/* =========================================================
   Summer-J — Minimal black & white
   ========================================================= */

@font-face {
  font-family: "Jejudoldam";
  src:
    url("../font/EF_jejudoldam(OTF).otf") format("opentype"),
    url("../font/EF_jejudoldam(TTF).ttf") format("truetype");
  font-weight: 400;
  font-style: normal;
  font-display: swap;
}

:root {
  --bg: #ffffff;
  --bg-alt: #f5f5f5;
  --ink: #0a0a0a;
  --ink-soft: #4a4a4a;
  --ink-mute: #8a8a8a;
  --line: #e6e6e6;
  --line-strong: #d0d0d0;
  --invert-bg: #0a0a0a;
  --invert-ink: #ffffff;
  --invert-ink-soft: #b8b8b8;
  --invert-line: #222;

  --radius: 4px;
  --radius-lg: 12px;
  --container: 1200px;
  --gutter: clamp(1.25rem, 4vw, 2.5rem);

  --font-sans:
    "Inter", -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, sans-serif;
  --font-serif: "Inter", Georgia, "Times New Roman", serif;

  --ease: cubic-bezier(0.2, 0.7, 0.2, 1);
  --t-fast: 160ms var(--ease);
  --t-base: 260ms var(--ease);
  --t-slow: 600ms var(--ease);
}

@media (prefers-color-scheme: dark) {
  /* keep brand identity: stay light-mode by default; users can override later */
}

/* ---------- Reset ---------- */
*,
*::before,
*::after {
  box-sizing: border-box;
}
html {
  scroll-behavior: smooth;
  -webkit-text-size-adjust: 100%;
}
@media (prefers-reduced-motion: reduce) {
  html {
    scroll-behavior: auto;
  }
  *,
  *::before,
  *::after {
    animation-duration: 0.001ms !important;
    animation-iteration-count: 1 !important;
    transition-duration: 0.001ms !important;
  }
}
body {
  margin: 0;
  font-family: var(--font-sans);
  font-size: 16px;
  line-height: 1.6;
  color: var(--ink);
  background: var(--bg);
  -webkit-font-smoothing: antialiased;
  -moz-osx-font-smoothing: grayscale;
}
img,
svg {
  display: block;
  max-width: 100%;
}
button {
  font: inherit;
  cursor: pointer;
}
a {
  color: inherit;
  text-decoration: none;
  transition: color var(--t-fast);
}
a:hover {
  color: var(--ink-soft);
}
ul {
  margin: 0;
  padding: 0;
  list-style: none;
}
h1,
h2,
h3,
p {
  margin: 0;
}

/* ---------- A11y ---------- */
.skip-link {
  position: absolute;
  left: -9999px;
  top: 0;
  background: var(--ink);
  color: var(--invert-ink);
  padding: 0.75rem 1rem;
  z-index: 1000;
}
.skip-link:focus {
  left: 0;
}

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

/* ---------- Layout primitives ---------- */
.container {
  max-width: var(--container);
  margin: 0 auto;
  padding: 0 var(--gutter);
}

.section {
  padding: clamp(4rem, 10vw, 8rem) 0;
  border-top: 1px solid var(--line);
}
.section-dark {
  background: var(--invert-bg);
  color: var(--invert-ink);
  border-top-color: var(--invert-bg);
}
.section-dark .eyebrow {
  color: var(--invert-ink-soft);
}
.section-dark h2 {
  color: var(--invert-ink);
}

.section-head {
  max-width: 720px;
  margin-bottom: clamp(2.5rem, 5vw, 4rem);
}
.section-head h2 {
  font-size: clamp(2rem, 4.5vw, 3.25rem);
  font-weight: 700;
  letter-spacing: -0.02em;
  line-height: 1.1;
  margin-top: 0.5rem;
}
.section-lead {
  margin-top: 1.25rem;
  font-size: 1.125rem;
  color: var(--ink-soft);
  max-width: 56ch;
}

.eyebrow {
  font-size: 0.75rem;
  font-weight: 600;
  letter-spacing: 0.16em;
  text-transform: uppercase;
  color: var(--ink-mute);
}

/* ---------- Header ---------- */
.site-header {
  position: sticky;
  top: 0;
  z-index: 50;
  background: rgba(255, 255, 255, 0.85);
  backdrop-filter: saturate(180%) blur(12px);
  -webkit-backdrop-filter: saturate(180%) blur(12px);
  border-bottom: 1px solid transparent;
  transition:
    border-color var(--t-base),
    background var(--t-base);
}
.site-header.is-scrolled {
  border-bottom-color: var(--line);
}
.header-inner {
  display: flex;
  align-items: center;
  justify-content: space-between;
  height: 72px;
}
.brand {
  display: inline-flex;
  align-items: center;
  gap: 0.625rem;
  font-weight: 700;
  letter-spacing: -0.01em;
}
.brand-name {
  font-family: "Jejudoldam", sans-serif;
  font-size: 1.5rem;
  line-height: 1;
  letter-spacing: 0.01em;
}

.nav ul {
  display: flex;
  align-items: center;
  gap: 2rem;
}
.nav a {
  font-size: 0.9375rem;
  color: var(--ink-soft);
  position: relative;
}
.nav a:hover {
  color: var(--ink);
}
.nav .nav-cta {
  background: var(--ink);
  color: var(--invert-ink);
  padding: 0.625rem 1.125rem;
  border-radius: var(--radius);
}
.nav .nav-cta:hover {
  background: var(--ink-soft);
  color: var(--invert-ink);
}

.menu-toggle {
  display: none;
  width: 40px;
  height: 40px;
  background: transparent;
  border: 1px solid var(--line);
  border-radius: var(--radius);
  padding: 0;
  flex-direction: column;
  align-items: center;
  justify-content: center;
  gap: 4px;
}
.menu-toggle span {
  display: block;
  width: 18px;
  height: 1.5px;
  background: var(--ink);
  transition:
    transform var(--t-base),
    opacity var(--t-fast);
}
.menu-toggle[aria-expanded="true"] span:nth-child(1) {
  transform: translateY(5.5px) rotate(45deg);
}
.menu-toggle[aria-expanded="true"] span:nth-child(2) {
  opacity: 0;
}
.menu-toggle[aria-expanded="true"] span:nth-child(3) {
  transform: translateY(-5.5px) rotate(-45deg);
}

.mobile-nav {
  display: none;
  border-top: 1px solid var(--line);
  background: var(--bg);
}
.mobile-nav ul {
  display: flex;
  flex-direction: column;
  padding: 1rem var(--gutter) 1.5rem;
}
.mobile-nav a {
  display: block;
  padding: 0.875rem 0;
  font-size: 1.125rem;
  border-bottom: 1px solid var(--line);
}
.mobile-nav.is-open {
  display: block;
}

/* ---------- Buttons ---------- */
.btn {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  gap: 0.5rem;
  padding: 0.875rem 1.5rem;
  font-size: 0.9375rem;
  font-weight: 500;
  border-radius: var(--radius);
  border: 1px solid transparent;
  transition:
    background var(--t-fast),
    color var(--t-fast),
    border-color var(--t-fast),
    transform var(--t-fast);
}
.btn-primary {
  background: var(--ink);
  color: var(--invert-ink);
}
.btn-primary:hover {
  background: #2a2a2a;
  color: var(--invert-ink);
  transform: translateY(-1px);
}
.btn-ghost {
  background: transparent;
  color: var(--ink);
  border-color: var(--line-strong);
}
.btn-ghost:hover {
  border-color: var(--ink);
  color: var(--ink);
}

/* ---------- Hero ---------- */
.hero {
  position: relative;
  padding: clamp(6rem, 14vw, 10rem) 0 clamp(5rem, 10vw, 8rem);
  overflow: hidden;
  border-top: none;
}
.hero-title {
  font-size: clamp(3rem, 9vw, 7rem);
  font-weight: 800;
  letter-spacing: -0.04em;
  line-height: 0.95;
  margin-top: 1.25rem;
  max-width: 14ch;
}
.hero-title .italic {
  font-style: italic;
  font-weight: 400;
  font-family: var(--font-serif);
  letter-spacing: -0.03em;
}
.hero-sub {
  margin-top: 1.75rem;
  font-size: clamp(1.0625rem, 1.6vw, 1.3125rem);
  color: var(--ink-soft);
  max-width: 52ch;
  line-height: 1.5;
}
.hero-cta {
  margin-top: 2.5rem;
  display: flex;
  gap: 0.75rem;
  flex-wrap: wrap;
}
.hero-grid {
  position: absolute;
  inset: 0;
  background-image:
    linear-gradient(to right, var(--line) 1px, transparent 1px),
    linear-gradient(to bottom, var(--line) 1px, transparent 1px);
  background-size: 80px 80px;
  mask-image: radial-gradient(
    ellipse 80% 60% at 50% 0%,
    #000 30%,
    transparent 75%
  );
  -webkit-mask-image: radial-gradient(
    ellipse 80% 60% at 50% 0%,
    #000 30%,
    transparent 75%
  );
  opacity: 0.55;
  z-index: -1;
  pointer-events: none;
}

/* ---------- Services ---------- */
.services-grid {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(280px, 1fr));
  gap: 1px;
  background: var(--line);
  border: 1px solid var(--line);
  border-radius: var(--radius-lg);
  overflow: hidden;
}
.service-card {
  position: relative;
  background: var(--bg);
  padding: 2.5rem 2rem;
  transition: background var(--t-base);
}
.service-card:hover {
  background: var(--bg-alt);
}
.service-num {
  font-size: 0.75rem;
  font-weight: 600;
  letter-spacing: 0.16em;
  color: var(--ink-mute);
}
.service-card h3 {
  margin-top: 1rem;
  font-size: 1.375rem;
  font-weight: 600;
  letter-spacing: -0.01em;
}
.service-card p {
  margin-top: 0.75rem;
  color: var(--ink-soft);
  font-size: 0.9375rem;
}

/* ---------- Work ---------- */
.work-grid {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(240px, 1fr));
  gap: 1.5rem;
}
.work-card {
  display: flex;
  flex-direction: column;
  gap: 1rem;
  transition: transform var(--t-base);
}
.work-card:hover {
  transform: translateY(-4px);
}
.work-thumb {
  aspect-ratio: 16 / 10;
  background: #161616;
  border-radius: var(--radius-lg);
  overflow: hidden;
  border: 1px solid #242424;
  position: relative;
  isolation: isolate;
}
.work-thumb::before {
  content: "";
  position: absolute;
  inset: 0;
  opacity: 0.28;
  transition: opacity var(--t-base);
  pointer-events: none;
}
.work-card:hover .work-thumb::before {
  opacity: 0.65;
}

/* 01 — Sleep EEG: brain wave readout */
.thumb-waves::before {
  background-image: url("data:image/svg+xml;utf8,<svg xmlns='http://www.w3.org/2000/svg' viewBox='0 0 400 250' preserveAspectRatio='xMidYMid slice'><g stroke='%23ffffff' stroke-width='1.25' fill='none' stroke-linecap='round'><path d='M-10 70 Q 50 30 100 70 T 210 70 T 320 70 T 430 70'/><path d='M-10 125 Q 30 95 60 125 T 120 125 T 180 125 T 240 125 T 300 125 T 360 125 T 420 125'/><path d='M-10 180 Q 70 140 140 180 T 290 180 T 440 180'/></g></svg>");
  background-size: 100% 100%;
  background-repeat: no-repeat;
}

/* 02 — Finance LMS: structured grid */
.thumb-grid::before {
  background-image:
    linear-gradient(#ffffff 1px, transparent 1px),
    linear-gradient(90deg, #ffffff 1px, transparent 1px);
  background-size: 22px 22px;
  background-position: center center;
}

/* 03 — Racing: motion / speed lines */
.thumb-speed::before {
  background-image: repeating-linear-gradient(
    -22deg,
    transparent 0,
    transparent 5px,
    #ffffff 5px,
    #ffffff 6px,
    transparent 6px,
    transparent 12px,
    #ffffff 12px,
    #ffffff 14px
  );
}

/* 04 — Laundry: concentric ripples */
.thumb-circles::before {
  background-image: repeating-radial-gradient(
    circle at center,
    transparent 0,
    transparent 14px,
    #ffffff 14px,
    #ffffff 15px
  );
}

.work-more {
  margin-top: 3rem;
  padding-top: 2rem;
  border-top: 1px solid var(--invert-line);
  font-size: 0.9375rem;
  color: var(--invert-ink-soft);
  display: flex;
  gap: 0.75rem;
  align-items: baseline;
}
.work-more span {
  font-size: 1.25rem;
  font-weight: 300;
  color: var(--invert-ink);
  line-height: 1;
}
.work-tag {
  font-size: 0.75rem;
  font-weight: 600;
  letter-spacing: 0.16em;
  text-transform: uppercase;
  color: var(--invert-ink-soft);
}
.work-card h3 {
  margin-top: 0.5rem;
  font-size: 1.375rem;
  font-weight: 600;
  letter-spacing: -0.01em;
}
.work-card p {
  margin-top: 0.5rem;
  color: var(--invert-ink-soft);
  font-size: 0.9375rem;
}

/* ---------- About ---------- */
.about-grid {
  display: grid;
  grid-template-columns: 1fr;
  gap: clamp(2rem, 5vw, 4rem);
}
@media (min-width: 900px) {
  .about-grid {
    grid-template-columns: 1fr 1.4fr;
    align-items: start;
  }
}
.about-grid h2 {
  font-size: clamp(2rem, 4.5vw, 3.25rem);
  font-weight: 700;
  letter-spacing: -0.02em;
  line-height: 1.1;
  margin-top: 0.5rem;
}
.about-body p + p {
  margin-top: 1.25rem;
}
.about-body p {
  font-size: 1.0625rem;
  color: var(--ink-soft);
  max-width: 60ch;
}
.stat-list {
  margin: 2.5rem 0 0;
  display: grid;
  grid-template-columns: repeat(3, 1fr);
  gap: 1.5rem;
  border-top: 1px solid var(--line);
  padding-top: 2rem;
}
.stat-list div {
  display: flex;
  flex-direction: column;
  gap: 0.25rem;
}
.stat-list dt {
  font-size: clamp(1.75rem, 4vw, 2.5rem);
  font-weight: 700;
  letter-spacing: -0.02em;
}
.stat-list dd {
  margin: 0;
  font-size: 0.8125rem;
  color: var(--ink-mute);
  letter-spacing: 0.04em;
}

/* ---------- Team ---------- */
.team-grid {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(220px, 1fr));
  gap: 2rem;
}
.team-card {
  padding: 2rem;
  border: 1px solid var(--line);
  border-radius: var(--radius-lg);
  transition: border-color var(--t-fast);
}
.team-card:hover {
  border-color: var(--ink);
}
.avatar {
  width: 56px;
  height: 56px;
  border-radius: 50%;
  background: var(--ink);
  color: var(--invert-ink);
  display: grid;
  place-items: center;
  font-weight: 600;
  font-size: 1rem;
  letter-spacing: 0.02em;
}
.team-card h3 {
  margin-top: 1.25rem;
  font-size: 1.125rem;
  font-weight: 600;
}
.team-card .role {
  margin-top: 0.25rem;
  font-size: 0.875rem;
  color: var(--ink-mute);
}

/* ---------- Contact ---------- */
.section-contact {
  background: var(--bg-alt);
}
.contact-grid {
  display: grid;
  grid-template-columns: 1fr;
  gap: clamp(2.5rem, 5vw, 4rem);
}
@media (min-width: 900px) {
  .contact-grid {
    grid-template-columns: 1fr 1fr;
    align-items: start;
  }
}
.contact-grid h2 {
  font-size: clamp(2rem, 4.5vw, 3.25rem);
  font-weight: 700;
  letter-spacing: -0.02em;
  line-height: 1.1;
  margin-top: 0.5rem;
}
.contact-lead {
  margin-top: 1.25rem;
  color: var(--ink-soft);
  font-size: 1.0625rem;
  max-width: 40ch;
}
.contact-list {
  margin-top: 2.5rem;
  border-top: 1px solid var(--line-strong);
}
.contact-list li {
  display: flex;
  justify-content: space-between;
  padding: 1rem 0;
  border-bottom: 1px solid var(--line-strong);
  font-size: 0.9375rem;
}
.contact-list span:first-child {
  color: var(--ink-mute);
  font-weight: 500;
}

.contact-form {
  display: grid;
  gap: 1.25rem;
  padding: 2rem;
  background: var(--bg);
  border: 1px solid var(--line);
  border-radius: var(--radius-lg);
}
.contact-form label {
  display: grid;
  gap: 0.5rem;
  font-size: 0.8125rem;
  font-weight: 600;
  letter-spacing: 0.04em;
  color: var(--ink-soft);
  text-transform: uppercase;
}
.contact-form input,
.contact-form textarea {
  font: inherit;
  font-size: 1rem;
  font-weight: 400;
  text-transform: none;
  letter-spacing: normal;
  color: var(--ink);
  padding: 0.75rem 0;
  background: transparent;
  border: 0;
  border-bottom: 1px solid var(--line-strong);
  border-radius: 0;
  transition: border-color var(--t-fast);
}
.contact-form input:focus,
.contact-form textarea:focus {
  outline: none;
  border-bottom-color: var(--ink);
}
.contact-form textarea {
  resize: vertical;
  min-height: 96px;
}
.contact-form .btn {
  justify-self: start;
  margin-top: 0.5rem;
}
.form-status {
  font-size: 0.875rem;
  color: var(--ink-soft);
  min-height: 1.25em;
}
.form-status.is-error {
  color: #b00020;
}
.form-status.is-success {
  color: #0a0a0a;
  font-weight: 600;
}

/* ---------- Footer ---------- */
.site-footer {
  border-top: 1px solid var(--line);
  padding: 3rem 0;
}
.footer-inner {
  display: flex;
  justify-content: space-between;
  align-items: flex-end;
  gap: 2rem;
  flex-wrap: wrap;
}
.footer-brand {
  font-size: 1.75rem;
}
.footer-tag {
  margin-top: 0.5rem;
  font-family: var(--font-serif);
  font-style: italic;
  color: var(--ink-soft);
}
.footer-meta {
  text-align: right;
  font-size: 0.875rem;
  color: var(--ink-mute);
  line-height: 1.7;
}

/* ---------- Reveal on scroll ---------- */
.reveal {
  opacity: 0;
  transform: translateY(16px);
  transition:
    opacity 700ms var(--ease),
    transform 700ms var(--ease);
}
.reveal.is-visible {
  opacity: 1;
  transform: translateY(0);
}

/* ---------- Responsive ---------- */
@media (max-width: 820px) {
  .nav {
    display: none;
  }
  .menu-toggle {
    display: inline-flex;
  }
  .footer-inner {
    align-items: flex-start;
  }
  .footer-meta {
    text-align: left;
  }
}
@media (max-width: 540px) {
  .stat-list {
    grid-template-columns: 1fr 1fr;
  }
  .stat-list div:nth-child(3) {
    grid-column: span 2;
  }
  .hero-cta {
    flex-direction: column;
    align-items: stretch;
  }
  .btn {
    width: 100%;
  }
}