/* ============================================================
   PraxAI — Practical AI
   Refined design system. Brand navy #001890 (logo / card).
   Type: Hanken Grotesk (Latin display) + Pretendard (KR/body)
   ============================================================ */

:root {
  /* Brand */
  --brand:       #001890;
  --brand-2:     #011c95;
  --brand-deep:  #050d3d;
  --accent:      #2747e0;
  --accent-2:    #4f6df5;

  /* Neutrals (light, airy) */
  --ink:        #0a1230;
  --body:       #4b5273;
  --muted:      #646b8a;
  --surface:    #ffffff;
  --surface-alt:#f5f7fd;
  --line:       #e7ebf6;
  --line-soft:  #eef1fa;

  /* Effects */
  --shadow-xs: 0 1px 3px rgba(10, 18, 48, .04);
  --shadow-sm: 0 6px 22px rgba(10, 24, 96, .06);
  --shadow-md: 0 18px 50px rgba(10, 24, 96, .10);
  --radius:    18px;
  --radius-sm: 11px;

  --font-display: "Hanken Grotesk", "Pretendard Variable", Pretendard, system-ui, sans-serif;
  --font-body: "Pretendard Variable", Pretendard, "Hanken Grotesk", system-ui, -apple-system, sans-serif;

  --container: 1180px;
  --ease: cubic-bezier(.22, 1, .36, 1);
}

* { box-sizing: border-box; margin: 0; padding: 0; }
html { scroll-behavior: smooth; scroll-padding-top: 80px; -webkit-text-size-adjust: 100%; }
body {
  font-family: var(--font-body);
  color: var(--body);
  background: var(--surface);
  line-height: 1.72;
  font-size: 17px;
  letter-spacing: -.005em;
  -webkit-font-smoothing: antialiased;
  text-rendering: optimizeLegibility;
}
img { max-width: 100%; display: block; }
a { color: inherit; text-decoration: none; }
em { font-style: normal; }
strong { font-weight: 600; }

.container { width: 100%; max-width: var(--container); margin: 0 auto; padding: 0 28px; }

h1, h2, h3 { color: var(--ink); font-family: var(--font-display); line-height: 1.16; letter-spacing: -.025em; font-weight: 700; word-break: keep-all; }

/* ---------- Buttons ---------- */
.btn {
  display: inline-flex; align-items: center; justify-content: center;
  font-family: var(--font-body); font-weight: 600; font-size: 15.5px; letter-spacing: -.01em;
  padding: 14px 26px; border-radius: var(--radius-sm); border: 1.5px solid transparent;
  cursor: pointer; transition: transform .3s var(--ease), box-shadow .3s var(--ease), background .25s, color .25s, border-color .25s;
  white-space: nowrap;
}
.btn-light { background: #fff; color: var(--brand); }
.btn-light:hover { transform: translateY(-2px); box-shadow: 0 12px 30px rgba(0, 0, 0, .16); }
.btn-outline { background: transparent; color: #fff; border-color: rgba(255, 255, 255, .45); }
.btn-outline:hover { background: rgba(255, 255, 255, .1); border-color: rgba(255, 255, 255, .8); transform: translateY(-2px); }

/* Keyboard focus visibility (a11y) */
:focus-visible { outline: 2px solid var(--accent-2); outline-offset: 3px; border-radius: 6px; }
.btn:focus-visible, .lang-toggle:focus-visible { outline-offset: 4px; }

/* ============================================================
   HEADER
   ============================================================ */
.site-header {
  position: fixed; inset: 0 0 auto 0; z-index: 100;
  transition: background .35s var(--ease), box-shadow .35s, border-color .35s;
  border-bottom: 1px solid transparent;
}
.header-inner { display: flex; align-items: center; justify-content: space-between; height: 80px; }
.brand { display: flex; align-items: center; gap: 13px; }
.brand-logo { height: 38px; width: auto; }
.brand-logo--blue { display: none; }
.brand-logo--white { display: block; }
.brand-ko {
  font-family: var(--font-body); font-weight: 600; font-size: 16.5px; letter-spacing: -.02em;
  line-height: 1; white-space: nowrap; color: rgba(255, 255, 255, .94); padding-left: 13px;
  border-left: 1px solid rgba(255, 255, 255, .3); transition: color .35s, border-color .35s;
}
.site-header.scrolled .brand-ko { color: var(--ink); border-left-color: var(--line); }

.nav { display: flex; gap: 38px; }
.nav a { font-size: 15px; font-weight: 500; color: rgba(255, 255, 255, .82); position: relative; transition: color .2s; }
.nav a::after { content: ""; position: absolute; left: 0; bottom: -6px; width: 0; height: 1.5px; background: currentColor; transition: width .28s var(--ease); }
.nav a:hover { color: #fff; }
.nav a:hover::after { width: 100%; }

.header-actions { display: flex; align-items: center; gap: 14px; }
.lang-toggle {
  display: inline-flex; align-items: center; min-height: 40px;
  background: rgba(255, 255, 255, .1); border: 1px solid rgba(255, 255, 255, .26); color: #fff;
  border-radius: 999px; padding: 8px 16px; font-family: var(--font-display); font-size: 12.5px;
  font-weight: 600; letter-spacing: .04em; cursor: pointer; transition: background .2s, border-color .2s;
}
.lang-toggle:hover { background: rgba(255, 255, 255, .2); }
.lang-opt { opacity: .45; transition: opacity .2s; }
.lang-opt.active { opacity: 1; }
.lang-sep { opacity: .4; margin: 0 4px; }

.site-header.scrolled {
  background: rgba(255, 255, 255, .82); backdrop-filter: saturate(180%) blur(16px);
  -webkit-backdrop-filter: saturate(180%) blur(16px);
  border-bottom-color: var(--line); box-shadow: var(--shadow-xs);
}
.site-header.scrolled .brand-logo--blue { display: block; }
.site-header.scrolled .brand-logo--white { display: none; }
.site-header.scrolled .nav a { color: var(--body); }
.site-header.scrolled .nav a:hover { color: var(--accent); }
.site-header.scrolled .lang-toggle { background: var(--surface-alt); border-color: var(--line); color: var(--brand); }
.site-header.scrolled .menu-btn span { background: var(--ink); }

.menu-btn { display: none; flex-direction: column; gap: 5px; background: none; border: none; cursor: pointer; padding: 6px; }
.menu-btn span { display: block; width: 23px; height: 2px; background: #fff; border-radius: 2px; transition: .3s; }
.menu-btn[aria-expanded="true"] span:nth-child(1) { transform: translateY(7px) rotate(45deg); }
.menu-btn[aria-expanded="true"] span:nth-child(2) { opacity: 0; }
.menu-btn[aria-expanded="true"] span:nth-child(3) { transform: translateY(-7px) rotate(-45deg); }

.mobile-nav { display: none; flex-direction: column; background: #fff; border-top: 1px solid var(--line); padding: 6px 28px 16px; box-shadow: var(--shadow-md); }
.mobile-nav a { padding: 15px 0; font-weight: 600; color: var(--ink); border-bottom: 1px solid var(--line-soft); }
.mobile-nav a:last-child { border-bottom: none; }
.mobile-nav.open { display: flex; }

/* ============================================================
   HERO
   ============================================================ */
.hero {
  position: relative; overflow: hidden; color: #fff; isolation: isolate;
  background:
    radial-gradient(120% 90% at 88% 18%, rgba(79, 109, 245, .35), transparent 55%),
    radial-gradient(90% 120% at 8% 100%, rgba(1, 28, 149, .55), transparent 60%),
    linear-gradient(160deg, #021a8a 0%, #001890 42%, #020e54 100%);
  padding: 188px 0 0;
}
.hero-mark {
  position: absolute; right: -8%; top: 46%; transform: translateY(-50%);
  width: min(620px, 64vw); height: auto; opacity: .07; z-index: -1;
  animation: spin 120s linear infinite;
}
@keyframes spin { to { transform: translateY(-50%) rotate(360deg); } }

.hero-inner { position: relative; max-width: 880px; padding-bottom: 120px; }
.hero-eyebrow {
  display: inline-block; font-family: var(--font-display); font-weight: 600; font-size: 13px;
  letter-spacing: .14em; color: rgba(255, 255, 255, .82); padding: 8px 16px; border-radius: 999px;
  background: rgba(255, 255, 255, .08); border: 1px solid rgba(255, 255, 255, .18); margin-bottom: 30px;
}
.hero-title { color: #fff; font-size: clamp(34px, 6.4vw, 76px); font-weight: 800; line-height: 1.08; letter-spacing: -.035em; margin-bottom: 26px; }
.hero-title em { color: #aac1ff; }
.hero-sub { font-size: clamp(17px, 1.9vw, 20px); line-height: 1.65; color: rgba(255, 255, 255, .86); max-width: 600px; margin-bottom: 40px; font-weight: 400; }
.hero-cta { display: flex; gap: 14px; flex-wrap: wrap; }

.hero-foot { position: relative; padding-top: 26px; padding-bottom: 26px; border-top: 1px solid rgba(255, 255, 255, .12); }
.hero-foot span { font-family: var(--font-display); font-size: 13.5px; letter-spacing: .02em; color: rgba(255, 255, 255, .6); }

/* ============================================================
   SECTION primitives
   ============================================================ */
.section { padding: 118px 0; }
.section--alt { background: var(--surface-alt); }
.section-head { max-width: 680px; margin: 0 auto 64px; text-align: center; }
.section-head--left { max-width: 620px; margin: 0 0 56px; text-align: left; }
.eyebrow { display: inline-block; font-family: var(--font-display); font-weight: 600; font-size: 12.5px; letter-spacing: .16em; color: var(--accent); margin-bottom: 18px; }
.eyebrow--light { color: #aac1ff; }
.section-title { font-size: clamp(29px, 4vw, 44px); font-weight: 800; letter-spacing: -.03em; }
.section-title--light { color: #fff; }
.section-desc { margin-top: 18px; font-size: 17.5px; color: var(--muted); line-height: 1.6; }
.section-desc--light { color: rgba(255, 255, 255, .72); }

/* ---------- ABOUT ---------- */
.about-grid { display: grid; grid-template-columns: 0.85fr 1.15fr; gap: 64px; align-items: start; }
.about-head .eyebrow { margin-bottom: 16px; }
.about-head .section-title { font-size: clamp(28px, 3.4vw, 40px); }
.about-lead { font-size: clamp(19px, 2vw, 23px); line-height: 1.55; color: var(--ink); font-weight: 500; letter-spacing: -.02em; margin-bottom: 24px; }
.about-text { font-size: 17px; color: var(--body); margin-bottom: 34px; }
.cred-strip { list-style: none; display: flex; flex-wrap: wrap; gap: 10px; }
.cred-strip li { font-family: var(--font-display); font-size: 13px; font-weight: 500; color: var(--accent); background: var(--surface-alt); border: 1px solid var(--line); padding: 8px 15px; border-radius: 999px; letter-spacing: -.01em; }

/* ---------- CAPABILITIES (pillars) ---------- */
.pillars { display: grid; grid-template-columns: 1fr 1fr; gap: 24px; }
.pillar {
  position: relative; background: #fff; border: 1px solid var(--line); border-radius: var(--radius);
  padding: 42px 40px 38px; box-shadow: var(--shadow-xs);
  transition: transform .4s var(--ease), box-shadow .4s var(--ease), border-color .4s;
}
.pillar:hover { transform: translateY(-5px); box-shadow: var(--shadow-md); border-color: #d4ddf7; }
.pillar-no { position: absolute; top: 36px; right: 40px; font-family: var(--font-display); font-size: 14px; font-weight: 700; color: var(--line); letter-spacing: .05em; }
.pillar-ico { display: inline-grid; place-items: center; width: 56px; height: 56px; border-radius: 15px; color: var(--accent); background: linear-gradient(140deg, rgba(39, 71, 224, .1), rgba(0, 24, 144, .06)); margin-bottom: 24px; }
.pillar-ico svg { width: 30px; height: 30px; }
.pillar h3 { font-size: 22px; margin-bottom: 13px; letter-spacing: -.025em; }
.pillar p { font-size: 15.5px; color: var(--body); }
.pillar-tag { display: inline-block; margin-top: 22px; font-family: var(--font-display); font-size: 12.5px; font-weight: 600; letter-spacing: .01em; color: var(--accent-2); }
.pillar-tag::before { content: ""; display: inline-block; width: 16px; height: 1.5px; background: currentColor; vertical-align: middle; margin-right: 9px; opacity: .6; }

/* ---------- DOMAINS ---------- */
.domains { display: grid; grid-template-columns: repeat(3, 1fr); gap: 22px; }
.domain {
  position: relative;
  display: flex; gap: 18px; background: #fff; border: 1px solid var(--line); border-radius: var(--radius);
  padding: 30px 28px; box-shadow: var(--shadow-xs);
  transition: transform .35s var(--ease), box-shadow .35s var(--ease), border-color .35s;
}

/* Clickable card overlay (stretched link) */
.card-link { position: absolute; inset: 0; z-index: 2; border-radius: inherit; }
.pillar, .domain { cursor: pointer; }
.pillar:hover, .domain:hover { border-color: var(--accent); }
.domain:hover { transform: translateY(-4px); box-shadow: var(--shadow-sm); border-color: #d4ddf7; }
.domain-ico { flex-shrink: 0; display: grid; place-items: center; width: 46px; height: 46px; border-radius: 12px; color: var(--accent); background: var(--surface-alt); border: 1px solid var(--line); }
.domain-ico svg { width: 26px; height: 26px; }
.domain-body h3 { font-size: 17.5px; margin-bottom: 9px; letter-spacing: -.02em; }
.domain-body p { font-size: 14.5px; color: var(--body); line-height: 1.62; }

/* ---------- SOLUTIONS ---------- */
.solutions { display: grid; grid-template-columns: 1fr 1fr; gap: 24px; }
.solution {
  position: relative; cursor: pointer;
  background: #fff; border: 1px solid var(--line); border-radius: var(--radius); padding: 34px 32px; box-shadow: var(--shadow-xs);
  transition: transform .4s var(--ease), box-shadow .4s var(--ease), border-color .4s;
}
.solution:hover { transform: translateY(-5px); box-shadow: var(--shadow-md); border-color: #d4ddf7; }
.solution-head { display: flex; align-items: center; gap: 16px; margin-bottom: 18px; }
.solution-ico { flex-shrink: 0; width: 52px; height: 52px; border-radius: 14px; display: grid; place-items: center; color: var(--accent); background: linear-gradient(140deg, rgba(39, 71, 224, .1), rgba(0, 24, 144, .06)); }
.solution-ico svg { width: 27px; height: 27px; }
.solution-name { display: block; font-family: var(--font-display); font-size: 22px; font-weight: 800; color: var(--ink); letter-spacing: -.02em; line-height: 1.1; }
.solution-cat { display: block; font-size: 13.5px; color: var(--accent); font-weight: 600; margin-top: 3px; }
.solution p { font-size: 15px; color: var(--body); margin-bottom: 18px; }
.solution-feats { list-style: none; display: flex; flex-wrap: wrap; gap: 8px; }
.solution-feats li { font-size: 12.5px; font-weight: 500; color: var(--accent-2); background: var(--surface-alt); border: 1px solid var(--line); padding: 6px 12px; border-radius: 999px; }
.section--alt .solution-feats li { background: #fff; }
.solution-link { display: inline-flex; align-items: center; gap: 7px; margin-top: 20px; font-family: var(--font-display); font-weight: 600; font-size: 14px; color: var(--accent); transition: gap .25s var(--ease); }
.solution-link .arrow { transition: transform .25s var(--ease); }
.solution-link:hover .arrow { transform: translateX(4px); }
.solutions-note { text-align: center; margin-top: 28px; font-size: 14.5px; color: var(--muted); }

/* ---------- RESEARCH ---------- */
.research-grid { display: grid; grid-template-columns: 1fr 1fr 1fr; gap: 28px; }
.res-block { background: #fff; border: 1px solid var(--line); border-radius: var(--radius); padding: 34px 32px; box-shadow: var(--shadow-xs); }
.res-k { display: block; font-family: var(--font-display); font-size: 12.5px; font-weight: 600; letter-spacing: .12em; color: var(--accent); text-transform: uppercase; margin-bottom: 22px; }
.res-list { list-style: none; display: flex; flex-direction: column; gap: 18px; }
.res-list li { display: flex; flex-direction: column; gap: 5px; }
.res-list:not(.res-list--compact) li { padding-bottom: 18px; border-bottom: 1px dashed var(--line); }
.res-list:not(.res-list--compact) li:last-child { padding-bottom: 0; border-bottom: none; }
.res-id { font-family: var(--font-display); font-weight: 600; font-size: 12.5px; color: var(--accent-2); letter-spacing: .02em; }
.res-t { font-size: 15px; color: var(--ink); font-weight: 500; line-height: 1.5; letter-spacing: -.01em; }
.res-list--compact li { gap: 3px; }
.res-list--compact .res-t { font-size: 14.5px; }
.res-j { font-family: var(--font-display); font-size: 12px; color: var(--muted); }
.res-award { display: flex; gap: 14px; padding-bottom: 18px; margin-bottom: 18px; border-bottom: 1px dashed var(--line); }
.res-award-yr { font-family: var(--font-display); font-weight: 700; font-size: 16px; color: var(--brand); flex-shrink: 0; }
.res-award div { display: flex; flex-direction: column; gap: 3px; }
.res-award strong { color: var(--ink); font-size: 15px; font-weight: 600; line-height: 1.4; }
.res-award span { font-size: 13px; color: var(--muted); }
.res-infra { font-size: 14px; color: var(--body); padding-top: 4px; }

/* ---------- CONTACT (navy) ---------- */
.section--contact { position: relative; overflow: hidden; background: linear-gradient(160deg, #021a8a 0%, #001890 45%, #020e54 100%); color: #fff; isolation: isolate; }
.contact-mark { position: absolute; right: -6%; bottom: -30%; width: min(460px, 50vw); opacity: .06; z-index: -1; }
.contact-grid { display: grid; grid-template-columns: 1fr 1fr 1.1fr; gap: 22px; }
.contact-card { background: rgba(255, 255, 255, .06); border: 1px solid rgba(255, 255, 255, .14); border-radius: var(--radius); padding: 32px 30px; backdrop-filter: blur(6px); }
.contact-k { display: block; font-family: var(--font-display); font-size: 12.5px; font-weight: 600; letter-spacing: .04em; color: #aac1ff; margin-bottom: 14px; }
.contact-addr { font-size: 16px; color: #fff; line-height: 1.6; }
.contact-card--reach { display: flex; flex-direction: column; }
.contact-line { display: block; font-size: 17px; font-weight: 600; color: #fff; margin-bottom: 9px; font-family: var(--font-display); letter-spacing: -.01em; overflow-wrap: anywhere; transition: color .2s; }
.contact-line:hover { color: #aac1ff; }
.contact-btn { margin-top: auto; align-self: flex-start; }

/* ============================================================
   FOOTER
   ============================================================ */
.site-footer { background: var(--brand-deep); color: rgba(255, 255, 255, .66); padding-top: 60px; }
.footer-inner { display: flex; justify-content: space-between; gap: 40px; flex-wrap: wrap; padding-bottom: 44px; }
.footer-brand-row { display: flex; align-items: center; gap: 14px; margin-bottom: 18px; }
.footer-logo { height: 40px; }
.footer-ko { font-family: var(--font-body); font-weight: 600; font-size: 19px; letter-spacing: -.02em; white-space: nowrap; color: #fff; padding-left: 14px; border-left: 1px solid rgba(255, 255, 255, .22); }
.footer-brand p { font-size: 14.5px; max-width: 300px; }
.footer-info { text-align: right; }
.footer-info p { font-size: 13.5px; margin-bottom: 6px; }
.footer-info strong { color: #fff; font-weight: 600; }
.footer-bottom { border-top: 1px solid rgba(255, 255, 255, .1); padding: 22px 0; font-size: 12.5px; color: rgba(255, 255, 255, .45); }

/* ============================================================
   Scroll reveal
   ============================================================ */
.reveal { opacity: 0; transform: translateY(26px); transition: opacity .7s var(--ease), transform .7s var(--ease); }
.reveal.in { opacity: 1; transform: none; }
.pillars .reveal:nth-child(2) { transition-delay: .07s; }
.pillars .reveal:nth-child(3) { transition-delay: .14s; }
.pillars .reveal:nth-child(4) { transition-delay: .07s; }
.domains .reveal:nth-child(3n+2) { transition-delay: .07s; }
.domains .reveal:nth-child(3n+3) { transition-delay: .14s; }

/* ============================================================
   Responsive
   ============================================================ */
@media (max-width: 960px) {
  .nav { display: none; }
  .menu-btn { display: flex; }
  .about-grid { grid-template-columns: 1fr; gap: 32px; }
  .pillars { grid-template-columns: 1fr; }
  .solutions { grid-template-columns: 1fr; }
  .domains { grid-template-columns: 1fr 1fr; }
  .research-grid { grid-template-columns: 1fr; }
  .contact-grid { grid-template-columns: 1fr; }
  .footer-info { text-align: left; }
}
@media (max-width: 600px) {
  .section { padding: 78px 0; }
  .header-inner { height: 64px; }
  .brand-logo { height: 30px; }
  .brand-ko { font-size: 14px; padding-left: 10px; }
  .hero { padding-top: 138px; }
  .hero-inner { padding-bottom: 80px; }
  .domains { grid-template-columns: 1fr; }
  .section-head { margin-bottom: 46px; }
  .pillar { padding: 34px 28px; }
  .footer-inner { flex-direction: column; }
}

@media (prefers-reduced-motion: reduce) {
  * { animation: none !important; scroll-behavior: auto !important; }
  .reveal { opacity: 1; transform: none; transition: none; }
}