/* ============================================
   Vilobh Meshram — Personal Website Styles
   ============================================ */

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

:root {
  --color-bg: #0a0a0b;
  --color-bg-alt: #111113;
  --color-surface: #18181b;
  --color-border: #27272a;
  --color-text: #fafafa;
  --color-text-secondary: #a1a1aa;
  --color-accent: #6366f1;
  --color-accent-hover: #818cf8;
  --color-accent-subtle: rgba(99, 102, 241, 0.1);
  --font-sans: 'Inter', -apple-system, BlinkMacSystemFont, 'Segoe UI', sans-serif;
  --font-mono: 'JetBrains Mono', 'Fira Code', monospace;
  --max-width: 1120px;
  --section-padding: 6rem 0;
  --transition: 0.2s ease;
}

html {
  scroll-behavior: smooth;
  -webkit-font-smoothing: antialiased;
  -moz-osx-font-smoothing: grayscale;
}

body {
  font-family: var(--font-sans);
  background: var(--color-bg);
  color: var(--color-text);
  line-height: 1.7;
  font-size: 16px;
}

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

a:hover {
  color: var(--color-accent-hover);
}

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

/* --- Layout --- */
.container {
  max-width: var(--max-width);
  margin: 0 auto;
  padding: 0 1.5rem;
}

.container-narrow {
  max-width: 720px;
}

.section {
  padding: var(--section-padding);
}

.section-alt {
  background: var(--color-bg-alt);
}

.section-title {
  font-size: 2rem;
  font-weight: 700;
  margin-bottom: 3rem;
  letter-spacing: -0.02em;
  position: relative;
  display: inline-block;
}

.section-title::after {
  content: '';
  display: block;
  width: 40px;
  height: 3px;
  background: var(--color-accent);
  margin-top: 0.75rem;
  border-radius: 2px;
}

.section-intro {
  color: var(--color-text-secondary);
  font-size: 1.1rem;
  margin-bottom: 2.5rem;
  max-width: 640px;
}

.subsection-title {
  font-size: 1.4rem;
  font-weight: 600;
  margin-top: 4rem;
  margin-bottom: 1.5rem;
  letter-spacing: -0.01em;
}

/* --- Buttons --- */
.btn {
  display: inline-block;
  padding: 0.75rem 1.75rem;
  border-radius: 8px;
  font-weight: 500;
  font-size: 0.95rem;
  transition: all var(--transition);
  cursor: pointer;
  border: none;
  font-family: var(--font-sans);
}

.btn-primary {
  background: var(--color-accent);
  color: #fff;
}

.btn-primary:hover {
  background: var(--color-accent-hover);
  color: #fff;
  transform: translateY(-1px);
}

.btn-outline {
  background: transparent;
  color: var(--color-text);
  border: 1px solid var(--color-border);
}

.btn-outline:hover {
  border-color: var(--color-accent);
  color: var(--color-accent);
  transform: translateY(-1px);
}

/* --- Navigation --- */
.nav {
  position: fixed;
  top: 0;
  left: 0;
  right: 0;
  z-index: 1000;
  background: rgba(10, 10, 11, 0.8);
  backdrop-filter: blur(20px);
  -webkit-backdrop-filter: blur(20px);
  border-bottom: 1px solid transparent;
  transition: border-color var(--transition);
}

.nav.scrolled {
  border-bottom-color: var(--color-border);
}

.nav-inner {
  max-width: var(--max-width);
  margin: 0 auto;
  padding: 0 1.5rem;
  display: flex;
  align-items: center;
  justify-content: space-between;
  height: 64px;
}

.nav-logo {
  font-weight: 700;
  font-size: 1.25rem;
  color: var(--color-text);
  letter-spacing: -0.02em;
}

.nav-logo:hover {
  color: var(--color-accent);
}

.nav-links {
  display: flex;
  list-style: none;
  gap: 2rem;
}

.nav-links a {
  color: var(--color-text-secondary);
  font-size: 0.9rem;
  font-weight: 400;
  transition: color var(--transition);
}

.nav-links a:hover {
  color: var(--color-text);
}

.nav-toggle {
  display: none;
  background: none;
  border: none;
  cursor: pointer;
  flex-direction: column;
  gap: 5px;
  padding: 4px;
}

.nav-toggle span {
  display: block;
  width: 24px;
  height: 2px;
  background: var(--color-text);
  border-radius: 1px;
  transition: all 0.3s ease;
}

/* --- Hero --- */
.hero {
  min-height: 100vh;
  display: flex;
  align-items: center;
  justify-content: center;
  padding: 6rem 1.5rem 4rem;
  position: relative;
  overflow: hidden;
}

.hero::before {
  content: '';
  position: absolute;
  top: -50%;
  left: -50%;
  width: 200%;
  height: 200%;
  background: radial-gradient(ellipse at 30% 20%, rgba(99, 102, 241, 0.08) 0%, transparent 50%),
              radial-gradient(ellipse at 70% 80%, rgba(99, 102, 241, 0.04) 0%, transparent 50%);
  pointer-events: none;
}

.hero-content {
  text-align: center;
  position: relative;
  z-index: 1;
  max-width: 800px;
}

.hero-label {
  font-family: var(--font-mono);
  font-size: 0.85rem;
  color: var(--color-accent);
  margin-bottom: 1.5rem;
  letter-spacing: 0.05em;
}

.hero-title {
  font-size: clamp(3rem, 8vw, 5rem);
  font-weight: 700;
  letter-spacing: -0.04em;
  line-height: 1.05;
  margin-bottom: 1.5rem;
  background: linear-gradient(135deg, var(--color-text) 0%, var(--color-text-secondary) 100%);
  -webkit-background-clip: text;
  -webkit-text-fill-color: transparent;
  background-clip: text;
}

.hero-subtitle {
  font-size: 1.2rem;
  color: var(--color-text-secondary);
  line-height: 1.7;
  max-width: 600px;
  margin: 0 auto 2.5rem;
}

.hero-cta {
  display: flex;
  gap: 1rem;
  justify-content: center;
  flex-wrap: wrap;
  margin-bottom: 3rem;
}

.hero-links {
  display: flex;
  gap: 1.5rem;
  justify-content: center;
}

.hero-links a {
  color: var(--color-text-secondary);
  transition: color var(--transition), transform var(--transition);
}

.hero-links a:hover {
  color: var(--color-accent);
  transform: translateY(-2px);
}

/* --- About --- */
.about-grid {
  display: grid;
  grid-template-columns: 1fr 1fr;
  gap: 4rem;
  align-items: start;
}

.about-text p {
  color: var(--color-text-secondary);
  margin-bottom: 1.25rem;
  font-size: 1.05rem;
}

.about-text strong {
  color: var(--color-text);
  font-weight: 500;
}

.about-highlights {
  display: grid;
  grid-template-columns: 1fr 1fr;
  gap: 1rem;
}

.highlight-card {
  background: var(--color-surface);
  border: 1px solid var(--color-border);
  border-radius: 12px;
  padding: 1.5rem;
  text-align: center;
  transition: border-color var(--transition), transform var(--transition);
}

.highlight-card:hover {
  border-color: var(--color-accent);
  transform: translateY(-2px);
}

.highlight-number {
  display: block;
  font-size: 2rem;
  font-weight: 700;
  color: var(--color-accent);
  letter-spacing: -0.02em;
}

.highlight-label {
  display: block;
  font-size: 0.85rem;
  color: var(--color-text-secondary);
  margin-top: 0.25rem;
}

/* --- Expertise --- */
.expertise-grid {
  display: grid;
  grid-template-columns: repeat(3, 1fr);
  gap: 1.5rem;
}

.expertise-card {
  background: var(--color-surface);
  border: 1px solid var(--color-border);
  border-radius: 12px;
  padding: 2rem;
  transition: border-color var(--transition), transform var(--transition);
}

.expertise-card:hover {
  border-color: var(--color-accent);
  transform: translateY(-3px);
}

.expertise-icon {
  color: var(--color-accent);
  margin-bottom: 1.25rem;
}

.expertise-card h3 {
  font-size: 1.1rem;
  font-weight: 600;
  margin-bottom: 0.75rem;
  letter-spacing: -0.01em;
}

.expertise-card p {
  font-size: 0.9rem;
  color: var(--color-text-secondary);
  line-height: 1.6;
}

/* --- Timeline (Experience) --- */
.timeline {
  position: relative;
  padding-left: 2rem;
}

.timeline::before {
  content: '';
  position: absolute;
  left: 6px;
  top: 8px;
  bottom: 8px;
  width: 2px;
  background: var(--color-border);
}

.timeline-item {
  position: relative;
  padding-bottom: 2.5rem;
}

.timeline-item:last-child {
  padding-bottom: 0;
}

.timeline-marker {
  position: absolute;
  left: -2rem;
  top: 6px;
  width: 14px;
  height: 14px;
  border-radius: 50%;
  background: var(--color-bg);
  border: 2px solid var(--color-accent);
  z-index: 1;
}

.timeline-item:first-child .timeline-marker {
  background: var(--color-accent);
}

.timeline-content {
  background: var(--color-surface);
  border: 1px solid var(--color-border);
  border-radius: 12px;
  padding: 1.5rem 2rem;
  transition: border-color var(--transition);
}

.timeline-content:hover {
  border-color: var(--color-accent);
}

.timeline-header {
  display: flex;
  align-items: center;
  gap: 0.75rem;
  margin-bottom: 0.25rem;
}

.timeline-content h3 {
  font-size: 1.15rem;
  font-weight: 600;
  letter-spacing: -0.01em;
}

.timeline-badge {
  font-family: var(--font-mono);
  font-size: 0.7rem;
  background: var(--color-accent-subtle);
  color: var(--color-accent);
  padding: 0.2rem 0.6rem;
  border-radius: 4px;
  font-weight: 500;
}

.timeline-role {
  font-size: 0.9rem;
  color: var(--color-accent);
  margin-bottom: 0.5rem;
}

.timeline-desc {
  font-size: 0.9rem;
  color: var(--color-text-secondary);
  line-height: 1.6;
}

/* --- Education --- */
.education-grid {
  display: grid;
  grid-template-columns: 1fr 1fr;
  gap: 1.5rem;
}

.education-card {
  background: var(--color-surface);
  border: 1px solid var(--color-border);
  border-radius: 12px;
  padding: 1.5rem 2rem;
  transition: border-color var(--transition);
}

.education-card:hover {
  border-color: var(--color-accent);
}

.education-card h4 {
  font-size: 1.05rem;
  font-weight: 600;
  margin-bottom: 0.5rem;
}

.education-card p {
  font-size: 0.9rem;
  color: var(--color-text-secondary);
}

/* --- Publications --- */
.publications {
  display: grid;
  gap: 1.5rem;
  margin-bottom: 2.5rem;
}

.pub-card {
  background: var(--color-surface);
  border: 1px solid var(--color-border);
  border-radius: 12px;
  padding: 2rem;
  transition: border-color var(--transition), transform var(--transition);
}

.pub-card:hover {
  border-color: var(--color-accent);
  transform: translateY(-2px);
}

.pub-tag {
  display: inline-block;
  font-family: var(--font-mono);
  font-size: 0.7rem;
  background: var(--color-accent-subtle);
  color: var(--color-accent);
  padding: 0.2rem 0.6rem;
  border-radius: 4px;
  font-weight: 500;
  margin-bottom: 0.75rem;
  text-transform: uppercase;
  letter-spacing: 0.05em;
}

.pub-title {
  font-size: 1.1rem;
  font-weight: 600;
  margin-bottom: 0.5rem;
  letter-spacing: -0.01em;
  line-height: 1.4;
}

.pub-meta {
  font-size: 0.85rem;
  color: var(--color-text-secondary);
  margin-bottom: 0.75rem;
}

.pub-desc {
  font-size: 0.9rem;
  color: var(--color-text-secondary);
  line-height: 1.6;
  margin-bottom: 1rem;
}

.pub-link {
  font-size: 0.9rem;
  font-weight: 500;
}

.research-profiles {
  display: flex;
  gap: 1rem;
  flex-wrap: wrap;
}

.profile-link {
  display: flex;
  align-items: center;
  gap: 0.5rem;
  background: var(--color-surface);
  border: 1px solid var(--color-border);
  border-radius: 8px;
  padding: 0.75rem 1.25rem;
  color: var(--color-text-secondary);
  font-size: 0.9rem;
  font-weight: 500;
  transition: all var(--transition);
}

.profile-link:hover {
  border-color: var(--color-accent);
  color: var(--color-accent);
  transform: translateY(-1px);
}

/* --- Open Source --- */
.oss-grid {
  display: grid;
  grid-template-columns: repeat(2, 1fr);
  gap: 1.5rem;
  margin-bottom: 2rem;
}

.oss-card {
  background: var(--color-surface);
  border: 1px solid var(--color-border);
  border-radius: 12px;
  padding: 1.5rem 2rem;
  transition: border-color var(--transition), transform var(--transition);
}

.oss-card:hover {
  border-color: var(--color-accent);
  transform: translateY(-2px);
}

.oss-card h3 {
  font-size: 1.05rem;
  font-weight: 600;
  margin-bottom: 0.5rem;
}

.oss-card p {
  font-size: 0.9rem;
  color: var(--color-text-secondary);
  line-height: 1.6;
}

.oss-cta {
  text-align: center;
  margin-top: 2rem;
}

/* --- Contact --- */
.contact-text {
  color: var(--color-text-secondary);
  font-size: 1.1rem;
  margin-bottom: 2.5rem;
  text-align: center;
}

.contact-links {
  display: flex;
  gap: 1rem;
  justify-content: center;
  flex-wrap: wrap;
}

.contact-card {
  display: flex;
  align-items: center;
  gap: 0.75rem;
  background: var(--color-surface);
  border: 1px solid var(--color-border);
  border-radius: 12px;
  padding: 1.25rem 2rem;
  color: var(--color-text);
  font-weight: 500;
  transition: all var(--transition);
}

.contact-card:hover {
  border-color: var(--color-accent);
  color: var(--color-accent);
  transform: translateY(-2px);
}

.contact-card svg {
  flex-shrink: 0;
}

/* --- Footer --- */
.footer {
  border-top: 1px solid var(--color-border);
  padding: 2rem 0;
  text-align: center;
}

.footer p {
  color: var(--color-text-secondary);
  font-size: 0.85rem;
}

/* ============================================
   Responsive
   ============================================ */
@media (max-width: 768px) {
  :root {
    --section-padding: 4rem 0;
  }

  /* Mobile nav */
  .nav-toggle {
    display: flex;
  }

  .nav-links {
    display: none;
    position: absolute;
    top: 64px;
    left: 0;
    right: 0;
    background: rgba(10, 10, 11, 0.95);
    backdrop-filter: blur(20px);
    -webkit-backdrop-filter: blur(20px);
    flex-direction: column;
    padding: 1.5rem;
    gap: 0;
    border-bottom: 1px solid var(--color-border);
  }

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

  .nav-links li {
    border-bottom: 1px solid var(--color-border);
  }

  .nav-links li:last-child {
    border-bottom: none;
  }

  .nav-links a {
    display: block;
    padding: 0.75rem 0;
    font-size: 1rem;
  }

  /* Hero */
  .hero {
    min-height: auto;
    padding: 8rem 1.5rem 4rem;
  }

  .hero-title {
    font-size: 2.5rem;
  }

  .hero-subtitle {
    font-size: 1.05rem;
  }

  /* About */
  .about-grid {
    grid-template-columns: 1fr;
    gap: 2.5rem;
  }

  /* Expertise */
  .expertise-grid {
    grid-template-columns: 1fr;
  }

  /* Education */
  .education-grid {
    grid-template-columns: 1fr;
  }

  /* Open Source */
  .oss-grid {
    grid-template-columns: 1fr;
  }

  /* Contact */
  .contact-links {
    flex-direction: column;
    align-items: center;
  }

  .contact-card {
    width: 100%;
    max-width: 320px;
    justify-content: center;
  }
}

@media (max-width: 480px) {
  .hero-title {
    font-size: 2rem;
  }

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

  .btn {
    width: 100%;
    max-width: 280px;
    text-align: center;
  }

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

  .section-title {
    font-size: 1.6rem;
  }
}