/* =========================================
   SIDDHARTH NISHTALA — PERSONAL SITE
   Dark Academic Nerd Aesthetic
   ========================================= */

/* ---- TOKENS ---- */
:root {
  --bg: #0e1117;
  --bg-card: #141820;
  --bg-card-hover: #1a2030;
  --border: rgba(255, 255, 255, 0.07);
  --border-hover: rgba(255, 255, 255, 0.15);
  --text: #d4d8e2;
  --text-muted: #6b7385;
  --text-light: #9aa3b5;
  --heading: #edf0f7;
  --accent: #7eb8f7;        /* cool blue */
  --accent-warm: #f7c07e;   /* amber — for accents/highlights */
  --accent-green: #7ef7b8;  /* for code */
  --mono: 'JetBrains Mono', 'Fira Code', monospace;
  --serif: 'Lora', 'Georgia', serif;
  --display: 'Instrument Serif', 'Lora', serif;
  --nav-h: 64px;
  --max-w: 900px;
  --grid-color: rgba(255, 255, 255, 0.025);
}

/* ---- RESET ---- */
*, *::before, *::after { box-sizing: border-box; margin: 0; padding: 0; }
html { scroll-behavior: smooth; }
body {
  background: var(--bg);
  color: var(--text);
  font-family: var(--serif);
  font-size: 16px;
  line-height: 1.75;
  min-height: 100vh;
  overflow-x: hidden;
}

/* ---- GRID BACKGROUND ---- */
.grid-bg {
  position: fixed;
  inset: 0;
  z-index: 0;
  background-image:
    linear-gradient(var(--grid-color) 1px, transparent 1px),
    linear-gradient(90deg, var(--grid-color) 1px, transparent 1px);
  background-size: 40px 40px;
  pointer-events: none;
}

main, nav, footer { position: relative; z-index: 1; }

/* ---- TYPOGRAPHY ---- */
h1, h2, h3, h4 { color: var(--heading); line-height: 1.2; }
.mono { font-family: var(--mono); font-size: 0.82em; letter-spacing: 0.01em; }
.accent { color: var(--accent); }
em { font-style: italic; color: var(--accent-warm); }
strong { color: var(--heading); font-weight: 600; }
a { color: var(--accent); text-decoration: none; transition: color 0.2s; }
a:hover { color: var(--accent-warm); }

/* ---- CURSOR BLINK ---- */
.cursor-blink {
  animation: blink 1.1s step-end infinite;
  color: var(--accent);
}
@keyframes blink { 50% { opacity: 0; } }

/* ---- NAV ---- */
.nav {
  position: sticky;
  top: 0;
  z-index: 100;
  height: var(--nav-h);
  display: flex;
  align-items: center;
  justify-content: space-between;
  padding: 0 clamp(1.5rem, 5vw, 3rem);
  background: rgba(14, 17, 23, 0.85);
  backdrop-filter: blur(12px);
  -webkit-backdrop-filter: blur(12px);
  border-bottom: 1px solid var(--border);
}
.nav-logo {
  font-family: var(--mono);
  font-size: 1.1rem;
  font-weight: 500;
  color: var(--heading);
  letter-spacing: -0.02em;
  text-decoration: none;
}
.nav-links {
  display: flex;
  list-style: none;
  gap: 2rem;
}
.nav-link {
  font-family: var(--mono);
  font-size: 0.8rem;
  color: var(--text-muted);
  text-decoration: none;
  transition: color 0.2s;
  position: relative;
}
.nav-link::after {
  content: '';
  position: absolute;
  bottom: -4px;
  left: 0;
  width: 0;
  height: 1px;
  background: var(--accent);
  transition: width 0.25s;
}
.nav-link:hover, .nav-link.active {
  color: var(--heading);
}
.nav-link:hover::after, .nav-link.active::after {
  width: 100%;
}
.nav-link.active { color: var(--accent); }

/* Hamburger */
.hamburger {
  display: none;
  flex-direction: column;
  gap: 5px;
  background: none;
  border: none;
  cursor: pointer;
  padding: 4px;
}
.hamburger span {
  display: block;
  width: 22px;
  height: 1.5px;
  background: var(--text-light);
  transition: all 0.3s;
}
.hamburger.open span:nth-child(1) { transform: translateY(6.5px) rotate(45deg); }
.hamburger.open span:nth-child(2) { opacity: 0; }
.hamburger.open span:nth-child(3) { transform: translateY(-6.5px) rotate(-45deg); }

/* ---- HOME PAGE ---- */
.home-main {
  max-width: var(--max-w);
  margin: 0 auto;
  padding: 2rem clamp(1.5rem, 5vw, 2.5rem) 5rem;
}

.hero {
  display: grid;
  grid-template-columns: 1fr 320px;
  gap: 4rem;
  align-items: center;
  padding: 0rem 0 5rem;
  animation: fadeUp 0.7s ease both;
}

.hero-eyebrow {
  font-family: var(--mono);
  font-size: 0.78rem;
  color: var(--accent);
  letter-spacing: 0.12em;
  text-transform: lowercase;
  margin-bottom: 0.75rem;
}

.hero-name {
  font-family: var(--display);
  font-size: clamp(2.6rem, 6vw, 4.5rem);
  font-weight: 400;
  line-height: 1.05;
  color: var(--heading);
  margin-bottom: 0.75rem;
  letter-spacing: -0.02em;
}

.hero-title {
  margin-bottom: 1.5rem;
  color: var(--text-muted);
}

.hero-bio {
  color: var(--text-light);
  font-size: 1.0rem;
  line-height: 1.8;
  margin-bottom: 1rem;
  max-width: 560px;
}

/* Social links */
.social-links {
  display: flex;
  flex-wrap: wrap;
  gap: 0.75rem;
  margin-top: 2rem;
}
.social-link {
  display: inline-flex;
  align-items: center;
  gap: 0.4rem;
  font-family: var(--mono);
  font-size: 0.75rem;
  color: var(--text-muted);
  padding: 0.45rem 0.9rem;
  border: 1px solid var(--border);
  border-radius: 4px;
  transition: all 0.2s;
  text-decoration: none;
}
.social-link:hover {
  color: var(--accent);
  border-color: var(--accent);
  background: rgba(126, 184, 247, 0.05);
}

/* Hero visual / avatar */
.hero-visual {
  display: flex;
  justify-content: center;
  align-items: center;
}
.avatar-container {
  position: relative;
  width: 220px;
  height: 220px;
}
.avatar-ring {
  position: absolute;
  inset: 0;
  border-radius: 50%;
  border: 1px solid var(--border);
  animation: spin 20s linear infinite;
}
.avatar-ring::before {
  content: '';
  position: absolute;
  top: -3px;
  left: 50%;
  transform: translateX(-50%);
  width: 6px;
  height: 6px;
  border-radius: 50%;
  background: var(--accent);
}
.avatar-placeholder {
  position: absolute;
  inset: 16px;
  border-radius: 50%;
  background: var(--bg-card);
  border: 1px solid var(--border);
  display: flex;
  align-items: center;
  justify-content: center;
  font-family: var(--mono);
  font-size: 2.5rem;
  font-weight: 500;
  color: var(--text-muted);
  background: url('../img/photo.jpg') center/cover no-repeat;
}

/* Floating tags */
.floating-tags { position: absolute; inset: 0; pointer-events: none; }
.tag {
  position: absolute;
  font-size: 0.65rem;
  color: var(--accent);
  background: rgba(126, 184, 247, 0.08);
  border: 1px solid rgba(126, 184, 247, 0.2);
  padding: 0.2rem 0.5rem;
  border-radius: 3px;
  animation: floatTag 6s ease-in-out infinite;
}
.tag-1 { top: 10%; right: -10%; animation-delay: 0s; }
.tag-2 { bottom: 20%; right: -15%; animation-delay: 1.5s; }
.tag-3 { bottom: 5%; left: 5%; animation-delay: 3s; }
.tag-4 { top: 15%; left: -5%; animation-delay: 4.5s; }

@keyframes floatTag {
  0%, 100% { transform: translateY(0); }
  50% { transform: translateY(-6px); }
}
@keyframes spin {
  from { transform: rotate(0deg); }
  to { transform: rotate(360deg); }
}

/* Section labels */
.section-label {
  color: var(--text-muted);
  font-size: 0.75rem;
  letter-spacing: 0.08em;
  margin-bottom: 2rem;
  padding-top: 1rem;
  border-top: 1px solid var(--border);
}

/* About cards */
.about-section { margin-bottom: 5rem; animation: fadeUp 0.7s 0.15s ease both; }
.about-grid {
  display: grid;
  grid-template-columns: repeat(3, 1fr);
  gap: 1.25rem;
}
.about-card {
  background: var(--bg-card);
  border: 1px solid var(--border);
  border-radius: 8px;
  padding: 1.5rem;
  transition: all 0.25s;
}
.about-card:hover {
  border-color: var(--border-hover);
  background: var(--bg-card-hover);
  transform: translateY(-2px);
}
.about-card-icon { font-size: 1.5rem; margin-bottom: 0.75rem; }
.about-card h3 { font-size: 0.95rem; margin-bottom: 0.5rem; }
.about-card p { font-size: 0.88rem; color: var(--text-light); line-height: 1.65; }

/* Recent posts */
.recent-section { animation: fadeUp 0.7s 0.3s ease both; }
.recent-posts { display: flex; flex-direction: column; gap: 0.5rem; margin-bottom: 1.5rem; }
.recent-post-card {
  display: flex;
  align-items: center;
  gap: 1.5rem;
  padding: 1rem 1.25rem;
  background: var(--bg-card);
  border: 1px solid var(--border);
  border-radius: 6px;
  text-decoration: none;
  transition: all 0.2s;
}
.recent-post-card:hover {
  border-color: var(--border-hover);
  background: var(--bg-card-hover);
  color: var(--heading);
}
.recent-post-card .post-date { color: var(--text-muted); flex-shrink: 0; }
.recent-post-card h4 { flex: 1; font-size: 0.95rem; font-weight: 400; font-family: var(--serif); color: var(--text); }
.recent-post-card:hover h4 { color: var(--heading); }
.post-arrow { color: var(--accent); margin-left: auto; flex-shrink: 0; }
.view-all-link {
  color: var(--text-muted);
  font-size: 0.78rem;
  text-decoration: none;
  transition: color 0.2s;
}
.view-all-link:hover { color: var(--accent); }

/* ---- INNER PAGES ---- */
.page-main {
  max-width: var(--max-w);
  margin: 0 auto;
  padding: 3.5rem clamp(1.5rem, 5vw, 2.5rem) 5rem;
  animation: fadeUp 0.6s ease both;
}

.page-header { margin-bottom: 3.5rem; }
.page-title {
  font-family: var(--display);
  font-size: clamp(2.2rem, 5vw, 3.5rem);
  font-weight: 400;
  letter-spacing: -0.02em;
  margin-bottom: 1rem;
}
.page-subtitle { color: var(--text-light); max-width: 600px; font-size: 1rem; }

/* ---- BLOG PAGE ---- */
.filter-bar {
  display: flex;
  flex-wrap: wrap;
  align-items: center;
  gap: 0.5rem;
  margin-bottom: 2.5rem;
}
.filter-label { color: var(--text-muted); margin-right: 0.25rem; }
.filter-btn {
  font-family: var(--mono);
  font-size: 0.72rem;
  color: var(--text-muted);
  background: none;
  border: 1px solid var(--border);
  border-radius: 3px;
  padding: 0.3rem 0.7rem;
  cursor: pointer;
  transition: all 0.2s;
}
.filter-btn:hover, .filter-btn.active {
  color: var(--accent);
  border-color: var(--accent);
  background: rgba(126, 184, 247, 0.05);
}

.posts-list { display: flex; flex-direction: column; gap: 0; }
.post-card {
  display: grid;
  grid-template-columns: 140px 1fr;
  gap: 2rem;
  padding: 2rem 0;
  border-bottom: 1px solid var(--border);
  transition: opacity 0.2s;
}
.post-card:first-child { border-top: 1px solid var(--border); }
.post-meta { padding-top: 0.2rem; }
.post-date { color: var(--text-muted); display: block; margin-bottom: 0.75rem; }
.post-tags { display: flex; flex-direction: column; gap: 0.35rem; }
.tag-pill {
  display: inline-block;
  font-family: var(--mono);
  font-size: 0.65rem;
  color: var(--accent-warm);
  background: rgba(247, 192, 126, 0.08);
  border: 1px solid rgba(247, 192, 126, 0.2);
  padding: 0.15rem 0.5rem;
  border-radius: 3px;
  width: fit-content;
}
.post-title {
  font-family: var(--display);
  font-size: 1.3rem;
  font-weight: 400;
  margin-bottom: 0.6rem;
}
.post-title a { color: var(--heading); text-decoration: none; transition: color 0.2s; }
.post-title a:hover { color: var(--accent); }
.post-excerpt { color: var(--text-light); font-size: 0.92rem; margin-bottom: 0.75rem; }
.read-more {
  font-size: 0.75rem;
  color: var(--text-muted);
  text-decoration: none;
  transition: color 0.2s;
}
.read-more:hover { color: var(--accent); }
.post-card.hidden { display: none; }
.empty-state {
  text-align: center;
  padding: 4rem 0;
  color: var(--text-muted);
}

/* ---- PUBLICATIONS PAGE ---- */
.pub-list { display: flex; flex-direction: column; gap: 0; }
.pub-card {
  display: grid;
  grid-template-columns: 50px 1fr;
  gap: 2rem;
  padding: 2.5rem 0;
  border-bottom: 1px solid var(--border);
}
.pub-card:first-child { border-top: 1px solid var(--border); }
.pub-number {
  color: var(--border-hover);
  font-size: 1.5rem;
  font-weight: 300;
  padding-top: 0.3rem;
}
.pub-venue-row {
  display: flex;
  align-items: center;
  gap: 1rem;
  margin-bottom: 0.75rem;
  flex-wrap: wrap;
}
.pub-venue { color: var(--text-muted); font-size: 0.75rem; }
.pub-badges { display: flex; gap: 0.4rem; }
.pub-badge {
  font-family: var(--mono);
  font-size: 0.65rem;
  color: var(--accent);
  background: rgba(126, 184, 247, 0.08);
  border: 1px solid rgba(126, 184, 247, 0.2);
  padding: 0.1rem 0.5rem;
  border-radius: 3px;
}
.pub-title {
  font-family: var(--display);
  font-size: 1.2rem;
  font-weight: 400;
  margin-bottom: 0.5rem;
  line-height: 1.3;
}
.pub-authors {
  font-size: 0.85rem;
  color: var(--text-muted);
  margin-bottom: 0.75rem;
  font-family: var(--mono);
}
.pub-abstract {
  font-size: 0.92rem;
  color: var(--text-light);
  margin-bottom: 1.25rem;
  line-height: 1.7;
  max-width: 680px;
}
.pub-links { display: flex; flex-wrap: wrap; gap: 0.5rem; }
.pub-link {
  display: inline-flex;
  align-items: center;
  gap: 0.35rem;
  font-family: var(--mono);
  font-size: 0.72rem;
  color: var(--text-muted);
  border: 1px solid var(--border);
  padding: 0.3rem 0.7rem;
  border-radius: 3px;
  text-decoration: none;
  transition: all 0.2s;
}
.pub-link:hover {
  color: var(--accent);
  border-color: var(--accent);
  background: rgba(126, 184, 247, 0.05);
}
.pub-link-blog {
  color: var(--accent-warm);
  border-color: rgba(247, 192, 126, 0.2);
}
.pub-link-blog:hover {
  color: var(--accent-warm);
  border-color: var(--accent-warm);
  background: rgba(247, 192, 126, 0.05);
}
.scholar-callout {
  margin-top: 3rem;
  font-size: 0.85rem;
  color: var(--text-muted);
}
.scholar-link {
  color: var(--accent);
  font-family: var(--mono);
  font-size: 0.78rem;
}

/* ---- RESUME PAGE ---- */
.resume-header {
  display: flex;
  align-items: flex-end;
  justify-content: space-between;
  flex-wrap: wrap;
  gap: 1rem;
}
.download-btn {
  display: inline-flex;
  align-items: center;
  gap: 0.4rem;
  font-size: 0.78rem;
  color: var(--text-muted);
  border: 1px solid var(--border);
  padding: 0.5rem 1rem;
  border-radius: 4px;
  text-decoration: none;
  transition: all 0.2s;
}
.download-btn:hover {
  color: var(--accent);
  border-color: var(--accent);
  background: rgba(126, 184, 247, 0.05);
}
.pdf-container {
  border: 1px solid var(--border);
  border-radius: 8px;
  overflow: hidden;
  background: var(--bg-card);
  min-height: 80vh;
  display: flex;
  flex-direction: column;
}
.pdf-embed {
  width: 100%;
  height: 85vh;
  border: none;
  display: block;
}
.pdf-fallback {
  display: none;
  padding: 3rem;
  text-align: center;
  color: var(--text-muted);
  font-size: 0.85rem;
}

/* ---- FOOTER ---- */
.footer {
  text-align: center;
  padding: 2rem;
  border-top: 1px solid var(--border);
  color: var(--text-muted);
  font-size: 0.75rem;
  display: flex;
  flex-direction: column;
  gap: 0.4rem;
}
.footer a { color: var(--text-muted); }
.footer a:hover { color: var(--accent); }
.footer-easter {
  color: rgba(255,255,255,0.12);
  cursor: default;
  transition: color 0.3s;
}
.footer-easter:hover { color: var(--accent-green); }

/* ---- ANIMATIONS ---- */
@keyframes fadeUp {
  from { opacity: 0; transform: translateY(16px); }
  to { opacity: 1; transform: translateY(0); }
}

/* ---- MOBILE ---- */
@media (max-width: 720px) {
  .nav-links {
    display: none;
    position: absolute;
    top: var(--nav-h);
    left: 0;
    right: 0;
    flex-direction: column;
    background: rgba(14, 17, 23, 0.97);
    backdrop-filter: blur(12px);
    border-bottom: 1px solid var(--border);
    padding: 1.5rem 2rem;
    gap: 1.25rem;
  }
  .nav-links.open { display: flex; }
  .hamburger { display: flex; }

  .hero {
    grid-template-columns: 1fr;
    padding: 2rem 0 3rem;
    gap: 2.5rem;
  }
  .hero-visual { order: -1; }
  .avatar-container { width: 160px; height: 160px; }

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

  .post-card {
    grid-template-columns: 1fr;
    gap: 0.75rem;
  }
  .post-meta {
    display: flex;
    align-items: center;
    gap: 1rem;
  }
  .post-tags { flex-direction: row; }

  .pub-card {
    grid-template-columns: 1fr;
    gap: 0.5rem;
  }
  .pub-number { display: none; }

  .pdf-embed { height: 60vh; }

  .resume-header { flex-direction: column; align-items: flex-start; }

  .tag-1, .tag-2, .tag-3, .tag-4 { display: none; }
}