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

:root {
  --bg:          #ffffff;
  --bg-2:        #f8fafc;
  --bg-3:        #f1f5f9;
  --surface:     #ffffff;
  --border:      rgba(0,0,0,0.08);
  --shadow:      0 4px 24px rgba(0,0,0,0.07);
  --shadow-lg:   0 12px 40px rgba(0,0,0,0.12);
  --text:        #0f172a;
  --text-muted:  #64748b;
  --accent-1:    #6366f1;
  --accent-2:    #a855f7;
  --accent-3:    #06b6d4;
  --radius:      16px;
  --radius-sm:   10px;
  --transition:  0.35s cubic-bezier(0.4,0,0.2,1);
}

html { scroll-behavior: smooth; }

body {
  font-family: 'Inter', sans-serif;
  background: var(--bg);
  color: var(--text);
  line-height: 1.7;
  overflow-x: hidden;
}

a { text-decoration: none; color: inherit; }
ul { list-style: none; }
img { max-width: 100%; display: block; }

/* ============================================================
   UTILITIES
   ============================================================ */
.container { max-width: 1100px; margin-inline: auto; padding-inline: 1.5rem; }

.gradient-text {
  background: linear-gradient(135deg, var(--accent-1), var(--accent-2));
  -webkit-background-clip: text;
  -webkit-text-fill-color: transparent;
  background-clip: text;
}

/* REVEAL ANIMATION */
.reveal {
  opacity: 0;
  transform: translateY(28px);
  transition: opacity 0.6s ease, transform 0.6s ease;
}
.reveal.visible {
  opacity: 1;
  transform: none;
}

/* BUTTONS */
.btn {
  display: inline-flex;
  align-items: center;
  gap: 0.4rem;
  padding: 0.75rem 1.75rem;
  border-radius: 999px;
  font-weight: 600;
  font-size: 0.95rem;
  cursor: pointer;
  transition: var(--transition);
  border: none;
  font-family: inherit;
}
.btn--primary {
  background: linear-gradient(135deg, var(--accent-1), var(--accent-2));
  color: #fff;
  box-shadow: 0 4px 20px rgba(99,102,241,0.35);
}
.btn--primary:hover {
  transform: translateY(-2px);
  box-shadow: 0 8px 28px rgba(99,102,241,0.45);
}
.btn--ghost {
  background: transparent;
  color: #fff;
  border: 2px solid rgba(255,255,255,0.6);
}
.btn--ghost:hover {
  background: rgba(255,255,255,0.15);
  border-color: #fff;
  transform: translateY(-2px);
}
.btn--full { width: 100%; justify-content: center; }

/* SECTION COMMON */
.section { padding-block: 7rem; }
.section__header { text-align: center; margin-bottom: 3.5rem; }
.section__label {
  font-size: 0.8rem;
  font-weight: 600;
  letter-spacing: 0.15em;
  text-transform: uppercase;
  color: var(--accent-1);
  margin-bottom: 0.5rem;
}
.section__title {
  font-size: clamp(1.8rem, 4vw, 2.6rem);
  font-weight: 800;
  letter-spacing: -0.03em;
  color: var(--text);
}

/* ============================================================
   NAV
   ============================================================ */
.nav {
  position: fixed;
  top: 0; left: 0; right: 0;
  z-index: 100;
  transition: background var(--transition), box-shadow var(--transition);
}
.nav.scrolled {
  background: rgba(255,255,255,0.92);
  box-shadow: 0 1px 24px rgba(0,0,0,0.08);
  backdrop-filter: blur(20px);
  -webkit-backdrop-filter: blur(20px);
}
.nav__inner {
  max-width: 1100px;
  margin-inline: auto;
  padding: 1.25rem 1.5rem;
  display: flex;
  align-items: center;
  justify-content: space-between;
}
.nav__logo {
  font-size: 1.3rem;
  font-weight: 800;
  background: linear-gradient(135deg, var(--accent-1), var(--accent-2));
  -webkit-background-clip: text;
  -webkit-text-fill-color: transparent;
  background-clip: text;
}
/* Hero 위에선 흰색, 스크롤 후엔 어두운 색 */
.nav:not(.scrolled) .nav__logo {
  background: none;
  -webkit-text-fill-color: #fff;
  color: #fff;
}
.nav:not(.scrolled) .nav__links a { color: rgba(255,255,255,0.8); }
.nav:not(.scrolled) .nav__links a:hover { color: #fff; }
.nav:not(.scrolled) .nav__menu-btn span { background: #fff; }

.nav.scrolled .nav__logo {
  background: linear-gradient(135deg, var(--accent-1), var(--accent-2));
  -webkit-background-clip: text;
  -webkit-text-fill-color: transparent;
  background-clip: text;
}

.nav__links {
  display: flex;
  gap: 2rem;
}
.nav__links a {
  font-size: 0.9rem;
  font-weight: 500;
  color: var(--text-muted);
  transition: color var(--transition);
}
.nav__links a:hover { color: var(--accent-1); }

.nav__menu-btn {
  display: none;
  flex-direction: column;
  gap: 5px;
  background: none;
  border: none;
  cursor: pointer;
  padding: 4px;
}
.nav__menu-btn span {
  display: block;
  width: 22px;
  height: 2px;
  background: var(--text);
  border-radius: 2px;
  transition: var(--transition);
}

.nav__mobile {
  display: none;
  flex-direction: column;
  background: rgba(255,255,255,0.97);
  border-top: 1px solid var(--border);
  padding: 1rem 1.5rem;
  backdrop-filter: blur(20px);
}
.nav__mobile.open { display: flex; }
.nav__mobile a {
  display: block;
  padding: 0.75rem 0;
  font-weight: 500;
  color: var(--text-muted);
  border-bottom: 1px solid var(--border);
}
.nav__mobile a:hover { color: var(--accent-1); }

/* ============================================================
   HERO — SLIDESHOW
   ============================================================ */
.hero {
  min-height: 100vh;
  display: flex;
  align-items: center;
  justify-content: center;
  text-align: center;
  position: relative;
  overflow: hidden;
  padding: 6rem 1.5rem 4rem;
}

/* Slideshow */
.hero__slides {
  position: absolute;
  inset: 0;
  z-index: 0;
}
.hero__slide {
  position: absolute;
  inset: 0;
  background-size: cover;
  background-position: center;
  opacity: 0;
  transition: opacity 1.2s ease;
}
.hero__slide.active { opacity: 1; }

/* Dark overlay for text readability */
.hero__overlay {
  position: absolute;
  inset: 0;
  z-index: 1;
  background: linear-gradient(
    to bottom,
    rgba(10,10,20,0.55) 0%,
    rgba(10,10,20,0.45) 60%,
    rgba(10,10,20,0.65) 100%
  );
}

/* Slideshow dots */
.hero__dots {
  position: absolute;
  bottom: 5rem;
  left: 50%;
  transform: translateX(-50%);
  z-index: 3;
  display: flex;
  gap: 8px;
}
.hero__dot {
  width: 8px; height: 8px;
  border-radius: 50%;
  background: rgba(255,255,255,0.4);
  border: none;
  cursor: pointer;
  padding: 0;
  transition: var(--transition);
}
.hero__dot.active {
  background: #fff;
  width: 24px;
  border-radius: 4px;
}

.hero__content {
  position: relative;
  z-index: 2;
  max-width: 760px;
  display: flex;
  flex-direction: column;
  align-items: center;
  gap: 1.25rem;
  color: #fff;
}
.hero__greeting { font-size: 1.05rem; color: rgba(255,255,255,0.75); }
.hero__name {
  font-size: clamp(2.4rem, 7vw, 4.5rem);
  font-weight: 800;
  letter-spacing: -0.04em;
  line-height: 1.1;
  color: #fff;
}
.hero__name .gradient-text {
  background: linear-gradient(135deg, #a5b4fc, #e879f9);
  -webkit-background-clip: text;
  -webkit-text-fill-color: transparent;
  background-clip: text;
}
.hero__role {
  font-size: clamp(1rem, 2.5vw, 1.3rem);
  color: rgba(255,255,255,0.8);
  min-height: 2em;
}
.typewriter {
  border-right: 2px solid rgba(255,255,255,0.7);
  padding-right: 4px;
  animation: blink 0.75s step-end infinite;
}
@keyframes blink { 50% { border-color: transparent; } }
.hero__desc {
  color: rgba(255,255,255,0.7);
  font-size: 1.05rem;
  max-width: 520px;
}
.hero__cta {
  display: flex;
  gap: 1rem;
  flex-wrap: wrap;
  justify-content: center;
  margin-top: 0.5rem;
}

.hero__scroll {
  position: absolute;
  bottom: 2.5rem;
  left: 50%;
  transform: translateX(-50%);
  z-index: 3;
}
.scroll-indicator {
  width: 26px; height: 42px;
  border: 2px solid rgba(255,255,255,0.4);
  border-radius: 999px;
  position: relative;
}
.scroll-indicator::after {
  content: '';
  position: absolute;
  top: 6px; left: 50%;
  transform: translateX(-50%);
  width: 4px; height: 8px;
  background: rgba(255,255,255,0.8);
  border-radius: 2px;
  animation: scrollDown 1.8s ease-in-out infinite;
}
@keyframes scrollDown {
  0%   { top: 6px; opacity: 1; }
  100% { top: 22px; opacity: 0; }
}

/* ============================================================
   ABOUT
   ============================================================ */
.about { background: var(--bg); }

.about__grid {
  display: grid;
  grid-template-columns: auto 1fr;
  gap: 4rem;
  align-items: start;
}
.about__image {
  display: flex;
  flex-direction: column;
  align-items: center;
  gap: 1rem;
}
.about__avatar {
  width: 200px; height: 200px;
  border-radius: 24px;
  overflow: hidden;
  box-shadow: var(--shadow-lg);
  flex-shrink: 0;
  background: linear-gradient(135deg, var(--accent-1), var(--accent-2));
  display: flex;
  align-items: center;
  justify-content: center;
}
.about__avatar img {
  width: 100%; height: 100%;
  object-fit: cover;
  display: block;
}
.avatar-placeholder {
  font-size: 2.5rem;
  font-weight: 800;
  color: #fff;
}
.about__badge {
  display: flex;
  align-items: center;
  gap: 0.5rem;
  padding: 0.4rem 1rem;
  border-radius: 999px;
  font-size: 0.8rem;
  font-weight: 500;
  background: var(--surface);
  border: 1px solid var(--border);
  box-shadow: var(--shadow);
  color: var(--text);
}
.badge__dot {
  width: 8px; height: 8px;
  border-radius: 50%;
  background: #22c55e;
  animation: pulse 2s infinite;
}
@keyframes pulse {
  0%, 100% { box-shadow: 0 0 0 0 rgba(34,197,94,0.5); }
  50%       { box-shadow: 0 0 0 6px rgba(34,197,94,0); }
}

.about__text { display: flex; flex-direction: column; gap: 1rem; }
.about__text p { color: var(--text-muted); }
.about__text strong { color: var(--text); font-weight: 600; }
.about__facts {
  display: flex;
  flex-wrap: wrap;
  gap: 0.6rem;
  margin-top: 0.5rem;
}
.about__facts li {
  background: var(--bg-3);
  border: 1px solid var(--border);
  border-radius: var(--radius-sm);
  padding: 0.4rem 0.9rem;
  font-size: 0.85rem;
  color: var(--text-muted);
}

/* ============================================================
   SKILLS
   ============================================================ */
.skills { background: var(--bg-2); }

.skills__grid {
  display: grid;
  grid-template-columns: repeat(3, 1fr);
  gap: 1.5rem;
}
.skill-card {
  background: var(--surface);
  border: 1px solid var(--border);
  border-radius: var(--radius);
  padding: 2rem;
  box-shadow: var(--shadow);
  transition: transform var(--transition), box-shadow var(--transition);
}
.skill-card:hover {
  transform: translateY(-6px);
  box-shadow: var(--shadow-lg);
}
.skill-card__icon { font-size: 2rem; margin-bottom: 1rem; }
.skill-card h3 {
  font-size: 1rem;
  font-weight: 700;
  margin-bottom: 1rem;
  color: var(--text);
}
.skill-card ul { display: flex; flex-direction: column; gap: 0.5rem; }
.skill-card li {
  font-size: 0.9rem;
  color: var(--text-muted);
  padding-left: 1rem;
  position: relative;
}
.skill-card li::before {
  content: '▸';
  position: absolute;
  left: 0;
  color: var(--accent-1);
}

/* ============================================================
   CAREER TIMELINE
   ============================================================ */
.career { background: var(--bg); }

.timeline {
  position: relative;
  max-width: 720px;
  margin-inline: auto;
  padding-left: 2rem;
}
.timeline::before {
  content: '';
  position: absolute;
  left: 0;
  top: 10px;
  bottom: 10px;
  width: 2px;
  background: linear-gradient(to bottom, var(--accent-1), var(--accent-2), rgba(99,102,241,0.1));
}
.timeline__item {
  position: relative;
  padding-bottom: 2rem;
}
.timeline__item:last-child { padding-bottom: 0; }

.timeline__dot {
  position: absolute;
  left: -2.4rem;
  top: 1.25rem;
  width: 12px; height: 12px;
  border-radius: 50%;
  background: linear-gradient(135deg, var(--accent-1), var(--accent-2));
  box-shadow: 0 0 0 3px #fff, 0 0 0 5px rgba(99,102,241,0.25);
  flex-shrink: 0;
}

.timeline__content {
  background: var(--surface);
  border: 1px solid var(--border);
  border-radius: var(--radius);
  padding: 1.4rem 1.6rem;
  box-shadow: var(--shadow);
  transition: transform var(--transition), box-shadow var(--transition);
}
.timeline__content:hover {
  transform: translateX(4px);
  box-shadow: var(--shadow-lg);
}

.timeline__header {
  display: flex;
  align-items: center;
  gap: 0.75rem;
  margin-bottom: 0.3rem;
}
.timeline__header h3 {
  font-size: 1rem;
  font-weight: 700;
  color: var(--text);
}
.timeline__badge {
  font-size: 0.7rem;
  font-weight: 600;
  padding: 0.15rem 0.6rem;
  border-radius: 999px;
  background: rgba(34,197,94,0.1);
  border: 1px solid rgba(34,197,94,0.3);
  color: #16a34a;
}
.timeline__period {
  font-size: 0.8rem;
  color: var(--accent-1);
  font-weight: 500;
  margin-bottom: 0.4rem;
}
.timeline__desc {
  font-size: 0.88rem;
  color: var(--text-muted);
}

/* ============================================================
   PROJECTS
   ============================================================ */
.projects { background: var(--bg-2); }

.projects__grid {
  display: grid;
  grid-template-columns: repeat(3, 1fr);
  gap: 1.5rem;
}
.project-card {
  background: var(--surface);
  border: 1px solid var(--border);
  border-radius: var(--radius);
  padding: 1.75rem;
  box-shadow: var(--shadow);
  display: flex;
  flex-direction: column;
  gap: 1.25rem;
  transition: transform var(--transition), box-shadow var(--transition);
}
.project-card:hover {
  transform: translateY(-6px);
  box-shadow: var(--shadow-lg);
}
.project-card__top { display: flex; justify-content: flex-end; }
.project-card__links { display: flex; gap: 0.75rem; }
.project-card__links a {
  color: var(--text-muted);
  transition: color var(--transition);
}
.project-card__links a:hover { color: var(--accent-1); }
.project-card__body { flex: 1; }
.project-card__body h3 {
  font-size: 1.05rem;
  font-weight: 700;
  margin-bottom: 0.6rem;
  color: var(--text);
}
.project-card__body p {
  font-size: 0.9rem;
  color: var(--text-muted);
  line-height: 1.6;
}
.project-card__tags {
  display: flex;
  flex-wrap: wrap;
  gap: 0.5rem;
}
.project-card__tags span {
  padding: 0.25rem 0.75rem;
  border-radius: 999px;
  font-size: 0.75rem;
  font-weight: 600;
  background: rgba(99,102,241,0.08);
  border: 1px solid rgba(99,102,241,0.2);
  color: var(--accent-1);
}

/* ============================================================
   AWARDS
   ============================================================ */
.awards { background: var(--bg); }

.awards__grid {
  display: grid;
  grid-template-columns: repeat(3, 1fr);
  gap: 1.5rem;
  max-width: 860px;
  margin-inline: auto;
}
.award-card {
  background: var(--surface);
  border: 1px solid var(--border);
  border-radius: var(--radius);
  padding: 2rem;
  box-shadow: var(--shadow);
  text-align: center;
  transition: transform var(--transition), box-shadow var(--transition);
}
.award-card:hover {
  transform: translateY(-6px);
  box-shadow: var(--shadow-lg);
}
.award-card__year {
  font-size: 0.75rem;
  font-weight: 700;
  letter-spacing: 0.1em;
  text-transform: uppercase;
  color: var(--accent-1);
  margin-bottom: 0.75rem;
}
.award-card__icon { font-size: 2.2rem; margin-bottom: 0.75rem; }
.award-card h3 {
  font-size: 0.95rem;
  font-weight: 700;
  margin-bottom: 0.5rem;
  color: var(--text);
}
.award-card p { font-size: 0.85rem; color: var(--text-muted); }
.award-card strong { color: var(--text); }

/* ============================================================
   CONTACT
   ============================================================ */
.contact { background: var(--bg-2); }

.contact__inner {
  display: grid;
  grid-template-columns: 1fr 1.4fr;
  gap: 4rem;
  align-items: start;
}
.contact__left p {
  font-size: 1.1rem;
  color: var(--text-muted);
  margin-bottom: 2rem;
  line-height: 1.8;
}
.contact__links { display: flex; flex-direction: column; gap: 1rem; }
.contact__links a {
  display: flex;
  align-items: center;
  gap: 0.75rem;
  color: var(--text-muted);
  font-size: 0.95rem;
  transition: color var(--transition);
}
.contact__links a:hover { color: var(--accent-1); }
.contact__icon { font-size: 1.1rem; }

.contact__form {
  background: var(--surface);
  border: 1px solid var(--border);
  border-radius: var(--radius);
  padding: 2.25rem;
  box-shadow: var(--shadow);
  display: flex;
  flex-direction: column;
  gap: 1.25rem;
}
.form-group { display: flex; flex-direction: column; gap: 0.4rem; }
.form-group label {
  font-size: 0.85rem;
  font-weight: 500;
  color: var(--text-muted);
}
.form-group input,
.form-group textarea {
  background: var(--bg-3);
  border: 1px solid var(--border);
  border-radius: var(--radius-sm);
  padding: 0.75rem 1rem;
  color: var(--text);
  font-family: inherit;
  font-size: 0.95rem;
  transition: border-color var(--transition), box-shadow var(--transition);
  resize: none;
}
.form-group input::placeholder,
.form-group textarea::placeholder { color: #94a3b8; }
.form-group input:focus,
.form-group textarea:focus {
  outline: none;
  border-color: var(--accent-1);
  box-shadow: 0 0 0 3px rgba(99,102,241,0.12);
  background: #fff;
}

/* ============================================================
   FOOTER
   ============================================================ */
.footer {
  padding: 2rem 0;
  text-align: center;
  border-top: 1px solid var(--border);
  color: var(--text-muted);
  font-size: 0.85rem;
  background: var(--bg);
}

/* ============================================================
   RESPONSIVE
   ============================================================ */
@media (max-width: 900px) {
  .skills__grid { grid-template-columns: repeat(2, 1fr); }
  .projects__grid { grid-template-columns: repeat(2, 1fr); }
  .awards__grid { grid-template-columns: repeat(2, 1fr); }
  .about__grid { grid-template-columns: 1fr; }
  .about__image { flex-direction: row; align-items: center; }
}

@media (max-width: 640px) {
  .nav__links { display: none; }
  .nav__menu-btn { display: flex; }

  .skills__grid { grid-template-columns: 1fr; }
  .projects__grid { grid-template-columns: 1fr; }
  .awards__grid { grid-template-columns: 1fr; }
  .contact__inner { grid-template-columns: 1fr; gap: 2rem; }
  .timeline { padding-left: 1.5rem; }
  .timeline__dot { left: -1.9rem; }

  .hero__name { font-size: 2.4rem; }
  .section { padding-block: 4.5rem; }
}