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

:root {
  --bg-primary: #0d1117;
  --bg-secondary: #161b22;
  --bg-tertiary: #21262d;
  --border: #30363d;
  --border-hover: #484f58;
  --text-primary: #e6edf3;
  --text-secondary: #8b949e;
  --text-tertiary: #6e7681;
  --accent-blue: #58a6ff;
  --accent-green: #3fb950;
  --accent-orange: #d29922;
  --accent-purple: #bc8cff;
  --accent-red: #f85149;
  --font-sans: -apple-system, BlinkMacSystemFont, 'Segoe UI', Helvetica, Arial, sans-serif;
  --font-mono: 'SF Mono', 'Fira Code', 'Cascadia Code', 'JetBrains Mono', monospace;
  --nav-height: 56px;
  --max-width: 1100px;
  --section-padding: 100px 0;
}

html {
  background: var(--bg-primary);
  scroll-behavior: smooth;
  scroll-padding-top: var(--nav-height);
  scrollbar-width: thin;
  scrollbar-color: var(--bg-tertiary) var(--bg-primary);
}

::-webkit-scrollbar {
  width: 10px;
}

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

::-webkit-scrollbar-thumb {
  background: var(--bg-tertiary);
  border-radius: 8px;
  border: 2px solid var(--bg-primary);
}

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

:focus-visible {
  outline: 2px solid var(--accent-blue);
  outline-offset: 3px;
  border-radius: 4px;
}

body {
  background: var(--bg-primary);
  color: var(--text-primary);
  font-family: var(--font-sans);
  line-height: 1.6;
  min-height: 100vh;
  transition: opacity 0.18s ease;
}

body.lang-switching {
  opacity: 0;
  pointer-events: none;
}

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

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

ul {
  list-style: none;
}

.container {
  max-width: var(--max-width);
  margin: 0 auto;
  padding: 0 24px;
}

::selection {
  background: var(--accent-blue);
  color: var(--bg-primary);
}

.btn {
  display: inline-flex;
  align-items: center;
  gap: 8px;
  padding: 12px 24px;
  border-radius: 6px;
  font-family: var(--font-mono);
  font-size: 14px;
  font-weight: 500;
  cursor: pointer;
  transition: all 0.2s;
  border: 1px solid var(--border);
}

.btn-primary {
  background: var(--accent-blue);
  color: var(--bg-primary);
  border-color: var(--accent-blue);
}

.btn-primary:hover {
  background: #79b8ff;
  border-color: #79b8ff;
}

.btn-outline {
  background: transparent;
  color: var(--accent-blue);
  border-color: var(--accent-blue);
}

.btn-outline:hover {
  background: rgba(88, 166, 255, 0.1);
}

.comment {
  color: var(--text-tertiary);
  font-family: var(--font-mono);
}

/* HEADER / NAV */
.header {
  position: fixed;
  top: 0;
  left: 0;
  right: 0;
  height: var(--nav-height);
  background: rgba(13, 17, 23, 0.9);
  backdrop-filter: blur(12px);
  border-bottom: 1px solid var(--border);
  z-index: 1000;
}

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

.nav-brand {
  display: flex;
  align-items: center;
  gap: 6px;
  font-family: var(--font-mono);
  font-size: 16px;
  font-weight: 600;
  color: var(--text-primary);
}

.nav-brand-icon {
  color: var(--accent-orange);
}

.nav-links {
  display: flex;
  align-items: center;
  gap: 4px;
}

.nav-link {
  padding: 8px 14px;
  font-family: var(--font-mono);
  font-size: 13px;
  color: var(--text-secondary);
  border-radius: 6px;
  transition: all 0.2s;
  position: relative;
}

.nav-link:hover {
  color: var(--text-primary);
  background: var(--bg-tertiary);
}

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

.nav-link.active::after {
  content: '';
  position: absolute;
  bottom: -2px;
  left: 14px;
  right: 14px;
  height: 2px;
  background: var(--accent-blue);
  border-radius: 1px;
}

.menu-toggle {
  display: none;
  background: none;
  border: none;
  cursor: pointer;
  padding: 8px;
  flex-direction: column;
  gap: 5px;
}

.menu-toggle span {
  display: block;
  width: 22px;
  height: 2px;
  background: var(--text-primary);
  border-radius: 2px;
  transition: all 0.3s;
}

.lang-toggle {
  background: var(--bg-tertiary);
  border: 1px solid var(--border);
  color: var(--text-secondary);
  font-family: var(--font-mono);
  font-size: 12px;
  font-weight: 600;
  padding: 4px 10px;
  border-radius: 6px;
  cursor: pointer;
  transition: all 0.2s;
  margin-left: 8px;
  letter-spacing: 0.5px;
}

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

.lang-toggle.pulse {
  animation: langPulse 0.4s ease;
}

@keyframes langPulse {
  0% {
    transform: scale(1);
  }
  40% {
    transform: scale(0.88);
  }
  100% {
    transform: scale(1);
  }
}

/* HERO */
.hero {
  min-height: 100vh;
  display: flex;
  align-items: center;
  padding-top: var(--nav-height);
}

.hero-content {
  display: flex;
  align-items: center;
  gap: 60px;
  max-width: var(--max-width);
}

.hero-text {
  flex: 1;
  max-width: 620px;
}

.hero-image {
  flex-shrink: 0;
}

.hero-image img {
  width: 260px;
  height: 260px;
  border-radius: 50%;
  object-fit: cover;
  border: 3px solid var(--border);
  box-shadow: 0 0 30px rgba(88, 166, 255, 0.08);
  transition: border-color 0.3s, box-shadow 0.3s;
}

.hero-image img:hover {
  border-color: var(--accent-blue);
  box-shadow: 0 0 40px rgba(88, 166, 255, 0.15);
}

.hero-greeting {
  font-family: var(--font-mono);
  font-size: 15px;
  color: var(--text-secondary);
  margin-bottom: 20px;
}

.hero-name {
  font-size: clamp(40px, 8vw, 72px);
  font-weight: 700;
  line-height: 1.1;
  margin-bottom: 10px;
  letter-spacing: -1px;
}

.hero-subtitle {
  font-size: clamp(20px, 4vw, 32px);
  font-weight: 500;
  color: var(--text-secondary);
  margin-bottom: 24px;
  line-height: 1.3;
}

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

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

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

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

.hero-desc {
  font-size: 16px;
  color: var(--text-secondary);
  max-width: 580px;
  margin-bottom: 36px;
  line-height: 1.7;
}

.hero-actions {
  display: flex;
  gap: 16px;
  flex-wrap: wrap;
}

.arrow {
  transition: transform 0.2s;
}

.btn:hover .arrow {
  transform: translateX(4px);
}

/* SECTIONS */
.section {
  padding: var(--section-padding);
}

.section-header {
  display: flex;
  align-items: center;
  gap: 12px;
  margin-bottom: 48px;
}

.section-number {
  font-family: var(--font-mono);
  font-size: 14px;
  color: var(--accent-blue);
  font-weight: 500;
}

.section-title {
  font-family: var(--font-mono);
  font-size: 22px;
  font-weight: 600;
  color: var(--text-primary);
  white-space: nowrap;
}

.section-line {
  flex: 1;
  height: 1px;
  background: var(--border);
}

/* PROJECTS */
.projects-grid {
  display: grid;
  grid-template-columns: repeat(auto-fill, minmax(320px, 1fr));
  gap: 16px;
}

.projects-archive {
  margin-top: 48px;
}

.archive-toggle {
  display: flex;
  align-items: center;
  gap: 8px;
  width: fit-content;
  margin: 0 auto;
  padding: 10px 20px;
  background: transparent;
  border: 1px solid var(--border);
  border-radius: 6px;
  color: var(--text-secondary);
  font-family: var(--font-mono);
  font-size: 13px;
  cursor: pointer;
  transition: all 0.2s;
}

.archive-toggle:hover {
  color: var(--text-primary);
  border-color: var(--border-hover);
  background: var(--bg-tertiary);
}

.archive-chevron {
  transition: transform 0.3s;
}

.archive-toggle.open .archive-chevron {
  transform: rotate(180deg);
}

.archive-collapse {
  display: grid;
  grid-template-rows: 0fr;
  transition: grid-template-rows 0.5s cubic-bezier(0.4, 0, 0.2, 1);
}

.archive-collapse.open {
  grid-template-rows: 1fr;
}

.archive-inner {
  overflow: hidden;
  min-height: 0;
  opacity: 0;
  transform: translateY(-10px);
  transition: opacity 0.4s ease, transform 0.5s cubic-bezier(0.4, 0, 0.2, 1);
}

.archive-collapse.open .archive-inner {
  opacity: 1;
  transform: translateY(0);
}

.archive-collapse.expanded .archive-inner {
  overflow: visible;
}

#archive-grid {
  margin-top: 16px;
  padding: 8px 8px 16px;
}

.project-card {
  background: var(--bg-secondary);
  border: 1px solid var(--border);
  border-radius: 8px;
  padding: 28px;
  transition: all 0.25s;
  display: flex;
  flex-direction: column;
}

.project-card:hover {
  border-color: var(--border-hover);
  transform: translateY(-4px);
  box-shadow: 0 8px 30px rgba(0, 0, 0, 0.3);
}

.project-header {
  display: flex;
  align-items: center;
  justify-content: space-between;
  margin-bottom: 20px;
}

.project-folder {
  color: var(--accent-orange);
}

.project-ext-links {
  display: flex;
  gap: 12px;
}

.project-working {
  display: inline-flex;
  align-items: center;
  gap: 6px;
  padding: 3px 10px;
  background: rgba(63, 185, 80, 0.12);
  border: 1px solid rgba(63, 185, 80, 0.35);
  border-radius: 999px;
  font-family: var(--font-mono);
  font-size: 11px;
  color: var(--accent-green);
  letter-spacing: 0.3px;
}

.working-dot {
  width: 8px;
  height: 8px;
  border-radius: 50%;
  background: var(--accent-green);
  animation: working-pulse 1.6s ease-in-out infinite;
}

@keyframes working-pulse {
  0%, 100% {
    opacity: 1;
    box-shadow: 0 0 0 0 rgba(63, 185, 80, 0.5);
  }
  50% {
    opacity: 0.6;
    box-shadow: 0 0 0 4px rgba(63, 185, 80, 0);
  }
}

.project-ext-link {
  color: var(--text-tertiary);
  transition: color 0.2s;
}

.project-ext-link:hover {
  color: var(--accent-blue);
}

.project-title {
  font-size: 18px;
  font-weight: 600;
  margin-bottom: 12px;
  color: var(--text-primary);
  transition: color 0.2s;
}

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

.project-desc {
  font-size: 14px;
  color: var(--text-secondary);
  line-height: 1.6;
  margin-bottom: 20px;
  flex: 1;
}

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

.project-tag {
  font-family: var(--font-mono);
  font-size: 12px;
  color: var(--accent-blue);
}

/* CURRICULUM */
.curriculum-content {
  display: grid;
  grid-template-columns: 1fr 1fr;
  gap: 48px;
}

.curriculum-left h3,
.curriculum-right h3 {
  font-family: var(--font-mono);
  font-size: 16px;
  font-weight: 600;
  color: var(--text-primary);
  margin-bottom: 20px;
  padding-bottom: 8px;
  border-bottom: 1px solid var(--border);
}

.edu-item {
  margin-bottom: 24px;
}

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

.edu-date {
  font-family: var(--font-mono);
  font-size: 12px;
  color: var(--accent-blue);
  margin-bottom: 4px;
}

.edu-title {
  font-size: 16px;
  font-weight: 600;
  color: var(--text-primary);
  margin-bottom: 4px;
}

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

.exp-list {
  list-style: none;
  display: flex;
  flex-direction: column;
  gap: 10px;
  padding: 0;
  margin-bottom: 32px;
}

.exp-list li {
  position: relative;
  padding-left: 18px;
  font-size: 14px;
  color: var(--text-secondary);
  line-height: 1.5;
}

.exp-list li::before {
  content: '▹';
  position: absolute;
  left: 0;
  color: var(--accent-blue);
}

.skills-grid {
  display: flex;
  flex-direction: column;
  gap: 20px;
  margin-bottom: 32px;
}

.skill-category-title {
  font-family: var(--font-mono);
  font-size: 12px;
  font-weight: 600;
  color: var(--text-tertiary);
  text-transform: uppercase;
  letter-spacing: 1px;
  margin-bottom: 8px;
}

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

.skill-tag {
  display: inline-flex;
  align-items: center;
  gap: 4px;
  padding: 6px 14px;
  background: var(--bg-tertiary);
  border: 1px solid var(--border);
  border-radius: 6px;
  font-family: var(--font-mono);
  font-size: 12px;
  color: var(--text-secondary);
  transition: all 0.2s;
}

.skill-tag:hover {
  border-color: var(--accent-blue);
  color: var(--accent-blue);
  background: rgba(88, 166, 255, 0.08);
}

.skill-dot {
  font-size: 10px;
}

.curriculum-download {
  margin-top: 32px;
}

.curriculum-download p {
  font-size: 14px;
  color: var(--text-secondary);
  margin-bottom: 12px;
}

/* CONTACT */
.contact-content {
  display: grid;
  grid-template-columns: 1fr 1fr;
  gap: 48px;
  align-items: start;
}

.contact-info h3 {
  font-family: var(--font-mono);
  font-size: 16px;
  font-weight: 600;
  margin-bottom: 16px;
}

.contact-info p {
  font-size: 15px;
  color: var(--text-secondary);
  margin-bottom: 28px;
  line-height: 1.7;
}

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

.contact-link {
  display: flex;
  align-items: center;
  gap: 12px;
  padding: 14px 18px;
  background: var(--bg-secondary);
  border: 1px solid var(--border);
  border-radius: 8px;
  transition: all 0.2s;
  font-size: 14px;
  color: var(--text-primary);
}

.contact-link:hover {
  border-color: var(--accent-blue);
  background: rgba(88, 166, 255, 0.05);
}

.contact-link-icon {
  width: 20px;
  height: 20px;
  flex-shrink: 0;
  color: var(--accent-blue);
}

.contact-link-label {
  font-family: var(--font-mono);
  font-size: 12px;
  color: var(--text-tertiary);
}

.contact-link-value {
  color: var(--text-primary);
}

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

.form-group {
  display: flex;
  flex-direction: column;
  gap: 6px;
}

.form-label {
  font-family: var(--font-mono);
  font-size: 12px;
  color: var(--text-tertiary);
  text-transform: uppercase;
  letter-spacing: 0.5px;
}

.form-input,
.form-textarea {
  padding: 12px 14px;
  background: var(--bg-secondary);
  border: 1px solid var(--border);
  border-radius: 6px;
  color: var(--text-primary);
  font-family: var(--font-sans);
  font-size: 14px;
  transition: border-color 0.2s;
  outline: none;
}

.form-input:focus,
.form-textarea:focus {
  border-color: var(--accent-blue);
}

.form-input::placeholder,
.form-textarea::placeholder {
  color: var(--text-tertiary);
}

.form-textarea {
  resize: vertical;
  min-height: 120px;
}

/* FOOTER */
.footer {
  border-top: 1px solid var(--border);
  padding: 32px 0;
}

.footer-content {
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 16px;
  flex-wrap: wrap;
}

.footer-info {
  font-family: var(--font-mono);
  font-size: 12px;
  color: var(--text-tertiary);
}

.footer-socials {
  display: flex;
  gap: 16px;
}

.footer-social-link {
  color: var(--text-tertiary);
  transition: color 0.2s;
  display: flex;
  align-items: center;
}

.footer-social-link:hover {
  color: var(--accent-blue);
}

.footer-social-link svg {
  width: 20px;
  height: 20px;
}

/* MOBILE OVERLAY */
.mobile-overlay {
  display: none;
}

/* ANIMATIONS */
.fade-in {
  animation: fadeIn 0.6s ease-out;
}

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

.reveal {
  opacity: 0;
  translate: 0 24px;
  transition: opacity 0.6s ease var(--rd, 0ms), translate 0.6s cubic-bezier(0.22, 1, 0.36, 1) var(--rd, 0ms);
}

.reveal.visible {
  opacity: 1;
  translate: 0 0;
}

@media (prefers-reduced-motion: reduce) {
  html {
    scroll-behavior: auto;
  }

  .reveal {
    opacity: 1;
    translate: none;
    transition: none;
  }

  .archive-collapse,
  .archive-inner {
    transition: none;
  }

  body {
    transition: none;
  }

  .working-dot,
  .fade-in,
  .lang-toggle.pulse {
    animation: none;
  }
}

/* RESPONSIVE */
@media (max-width: 768px) {
  :root {
    --section-padding: 60px 0;
  }

  .nav-links {
    display: none;
    position: fixed;
    top: var(--nav-height);
    left: 0;
    right: 0;
    bottom: 0;
    background: var(--bg-primary);
    flex-direction: column;
    justify-content: center;
    gap: 8px;
    padding: 24px;
    z-index: 999;
  }

  .nav-links.open {
    display: flex;
  }

  .nav-link {
    font-size: 20px;
    padding: 16px 20px;
    text-align: center;
  }

  .nav-link.active::after {
    display: none;
  }

  .menu-toggle {
    display: flex;
  }

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

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

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

  .hero {
    min-height: calc(100vh - var(--nav-height));
    padding-top: 0;
  }

  .hero-content {
    flex-direction: column-reverse;
    gap: 40px;
    padding: 40px 0;
  }

  .hero-image img {
    width: 180px;
    height: 180px;
  }

  .hero-actions {
    flex-direction: column;
  }

  .btn {
    width: 100%;
    justify-content: center;
  }

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

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

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

  .footer-content {
    flex-direction: column;
    text-align: center;
  }
}

@media (max-width: 480px) {
  .container {
    padding: 0 16px;
  }

  .project-card {
    padding: 20px;
  }

  .section-header {
    flex-wrap: wrap;
  }

  .section-line {
    display: none;
  }
}