/* CSS Reset & Variables */
*,
*::before,
*::after {
  margin: 0;
  padding: 0;
  box-sizing: border-box;
}

:root {
  /* Colors */
  --color-bg: #0f172a;
  --color-bg-secondary: #1e293b;
  --color-text: #e2e8f0;
  --color-text-secondary: #94a3b8;
  --color-accent: #38bdf8;
  --color-accent-hover: #7dd3fc;
  --color-border: #334155;

  /* Typography */
  --font-sans: "Inter", "Noto Sans KR", -apple-system, BlinkMacSystemFont, sans-serif;

  /* Spacing */
  --container-max: 1200px;
  --section-padding: 6rem 1.5rem;

  /* Transitions */
  --transition: 0.3s ease;
}

html {
  scroll-behavior: smooth;
}

body {
  font-family: var(--font-sans);
  background-color: var(--color-bg);
  color: var(--color-text);
  line-height: 1.6;
  -webkit-font-smoothing: antialiased;
}

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

ul {
  list-style: none;
}

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

/* Header */
.header {
  position: fixed;
  top: 0;
  left: 0;
  right: 0;
  z-index: 100;
  background: rgba(15, 23, 42, 0.8);
  backdrop-filter: blur(12px);
  border-bottom: 1px solid var(--color-border);
}

.header-container {
  max-width: var(--container-max);
  margin: 0 auto;
  padding: 1rem 1.5rem;
  display: flex;
  align-items: center;
  justify-content: space-between;
}

.logo {
  font-size: 1.25rem;
  font-weight: 700;
  color: var(--color-accent);
}

.nav {
  display: flex;
  gap: 2rem;
}

.nav-link {
  font-size: 0.875rem;
  font-weight: 500;
  color: var(--color-text-secondary);
  transition: color var(--transition);
}

.nav-link:hover {
  color: var(--color-accent);
}

.menu-toggle {
  display: none;
  background: none;
  border: none;
  cursor: pointer;
  padding: 0.5rem;
}

.hamburger {
  display: block;
  width: 24px;
  height: 2px;
  background: var(--color-text);
  position: relative;
  transition: var(--transition);
}

.hamburger::before,
.hamburger::after {
  content: "";
  position: absolute;
  width: 24px;
  height: 2px;
  background: var(--color-text);
  left: 0;
  transition: var(--transition);
}

.hamburger::before {
  top: -8px;
}

.hamburger::after {
  bottom: -8px;
}

/* Mobile Navigation */
.mobile-nav {
  display: none;
  position: fixed;
  top: 0;
  left: 0;
  right: 0;
  bottom: 0;
  background: var(--color-bg);
  z-index: 99;
  padding-top: 5rem;
  opacity: 0;
  visibility: hidden;
  transition: var(--transition);
}

.mobile-nav.active {
  opacity: 1;
  visibility: visible;
}

.mobile-nav-links {
  display: flex;
  flex-direction: column;
  align-items: center;
  gap: 2rem;
  padding: 2rem;
}

.mobile-nav-link {
  font-size: 1.5rem;
  font-weight: 600;
  color: var(--color-text);
  transition: color var(--transition);
}

.mobile-nav-link:hover {
  color: var(--color-accent);
}

/* Hero Section */
.hero {
  height: 100vh;
  min-height: 100vh;
  display: flex;
  align-items: center;
  padding: 8rem 1.5rem 4rem;
}

.hero-container {
  max-width: var(--container-max);
  margin: 0 auto;
  display: grid;
  grid-template-columns: 1fr 1fr;
  gap: 4rem;
  align-items: center;
}

.hero-greeting {
  font-size: 1rem;
  color: var(--color-accent);
  margin-bottom: 1rem;
  font-weight: 500;
}

.hero-title {
  font-size: clamp(2rem, 5vw, 3.5rem);
  font-weight: 700;
  line-height: 1.2;
  margin-bottom: 1.5rem;
}

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

.hero-description {
  font-size: 1.125rem;
  color: var(--color-text-secondary);
  margin-bottom: 2rem;
  line-height: 1.7;
}

.hero-links {
  display: flex;
  flex-wrap: wrap;
  gap: 1rem;
}

.hero-link {
  display: inline-flex;
  align-items: center;
  gap: 0.5rem;
  padding: 0.75rem 1.25rem;
  background: var(--color-bg-secondary);
  border: 1px solid var(--color-border);
  border-radius: 8px;
  font-size: 0.875rem;
  color: var(--color-text-secondary);
  transition: all var(--transition);
}

.hero-link:hover {
  color: var(--color-accent);
  border-color: var(--color-accent);
}

.hero-image {
  display: flex;
  justify-content: center;
}

.hero-image picture {
  width: 320px;
  height: 320px;
  border-radius: 50%;
  overflow: hidden;
  border: 4px solid var(--color-border);
}

.hero-image img {
  width: 100%;
  height: 100%;
  object-fit: cover;
}

/* Section Styles */
.section-container {
  max-width: var(--container-max);
  margin: 0 auto;
}

.section-title {
  font-size: 2rem;
  font-weight: 700;
  margin-bottom: 3rem;
  position: relative;
  display: inline-block;
}

.section-title::after {
  content: "";
  position: absolute;
  bottom: -8px;
  left: 0;
  width: 60px;
  height: 3px;
  background: var(--color-accent);
  border-radius: 2px;
}

/* About Section */
.about {
  height: 100vh;
  min-height: 100vh;
  display: flex;
  flex-direction: column;
  justify-content: flex-start;
  padding: var(--section-padding);
  padding-top: 8rem;
  background: var(--color-bg-secondary);
}

.about-intro {
  font-size: 1.125rem;
  color: var(--color-text-secondary);
  line-height: 1.8;
  margin-bottom: 3rem;
  max-width: 800px;
}

.about-grid {
  display: grid;
  grid-template-columns: repeat(3, 1fr);
  gap: 2rem;
}

.about-card {
  background: var(--color-bg);
  border: 1px solid var(--color-border);
  border-radius: 12px;
  padding: 2rem;
  transition: all var(--transition);
}

.about-card:hover {
  border-color: var(--color-accent);
  transform: translateY(-4px);
}

.about-card-title {
  font-size: 1rem;
  font-weight: 600;
  color: var(--color-accent);
  margin-bottom: 1.25rem;
}

.about-list li {
  font-size: 0.9375rem;
  color: var(--color-text-secondary);
  padding: 0.5rem 0;
  border-bottom: 1px solid var(--color-border);
  display: flex;
  align-items: center;
  justify-content: space-between;
  flex-wrap: wrap;
  gap: 0.5rem;
}

.about-list li:last-child {
  border-bottom: none;
}

.tag {
  font-size: 0.75rem;
  background: var(--color-accent);
  color: var(--color-bg);
  padding: 0.25rem 0.5rem;
  border-radius: 4px;
  font-weight: 500;
}

/* Projects Section */
.projects {
  height: 100vh;
  min-height: 100vh;
  display: flex;
  flex-direction: column;
  /* 수직 중앙 정렬로 변경 */
  justify-content: center;
  padding: var(--section-padding);
  padding-top: 8rem;
}

.project-grid {
  display: grid;
  grid-template-columns: repeat(4, 1fr);
  gap: 1.5rem;
}

.project-card {
  background: var(--color-bg-secondary);
  border: 1px solid var(--color-border);
  border-radius: 12px;
  overflow: hidden;
  transition: all var(--transition);
}

.project-card:hover {
  border-color: var(--color-accent);
  transform: translateY(-4px);
}

.project-image {
  position: relative;
  overflow: hidden;
  aspect-ratio: 16 / 10;
}

.project-image img {
  width: 100%;
  height: 100%;
  object-fit: cover;
  transition: transform var(--transition);
}

.project-placeholder {
  width: 100%;
  height: 100%;
  background: linear-gradient(135deg, var(--color-bg) 0%, var(--color-border) 100%);
  display: flex;
  align-items: center;
  justify-content: center;
  color: var(--color-text-secondary);
  font-size: 1rem;
  font-weight: 500;
}

.project-card:hover .project-image img {
  transform: scale(1.05);
}

.project-overlay {
  position: absolute;
  inset: 0;
  background: rgba(56, 189, 248, 0.9);
  display: flex;
  align-items: center;
  justify-content: center;
  opacity: 0;
  transition: opacity var(--transition);
}

.project-card:hover .project-overlay {
  opacity: 1;
}

.view-project {
  font-size: 1rem;
  font-weight: 600;
  color: var(--color-bg);
}

.project-info {
  padding: 1.5rem;
}

.project-title {
  font-size: 1.25rem;
  font-weight: 600;
  margin-bottom: 0.5rem;
}

.project-description {
  font-size: 0.875rem;
  color: var(--color-text-secondary);
  margin-bottom: 1rem;
  line-height: 1.6;
}

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

.project-tag {
  font-size: 0.75rem;
  background: var(--color-bg);
  color: var(--color-accent);
  padding: 0.25rem 0.75rem;
  border-radius: 9999px;
  border: 1px solid var(--color-border);
}

/* Skills & Contact Combined Section */
.skills-contact {
  height: 100vh;
  min-height: 100vh;
  display: flex;
  flex-direction: column;
  justify-content: center;
  padding: var(--section-padding);
  padding-top: 8rem;
  background: var(--color-bg-secondary);
}

/* 좌우 배치에서 위아래 배치로 변경, 각각 50% 높이 */
.skills-contact-wrapper {
  display: flex;
  flex-direction: column;
  gap: 3rem;
  height: calc(100vh - 12rem);
}

.skills-area {
  flex: 1;
  display: flex;
  flex-direction: column;
}

.skills-area .section-title {
  margin-bottom: 1.5rem;
}

/* Skills 그리드를 가로로 배치 */
.skills-grid {
  display: grid;
  grid-template-columns: repeat(3, 1fr);
  gap: 1.5rem;
  flex: 1;
}

.skill-category {
  background: var(--color-bg);
  border: 1px solid var(--color-border);
  border-radius: 12px;
  padding: 1.5rem;
}

.skill-category-title {
  font-size: 0.875rem;
  font-weight: 600;
  color: var(--color-text-secondary);
  text-transform: uppercase;
  letter-spacing: 0.05em;
  margin-bottom: 1rem;
}

.skill-items {
  display: flex;
  flex-wrap: wrap;
  gap: 0.75rem;
}

.skill-item {
  font-size: 0.875rem;
  background: var(--color-bg-secondary);
  color: var(--color-text);
  padding: 0.5rem 1rem;
  border-radius: 8px;
  border: 1px solid var(--color-border);
  transition: all var(--transition);
}

.skill-item:hover {
  border-color: var(--color-accent);
  color: var(--color-accent);
}

/* Contact 영역을 하단에 배치 */
.contact-area {
  flex: 1;
  display: flex;
  flex-direction: column;
  justify-content: center;
  padding-top: 2rem;
  border-top: 1px solid var(--color-border);
}

.contact-area .section-title {
  margin-bottom: 1rem;
}

.contact-text {
  font-size: 1.125rem;
  color: var(--color-text-secondary);
  margin-bottom: 1.5rem;
  line-height: 1.7;
}

.contact-links {
  display: flex;
  gap: 1rem;
}

.contact-link {
  display: inline-flex;
  align-items: center;
  gap: 0.75rem;
  padding: 1rem 1.5rem;
  background: var(--color-bg);
  border: 1px solid var(--color-border);
  border-radius: 8px;
  font-size: 1rem;
  color: var(--color-text);
  transition: all var(--transition);
}

.contact-link:hover {
  border-color: var(--color-accent);
  color: var(--color-accent);
}

/* Footer */
.footer {
  padding: 2rem 1.5rem;
  border-top: 1px solid var(--color-border);
}

.footer-container {
  max-width: var(--container-max);
  margin: 0 auto;
  text-align: center;
}

.footer p {
  font-size: 0.875rem;
  color: var(--color-text-secondary);
}

/* Responsive Design */
@media (max-width: 1024px) {
  .hero-container {
    grid-template-columns: 1fr;
    text-align: center;
  }

  .hero-content {
    order: 2;
  }

  .hero-image {
    order: 1;
  }

  .hero-links {
    justify-content: center;
  }

  .about-grid {
    grid-template-columns: repeat(2, 1fr);
  }

  .project-grid {
    grid-template-columns: repeat(2, 1fr);
  }

  /* 태블릿에서 Skills 그리드 2열로 변경 */
  .skills-grid {
    grid-template-columns: repeat(2, 1fr);
  }

  .skills-contact-wrapper {
    grid-template-columns: 1fr;
    gap: 3rem;
  }
}

@media (max-width: 768px) {
  .nav {
    display: none;
  }

  .menu-toggle {
    display: block;
  }

  .mobile-nav {
    display: block;
  }

  .hero {
    /* 모바일에서 프로필 사진 위 여백 증가 */
    padding-top: 8rem;
    min-height: auto;
    padding-bottom: 4rem;
  }

  /* 모바일에서 프로필 이미지 상단 마진 추가 */
  .hero-image {
    margin-top: 2rem;
  }

  .hero-image picture {
    width: 200px;
    height: 200px;
  }

  .hero-title {
    font-size: 1.75rem;
  }

  .about-grid,
  .project-grid {
    grid-template-columns: 1fr;
  }

  .section-title {
    font-size: 1.5rem;
  }

  :root {
    --section-padding: 4rem 1rem;
  }

  .hero,
  .about,
  .projects,
  .skills-contact {
    height: auto;
    min-height: auto;
    padding-top: 4rem;
    padding-bottom: 4rem;
  }

  /* 모바일에서 세로 배치 */
  .skills-contact-wrapper {
    height: auto;
    gap: 2rem;
  }

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

  .contact-links {
    flex-direction: column;
  }

  .contact-link {
    width: 100%;
  }

  .skills-contact-wrapper {
    gap: 2rem;
  }
}

/* Animation */
@keyframes fadeIn {
  from {
    opacity: 0;
    transform: translateY(20px);
  }
  to {
    opacity: 1;
    transform: translateY(0);
  }
}

.hero-content,
.hero-image {
  animation: fadeIn 0.8s ease forwards;
}

.hero-image {
  animation-delay: 0.2s;
}