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

:root {
  --bg: #0d1117;
  --bg-secondary: #161b22;
  --border: #30363d;
  --text: #e6edf3;
  --text-secondary: #8b949e;
  --accent: #64d2ff;
  --accent-hover: #40b8e0;
  --link: #79b8ff;
  --glow: rgba(100, 210, 255, 0.4);
}

html {
  scroll-behavior: smooth;
}

body {
  font-family: -apple-system, BlinkMacSystemFont, "Segoe UI", Helvetica, Arial, sans-serif;
  background: var(--bg);
  color: var(--text);
  line-height: 1.6;
  min-height: 100vh;
}

a {
  color: var(--link);
  text-decoration: none;
}

a:hover {
  text-decoration: underline;
}

.container {
  max-width: 800px;
  margin: 0 auto;
  padding: 0 1.5rem;
}

/* ===== Navigation ===== */
.nav {
  position: fixed;
  top: 0;
  left: 0;
  right: 0;
  z-index: 100;
  padding: 0.75rem 0;
  background: rgba(13, 17, 23, 0.8);
  backdrop-filter: blur(12px);
  -webkit-backdrop-filter: blur(12px);
  border-bottom: 1px solid transparent;
  transition: border-color 0.3s, background 0.3s;
}

.nav.scrolled {
  border-bottom-color: var(--border);
  background: rgba(13, 17, 23, 0.95);
}

.nav-inner {
  display: flex;
  align-items: center;
  justify-content: space-between;
}

.nav-logo {
  font-size: 1.2rem;
  font-weight: 700;
  color: var(--text);
}

.nav-logo:hover {
  text-decoration: none;
}

.nav-links {
  list-style: none;
  display: flex;
  gap: 1.5rem;
}

.nav-link {
  color: var(--text-secondary);
  font-size: 0.9rem;
  font-weight: 500;
  position: relative;
  transition: color 0.3s;
}

.nav-link:hover {
  color: var(--text);
  text-decoration: none;
}

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

.nav-link.active::after {
  content: "";
  position: absolute;
  bottom: -4px;
  left: 0;
  right: 0;
  height: 2px;
  background: var(--accent);
  border-radius: 1px;
}

/* ===== Hero ===== */
.hero {
  position: relative;
  padding: 8rem 0 4rem;
  text-align: center;
  border-bottom: 1px solid transparent;
  background-image: linear-gradient(transparent, var(--bg));
  overflow: hidden;
}

.hero-gradient {
  position: absolute;
  inset: 0;
  background: radial-gradient(ellipse at 50% 0%, rgba(100, 210, 255, 0.08) 0%, transparent 70%);
  pointer-events: none;
}

.hero-title {
  font-size: 3rem;
  font-weight: 700;
  margin-bottom: 0.5rem;
  text-shadow: 0 0 30px var(--glow);
}

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

.hero-subtitle {
  font-size: 1.1rem;
  color: var(--text-secondary);
  margin-bottom: 1rem;
}

.hero-desc {
  font-size: 1rem;
  color: var(--text-secondary);
  max-width: 500px;
  margin: 0 auto;
  min-height: 1.6em;
}

.hero-desc .cursor {
  display: inline-block;
  width: 2px;
  height: 1em;
  background: var(--accent);
  margin-left: 2px;
  vertical-align: text-bottom;
  animation: blink 1s step-end infinite;
}

@keyframes blink {
  50% { opacity: 0; }
}

/* ===== Section dividers ===== */
.section {
  padding: 4rem 0;
  border-bottom: 1px solid transparent;
  position: relative;
}

.section::after {
  content: "";
  position: absolute;
  bottom: 0;
  left: 50%;
  transform: translateX(-50%);
  width: min(80%, 600px);
  height: 1px;
  background: linear-gradient(90deg, transparent, var(--border), var(--accent), var(--border), transparent);
}

.section:last-of-type::after {
  display: none;
}

.section-title {
  font-size: 1.5rem;
  font-weight: 600;
  margin-bottom: 1.5rem;
  text-shadow: 0 0 20px rgba(100, 210, 255, 0.3);
}

/* ===== Fade-in animation ===== */
.fade-in {
  opacity: 0;
  transform: translateY(30px);
  transition: opacity 0.6s ease-out, transform 0.6s ease-out;
}

.fade-in.visible {
  opacity: 1;
  transform: translateY(0);
}

/* ===== Skills ===== */
.skills-grid {
  display: grid;
  grid-template-columns: 1fr;
  gap: 1.5rem;
}

.skill-category {
  background: rgba(22, 27, 34, 0.6);
  backdrop-filter: blur(8px);
  -webkit-backdrop-filter: blur(8px);
  border: 1px solid var(--border);
  border-radius: 12px;
  padding: 1.5rem;
  transition: border-color 0.3s;
}

.skill-category:hover {
  border-color: rgba(100, 210, 255, 0.3);
}

.skill-category-title {
  font-size: 0.85rem;
  font-weight: 600;
  color: var(--accent);
  text-transform: uppercase;
  letter-spacing: 0.05em;
  margin-bottom: 1rem;
}

.skill-badges {
  display: flex;
  flex-wrap: wrap;
  gap: 0.5rem;
}

.skill-badge {
  font-size: 0.8rem;
  padding: 0.35rem 0.85rem;
  background: rgba(100, 210, 255, 0.1);
  color: var(--text);
  border: 1px solid rgba(100, 210, 255, 0.2);
  border-radius: 20px;
  transition: background 0.3s, border-color 0.3s, box-shadow 0.3s;
}

.skill-badge:hover {
  background: rgba(100, 210, 255, 0.2);
  border-color: rgba(100, 210, 255, 0.4);
  box-shadow: 0 0 10px rgba(100, 210, 255, 0.15);
}

/* ===== Project Grid ===== */
.project-grid {
  display: grid;
  grid-template-columns: 1fr;
  gap: 1rem;
}

.project-card {
  display: block;
  background: rgba(22, 27, 34, 0.6);
  backdrop-filter: blur(8px);
  -webkit-backdrop-filter: blur(8px);
  border: 1px solid var(--border);
  border-radius: 12px;
  padding: 1.5rem;
  color: var(--text);
  transition: transform 0.3s ease, border-color 0.3s, box-shadow 0.3s;
}

.project-card:hover {
  transform: translateY(-4px);
  border-color: var(--accent);
  box-shadow: 0 0 20px rgba(100, 210, 255, 0.15), 0 8px 25px rgba(0, 0, 0, 0.3);
  text-decoration: none;
}

.project-card h3 {
  font-size: 1.1rem;
  margin-bottom: 0.5rem;
}

.project-card p {
  font-size: 0.9rem;
  color: var(--text-secondary);
  margin-bottom: 0.75rem;
}

.tag-list {
  display: flex;
  flex-wrap: wrap;
  gap: 0.5rem;
  list-style: none;
}

.tag {
  font-size: 0.75rem;
  background: rgba(100, 210, 255, 0.1);
  color: var(--accent);
  padding: 0.2rem 0.6rem;
  border: 1px solid rgba(100, 210, 255, 0.2);
  border-radius: 12px;
  transition: background 0.3s;
}

.project-card:hover .tag {
  background: rgba(100, 210, 255, 0.2);
}

/* ===== Contact ===== */
.contact-grid {
  display: grid;
  grid-template-columns: 1fr;
  gap: 1rem;
}

.contact-card {
  display: flex;
  flex-direction: column;
  align-items: center;
  gap: 0.5rem;
  background: rgba(22, 27, 34, 0.6);
  backdrop-filter: blur(8px);
  -webkit-backdrop-filter: blur(8px);
  border: 1px solid var(--border);
  border-radius: 12px;
  padding: 2rem 1.5rem;
  color: var(--text);
  transition: transform 0.3s ease, border-color 0.3s, box-shadow 0.3s;
}

.contact-card:hover {
  transform: translateY(-4px);
  border-color: var(--accent);
  box-shadow: 0 0 20px rgba(100, 210, 255, 0.15), 0 8px 25px rgba(0, 0, 0, 0.3);
  text-decoration: none;
}

.contact-icon {
  font-size: 1.8rem;
}

.contact-label {
  font-size: 0.8rem;
  color: var(--text-secondary);
  text-transform: uppercase;
  letter-spacing: 0.05em;
}

.contact-value {
  font-size: 0.95rem;
  color: var(--accent);
}

/* ===== Footer ===== */
.footer {
  padding: 2rem 0;
  text-align: center;
  color: var(--text-secondary);
  font-size: 0.85rem;
}

/* ===== Project Detail Page ===== */
.back-link {
  display: inline-block;
  margin-bottom: 1.5rem;
  color: var(--text-secondary);
  font-size: 0.9rem;
}

.back-link:hover {
  color: var(--text);
}

.project-detail {
  padding: 6rem 0 3rem;
}

.project-detail h1 {
  font-size: 2rem;
  margin-bottom: 1rem;
  text-shadow: 0 0 20px rgba(100, 210, 255, 0.3);
}

.project-detail .description {
  color: var(--text-secondary);
  margin-bottom: 1.5rem;
  line-height: 1.8;
}

.project-detail .tag-list {
  margin-bottom: 1.5rem;
}

.project-detail .project-link {
  display: inline-block;
  background: var(--accent);
  color: var(--bg);
  padding: 0.5rem 1.2rem;
  border-radius: 6px;
  font-weight: 600;
  font-size: 0.9rem;
  transition: background 0.3s, box-shadow 0.3s;
}

.project-detail .project-link:hover {
  background: var(--accent-hover);
  box-shadow: 0 0 15px rgba(100, 210, 255, 0.3);
  text-decoration: none;
}

/* ===== Responsive ===== */
@media (min-width: 600px) {
  .project-grid {
    grid-template-columns: repeat(2, 1fr);
  }

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

  .skills-grid {
    grid-template-columns: repeat(3, 1fr);
  }
}

@media (max-width: 480px) {
  .nav-links {
    gap: 1rem;
  }

  .nav-link {
    font-size: 0.8rem;
  }

  .hero-title {
    font-size: 2.2rem;
  }
}