/* ============================================================
   NRK RAJU GUTHIKONDA — Portfolio Stylesheet
   ============================================================ */

/* ---------- CSS Variables ---------- */
:root {
  --bg-primary: #0d1117;
  --bg-secondary: #161b22;
  --bg-card: #1c2333;
  --bg-card-hover: #222d42;
  --accent: #58a6ff;
  --accent-2: #7ee8fa;
  --accent-gradient: linear-gradient(135deg, #58a6ff 0%, #7ee8fa 50%, #80ffdb 100%);
  --text-primary: #e6edf3;
  --text-secondary: #8b949e;
  --text-muted: #6e7681;
  --border: #30363d;
  --nav-bg: rgba(13, 17, 23, 0.85);
  --radius: 12px;
  --radius-sm: 8px;
  --shadow: 0 8px 32px rgba(0, 0, 0, 0.3);
  --shadow-hover: 0 12px 48px rgba(88, 166, 255, 0.15);
  --transition: 0.3s cubic-bezier(0.4, 0, 0.2, 1);
  --max-width: 1200px;
}

/* ---------- Reset ---------- */
*, *::before, *::after { box-sizing: border-box; margin: 0; padding: 0; }
html { scroll-behavior: smooth; font-size: 16px; }
body {
  font-family: 'Inter', -apple-system, BlinkMacSystemFont, 'Segoe UI', sans-serif;
  background: var(--bg-primary);
  color: var(--text-primary);
  line-height: 1.6;
  overflow-x: hidden;
}
a { color: var(--accent); text-decoration: none; transition: color var(--transition); }
a:hover { color: var(--accent-2); }
img { max-width: 100%; display: block; }
ul { list-style: none; }
::selection { background: rgba(88, 166, 255, 0.3); color: #fff; }

/* ---------- Utility ---------- */
.container { max-width: var(--max-width); margin: 0 auto; padding: 0 24px; }
.section-title {
  font-size: 2rem;
  font-weight: 700;
  margin-bottom: 0.5rem;
  background: var(--accent-gradient);
  -webkit-background-clip: text;
  -webkit-text-fill-color: transparent;
  background-clip: text;
}
.section-subtitle {
  color: var(--text-secondary);
  font-size: 1.1rem;
  margin-bottom: 2.5rem;
}
section { padding: 80px 0; }
.fade-in {
  opacity: 0;
  transform: translateY(30px);
  transition: opacity 0.6s ease, transform 0.6s ease;
}
.fade-in.visible { opacity: 1; transform: translateY(0); }

/* ---------- Navigation ---------- */
.navbar {
  position: fixed;
  top: 0; left: 0; right: 0;
  z-index: 1000;
  background: var(--nav-bg);
  backdrop-filter: blur(16px);
  -webkit-backdrop-filter: blur(16px);
  border-bottom: 1px solid var(--border);
  padding: 0 24px;
  transition: box-shadow var(--transition);
}
.navbar.scrolled { box-shadow: 0 4px 24px rgba(0, 0, 0, 0.4); }
.nav-inner {
  max-width: var(--max-width);
  margin: 0 auto;
  display: flex;
  align-items: center;
  justify-content: space-between;
  height: 64px;
}
.nav-logo {
  font-weight: 700;
  font-size: 1.25rem;
  color: var(--text-primary);
  display: flex;
  align-items: center;
  gap: 8px;
}
.nav-logo .dot {
  width: 10px; height: 10px;
  border-radius: 50%;
  background: var(--accent-gradient);
  display: inline-block;
}
.nav-links { display: flex; gap: 28px; align-items: center; }
.nav-links a {
  color: var(--text-secondary);
  font-size: 0.9rem;
  font-weight: 500;
  position: relative;
  padding: 4px 0;
}
.nav-links a::after {
  content: '';
  position: absolute;
  bottom: -2px; left: 0;
  width: 0; height: 2px;
  background: var(--accent-gradient);
  transition: width var(--transition);
}
.nav-links a:hover { color: var(--text-primary); }
.nav-links a:hover::after { width: 100%; }

/* Mobile nav */
.nav-toggle { display: none; background: none; border: none; color: var(--text-primary); font-size: 1.5rem; cursor: pointer; }

@media (max-width: 768px) {
  .nav-toggle { display: block; }
  .nav-links {
    position: fixed;
    top: 64px; right: -100%;
    width: 260px;
    height: calc(100vh - 64px);
    background: var(--bg-secondary);
    flex-direction: column;
    padding: 32px 24px;
    gap: 20px;
    transition: right var(--transition);
    border-left: 1px solid var(--border);
  }
  .nav-links.open { right: 0; }
}

/* ---------- Hero ---------- */
.hero {
  min-height: 100vh;
  display: flex;
  align-items: center;
  padding-top: 64px;
  position: relative;
  overflow: hidden;
}
.hero::before {
  content: '';
  position: absolute;
  top: -200px; right: -200px;
  width: 600px; height: 600px;
  background: radial-gradient(circle, rgba(88,166,255,0.08) 0%, transparent 70%);
  pointer-events: none;
}
.hero::after {
  content: '';
  position: absolute;
  bottom: -150px; left: -150px;
  width: 500px; height: 500px;
  background: radial-gradient(circle, rgba(126,232,250,0.06) 0%, transparent 70%);
  pointer-events: none;
}
.hero-content {
  display: grid;
  grid-template-columns: 1fr auto;
  gap: 48px;
  align-items: center;
}
.hero-text h1 {
  font-size: 3.2rem;
  font-weight: 800;
  line-height: 1.15;
  margin-bottom: 12px;
}
.hero-text h1 .gradient {
  background: var(--accent-gradient);
  -webkit-background-clip: text;
  -webkit-text-fill-color: transparent;
  background-clip: text;
}
.hero-text .role {
  font-size: 1.25rem;
  color: var(--text-secondary);
  margin-bottom: 8px;
  font-weight: 500;
}
.hero-text .tagline {
  font-size: 1.1rem;
  color: var(--accent-2);
  margin-bottom: 28px;
  font-style: italic;
}
.hero-buttons { display: flex; gap: 16px; flex-wrap: wrap; }
.btn {
  display: inline-flex;
  align-items: center;
  gap: 8px;
  padding: 12px 28px;
  border-radius: 50px;
  font-weight: 600;
  font-size: 0.95rem;
  transition: all var(--transition);
  cursor: pointer;
  border: none;
}
.btn-primary {
  background: var(--accent-gradient);
  color: #0d1117;
}
.btn-primary:hover {
  transform: translateY(-2px);
  box-shadow: 0 8px 24px rgba(88, 166, 255, 0.3);
  color: #0d1117;
}
.btn-outline {
  background: transparent;
  border: 2px solid var(--border);
  color: var(--text-primary);
}
.btn-outline:hover {
  border-color: var(--accent);
  color: var(--accent);
  transform: translateY(-2px);
}
.hero-avatar {
  width: 280px;
  height: 280px;
  border-radius: 50%;
  background: var(--bg-card);
  border: 3px solid var(--border);
  display: flex;
  align-items: center;
  justify-content: center;
  font-size: 5rem;
  color: var(--accent);
  position: relative;
  overflow: hidden;
}
.hero-avatar::before {
  content: '';
  position: absolute;
  inset: -3px;
  border-radius: 50%;
  background: var(--accent-gradient);
  z-index: -1;
  opacity: 0.5;
}

@media (max-width: 768px) {
  .hero-content { grid-template-columns: 1fr; text-align: center; }
  .hero-avatar { margin: 0 auto 24px; width: 200px; height: 200px; font-size: 3.5rem; order: -1; }
  .hero-text h1 { font-size: 2.2rem; }
  .hero-buttons { justify-content: center; }
}

/* ---------- Stats Bar ---------- */
.stats-bar {
  background: var(--bg-secondary);
  border-top: 1px solid var(--border);
  border-bottom: 1px solid var(--border);
  padding: 32px 0;
}
.stats-grid {
  display: flex;
  justify-content: center;
  flex-wrap: wrap;
  gap: 48px;
}
.stat-item { text-align: center; }
.stat-number {
  font-size: 2rem;
  font-weight: 800;
  background: var(--accent-gradient);
  -webkit-background-clip: text;
  -webkit-text-fill-color: transparent;
  background-clip: text;
}
.stat-label { color: var(--text-secondary); font-size: 0.85rem; margin-top: 4px; text-transform: uppercase; letter-spacing: 1px; }

/* ---------- About ---------- */
#about .about-content {
  display: grid;
  grid-template-columns: 1fr 1fr;
  gap: 48px;
  align-items: start;
}
.about-text p { margin-bottom: 16px; color: var(--text-secondary); font-size: 1.05rem; }
.about-text p strong { color: var(--text-primary); }
.about-highlights {
  display: grid;
  gap: 16px;
}
.highlight-card {
  background: var(--bg-card);
  border: 1px solid var(--border);
  border-radius: var(--radius);
  padding: 20px;
  display: flex;
  gap: 16px;
  align-items: flex-start;
  transition: all var(--transition);
}
.highlight-card:hover {
  border-color: var(--accent);
  transform: translateX(4px);
}
.highlight-card .icon {
  font-size: 1.5rem;
  min-width: 40px;
  height: 40px;
  display: flex;
  align-items: center;
  justify-content: center;
  border-radius: var(--radius-sm);
  background: rgba(88, 166, 255, 0.1);
}
.highlight-card h4 { font-size: 1rem; margin-bottom: 4px; }
.highlight-card p { font-size: 0.85rem; color: var(--text-secondary); }

@media (max-width: 768px) {
  #about .about-content { grid-template-columns: 1fr; }
}

/* ---------- Flagship Projects ---------- */
.flagship-grid {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(320px, 1fr));
  gap: 24px;
}
.flagship-card {
  background: var(--bg-card);
  border: 1px solid var(--border);
  border-radius: var(--radius);
  padding: 28px;
  position: relative;
  overflow: hidden;
  transition: all var(--transition);
}
.flagship-card::before {
  content: '';
  position: absolute;
  top: 0; left: 0; right: 0;
  height: 3px;
  background: var(--accent-gradient);
}
.flagship-card:hover {
  border-color: var(--accent);
  transform: translateY(-4px);
  box-shadow: var(--shadow-hover);
}
.flagship-card .emoji { font-size: 2.5rem; margin-bottom: 16px; }
.flagship-card h3 { font-size: 1.2rem; margin-bottom: 8px; }
.flagship-card p { color: var(--text-secondary); font-size: 0.9rem; margin-bottom: 16px; }
.flagship-card .tech-badges { display: flex; flex-wrap: wrap; gap: 6px; margin-bottom: 16px; }
.badge {
  background: rgba(88, 166, 255, 0.1);
  color: var(--accent);
  padding: 4px 10px;
  border-radius: 50px;
  font-size: 0.75rem;
  font-weight: 600;
  border: 1px solid rgba(88, 166, 255, 0.2);
}
.flagship-card .card-link {
  display: inline-flex;
  align-items: center;
  gap: 6px;
  color: var(--accent);
  font-weight: 600;
  font-size: 0.9rem;
}
.flagship-card .card-link:hover { gap: 10px; }

/* ---------- Category Section ---------- */
.category-tabs {
  display: flex;
  flex-wrap: wrap;
  gap: 8px;
  margin-bottom: 32px;
  justify-content: center;
}
.tab-btn {
  background: var(--bg-card);
  border: 1px solid var(--border);
  color: var(--text-secondary);
  padding: 8px 20px;
  border-radius: 50px;
  cursor: pointer;
  font-size: 0.9rem;
  font-weight: 500;
  transition: all var(--transition);
  font-family: inherit;
}
.tab-btn:hover, .tab-btn.active {
  background: rgba(88, 166, 255, 0.1);
  border-color: var(--accent);
  color: var(--accent);
}
.projects-grid {
  display: grid;
  grid-template-columns: repeat(auto-fill, minmax(300px, 1fr));
  gap: 16px;
}
.project-card {
  background: var(--bg-card);
  border: 1px solid var(--border);
  border-radius: var(--radius);
  padding: 20px;
  transition: all var(--transition);
  display: flex;
  flex-direction: column;
}
.project-card:hover {
  border-color: var(--accent);
  transform: translateY(-2px);
  box-shadow: var(--shadow-hover);
}
.project-card h4 {
  font-size: 0.95rem;
  margin-bottom: 8px;
  display: flex;
  align-items: center;
  gap: 8px;
}
.project-card h4 .repo-icon { color: var(--text-muted); font-size: 0.85rem; }
.project-card p { color: var(--text-secondary); font-size: 0.82rem; flex-grow: 1; margin-bottom: 12px; }
.project-card .card-footer {
  display: flex;
  justify-content: space-between;
  align-items: center;
}
.project-card .lang-dot {
  width: 10px; height: 10px;
  border-radius: 50%;
  display: inline-block;
  margin-right: 4px;
}
.project-card .lang-dot.python { background: #3572A5; }
.project-card .lang-dot.typescript { background: #2b7489; }
.project-card .lang-dot.javascript { background: #f1e05a; }
.project-card .lang-dot.html { background: #e34c26; }
.project-card .lang-label { font-size: 0.8rem; color: var(--text-muted); }
.project-card .card-link { font-size: 0.8rem; font-weight: 600; }

.category-group { display: none; }
.category-group.active { display: grid; }

/* ---------- Skills ---------- */
.skills-grid {
  display: grid;
  grid-template-columns: repeat(auto-fill, minmax(140px, 1fr));
  gap: 12px;
}
.skill-tag {
  background: var(--bg-card);
  border: 1px solid var(--border);
  border-radius: var(--radius-sm);
  padding: 14px 16px;
  text-align: center;
  font-weight: 600;
  font-size: 0.9rem;
  transition: all var(--transition);
  display: flex;
  align-items: center;
  justify-content: center;
  gap: 8px;
}
.skill-tag:hover {
  border-color: var(--accent);
  background: rgba(88, 166, 255, 0.08);
  transform: translateY(-2px);
}
.skill-tag i { color: var(--accent); }

/* ---------- Publications ---------- */
.publications-list {
  display: grid;
  gap: 16px;
  max-width: 700px;
}
.pub-card {
  background: var(--bg-card);
  border: 1px solid var(--border);
  border-radius: var(--radius);
  padding: 24px;
  transition: all var(--transition);
}
.pub-card:hover { border-color: var(--accent); transform: translateX(4px); }
.pub-card h4 { margin-bottom: 6px; }
.pub-card .pub-meta { color: var(--text-muted); font-size: 0.85rem; }
.pub-card .pub-status {
  display: inline-block;
  margin-top: 8px;
  font-size: 0.8rem;
  padding: 3px 12px;
  border-radius: 50px;
  background: rgba(126, 232, 250, 0.1);
  color: var(--accent-2);
  border: 1px solid rgba(126, 232, 250, 0.2);
}

/* ---------- Contact ---------- */
#contact { text-align: center; }
.contact-links {
  display: flex;
  justify-content: center;
  gap: 24px;
  flex-wrap: wrap;
}
.contact-card {
  background: var(--bg-card);
  border: 1px solid var(--border);
  border-radius: var(--radius);
  padding: 24px 32px;
  display: flex;
  align-items: center;
  gap: 16px;
  transition: all var(--transition);
  min-width: 220px;
}
.contact-card:hover {
  border-color: var(--accent);
  transform: translateY(-4px);
  box-shadow: var(--shadow-hover);
  color: var(--text-primary);
}
.contact-card i { font-size: 1.5rem; color: var(--accent); }
.contact-card span { font-weight: 600; }

/* ---------- Footer ---------- */
.footer {
  border-top: 1px solid var(--border);
  padding: 32px 0;
  text-align: center;
  color: var(--text-muted);
  font-size: 0.85rem;
}
.footer a { color: var(--text-secondary); }
.footer a:hover { color: var(--accent); }

/* ---------- Scroll-to-top ---------- */
.scroll-top {
  position: fixed;
  bottom: 32px; right: 32px;
  width: 44px; height: 44px;
  border-radius: 50%;
  background: var(--accent-gradient);
  color: #0d1117;
  border: none;
  cursor: pointer;
  display: flex;
  align-items: center;
  justify-content: center;
  font-size: 1.1rem;
  opacity: 0;
  transform: translateY(20px);
  transition: all var(--transition);
  z-index: 99;
}
.scroll-top.visible { opacity: 1; transform: translateY(0); }
.scroll-top:hover { box-shadow: 0 4px 20px rgba(88, 166, 255, 0.4); }

/* ---------- Count animation ---------- */
@keyframes countPulse {
  0%, 100% { transform: scale(1); }
  50% { transform: scale(1.05); }
}

/* ---------- Responsive grid tweaks ---------- */
@media (max-width: 600px) {
  .projects-grid { grid-template-columns: 1fr; }
  .flagship-grid { grid-template-columns: 1fr; }
  .stats-grid { gap: 24px; }
  .section-title { font-size: 1.6rem; }
  section { padding: 48px 0; }
  .skills-grid { grid-template-columns: repeat(auto-fill, minmax(120px, 1fr)); }
}