/* =========================================================
   DESIGN TOKENS
   ========================================================= */
:root {
  /* Colors - Light */
  --bg:           #f5f5f7;
  --bg-alt:       #ffffff;
  --bg-card:      #ffffff;
  --bg-header:    rgba(245, 245, 247, 0.85);
  --text:         #1c1c1e;
  --text-sub:     #6e6e73;
  --text-muted:   #aeaeb2;
  --accent:       #0057b7;
  --accent-hover: #003d87;
  --accent-rgb:   0, 87, 183;
  --border:       #e0e0e5;
  --border-card:  rgba(0, 0, 0, 0.07);
  --shadow-card:  0 1px 3px rgba(0,0,0,0.06), 0 4px 16px rgba(0,0,0,0.06);
  --shadow-hover: 0 4px 6px rgba(0,0,0,0.05), 0 12px 28px rgba(0,0,0,0.1);
  --orb-1:        rgba(0, 87, 183, 0.12);
  --orb-2:        rgba(100, 60, 220, 0.09);
  --blur-overlay-bg: rgba(245, 245, 247, 0.78);
  --blur-overlay-text: #1c1c1e;
  --tag-bg:       rgba(0, 87, 183, 0.08);
  --tag-text:     #0057b7;
  --grid-color:   rgba(0, 0, 0, 0.04);
  --hero-badge-bg: rgba(0, 87, 183, 0.1);
  --hero-badge-text: #0057b7;

  /* Typography */
  --font: -apple-system, BlinkMacSystemFont, 'Apple SD Gothic Neo',
          'Malgun Gothic', 'Segoe UI', Roboto, sans-serif;

  /* Spacing */
  --radius-sm:  8px;
  --radius:     14px;
  --radius-lg:  20px;

  /* Transitions */
  --transition: 0.2s ease;
  --transition-slow: 0.35s ease;
}

[data-theme="dark"] {
  --bg:           #0c0c0e;
  --bg-alt:       #111113;
  --bg-card:      #1c1c1e;
  --bg-header:    rgba(12, 12, 14, 0.88);
  --text:         #f5f5f7;
  --text-sub:     #98989d;
  --text-muted:   #6e6e73;
  --accent:       #3ea6ff;
  --accent-hover: #60b8ff;
  --accent-rgb:   62, 166, 255;
  --border:       #2c2c2e;
  --border-card:  rgba(255, 255, 255, 0.07);
  --shadow-card:  0 1px 3px rgba(0,0,0,0.3), 0 4px 16px rgba(0,0,0,0.3);
  --shadow-hover: 0 4px 6px rgba(0,0,0,0.3), 0 12px 28px rgba(0,0,0,0.45);
  --orb-1:        rgba(62, 166, 255, 0.1);
  --orb-2:        rgba(140, 80, 255, 0.09);
  --blur-overlay-bg: rgba(12, 12, 14, 0.82);
  --blur-overlay-text: #f5f5f7;
  --tag-bg:       rgba(62, 166, 255, 0.12);
  --tag-text:     #3ea6ff;
  --grid-color:   rgba(255, 255, 255, 0.03);
  --hero-badge-bg: rgba(62, 166, 255, 0.12);
  --hero-badge-text: #3ea6ff;
}

/* =========================================================
   RESET & BASE
   ========================================================= */
*, *::before, *::after {
  box-sizing: border-box;
  margin: 0;
  padding: 0;
}

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

body {
  font-family: var(--font);
  background: var(--bg);
  color: var(--text);
  line-height: 1.6;
  transition: background var(--transition-slow), color var(--transition-slow);
  overflow-x: hidden;
}

img, svg {
  display: block;
  max-width: 100%;
}

a {
  color: inherit;
  text-decoration: none;
}

button {
  font: inherit;
  cursor: pointer;
  border: none;
  background: none;
}

/* =========================================================
   ACCESSIBILITY
   ========================================================= */
.skip-link {
  position: absolute;
  top: -999px;
  left: 1rem;
  padding: 0.5rem 1rem;
  background: var(--accent);
  color: #fff;
  border-radius: var(--radius-sm);
  font-size: 0.875rem;
  z-index: 9999;
  transition: top var(--transition);
}
.skip-link:focus {
  top: 1rem;
}

/* =========================================================
   LAYOUT
   ========================================================= */
.container {
  width: 100%;
  max-width: 1100px;
  margin: 0 auto;
  padding: 0 1.5rem;
}

/* =========================================================
   HEADER
   ========================================================= */
.header {
  position: fixed;
  top: 0;
  left: 0;
  right: 0;
  z-index: 100;
  background: var(--bg-header);
  backdrop-filter: blur(20px) saturate(180%);
  -webkit-backdrop-filter: blur(20px) saturate(180%);
  border-bottom: 1px solid var(--border);
  transition: background var(--transition-slow), border-color var(--transition-slow);
}

.header-inner {
  display: flex;
  align-items: center;
  height: 60px;
  gap: 1rem;
}

.brand {
  font-size: 1.1rem;
  font-weight: 700;
  letter-spacing: -0.02em;
  color: var(--text);
  flex-shrink: 0;
  transition: color var(--transition);
}
.brand:hover { color: var(--accent); }

.nav {
  display: flex;
  align-items: center;
  gap: 0.25rem;
  margin-left: auto;
}

.nav-link {
  padding: 0.4rem 0.75rem;
  font-size: 0.9rem;
  font-weight: 500;
  color: var(--text-sub);
  border-radius: var(--radius-sm);
  transition: color var(--transition), background var(--transition);
}
.nav-link:hover {
  color: var(--text);
  background: var(--border-card);
}

.header-end {
  display: flex;
  align-items: center;
  gap: 0.25rem;
  margin-left: 0.5rem;
}

.btn-lang {
  display: flex;
  align-items: center;
  justify-content: center;
  height: 28px;
  padding: 0 0.6rem;
  border-radius: 999px;
  font-size: 0.72rem;
  font-weight: 700;
  letter-spacing: 0.05em;
  color: var(--text-sub);
  border: 1.5px solid var(--border);
  transition: color var(--transition), background var(--transition), border-color var(--transition);
}
.btn-lang:hover {
  color: var(--text);
  background: var(--border-card);
  border-color: var(--text-muted);
}

.btn-theme {
  display: flex;
  align-items: center;
  justify-content: center;
  width: 36px;
  height: 36px;
  border-radius: 50%;
  color: var(--text-sub);
  transition: color var(--transition), background var(--transition);
}
.btn-theme:hover {
  color: var(--text);
  background: var(--border-card);
}

/* header scrolled state */
.header--scrolled {
  box-shadow: 0 1px 12px rgba(0,0,0,0.08);
}
[data-theme="dark"] .header--scrolled {
  box-shadow: 0 1px 12px rgba(0,0,0,0.4);
}

/* icon visibility based on theme */
.icon-sun  { display: none; }
.icon-moon { display: block; }
[data-theme="dark"] .icon-sun  { display: block; }
[data-theme="dark"] .icon-moon { display: none; }

/* =========================================================
   HERO
   ========================================================= */
.hero {
  position: relative;
  min-height: 100svh;
  display: flex;
  align-items: center;
  justify-content: center;
  padding: 100px 0 80px;
  overflow: hidden;
  background: var(--bg);
  transition: background var(--transition-slow);
}

.hero-bg {
  position: absolute;
  inset: 0;
  pointer-events: none;
}

.hero-grid {
  position: absolute;
  inset: 0;
  background-image:
    linear-gradient(var(--grid-color) 1px, transparent 1px),
    linear-gradient(90deg, var(--grid-color) 1px, transparent 1px);
  background-size: 48px 48px;
  mask-image: radial-gradient(ellipse 80% 60% at 50% 50%, black 20%, transparent 80%);
}

.hero-orb {
  position: absolute;
  border-radius: 50%;
  filter: blur(72px);
  pointer-events: none;
}
.hero-orb--1 {
  width: 500px;
  height: 500px;
  top: 10%;
  left: -5%;
  background: var(--orb-1);
  animation: float1 14s ease-in-out infinite;
}
.hero-orb--2 {
  width: 420px;
  height: 420px;
  bottom: 5%;
  right: -5%;
  background: var(--orb-2);
  animation: float2 18s ease-in-out infinite;
}

@keyframes float1 {
  0%, 100% { transform: translate(0, 0) scale(1); }
  50%       { transform: translate(30px, -20px) scale(1.05); }
}
@keyframes float2 {
  0%, 100% { transform: translate(0, 0) scale(1); }
  50%       { transform: translate(-25px, 25px) scale(1.04); }
}

.hero-content {
  position: relative;
  z-index: 1;
  text-align: center;
  display: flex;
  flex-direction: column;
  align-items: center;
  gap: 1.25rem;
  animation: fadeUp 0.7s ease both;
}

@keyframes fadeUp {
  from { opacity: 0; transform: translateY(24px); }
  to   { opacity: 1; transform: translateY(0); }
}

.hero-badge {
  display: inline-block;
  padding: 0.35rem 1rem;
  background: var(--hero-badge-bg);
  color: var(--hero-badge-text);
  border-radius: 999px;
  font-size: 0.8125rem;
  font-weight: 600;
  letter-spacing: 0.03em;
  transition: background var(--transition-slow), color var(--transition-slow);
}

.hero-name {
  font-size: clamp(3rem, 8vw, 5.5rem);
  font-weight: 800;
  letter-spacing: -0.04em;
  line-height: 1;
  color: var(--text);
  transition: color var(--transition-slow);
}

.hero-desc {
  font-size: clamp(1rem, 2.5vw, 1.15rem);
  color: var(--text-sub);
  line-height: 1.7;
  max-width: 420px;
  transition: color var(--transition-slow);
}

.hero-cta {
  display: inline-flex;
  align-items: center;
  gap: 0.5rem;
  margin-top: 0.5rem;
  padding: 0.75rem 1.5rem;
  background: var(--accent);
  color: #fff;
  border-radius: 999px;
  font-size: 0.9375rem;
  font-weight: 600;
  transition: background var(--transition), transform var(--transition), box-shadow var(--transition);
}
.hero-cta:hover {
  background: var(--accent-hover);
  transform: translateY(-2px);
  box-shadow: 0 8px 24px rgba(var(--accent-rgb), 0.35);
}
.hero-cta svg {
  transition: transform var(--transition);
}
.hero-cta:hover svg {
  transform: translateY(3px);
}

/* =========================================================
   SECTION
   ========================================================= */
.section {
  padding: 100px 0;
  background: var(--bg);
  transition: background var(--transition-slow);
}

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

.section-header {
  margin-bottom: 3rem;
}

.section-title {
  font-size: clamp(1.75rem, 4vw, 2.5rem);
  font-weight: 800;
  letter-spacing: -0.03em;
  color: var(--text);
  line-height: 1.1;
  transition: color var(--transition-slow);
}

.section-desc {
  margin-top: 0.5rem;
  font-size: 1rem;
  color: var(--text-sub);
  transition: color var(--transition-slow);
}

/* =========================================================
   ABOUT
   ========================================================= */
.about-layout {
  display: flex;
  align-items: center;
  gap: 3.5rem;
}

.about-photo-wrap {
  flex-shrink: 0;
}

.about-photo {
  width: 200px;
  height: 200px;
  border-radius: 50%;
  object-fit: cover;
  object-position: center top;
  border: 3px solid var(--border);
  box-shadow: var(--shadow-card);
  transition: border-color var(--transition-slow), box-shadow var(--transition-slow);
}

.about-name {
  font-size: clamp(1.6rem, 3vw, 2.2rem);
  font-weight: 800;
  letter-spacing: -0.03em;
  color: var(--text);
  margin-bottom: 0.75rem;
  transition: color var(--transition-slow);
}

.about-desc {
  font-size: 1rem;
  color: var(--text-sub);
  line-height: 1.75;
  max-width: 520px;
  margin-bottom: 1.25rem;
  transition: color var(--transition-slow);
}

.about-tags {
  display: flex;
  flex-wrap: wrap;
  gap: 0.5rem;
}

@media (max-width: 700px) {
  .about-layout {
    flex-direction: column;
    align-items: flex-start;
    gap: 1.75rem;
  }
  .about-photo {
    width: 130px;
    height: 130px;
  }
}

/* =========================================================
   PROJECT CATEGORIES
   ========================================================= */
.cat {
  margin-bottom: 4rem;
  animation: fadeUp 0.5s ease both;
}
.cat:last-child { margin-bottom: 0; }

.cat-header {
  display: flex;
  align-items: baseline;
  gap: 0.75rem;
  margin-bottom: 1.5rem;
  padding-bottom: 1rem;
  border-bottom: 1px solid var(--border);
  transition: border-color var(--transition-slow);
}

.cat-title {
  font-size: 1.2rem;
  font-weight: 700;
  letter-spacing: -0.02em;
  color: var(--text);
  transition: color var(--transition-slow);
}

.cat-subtitle {
  font-size: 0.875rem;
  color: var(--text-muted);
  transition: color var(--transition-slow);
}

.cat-grid {
  display: grid;
  grid-template-columns: repeat(3, 1fr);
  gap: 1rem;
}

/* =========================================================
   PROJECT CARD
   ========================================================= */
.card {
  position: relative;
  background: var(--bg-card);
  border: 1px solid var(--border-card);
  border-radius: var(--radius);
  padding: 1.375rem;
  box-shadow: var(--shadow-card);
  transition:
    transform var(--transition),
    box-shadow var(--transition),
    background var(--transition-slow),
    border-color var(--transition-slow);
  overflow: hidden;
  display: flex;
  flex-direction: column;
  gap: 0.625rem;
}

.card:not(.card--locked):hover {
  transform: translateY(-4px);
  box-shadow: var(--shadow-hover);
}

.card-icon {
  font-size: 1.75rem;
  line-height: 1;
  margin-bottom: 0.125rem;
}

.card-name {
  font-size: 1rem;
  font-weight: 700;
  color: var(--text);
  letter-spacing: -0.01em;
  transition: color var(--transition-slow);
}

.card-desc {
  font-size: 0.8375rem;
  color: var(--text-sub);
  line-height: 1.55;
  flex: 1;
  transition: color var(--transition-slow);
}

.card-tags {
  display: flex;
  flex-wrap: wrap;
  gap: 0.375rem;
  margin-top: auto;
}

.tag {
  display: inline-block;
  padding: 0.2rem 0.55rem;
  background: var(--tag-bg);
  color: var(--tag-text);
  border-radius: 999px;
  font-size: 0.72rem;
  font-weight: 600;
  letter-spacing: 0.01em;
  transition: background var(--transition-slow), color var(--transition-slow);
}

/* =========================================================
   COMING SOON (LOCKED) CARD
   ========================================================= */
.card--locked .card-body {
  filter: blur(5px);
  user-select: none;
  pointer-events: none;
  opacity: 0.7;
}

.card-overlay {
  position: absolute;
  inset: 0;
  display: flex;
  flex-direction: column;
  align-items: center;
  justify-content: center;
  gap: 0.5rem;
  background: var(--blur-overlay-bg);
  backdrop-filter: blur(2px);
  -webkit-backdrop-filter: blur(2px);
  border-radius: var(--radius);
  z-index: 2;
  transition: background var(--transition-slow);
}

.card-overlay-icon {
  font-size: 1.5rem;
  opacity: 0.6;
  animation: pulse 3s ease-in-out infinite;
}

@keyframes pulse {
  0%, 100% { opacity: 0.5; transform: scale(1); }
  50%       { opacity: 0.85; transform: scale(1.08); }
}

.card-overlay-text {
  font-size: 0.8125rem;
  font-weight: 600;
  color: var(--blur-overlay-text);
  opacity: 0.65;
  letter-spacing: 0.04em;
  transition: color var(--transition-slow);
}

.card-overlay-dot {
  display: flex;
  gap: 4px;
  margin-top: 0.25rem;
}
.card-overlay-dot span {
  width: 4px;
  height: 4px;
  border-radius: 50%;
  background: var(--text-muted);
  animation: blink 1.4s infinite both;
}
.card-overlay-dot span:nth-child(2) { animation-delay: 0.2s; }
.card-overlay-dot span:nth-child(3) { animation-delay: 0.4s; }

@keyframes blink {
  0%, 80%, 100% { opacity: 0.2; }
  40%            { opacity: 1; }
}

/* =========================================================
   CONTACT
   ========================================================= */
.contact-grid {
  display: grid;
  grid-template-columns: repeat(2, 1fr);
  gap: 1rem;
  max-width: 560px;
}

.contact-card {
  display: flex;
  flex-direction: column;
  gap: 0.375rem;
  padding: 1.5rem;
  background: var(--bg-card);
  border: 1px solid var(--border-card);
  border-radius: var(--radius);
  box-shadow: var(--shadow-card);
  transition:
    transform var(--transition),
    box-shadow var(--transition),
    background var(--transition-slow);
}

.contact-card:hover {
  transform: translateY(-3px);
  box-shadow: var(--shadow-hover);
}

.contact-card-icon {
  color: var(--accent);
  transition: color var(--transition-slow);
}

.contact-card-label {
  font-size: 0.75rem;
  font-weight: 600;
  color: var(--text-muted);
  text-transform: uppercase;
  letter-spacing: 0.08em;
  margin-top: 0.25rem;
  transition: color var(--transition-slow);
}

.contact-card-value {
  font-size: 0.9rem;
  font-weight: 500;
  color: var(--text);
  transition: color var(--transition-slow);
}

/* =========================================================
   FOOTER
   ========================================================= */
.footer {
  background: var(--bg-alt);
  border-top: 1px solid var(--border);
  padding: 1.5rem 0;
  transition: background var(--transition-slow), border-color var(--transition-slow);
}

.footer-inner {
  display: flex;
  align-items: center;
  gap: 0.5rem;
  font-size: 0.8375rem;
  color: var(--text-muted);
  transition: color var(--transition-slow);
}

.footer-dot {
  opacity: 0.4;
}

/* =========================================================
   RESPONSIVE
   ========================================================= */
@media (max-width: 900px) {
  .cat-grid {
    grid-template-columns: repeat(2, 1fr);
  }
}

@media (max-width: 600px) {
  .container { padding: 0 1.25rem; }

  .nav-link { display: none; }

  .cat-grid {
    grid-template-columns: 1fr;
  }

  .contact-grid {
    grid-template-columns: 1fr;
  }

  .hero-name {
    font-size: 3rem;
  }

  .section { padding: 70px 0; }
}

/* =========================================================
   STAGGERED ANIMATION FOR CARDS
   ========================================================= */
.card {
  animation: cardIn 0.45s ease both;
}
@keyframes cardIn {
  from { opacity: 0; transform: translateY(16px); }
  to   { opacity: 1; transform: translateY(0); }
}

.cat:nth-child(1) .card:nth-child(1)  { animation-delay: 0.05s; }
.cat:nth-child(1) .card:nth-child(2)  { animation-delay: 0.10s; }
.cat:nth-child(1) .card:nth-child(3)  { animation-delay: 0.15s; }
.cat:nth-child(2) .card:nth-child(1)  { animation-delay: 0.10s; }
.cat:nth-child(2) .card:nth-child(2)  { animation-delay: 0.15s; }
.cat:nth-child(2) .card:nth-child(3)  { animation-delay: 0.20s; }
.cat:nth-child(3) .card:nth-child(1)  { animation-delay: 0.15s; }
.cat:nth-child(3) .card:nth-child(2)  { animation-delay: 0.20s; }
.cat:nth-child(3) .card:nth-child(3)  { animation-delay: 0.25s; }

/* Respect user motion preference */
@media (prefers-reduced-motion: reduce) {
  *, *::before, *::after {
    animation-duration: 0.01ms !important;
    transition-duration: 0.01ms !important;
  }
  html { scroll-behavior: auto; }
}