/* ===========================
   CSS Variables & Reset
   =========================== */
:root {
  --bg-primary: #0a0a0f;
  --bg-secondary: #1a1a2e;
  --bg-card: rgba(255, 255, 255, 0.03);
  --bg-card-hover: rgba(255, 255, 255, 0.06);
  --accent: #00d4ff;
  --accent-purple: #7c3aed;
  --text-primary: #e4e4e7;
  --text-secondary: #a1a1aa;
  --text-muted: #71717a;
  --border: rgba(255, 255, 255, 0.08);
  --border-hover: rgba(0, 212, 255, 0.3);
  --font-family: 'Noto Sans KR', -apple-system, BlinkMacSystemFont, sans-serif;
  --nav-height: 70px;
  --container-max: 1100px;
  --transition: 0.3s cubic-bezier(0.4, 0, 0.2, 1);
}

*,
*::before,
*::after {
  margin: 0;
  padding: 0;
  box-sizing: border-box;
}

html {
  scroll-behavior: smooth;
  scroll-padding-top: var(--nav-height);
}

body {
  font-family: var(--font-family);
  background: var(--bg-primary);
  color: var(--text-primary);
  line-height: 1.7;
  overflow-x: hidden;
  -webkit-font-smoothing: antialiased;
}

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

ul {
  list-style: none;
}

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

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

/* ===========================
   Utility
   =========================== */
.container {
  width: 100%;
  max-width: var(--container-max);
  margin: 0 auto;
  padding: 0 24px;
}

.accent {
  color: var(--accent);
}

.highlight {
  color: var(--accent);
  font-weight: 500;
}

.section {
  padding: 100px 0;
}

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

.section-title {
  font-size: 2rem;
  font-weight: 700;
  margin-bottom: 56px;
  text-align: center;
  position: relative;
}

.section-title::after {
  content: '';
  display: block;
  width: 48px;
  height: 3px;
  background: linear-gradient(90deg, var(--accent), var(--accent-purple));
  margin: 16px auto 0;
  border-radius: 2px;
}

/* ===========================
   Navbar
   =========================== */
.navbar {
  position: fixed;
  top: 0;
  left: 0;
  right: 0;
  height: var(--nav-height);
  z-index: 1000;
  transition: background var(--transition), box-shadow var(--transition);
}

.navbar.scrolled {
  background: rgba(10, 10, 15, 0.85);
  backdrop-filter: blur(16px);
  -webkit-backdrop-filter: blur(16px);
  box-shadow: 0 1px 0 var(--border);
}

.nav-container {
  max-width: var(--container-max);
  margin: 0 auto;
  padding: 0 24px;
  height: 100%;
  display: flex;
  align-items: center;
  justify-content: space-between;
}

.nav-logo {
  font-size: 1.5rem;
  font-weight: 900;
  letter-spacing: -0.02em;
}

.nav-menu {
  display: flex;
  gap: 32px;
}

.nav-link {
  font-size: 0.9rem;
  font-weight: 400;
  color: var(--text-secondary);
  transition: color var(--transition);
  position: relative;
}

.nav-link::after {
  content: '';
  position: absolute;
  bottom: -4px;
  left: 0;
  width: 0;
  height: 2px;
  background: var(--accent);
  transition: width var(--transition);
}

.nav-link:hover,
.nav-link.active {
  color: var(--text-primary);
}

.nav-link:hover::after,
.nav-link.active::after {
  width: 100%;
}

/* Mobile toggle */
.nav-toggle {
  display: none;
  flex-direction: column;
  gap: 5px;
  padding: 4px;
}

.nav-toggle span {
  display: block;
  width: 24px;
  height: 2px;
  background: var(--text-primary);
  border-radius: 2px;
  transition: var(--transition);
}

.nav-toggle.active span:nth-child(1) {
  transform: rotate(45deg) translate(5px, 5px);
}

.nav-toggle.active span:nth-child(2) {
  opacity: 0;
}

.nav-toggle.active span:nth-child(3) {
  transform: rotate(-45deg) translate(5px, -5px);
}

/* ===========================
   Hero Section
   =========================== */
.hero {
  min-height: 100vh;
  display: flex;
  align-items: center;
  justify-content: center;
  position: relative;
  overflow: hidden;
  text-align: center;
}

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

.hero-glow {
  position: absolute;
  border-radius: 50%;
  filter: blur(120px);
  opacity: 0.15;
}

.hero-glow--1 {
  width: 500px;
  height: 500px;
  background: var(--accent);
  top: -100px;
  right: -100px;
}

.hero-glow--2 {
  width: 400px;
  height: 400px;
  background: var(--accent-purple);
  bottom: -50px;
  left: -50px;
}

.hero-content {
  position: relative;
  z-index: 1;
}

.hero-greeting {
  font-size: 1.1rem;
  color: var(--accent);
  font-weight: 400;
  margin-bottom: 12px;
}

.hero-name {
  font-size: clamp(3rem, 8vw, 5.5rem);
  font-weight: 900;
  letter-spacing: -0.03em;
  line-height: 1.1;
  margin-bottom: 20px;
}

.hero-typing-wrapper {
  font-size: clamp(1rem, 2.5vw, 1.35rem);
  color: var(--text-secondary);
  min-height: 2em;
  margin-bottom: 24px;
}

.typing-cursor {
  animation: blink 1s step-end infinite;
  color: var(--accent);
  font-weight: 300;
}

@keyframes blink {
  0%, 100% { opacity: 1; }
  50% { opacity: 0; }
}

.hero-description {
  font-size: 1.05rem;
  color: var(--text-secondary);
  line-height: 1.8;
  margin-bottom: 40px;
  max-width: 520px;
  margin-left: auto;
  margin-right: auto;
}

.hero-cta {
  display: flex;
  gap: 16px;
  justify-content: center;
  flex-wrap: wrap;
}

/* Buttons */
.btn {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  padding: 12px 28px;
  border-radius: 8px;
  font-size: 0.95rem;
  font-weight: 500;
  transition: all var(--transition);
}

.btn-primary {
  background: linear-gradient(135deg, var(--accent), var(--accent-purple));
  color: #fff;
}

.btn-primary:hover {
  transform: translateY(-2px);
  box-shadow: 0 8px 24px rgba(0, 212, 255, 0.25);
}

.btn-outline {
  border: 1px solid var(--border);
  color: var(--text-primary);
  background: var(--bg-card);
  backdrop-filter: blur(8px);
}

.btn-outline:hover {
  border-color: var(--accent);
  color: var(--accent);
  transform: translateY(-2px);
}

/* Scroll indicator */
.scroll-indicator {
  position: absolute;
  bottom: 32px;
  left: 50%;
  transform: translateX(-50%);
  z-index: 1;
}

.scroll-arrow {
  width: 24px;
  height: 24px;
  border-right: 2px solid var(--text-muted);
  border-bottom: 2px solid var(--text-muted);
  transform: rotate(45deg);
  animation: scrollBounce 2s infinite;
}

@keyframes scrollBounce {
  0%, 20%, 50%, 80%, 100% { transform: rotate(45deg) translateY(0); }
  40% { transform: rotate(45deg) translateY(8px); }
  60% { transform: rotate(45deg) translateY(4px); }
}

/* ===========================
   About Section
   =========================== */
.about-grid {
  display: grid;
  grid-template-columns: 1fr 1fr;
  gap: 48px;
  align-items: start;
}

.about-text p {
  margin-bottom: 16px;
  color: var(--text-secondary);
  font-size: 0.95rem;
  line-height: 1.9;
}

.about-keywords {
  display: flex;
  flex-direction: column;
  gap: 16px;
}

.keyword-card {
  padding: 24px;
  background: var(--bg-card);
  border: 1px solid var(--border);
  border-radius: 12px;
  backdrop-filter: blur(8px);
  transition: all var(--transition);
}

.keyword-card:hover {
  border-color: var(--border-hover);
  background: var(--bg-card-hover);
  transform: translateY(-2px);
}

.keyword-icon {
  font-size: 1.5rem;
  margin-bottom: 8px;
}

.keyword-card h3 {
  font-size: 1rem;
  font-weight: 600;
  margin-bottom: 4px;
}

.keyword-card p {
  font-size: 0.85rem;
  color: var(--text-secondary);
}

/* ===========================
   Skills Section
   =========================== */
.skills-grid {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(280px, 1fr));
  gap: 24px;
}

.skill-category {
  padding: 28px;
  background: var(--bg-card);
  border: 1px solid var(--border);
  border-radius: 12px;
  backdrop-filter: blur(8px);
  transition: all var(--transition);
}

.skill-category:hover {
  border-color: var(--border-hover);
  transform: translateY(-2px);
}

.skill-category-title {
  font-size: 1rem;
  font-weight: 600;
  margin-bottom: 16px;
  color: var(--text-primary);
}

.skill-icon {
  margin-right: 8px;
}

.skill-tags {
  display: flex;
  flex-wrap: wrap;
  gap: 8px;
}

.skill-tag {
  padding: 6px 14px;
  background: rgba(0, 212, 255, 0.08);
  border: 1px solid rgba(0, 212, 255, 0.15);
  border-radius: 20px;
  font-size: 0.82rem;
  color: var(--accent);
  font-weight: 400;
}

.skill-tag--learning {
  background: rgba(124, 58, 237, 0.08);
  border-color: rgba(124, 58, 237, 0.2);
  color: #a78bfa;
}

/* ===========================
   Projects Section
   =========================== */
.projects-grid {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(320px, 1fr));
  gap: 24px;
}

.project-card {
  padding: 32px;
  background: var(--bg-card);
  border: 1px solid var(--border);
  border-radius: 16px;
  backdrop-filter: blur(8px);
  transition: all var(--transition);
  display: flex;
  flex-direction: column;
}

.project-card:hover {
  border-color: var(--border-hover);
  transform: translateY(-4px);
  box-shadow: 0 16px 48px rgba(0, 0, 0, 0.3);
}

.project-card-header {
  display: flex;
  justify-content: space-between;
  align-items: center;
  margin-bottom: 16px;
  flex-wrap: wrap;
  gap: 8px;
}

.project-label {
  font-size: 0.75rem;
  text-transform: uppercase;
  letter-spacing: 0.08em;
  color: var(--accent);
  font-weight: 500;
}

.project-period {
  font-size: 0.8rem;
  color: var(--text-muted);
}

.project-title {
  font-size: 1.3rem;
  font-weight: 700;
  margin-bottom: 12px;
}

.project-summary {
  font-size: 0.9rem;
  color: var(--text-secondary);
  line-height: 1.7;
  margin-bottom: 20px;
  flex-grow: 1;
}

.project-tech {
  display: flex;
  flex-wrap: wrap;
  gap: 6px;
  margin-bottom: 20px;
}

.project-tech span {
  padding: 4px 10px;
  background: rgba(255, 255, 255, 0.05);
  border-radius: 4px;
  font-size: 0.75rem;
  color: var(--text-secondary);
}

.project-links {
  margin-bottom: 16px;
}

.project-live-link {
  display: inline-flex;
  align-items: center;
  gap: 6px;
  font-size: 0.85rem;
  color: var(--accent);
  font-weight: 500;
  transition: opacity var(--transition);
}

.project-live-link:hover {
  opacity: 0.8;
}

.project-detail-btn {
  font-size: 0.85rem;
  color: var(--text-secondary);
  padding: 10px 0;
  transition: color var(--transition);
  text-align: left;
}

.project-detail-btn:hover {
  color: var(--accent);
}

/* ===========================
   Modal
   =========================== */
.modal-overlay {
  position: fixed;
  inset: 0;
  background: rgba(0, 0, 0, 0.7);
  backdrop-filter: blur(4px);
  z-index: 2000;
  display: flex;
  align-items: center;
  justify-content: center;
  padding: 24px;
  opacity: 0;
  visibility: hidden;
  transition: all 0.3s ease;
}

.modal-overlay.active {
  opacity: 1;
  visibility: visible;
}

.modal {
  background: var(--bg-secondary);
  border: 1px solid var(--border);
  border-radius: 16px;
  padding: 40px;
  max-width: 600px;
  width: 100%;
  max-height: 80vh;
  overflow-y: auto;
  position: relative;
  transform: translateY(20px) scale(0.97);
  transition: transform 0.3s ease;
}

.modal-overlay.active .modal {
  transform: translateY(0) scale(1);
}

.modal-close {
  position: absolute;
  top: 16px;
  right: 20px;
  font-size: 1.8rem;
  color: var(--text-muted);
  transition: color var(--transition);
  line-height: 1;
}

.modal-close:hover {
  color: var(--text-primary);
}

.modal-title {
  font-size: 1.5rem;
  font-weight: 700;
  margin: 12px 0 16px;
}

.modal-meta {
  display: flex;
  gap: 16px;
  flex-wrap: wrap;
  font-size: 0.85rem;
  color: var(--text-muted);
  margin-bottom: 24px;
}

.modal-body h4 {
  font-size: 0.95rem;
  font-weight: 600;
  margin: 24px 0 12px;
  color: var(--accent);
}

.modal-body ul {
  list-style: none;
  padding: 0;
}

.modal-body li {
  position: relative;
  padding-left: 20px;
  margin-bottom: 8px;
  font-size: 0.9rem;
  color: var(--text-secondary);
  line-height: 1.7;
}

.modal-body li::before {
  content: '';
  position: absolute;
  left: 0;
  top: 10px;
  width: 6px;
  height: 6px;
  border-radius: 50%;
  background: var(--accent);
}

.modal-body .project-tech {
  margin-top: 8px;
}

.modal-link {
  margin-top: 24px;
  text-align: center;
}

/* ===========================
   Education / Timeline
   =========================== */
.timeline {
  position: relative;
  max-width: 650px;
  margin: 0 auto;
  padding-left: 32px;
}

.timeline::before {
  content: '';
  position: absolute;
  left: 7px;
  top: 8px;
  bottom: 8px;
  width: 2px;
  background: var(--border);
}

.timeline-item {
  position: relative;
  margin-bottom: 40px;
}

.timeline-item:last-child {
  margin-bottom: 0;
}

.timeline-dot {
  position: absolute;
  left: -28px;
  top: 6px;
  width: 16px;
  height: 16px;
  border-radius: 50%;
  background: var(--bg-secondary);
  border: 3px solid var(--accent);
}

.timeline-content {
  padding: 24px;
  background: var(--bg-card);
  border: 1px solid var(--border);
  border-radius: 12px;
  backdrop-filter: blur(8px);
  transition: all var(--transition);
}

.timeline-content:hover {
  border-color: var(--border-hover);
}

.timeline-date {
  display: inline-block;
  font-size: 0.8rem;
  color: var(--accent);
  font-weight: 500;
  margin-bottom: 8px;
}

.timeline-content h3 {
  font-size: 1.1rem;
  font-weight: 700;
  margin-bottom: 4px;
}

.timeline-content p {
  font-size: 0.9rem;
  color: var(--text-secondary);
}

.timeline-detail {
  margin-top: 4px;
  font-size: 0.82rem !important;
  color: var(--text-muted) !important;
}

/* ===========================
   Contact Section
   =========================== */
.contact-subtitle {
  text-align: center;
  color: var(--text-secondary);
  font-size: 1rem;
  line-height: 1.8;
  margin-bottom: 48px;
}

.contact-grid {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(260px, 1fr));
  gap: 24px;
  max-width: 600px;
  margin: 0 auto;
}

.contact-card {
  display: flex;
  flex-direction: column;
  align-items: center;
  text-align: center;
  padding: 32px 24px;
  background: var(--bg-card);
  border: 1px solid var(--border);
  border-radius: 12px;
  backdrop-filter: blur(8px);
  transition: all var(--transition);
}

.contact-card:hover {
  border-color: var(--border-hover);
  transform: translateY(-4px);
  box-shadow: 0 12px 32px rgba(0, 0, 0, 0.2);
}

.contact-icon {
  font-size: 1.8rem;
  color: var(--accent);
  margin-bottom: 12px;
  display: flex;
  align-items: center;
  justify-content: center;
}

.contact-icon svg {
  color: var(--accent);
}

.contact-card h3 {
  font-size: 1rem;
  font-weight: 600;
  margin-bottom: 4px;
}

.contact-card p {
  font-size: 0.85rem;
  color: var(--text-secondary);
  word-break: break-all;
}

/* ===========================
   Footer
   =========================== */
.footer {
  padding: 32px 0;
  text-align: center;
  border-top: 1px solid var(--border);
}

.footer p {
  font-size: 0.82rem;
  color: var(--text-muted);
}

/* ===========================
   Scroll Animations
   =========================== */
.animate-on-scroll {
  opacity: 0;
  transform: translateY(30px);
  transition: opacity 0.6s ease, transform 0.6s ease;
}

.animate-on-scroll.visible {
  opacity: 1;
  transform: translateY(0);
}

/* ===========================
   Responsive
   =========================== */
@media (max-width: 768px) {
  .nav-toggle {
    display: flex;
  }

  .nav-menu {
    position: fixed;
    top: var(--nav-height);
    left: 0;
    right: 0;
    background: rgba(10, 10, 15, 0.95);
    backdrop-filter: blur(16px);
    -webkit-backdrop-filter: blur(16px);
    flex-direction: column;
    align-items: center;
    padding: 32px 0;
    gap: 24px;
    border-bottom: 1px solid var(--border);
    transform: translateY(-100%);
    opacity: 0;
    visibility: hidden;
    transition: all 0.35s ease;
  }

  .nav-menu.active {
    transform: translateY(0);
    opacity: 1;
    visibility: visible;
  }

  .nav-link {
    font-size: 1.05rem;
  }

  .section {
    padding: 72px 0;
  }

  .section-title {
    font-size: 1.6rem;
    margin-bottom: 40px;
  }

  .about-grid {
    grid-template-columns: 1fr;
    gap: 32px;
  }

  .hero-description br {
    display: none;
  }

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

  .modal {
    padding: 28px;
    margin: 16px;
  }

  .timeline {
    padding-left: 28px;
  }

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

@media (max-width: 480px) {
  .hero-name {
    font-size: 2.5rem;
  }

  .hero-cta {
    flex-direction: column;
    align-items: center;
  }

  .btn {
    width: 100%;
    max-width: 240px;
  }

  .skill-category {
    padding: 20px;
  }

  .project-card {
    padding: 24px;
  }
}

/* ===========================
   Scrollbar
   =========================== */
::-webkit-scrollbar {
  width: 6px;
}

::-webkit-scrollbar-track {
  background: var(--bg-primary);
}

::-webkit-scrollbar-thumb {
  background: var(--border);
  border-radius: 3px;
}

::-webkit-scrollbar-thumb:hover {
  background: var(--text-muted);
}