --radius-xl: 24px;
  --radius-lg: 16px;
  --radius-md: 8px;
  --max: 1300px;

  /* elevation — softer and cooler than the imported defaults --------------- */
  --shadow: 0 20px 40px rgba(32, 48, 91, 0.10);
  --shadow-soft: 0 10px 30px rgba(0, 125, 209, 0.08);
}

/* --- typography ----------------------------------------------------------
   The inline blocks used to set Inter first. Roboto carries Latin, Noto Sans JP
   carries kana and kanji — per-glyph, so mixed sentences stay correct.
   ------------------------------------------------------------------------ */
body,
button,
input,
select,
textarea {
  font-family: 'Roboto', 'Noto Sans JP', system-ui, -apple-system, sans-serif;
}

body {
  color: var(--ink);
  -webkit-font-smoothing: antialiased;
  text-rendering: optimizeLegibility;
}

h1, h2, h3, h4 {
  letter-spacing: -0.018em;
  line-height: 1.22;
}

h1 { font-weight: 700; }
h2 { font-weight: 700; }
h3 { font-weight: 700; }

/* Japanese sets tighter than Latin at the same size and does not want
   negative tracking — kana lose their counters. */
:lang(ja) h1,
:lang(ja) h2,
:lang(ja) h3,
:lang(ja) h4 {
  letter-spacing: 0;
  line-height: 1.4;
}

:lang(ja) body {
  line-height: 1.85;
}

/* --- site navigation -----------------------------------------------------
   These pages now carry the real .robo-nav from styles.css instead of the
   WordPress header. It is fixed at 80px, so the page needs an offset and
   the sticky in-page subnav has to sit below it.
   ------------------------------------------------------------------------ */
body { padding-top: 80px; }

.subnav {
  top: 80px;
  background: rgba(244, 248, 251, 0.92);
  backdrop-filter: blur(12px);
  -webkit-backdrop-filter: blur(12px);
  border-bottom: 1px solid var(--line);
}

.subnav a {
  font-weight: 500;
  transition: color 120ms cubic-bezier(0.16, 1, 0.3, 1);
}

.subnav a.active,
.subnav a:hover {
  color: var(--primary);
}

.subnav a.subnav-cta {
  background: var(--primary);
  color: #fff;
  border-radius: 999px;
}

.subnav a.subnav-cta:hover {
  background: var(--primary-dark);
  color: #fff;
}

/* --- hero ----------------------------------------------------------------
   The imported hero paints two violet radial washes. Repaint in brand blue
   and cyan, and calm the intensity.
   ------------------------------------------------------------------------ */
.hero {
  background:
    radial-gradient(circle at 84% 8%, rgba(0, 125, 209, 0.14), transparent 34%),
    radial-gradient(circle at 12% 94%, rgba(0, 195, 255, 0.10), transparent 38%),
    var(--surface);
  border-bottom: 1px solid var(--line);
}

.eyebrow {
  color: var(--primary-dark);
  font-weight: 700;
  letter-spacing: 0.12em;
  text-transform: uppercase;
}

.hero-lead {
  color: var(--ink-soft);
  line-height: 1.7;
}

/* --- buttons -------------------------------------------------------------- */
.btn-primary {
  background: var(--primary);
  border-color: var(--primary);
  color: #fff;
  box-shadow: 0 4px 15px rgba(0, 125, 209, 0.28);
}

.btn-primary:hover {
  background: var(--primary-dark);
  border-color: var(--primary-dark);
  box-shadow: 0 8px 25px rgba(32, 48, 91, 0.24);
}

.btn-secondary {
  border-color: var(--line);
  color: var(--ink);
  background: #fff;
}

.btn-secondary:hover {
  border-color: var(--primary);
  color: var(--primary);
}

/* --- cards & sections ----------------------------------------------------- */
.card {
  border-radius: var(--radius-lg);
  border-color: var(--line);
  box-shadow: var(--shadow-soft);
  transition: transform 240ms cubic-bezier(0.16, 1, 0.3, 1),
              box-shadow 240ms cubic-bezier(0.16, 1, 0.3, 1),
              border-color 240ms cubic-bezier(0.16, 1, 0.3, 1);
}

.card:hover {
  transform: translateY(-3px);
  border-color: rgba(0, 125, 209, 0.3);
  box-shadow: var(--shadow);
}

.section-kicker {
  color: var(--primary-dark);
  font-weight: 700;
  letter-spacing: 0.12em;
  text-transform: uppercase;
}

.section-head h2 {
  color: var(--ink);
}

.section-head p {
  color: var(--muted);
  line-height: 1.7;
}

.section-alt {
  background: var(--surface-soft);
}

/* the dark "5-step" band — recolour off violet onto Robo Lab midnight */
.steps-dark {
  background: linear-gradient(135deg, #20305B 0%, #0F172A 100%);
}

/* --- breadcrumb ----------------------------------------------------------- */
.breadcrumb {
  color: var(--muted);
  font-size: 0.86rem;
}

.breadcrumb a {
  color: var(--muted);
  border-bottom: 1px solid transparent;
}

.breadcrumb a:hover {
  color: var(--primary);
  border-bottom-color: rgba(0, 125, 209, 0.4);
}

/* --- footer ---------------------------------------------------------------
   Native footer already present on these pages; align it with the site.
   ------------------------------------------------------------------------ */
footer {
  background: #111827;
  color: rgba(255, 255, 255, 0.72);
  border-top: 1px solid rgba(255, 255, 255, 0.06);
}

footer a {
  color: rgba(255, 255, 255, 0.72);
  transition: color 120ms cubic-bezier(0.16, 1, 0.3, 1);
}

footer a:hover { color: #fff; }

/* --- accessibility -------------------------------------------------------- */
a:focus-visible,
button:focus-visible {
  outline: 2px solid var(--primary);
  outline-offset: 2px;
  border-radius: var(--radius-md);
}

@media (prefers-reduced-motion: reduce) {
  .card,
  .card:hover { transition: none; transform: none; }
  html { scroll-behavior: auto; }
}

@media (max-width: 900px) {
  body { padding-top: 70px; }
  .subnav { top: 70px; }
}