/* Blue Innovation x Eduba. Bespoke landing page styles.
   Palette, typography, and UI rhythm sourced from blue-i.co.jp live CSS.
*/

:root {
  --bi-primary: #0058A1;
  --bi-secondary: #036EB7;
  --bi-accent: #4B8CCA;
  --bi-heading: #231815;
  --bi-body: #373B42;
  --bi-muted: #838383;
  --bi-surface: #F2F2F5;
  --bi-bg: #FFFFFF;
  --bi-emphasis: #C43366;

  --bi-radius-sm: 2px;
  --bi-radius-md: 4px;
  --bi-radius-lg: 8px;

  --bi-shadow-subtle: 0 1px 2px rgba(35, 24, 21, 0.06);
  --bi-shadow-medium: 0 4px 16px rgba(0, 88, 161, 0.10);

  --bi-maxw: 1120px;
  --bi-gutter: clamp(20px, 4vw, 40px);
  --bi-section: clamp(56px, 8vw, 96px);

  --font-stack: "Helvetica Neue", "san francisco", "Segoe UI",
    "Hiragino Kaku Gothic ProN", "Hiragino Sans", "BIZ UDPGothic",
    Meiryo, sans-serif;
}

* { box-sizing: border-box; }

html { scroll-behavior: smooth; }

body {
  margin: 0;
  font-family: var(--font-stack);
  font-weight: 400;
  font-size: 16px;
  line-height: 1.7;
  color: var(--bi-body);
  background: var(--bi-bg);
  -webkit-font-smoothing: antialiased;
  -moz-osx-font-smoothing: grayscale;
}

a {
  color: var(--bi-secondary);
  text-decoration: none;
  border-bottom: 1px solid rgba(3, 110, 183, 0.28);
  transition: color 120ms ease, border-color 120ms ease;
}
a:hover, a:focus-visible {
  color: var(--bi-primary);
  border-bottom-color: var(--bi-primary);
}
a:focus-visible { outline: 2px solid var(--bi-accent); outline-offset: 3px; border-radius: 2px; }

h1, h2, h3, h4 {
  color: var(--bi-heading);
  font-weight: 700;
  letter-spacing: 0;
  line-height: 1.3;
  margin: 0;
}

p { margin: 0 0 1em; }

/* ---------- Site header ---------- */
.site-header {
  position: sticky;
  top: 0;
  z-index: 20;
  background: rgba(255, 255, 255, 0.94);
  backdrop-filter: saturate(1.2) blur(8px);
  border-bottom: 1px solid #E7E9EE;
}

.site-header__inner {
  max-width: var(--bi-maxw);
  margin: 0 auto;
  padding: 18px var(--bi-gutter);
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 16px;
}

.site-header__logo { display: inline-flex; align-items: center; border: 0; }
.site-header__logo img { height: 34px; width: auto; display: block; }
.site-header__logo:hover { border: 0; }

.site-header__meta {
  font-size: 12px;
  letter-spacing: 0.08em;
  text-transform: uppercase;
  color: var(--bi-muted);
}

/* ---------- Hero ---------- */
.hero {
  position: relative;
  padding: calc(var(--bi-section) * 0.9) var(--bi-gutter) var(--bi-section);
  background:
    radial-gradient(1200px 500px at 85% -10%, rgba(75, 140, 202, 0.18), transparent 60%),
    linear-gradient(180deg, #F5F8FC 0%, #FFFFFF 100%);
  overflow: hidden;
}

.hero__grid-lines {
  position: absolute;
  inset: 0;
  background-image:
    linear-gradient(to right, rgba(0, 88, 161, 0.05) 1px, transparent 1px);
  background-size: 80px 100%;
  pointer-events: none;
  mask-image: linear-gradient(to bottom, rgba(0,0,0,0.9), transparent 80%);
}

.hero__inner {
  max-width: var(--bi-maxw);
  margin: 0 auto;
  position: relative;
}

.eyebrow {
  display: inline-flex;
  align-items: center;
  gap: 10px;
  font-size: 12px;
  letter-spacing: 0.14em;
  text-transform: uppercase;
  color: var(--bi-primary);
  font-weight: 700;
  margin-bottom: 22px;
}
.eyebrow::before {
  content: "";
  width: 28px;
  height: 2px;
  background: var(--bi-primary);
}

.hero h1 {
  font-size: clamp(28px, 4.4vw, 48px);
  max-width: 22ch;
  margin-bottom: 20px;
}

.hero__lede {
  max-width: 64ch;
  font-size: clamp(16px, 1.6vw, 19px);
  color: var(--bi-body);
  margin-bottom: 28px;
}

.hero__meta {
  display: flex;
  flex-wrap: wrap;
  gap: 10px 18px;
  font-size: 13px;
  color: var(--bi-muted);
}

.hero__meta span {
  display: inline-flex;
  align-items: center;
  gap: 8px;
}
.hero__meta span::before {
  content: "";
  width: 6px; height: 6px;
  background: var(--bi-accent);
  transform: rotate(45deg);
}

/* Polygon mark echo */
.hero__mark {
  position: absolute;
  right: calc(var(--bi-gutter) * -0.2);
  top: -20px;
  width: min(380px, 38vw);
  opacity: 0.9;
  pointer-events: none;
}
@media (max-width: 900px) { .hero__mark { display: none; } }

/* ---------- Section shell ---------- */
.section {
  padding: var(--bi-section) var(--bi-gutter);
}
.section__inner {
  max-width: var(--bi-maxw);
  margin: 0 auto;
}

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

.section__eyebrow {
  font-size: 12px;
  letter-spacing: 0.14em;
  text-transform: uppercase;
  color: var(--bi-primary);
  font-weight: 700;
  margin-bottom: 14px;
}

.section__title {
  font-size: clamp(22px, 2.6vw, 30px);
  margin-bottom: 28px;
  max-width: 30ch;
}

/* ---------- Context band ---------- */
.context {
  display: grid;
  grid-template-columns: repeat(3, 1fr);
  gap: 20px;
}
.context__card {
  background: var(--bi-bg);
  border-top: 3px solid var(--bi-primary);
  padding: 24px 22px 22px;
  box-shadow: var(--bi-shadow-subtle);
  border-radius: 0 0 var(--bi-radius-md) var(--bi-radius-md);
}
.context__card h3 {
  font-size: 14px;
  letter-spacing: 0.06em;
  text-transform: uppercase;
  margin-bottom: 10px;
  color: var(--bi-primary);
}
.context__card p {
  font-size: 15px;
  margin: 0;
  color: var(--bi-body);
}
@media (max-width: 780px) {
  .context { grid-template-columns: 1fr; }
}

/* ---------- Reading body ---------- */
.prose { max-width: 72ch; }
.prose p { font-size: 17px; }
.prose p + p { margin-top: 1em; }

.callout {
  margin: 28px 0;
  padding: 22px 24px;
  border-left: 3px solid var(--bi-secondary);
  background: #F5F8FC;
  border-radius: 0 var(--bi-radius-md) var(--bi-radius-md) 0;
}
.callout p { margin: 0; font-size: 16px; }
.callout strong { color: var(--bi-heading); }

/* ---------- Framework block ---------- */
.framework {
  display: grid;
  grid-template-columns: repeat(3, 1fr);
  gap: 16px;
  margin-top: 28px;
}
.framework__row {
  background: var(--bi-bg);
  border: 1px solid #E2E6EC;
  padding: 20px;
  border-radius: var(--bi-radius-md);
}
.framework__pct {
  font-size: 26px;
  font-weight: 700;
  color: var(--bi-primary);
  line-height: 1;
  margin-bottom: 6px;
}
.framework__label {
  font-size: 12px;
  letter-spacing: 0.08em;
  text-transform: uppercase;
  color: var(--bi-muted);
  font-weight: 700;
  margin-bottom: 10px;
}
.framework__row p { font-size: 14px; margin: 0; }
.framework__row--emphasis {
  background: var(--bi-primary);
  border-color: var(--bi-primary);
  color: #fff;
}
.framework__row--emphasis .framework__pct { color: #fff; }
.framework__row--emphasis .framework__label { color: rgba(255,255,255,0.8); }
.framework__row--emphasis p { color: #fff; }
@media (max-width: 780px) {
  .framework { grid-template-columns: 1fr; }
}

/* ---------- Case + Paper cards ---------- */
.evidence {
  display: grid;
  grid-template-columns: 1.1fr 1fr;
  gap: 20px;
}
@media (max-width: 900px) { .evidence { grid-template-columns: 1fr; } }

.evidence__card {
  background: var(--bi-bg);
  border-top: 3px solid var(--bi-primary);
  box-shadow: var(--bi-shadow-subtle);
  padding: 28px 26px;
  border-radius: 0 0 var(--bi-radius-md) var(--bi-radius-md);
}
.evidence__card--paper { border-top-color: var(--bi-accent); }
.evidence__tag {
  font-size: 11px;
  letter-spacing: 0.12em;
  text-transform: uppercase;
  color: var(--bi-primary);
  font-weight: 700;
}
.evidence__card--paper .evidence__tag { color: var(--bi-accent); }
.evidence__card h3 {
  font-size: 20px;
  margin: 8px 0 12px;
}
.evidence__card p { font-size: 15px; margin: 0 0 12px; }
.evidence__stat {
  font-size: 14px;
  color: var(--bi-heading);
  border-top: 1px solid #E7E9EE;
  padding-top: 12px;
  margin-top: 8px;
}
.evidence__stat strong { color: var(--bi-primary); font-weight: 700; }
.evidence__links {
  list-style: none;
  padding: 0;
  margin: 12px 0 0;
  font-size: 14px;
}
.evidence__links li { margin-bottom: 6px; }

/* ---------- Credibility row ---------- */
.cred {
  display: grid;
  grid-template-columns: repeat(4, 1fr);
  gap: 14px;
}
.cred__item {
  padding: 20px 18px;
  background: var(--bi-bg);
  border-radius: var(--bi-radius-md);
  border: 1px solid #E2E6EC;
}
.cred__figure {
  font-size: 22px;
  font-weight: 700;
  color: var(--bi-primary);
  line-height: 1.1;
  margin-bottom: 6px;
}
.cred__item p { font-size: 13px; margin: 0; color: var(--bi-body); }
@media (max-width: 900px) { .cred { grid-template-columns: repeat(2, 1fr); } }
@media (max-width: 480px) { .cred { grid-template-columns: 1fr; } }

/* ---------- CTA ---------- */
.cta {
  background:
    linear-gradient(180deg, #003E72 0%, #0058A1 70%, #036EB7 100%);
  color: #fff;
  padding: var(--bi-section) var(--bi-gutter);
  position: relative;
  overflow: hidden;
}
.cta::after {
  content: "";
  position: absolute;
  right: -60px; bottom: -60px;
  width: 360px; height: 360px;
  background:
    conic-gradient(from 210deg, rgba(255,255,255,0.14), rgba(255,255,255,0) 60%);
  clip-path: polygon(50% 0, 100% 100%, 0 100%);
  pointer-events: none;
}
.cta__inner {
  max-width: var(--bi-maxw);
  margin: 0 auto;
  position: relative;
  display: grid;
  grid-template-columns: 1.2fr 1fr;
  gap: 40px;
  align-items: center;
}
@media (max-width: 900px) { .cta__inner { grid-template-columns: 1fr; } }

.cta h2 {
  color: #fff;
  font-size: clamp(24px, 3vw, 34px);
  margin-bottom: 14px;
  max-width: 22ch;
}
.cta p { color: rgba(255,255,255,0.86); font-size: 17px; max-width: 52ch; }

.cta__card {
  background: rgba(255,255,255,0.06);
  border: 1px solid rgba(255,255,255,0.18);
  padding: 26px;
  border-radius: var(--bi-radius-lg);
  backdrop-filter: blur(6px);
}
.cta__card h3 {
  color: #fff;
  font-size: 15px;
  letter-spacing: 0.06em;
  text-transform: uppercase;
  margin-bottom: 10px;
}
.cta__card p { color: rgba(255,255,255,0.82); font-size: 15px; margin-bottom: 18px; }

.btn {
  display: inline-flex;
  align-items: center;
  gap: 10px;
  padding: 14px 22px;
  min-height: 48px;
  background: #fff;
  color: var(--bi-primary);
  font-weight: 700;
  font-size: 15px;
  letter-spacing: 0.02em;
  border-radius: var(--bi-radius-md);
  border: 0;
  cursor: pointer;
  text-decoration: none;
  transition: transform 120ms ease, box-shadow 120ms ease, background 120ms ease;
  box-shadow: var(--bi-shadow-medium);
}
.btn:hover, .btn:focus-visible { transform: translateY(-1px); background: #F5F8FC; color: var(--bi-primary); border: 0; }
.btn::after {
  content: "";
  width: 10px; height: 10px;
  border-top: 2px solid var(--bi-primary);
  border-right: 2px solid var(--bi-primary);
  transform: rotate(45deg);
}

.cta__signoff {
  margin-top: 14px;
  font-size: 13px;
  color: rgba(255,255,255,0.7);
}

/* ---------- Footer ---------- */
.site-footer {
  padding: 32px var(--bi-gutter);
  border-top: 1px solid #E7E9EE;
  background: var(--bi-bg);
}
.site-footer__inner {
  max-width: var(--bi-maxw);
  margin: 0 auto;
  display: flex;
  flex-wrap: wrap;
  gap: 12px;
  justify-content: space-between;
  font-size: 13px;
  color: var(--bi-muted);
}
.site-footer a { color: var(--bi-muted); border-bottom-color: rgba(131,131,131,0.4); }
.site-footer a:hover { color: var(--bi-primary); border-bottom-color: var(--bi-primary); }

/* ---------- Mobile 375px polish ---------- */
@media (max-width: 480px) {
  :root { --bi-section: 56px; }
  .site-header__meta { display: none; }
  .hero h1 { font-size: 28px; }
  .hero__lede { font-size: 16px; }
  .section__title { font-size: 22px; }
  .evidence__card { padding: 22px 20px; }
  .cta { padding: 56px 20px; }
  .btn { width: 100%; justify-content: center; }
}

/* ---------- Reduced motion ---------- */
@media (prefers-reduced-motion: reduce) {
  * { transition: none !important; animation: none !important; }
  html { scroll-behavior: auto; }
}