/* ===========================================
   Portfolio - Neo-Minimalist Design
   4 Colors Only: bg, text, secondary, accent
   =========================================== */

/* CSS Variables */
:root {
  /* Dark mode (default) */
  --bg-primary: #0a0a0a;
  --text-primary: #ffffff;
  --text-secondary: #888888;
  --accent-blue: #2563eb;

  /* Typography */
  --font-sans: -apple-system, BlinkMacSystemFont, 'Segoe UI', Roboto, 'Helvetica Neue', Arial, sans-serif;
  --line-height: 1.8;

  /* Spacing */
  --section-padding: 120px;
  --container-max: 1200px;

  /* Transitions */
  --transition: all 0.3s ease-in-out;
}

[data-theme="light"] {
  --bg-primary: #ffffff;
  --text-primary: #0a0a0a;
  --text-secondary: #666666;
}

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

html {
  scroll-behavior: smooth;
  font-size: 16px;
}

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

a {
  color: var(--accent-blue);
  text-decoration: none;
  transition: var(--transition);
}

a:hover {
  opacity: 0.8;
}

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

/* Container */
.container {
  max-width: var(--container-max);
  margin: 0 auto;
  padding: 0 40px;
}

@media (max-width: 768px) {
  .container {
    padding: 0 20px;
  }
}

/* ===========================================
   Header
   =========================================== */
.header {
  position: fixed;
  top: 0;
  left: 0;
  right: 0;
  height: 60px;
  background-color: rgba(10, 10, 10, 0.9);
  backdrop-filter: blur(10px);
  -webkit-backdrop-filter: blur(10px);
  border-bottom: 1px solid rgba(255, 255, 255, 0.1);
  z-index: 1000;
  transition: var(--transition);
}

[data-theme="light"] .header {
  background-color: rgba(255, 255, 255, 0.9);
  border-bottom-color: rgba(0, 0, 0, 0.1);
}

.header-container {
  max-width: var(--container-max);
  margin: 0 auto;
  padding: 0 40px;
  height: 100%;
  display: flex;
  align-items: center;
  justify-content: space-between;
}

.logo {
  font-size: 14px;
  font-weight: 700;
  letter-spacing: 2px;
  color: var(--text-primary);
}

.logo:hover {
  color: var(--accent-blue);
  opacity: 1;
}

.nav {
  display: flex;
  gap: 40px;
}

.nav-link {
  font-size: 14px;
  color: var(--text-secondary);
  position: relative;
}

.nav-link::after {
  content: '';
  position: absolute;
  bottom: -4px;
  left: 0;
  width: 0;
  height: 1px;
  background-color: var(--accent-blue);
  transition: var(--transition);
}

.nav-link:hover,
.nav-link.active {
  color: var(--text-primary);
  opacity: 1;
}

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

.header-controls {
  display: flex;
  align-items: center;
  gap: 20px;
}

.theme-toggle,
.lang-toggle {
  color: var(--text-secondary);
  font-size: 14px;
  transition: var(--transition);
}

.theme-toggle:hover,
.lang-toggle:hover {
  color: var(--text-primary);
}

.lang-toggle {
  display: flex;
  align-items: center;
  gap: 8px;
}

.lang-toggle .lang-active {
  color: var(--accent-blue);
}

.lang-divider {
  color: var(--text-secondary);
}

/* Mobile Menu Toggle */
.mobile-menu-toggle {
  display: none;
  flex-direction: column;
  gap: 5px;
  padding: 5px;
}

.mobile-menu-toggle span {
  width: 20px;
  height: 1px;
  background-color: var(--text-primary);
  transition: var(--transition);
}

@media (max-width: 768px) {
  .header-container {
    padding: 0 20px;
  }

  .nav {
    display: none;
    position: absolute;
    top: 60px;
    left: 0;
    right: 0;
    background-color: var(--bg-primary);
    flex-direction: column;
    padding: 20px;
    gap: 20px;
    border-bottom: 1px solid rgba(255, 255, 255, 0.1);
  }

  [data-theme="light"] .nav {
    border-bottom-color: rgba(0, 0, 0, 0.1);
  }

  .nav.active {
    display: flex;
  }

  .mobile-menu-toggle {
    display: flex;
  }

  .mobile-menu-toggle.active span:nth-child(1) {
    transform: rotate(45deg) translate(4px, 4px);
  }

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

  .mobile-menu-toggle.active span:nth-child(3) {
    transform: rotate(-45deg) translate(4px, -4px);
  }
}

/* ===========================================
   Hero Section
   =========================================== */
.hero {
  min-height: 100vh;
  display: flex;
  flex-direction: column;
  justify-content: center;
  align-items: center;
  text-align: center;
  padding: 60px 40px;
  position: relative;
}

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

.hero-subtitle {
  font-size: 14px;
  color: var(--text-secondary);
  letter-spacing: 4px;
  text-transform: uppercase;
  margin-bottom: 20px;
}

.hero-title {
  font-size: clamp(40px, 8vw, 80px);
  font-weight: 700;
  line-height: 1.1;
  margin-bottom: 20px;
}

.hero-name-en {
  display: block;
  letter-spacing: 4px;
}

.hero-name-ko {
  display: block;
  font-size: 0.5em;
  font-weight: 400;
  color: var(--text-secondary);
  margin-top: 10px;
}

.hero-tagline {
  font-size: clamp(16px, 2.5vw, 24px);
  color: var(--text-secondary);
  max-width: 600px;
  margin-bottom: 40px;
}

.hero-line {
  width: 200px;
  height: 1px;
  background-color: var(--accent-blue);
  margin-bottom: 40px;
}

.hero-links {
  display: flex;
  align-items: center;
  gap: 8px;
  font-size: 16px;
}

.hero-links a {
  color: var(--accent-blue);
}

.hero-links a:hover {
  text-decoration: underline;
}

.link-divider {
  color: var(--text-secondary);
}

.scroll-indicator {
  position: absolute;
  bottom: 40px;
  display: flex;
  flex-direction: column;
  align-items: center;
  gap: 10px;
  font-size: 12px;
  color: var(--text-secondary);
  animation: bounce 2s infinite;
}

.scroll-arrow {
  font-size: 20px;
}

@keyframes bounce {
  0%, 20%, 50%, 80%, 100% {
    transform: translateY(0);
  }
  40% {
    transform: translateY(-10px);
  }
  60% {
    transform: translateY(-5px);
  }
}

@media (max-width: 768px) {
  .hero {
    padding: 60px 20px;
  }
}

/* ===========================================
   Sections
   =========================================== */
.section {
  padding: var(--section-padding) 0;
}

@media (max-width: 768px) {
  .section {
    padding: 80px 0;
  }
}

.section-header {
  margin-bottom: 60px;
}

.section-header h2 {
  font-size: clamp(32px, 5vw, 48px);
  font-weight: 700;
  margin-bottom: 20px;
}

.section-line {
  width: 100%;
  height: 1px;
  background-color: var(--text-secondary);
  opacity: 0.3;
}

/* ===========================================
   About Section
   =========================================== */
.about-content {
  display: grid;
  grid-template-columns: 1.5fr 1fr;
  gap: 80px;
}

.about-text p {
  font-size: 18px;
  color: var(--text-secondary);
  margin-bottom: 24px;
  line-height: 2;
}

.about-text p:last-child {
  margin-bottom: 0;
}

.about-details {
  display: flex;
  flex-direction: column;
  gap: 40px;
}

.about-item h4 {
  font-size: 14px;
  color: var(--accent-blue);
  text-transform: uppercase;
  letter-spacing: 2px;
  margin-bottom: 8px;
}

.about-item p {
  font-size: 16px;
  color: var(--text-secondary);
}

@media (max-width: 900px) {
  .about-content {
    grid-template-columns: 1fr;
    gap: 60px;
  }
}

/* ===========================================
   Skills Section
   =========================================== */
.skills-grid {
  display: grid;
  grid-template-columns: repeat(4, 1fr);
  gap: 40px;
}

.skill-item {
  text-align: center;
}

.skill-icon {
  width: 40px;
  height: 40px;
  margin: 0 auto 16px;
  color: var(--accent-blue);
}

.skill-icon svg {
  width: 100%;
  height: 100%;
}

.skill-item h4 {
  font-size: 18px;
  font-weight: 600;
  margin-bottom: 8px;
}

.skill-item p {
  font-size: 14px;
  color: var(--text-secondary);
}

@media (max-width: 900px) {
  .skills-grid {
    grid-template-columns: repeat(3, 1fr);
  }
}

@media (max-width: 600px) {
  .skills-grid {
    grid-template-columns: repeat(2, 1fr);
    gap: 30px;
  }
}

/* ===========================================
   Projects Section
   =========================================== */
.project-tabs {
  display: flex;
  gap: 20px;
  margin-bottom: 40px;
  border-bottom: 1px solid rgba(255, 255, 255, 0.1);
  padding-bottom: 20px;
}

[data-theme="light"] .project-tabs {
  border-bottom-color: rgba(0, 0, 0, 0.1);
}

.tab-btn {
  font-size: 14px;
  color: var(--text-secondary);
  padding: 8px 0;
  position: relative;
  transition: var(--transition);
}

.tab-btn::after {
  content: '';
  position: absolute;
  bottom: -21px;
  left: 0;
  width: 0;
  height: 2px;
  background-color: var(--accent-blue);
  transition: var(--transition);
}

.tab-btn:hover,
.tab-btn.active {
  color: var(--text-primary);
}

.tab-btn.active::after {
  width: 100%;
}

.projects-list {
  display: flex;
  flex-direction: column;
}

.project-item {
  padding: 40px 0;
  border-bottom: 1px solid rgba(255, 255, 255, 0.1);
  transition: var(--transition);
}

[data-theme="light"] .project-item {
  border-bottom-color: rgba(0, 0, 0, 0.1);
}

.project-item:first-child {
  border-top: 1px solid rgba(255, 255, 255, 0.1);
}

[data-theme="light"] .project-item:first-child {
  border-top-color: rgba(0, 0, 0, 0.1);
}

.project-item.hidden {
  display: none;
}

.project-header {
  display: flex;
  flex-wrap: wrap;
  align-items: center;
  gap: 16px;
  margin-bottom: 16px;
}

.project-date {
  font-size: 14px;
  color: var(--text-secondary);
}

.project-badge {
  font-size: 12px;
  color: var(--accent-blue);
  padding: 4px 12px;
  border: 1px solid var(--accent-blue);
  border-radius: 20px;
}

.project-tags {
  display: flex;
  flex-wrap: wrap;
  gap: 8px;
  margin-left: auto;
}

.project-tags span {
  font-size: 12px;
  color: var(--accent-blue);
}

.project-title {
  font-size: 24px;
  font-weight: 600;
  margin-bottom: 12px;
  transition: var(--transition);
}

.project-item:hover .project-title {
  color: var(--accent-blue);
}

.project-desc {
  font-size: 16px;
  color: var(--text-secondary);
  margin-bottom: 16px;
  max-width: 800px;
}

.project-link {
  font-size: 14px;
  color: var(--accent-blue);
  transition: var(--transition);
}

.project-link:hover {
  text-decoration: underline;
}

@media (max-width: 768px) {
  .project-header {
    flex-direction: column;
    align-items: flex-start;
  }

  .project-tags {
    margin-left: 0;
  }
}

/* ===========================================
   Contact Section
   =========================================== */
.contact-content {
  text-align: center;
  max-width: 600px;
  margin: 0 auto;
}

.contact-content > p {
  font-size: 18px;
  color: var(--text-secondary);
  margin-bottom: 40px;
  line-height: 1.8;
}

.contact-links {
  display: flex;
  flex-direction: column;
  gap: 16px;
}

.contact-link {
  font-size: 16px;
  color: var(--text-primary);
  transition: var(--transition);
}

.contact-link:hover {
  color: var(--accent-blue);
  opacity: 1;
}

/* ===========================================
   Footer
   =========================================== */
.footer {
  padding: 40px;
  text-align: center;
}

.footer-line {
  width: 100%;
  height: 1px;
  background-color: var(--text-secondary);
  opacity: 0.2;
  margin-bottom: 40px;
}

.footer p {
  font-size: 14px;
  color: var(--text-secondary);
  margin-bottom: 8px;
}

.footer-made {
  font-size: 12px;
}

/* ===========================================
   Modal
   =========================================== */
.modal {
  position: fixed;
  top: 0;
  left: 0;
  right: 0;
  bottom: 0;
  background-color: rgba(10, 10, 10, 0.95);
  z-index: 2000;
  display: none;
  overflow-y: auto;
  padding: 60px 40px;
}

[data-theme="light"] .modal {
  background-color: rgba(255, 255, 255, 0.98);
}

.modal.active {
  display: block;
}

.modal-close {
  position: fixed;
  top: 20px;
  right: 30px;
  font-size: 40px;
  color: var(--text-secondary);
  background: none;
  border: none;
  cursor: pointer;
  transition: var(--transition);
  z-index: 2001;
  line-height: 1;
}

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

.modal-content {
  max-width: 800px;
  margin: 0 auto;
  padding-top: 40px;
}

.modal-header {
  margin-bottom: 40px;
  padding-bottom: 40px;
  border-bottom: 1px solid rgba(255, 255, 255, 0.1);
}

[data-theme="light"] .modal-header {
  border-bottom-color: rgba(0, 0, 0, 0.1);
}

.modal-date {
  font-size: 14px;
  color: var(--text-secondary);
  margin-bottom: 16px;
}

.modal-title {
  font-size: clamp(28px, 5vw, 40px);
  font-weight: 700;
  margin-bottom: 8px;
}

.modal-title-ko {
  font-size: clamp(18px, 3vw, 24px);
  color: var(--text-secondary);
  font-weight: 400;
  margin-bottom: 24px;
}

.modal-badge {
  display: inline-block;
  font-size: 14px;
  color: var(--accent-blue);
  padding: 6px 16px;
  border: 1px solid var(--accent-blue);
  border-radius: 20px;
  margin-bottom: 24px;
}

.modal-tags {
  display: flex;
  flex-wrap: wrap;
  gap: 12px;
}

.modal-tags span {
  font-size: 14px;
  color: var(--accent-blue);
}

.modal-section {
  margin-bottom: 40px;
}

.modal-section h4 {
  font-size: 14px;
  color: var(--accent-blue);
  text-transform: uppercase;
  letter-spacing: 2px;
  margin-bottom: 16px;
}

.modal-section p,
.modal-section li {
  font-size: 16px;
  color: var(--text-secondary);
  line-height: 1.9;
}

.modal-section ul {
  list-style: none;
}

.modal-section li {
  padding-left: 20px;
  position: relative;
  margin-bottom: 8px;
}

.modal-section li::before {
  content: '•';
  position: absolute;
  left: 0;
  color: var(--accent-blue);
}

.modal-links {
  display: flex;
  gap: 24px;
  padding-top: 40px;
  border-top: 1px solid rgba(255, 255, 255, 0.1);
}

[data-theme="light"] .modal-links {
  border-top-color: rgba(0, 0, 0, 0.1);
}

.modal-links a {
  font-size: 14px;
  color: var(--accent-blue);
}

.modal-links a:hover {
  text-decoration: underline;
}

.modal-nav {
  max-width: 800px;
  margin: 60px auto 0;
  display: flex;
  justify-content: space-between;
  padding-top: 40px;
  border-top: 1px solid rgba(255, 255, 255, 0.1);
}

[data-theme="light"] .modal-nav {
  border-top-color: rgba(0, 0, 0, 0.1);
}

.modal-nav-btn {
  font-size: 14px;
  color: var(--text-secondary);
  transition: var(--transition);
}

.modal-nav-btn:hover {
  color: var(--accent-blue);
}

@media (max-width: 768px) {
  .modal {
    padding: 40px 20px;
  }

  .modal-close {
    top: 15px;
    right: 20px;
    font-size: 32px;
  }
}

/* ===========================================
   Experience Section
   =========================================== */
.experience-list {
  display: flex;
  flex-direction: column;
  gap: 32px;
}

.experience-item {
  border-left: 2px solid var(--accent-blue);
  padding: 24px 0 24px 32px;
}

.experience-header {
  display: flex;
  align-items: flex-start;
  justify-content: space-between;
  gap: 16px;
  margin-bottom: 12px;
  flex-wrap: wrap;
}

.experience-company {
  font-size: 1.25rem;
  font-weight: 600;
  color: var(--text-primary);
  margin: 0 0 4px 0;
}

.experience-period {
  font-size: 0.875rem;
  color: var(--text-secondary);
  margin: 0;
}

.experience-badge {
  font-size: 0.8rem;
  font-weight: 500;
  color: var(--accent-blue);
  border: 1px solid var(--accent-blue);
  padding: 4px 12px;
  border-radius: 4px;
  white-space: nowrap;
}

.experience-desc {
  color: var(--text-secondary);
  line-height: 1.7;
  margin: 0 0 12px 0;
}

.experience-highlights {
  list-style: none;
  padding: 0;
  margin: 0;
  display: flex;
  flex-direction: column;
  gap: 6px;
}

.experience-highlights li {
  color: var(--text-secondary);
  font-size: 0.9rem;
  padding-left: 16px;
  position: relative;
}

.experience-highlights li::before {
  content: '·';
  position: absolute;
  left: 0;
  color: var(--accent-blue);
}

@media (max-width: 768px) {
  .experience-item {
    padding: 20px 0 20px 20px;
  }

  .experience-header {
    flex-direction: column;
    gap: 8px;
  }
}

/* ===========================================
   Awards Section
   =========================================== */
.awards-grid {
  display: grid;
  grid-template-columns: 1fr 1fr;
  gap: 48px;
}

.awards-category-title {
  font-size: 0.8rem;
  font-weight: 600;
  letter-spacing: 0.1em;
  text-transform: uppercase;
  color: var(--text-secondary);
  margin: 0 0 24px 0;
}

.awards-list {
  list-style: none;
  padding: 0;
  margin: 0;
  display: flex;
  flex-direction: column;
  gap: 20px;
}

.award-item {
  display: flex;
  gap: 20px;
  align-items: flex-start;
}

.award-year {
  font-size: 0.8rem;
  font-weight: 600;
  color: var(--accent-blue);
  min-width: 36px;
  padding-top: 2px;
}

.award-info {
  display: flex;
  flex-direction: column;
  gap: 4px;
}

.award-name {
  font-size: 0.95rem;
  color: var(--text-primary);
  margin: 0;
  line-height: 1.5;
}

.award-project {
  font-size: 0.8rem;
  color: var(--text-secondary);
  margin: 0;
}

@media (max-width: 768px) {
  .awards-grid {
    grid-template-columns: 1fr;
    gap: 36px;
  }
}

/* ===========================================
   Utility Classes
   =========================================== */
.sr-only {
  position: absolute;
  width: 1px;
  height: 1px;
  padding: 0;
  margin: -1px;
  overflow: hidden;
  clip: rect(0, 0, 0, 0);
  white-space: nowrap;
  border: 0;
}