/* ═══════════════════════════════════════════
   Rishi Banerjee — Personal Site
   Design: Light & professional
   ═══════════════════════════════════════════ */

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

:root {
  --color-bg: #ffffff;
  --color-bg-alt: #f8fafc;
  --color-text: #1e293b;
  --color-text-secondary: #64748b;
  --color-accent: #2563eb;
  --color-accent-hover: #1d4ed8;
  --color-border: #e2e8f0;
  --color-card-bg: #ffffff;
  --color-card-shadow: rgba(0, 0, 0, 0.04);
  --color-tag-bg: #f1f5f9;
  --color-tag-text: #475569;
  --font-sans: 'Inter', system-ui, -apple-system, BlinkMacSystemFont, 'Segoe UI', sans-serif;
  --font-mono: 'JetBrains Mono', 'SF Mono', 'Fira Code', monospace;
  --max-width: 1080px;
  --space-xs: 0.25rem;
  --space-sm: 0.5rem;
  --space-md: 1rem;
  --space-lg: 1.5rem;
  --space-xl: 2.5rem;
  --space-2xl: 4rem;
  --space-3xl: 6rem;
  --radius-sm: 6px;
  --radius-md: 10px;
  --radius-lg: 16px;
  --radius-full: 9999px;
}

html { scroll-behavior: smooth; }

body {
  font-family: var(--font-sans);
  color: var(--color-text);
  background: var(--color-bg);
  line-height: 1.7;
  font-size: 16px;
  -webkit-font-smoothing: antialiased;
  -moz-osx-font-smoothing: grayscale;
}

a {
  color: var(--color-accent);
  text-decoration: none;
  transition: color 0.2s ease;
}
a:hover { color: var(--color-accent-hover); }

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

/* --- Typography --- */
h1, h2, h3, h4 {
  font-weight: 600;
  line-height: 1.3;
  letter-spacing: -0.02em;
}
h1 { font-size: 2.5rem; }
h2 { font-size: 1.75rem; margin-bottom: var(--space-lg); }
h3 { font-size: 1.25rem; }
p { margin-bottom: var(--space-md); }

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

section {
  padding: var(--space-3xl) 0;
}

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

/* --- Navigation --- */
.nav {
  position: fixed;
  top: 0;
  left: 0;
  right: 0;
  background: rgba(255, 255, 255, 0.85);
  backdrop-filter: blur(12px);
  -webkit-backdrop-filter: blur(12px);
  border-bottom: 1px solid var(--color-border);
  z-index: 100;
  padding: var(--space-md) 0;
}

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

.nav-brand {
  font-weight: 700;
  font-size: 1.1rem;
  color: var(--color-text);
}
.nav-brand:hover { color: var(--color-accent); }

.nav-links {
  display: flex;
  gap: var(--space-lg);
  list-style: none;
}

.nav-links a {
  color: var(--color-text-secondary);
  font-size: 0.9rem;
  font-weight: 500;
  transition: color 0.2s ease;
}
.nav-links a:hover { color: var(--color-text); }

.nav-toggle {
  display: none;
  background: none;
  border: none;
  cursor: pointer;
  padding: var(--space-sm);
}

.nav-toggle span {
  display: block;
  width: 22px;
  height: 2px;
  background: var(--color-text);
  margin: 5px 0;
  transition: 0.3s;
}

/* --- Hero --- */
.hero {
  padding-top: calc(var(--space-3xl) + 60px);
  padding-bottom: var(--space-3xl);
}

.hero-content {
  display: flex;
  align-items: center;
  gap: var(--space-2xl);
}

.hero-text { flex: 1; }

.hero-photo {
  width: 200px;
  height: 200px;
  border-radius: var(--radius-full);
  object-fit: cover;
  border: 4px solid var(--color-border);
  flex-shrink: 0;
}

.hero-title {
  font-size: 3rem;
  font-weight: 700;
  letter-spacing: -0.03em;
  margin-bottom: var(--space-sm);
}

.hero-subtitle {
  font-size: 1.2rem;
  color: var(--color-text-secondary);
  margin-bottom: var(--space-lg);
  font-weight: 400;
}

.hero-links {
  display: flex;
  gap: var(--space-md);
  align-items: center;
}

.hero-links a {
  display: inline-flex;
  align-items: center;
  gap: var(--space-xs);
  color: var(--color-text-secondary);
  font-size: 0.9rem;
  font-weight: 500;
  padding: var(--space-sm) var(--space-md);
  border: 1px solid var(--color-border);
  border-radius: var(--radius-full);
  transition: all 0.2s ease;
}

.hero-links a:hover {
  color: var(--color-accent);
  border-color: var(--color-accent);
  background: rgba(37, 99, 235, 0.04);
}

.hero-links svg {
  width: 18px;
  height: 18px;
}

/* --- Section Headers --- */
.section-label {
  font-size: 0.8rem;
  font-weight: 600;
  text-transform: uppercase;
  letter-spacing: 0.08em;
  color: var(--color-accent);
  margin-bottom: var(--space-sm);
}

/* --- About --- */
.about-text {
  font-size: 1.1rem;
  color: var(--color-text-secondary);
  max-width: 720px;
  line-height: 1.8;
}

.about-text strong {
  color: var(--color-text);
  font-weight: 600;
}

/* --- Experience --- */
.experience-list {
  display: flex;
  flex-direction: column;
  gap: var(--space-xl);
}

.experience-item {
  display: grid;
  grid-template-columns: 160px 1fr;
  gap: var(--space-lg);
}

.experience-date {
  font-size: 0.85rem;
  color: var(--color-text-secondary);
  font-weight: 500;
  padding-top: 3px;
}

.experience-content h3 {
  margin-bottom: var(--space-xs);
}

.experience-company {
  color: var(--color-text-secondary);
  font-size: 0.95rem;
  margin-bottom: var(--space-sm);
}

.experience-desc {
  color: var(--color-text-secondary);
  font-size: 0.95rem;
  line-height: 1.7;
}

.experience-desc li {
  margin-bottom: var(--space-xs);
  margin-left: var(--space-lg);
}

/* --- Projects --- */
.projects-grid {
  display: grid;
  grid-template-columns: 1fr;
  gap: var(--space-lg);
}

.project-card {
  background: var(--color-card-bg);
  border: 1px solid var(--color-border);
  border-radius: var(--radius-lg);
  padding: var(--space-xl);
  transition: all 0.25s ease;
  display: flex;
  flex-direction: column;
  gap: var(--space-md);
  text-decoration: none;
  color: inherit;
}

.project-card:hover {
  border-color: var(--color-accent);
  box-shadow: 0 4px 24px var(--color-card-shadow), 0 0 0 1px rgba(37, 99, 235, 0.1);
  transform: translateY(-2px);
  color: inherit;
}

.project-card-header {
  display: flex;
  align-items: flex-start;
  justify-content: space-between;
  gap: var(--space-md);
}

.project-card-header h3 {
  font-size: 1.3rem;
}

.project-card-arrow {
  color: var(--color-text-secondary);
  transition: transform 0.2s ease, color 0.2s ease;
  flex-shrink: 0;
  margin-top: 4px;
}

.project-card:hover .project-card-arrow {
  transform: translateX(4px);
  color: var(--color-accent);
}

.project-card p {
  color: var(--color-text-secondary);
  font-size: 0.95rem;
  margin-bottom: 0;
  line-height: 1.7;
}

.project-tags {
  display: flex;
  flex-wrap: wrap;
  gap: var(--space-sm);
}

.tag {
  font-size: 0.78rem;
  font-weight: 500;
  padding: var(--space-xs) var(--space-sm);
  background: var(--color-tag-bg);
  color: var(--color-tag-text);
  border-radius: var(--radius-full);
  font-family: var(--font-mono);
  letter-spacing: 0.01em;
}

.project-links {
  display: flex;
  gap: var(--space-md);
  margin-top: auto;
  padding-top: var(--space-sm);
}

.project-link {
  font-size: 0.85rem;
  font-weight: 500;
  display: inline-flex;
  align-items: center;
  gap: 4px;
}

/* --- Projects Listing Page --- */
.projects-grid-2col {
  grid-template-columns: repeat(2, 1fr);
}

@media (max-width: 768px) {
  .projects-grid-2col {
    grid-template-columns: 1fr;
  }
}

div.project-card {
  cursor: default;
}

div.project-card:hover {
  transform: none;
  border-color: var(--color-border);
  box-shadow: none;
}

.projects-view-all {
  text-align: center;
  margin-top: var(--space-xl);
}

.projects-view-all a {
  display: inline-flex;
  align-items: center;
  gap: var(--space-sm);
  font-size: 0.95rem;
  font-weight: 600;
}

/* --- Skills / Expertise --- */
.expertise-grid {
  display: grid;
  grid-template-columns: repeat(3, 1fr);
  gap: var(--space-lg);
}

.expertise-card {
  padding: var(--space-lg);
  border: 1px solid var(--color-border);
  border-radius: var(--radius-md);
  background: var(--color-card-bg);
}

.expertise-card h3 {
  margin-bottom: var(--space-sm);
  font-size: 1.05rem;
}

.expertise-card p {
  color: var(--color-text-secondary);
  font-size: 0.9rem;
  margin-bottom: 0;
}

/* --- Stats Row --- */
.stats-row {
  display: grid;
  grid-template-columns: repeat(4, 1fr);
  gap: var(--space-lg);
  margin-top: var(--space-xl);
  padding-top: var(--space-xl);
  border-top: 1px solid var(--color-border);
}

.stat-item {
  text-align: center;
}

.stat-number {
  display: block;
  font-size: 1.8rem;
  font-weight: 700;
  color: var(--color-text);
  letter-spacing: -0.02em;
  line-height: 1.2;
}

.stat-label {
  display: block;
  font-size: 0.8rem;
  color: var(--color-text-secondary);
  margin-top: var(--space-xs);
  font-weight: 500;
}

/* --- Company Logos Row --- */
.logos-label {
  text-align: center;
  font-size: 0.75rem;
  font-weight: 600;
  text-transform: uppercase;
  letter-spacing: 0.1em;
  color: var(--color-text-secondary);
  opacity: 0.6;
  margin-bottom: 0;
  padding-top: var(--space-lg);
}

.logos-row {
  display: flex;
  align-items: center;
  justify-content: center;
  gap: var(--space-2xl);
  flex-wrap: wrap;
  padding: var(--space-xl) 0;
}

.logo-name {
  font-size: 1.1rem;
  font-weight: 600;
  color: var(--color-text-secondary);
  opacity: 0.5;
  letter-spacing: 0.01em;
  transition: opacity 0.2s ease;
}

.logo-name:hover {
  opacity: 0.8;
}

.logo-img {
  height: 28px;
  width: auto;
  object-fit: contain;
  opacity: 0.5;
  filter: grayscale(100%);
  transition: opacity 0.2s ease, filter 0.2s ease;
}

.logo-img:hover {
  opacity: 0.8;
  filter: grayscale(0%);
}

.logo-img.logo-invert {
  filter: grayscale(100%) invert(1);
}

.logo-img.logo-invert:hover {
  filter: invert(1);
}

/* --- Testimonials --- */
.testimonials-grid {
  display: grid;
  grid-template-columns: repeat(3, 1fr);
  gap: var(--space-lg);
}

.testimonial-card {
  padding: var(--space-lg);
  border: 1px solid var(--color-border);
  border-radius: var(--radius-md);
  background: var(--color-card-bg);
  margin: 0;
}

.testimonial-card p {
  font-size: 0.95rem;
  color: var(--color-text-secondary);
  font-style: italic;
  line-height: 1.7;
  margin-bottom: var(--space-md);
}

.testimonial-card footer {
  display: flex;
  flex-direction: column;
  gap: 2px;
}

.testimonial-card footer strong {
  font-size: 0.85rem;
  color: var(--color-text);
}

.testimonial-card footer span {
  font-size: 0.8rem;
  color: var(--color-text-secondary);
}

/* --- Education --- */
.education-grid {
  display: grid;
  grid-template-columns: 1fr 1fr;
  gap: var(--space-lg);
}

.education-card {
  padding: var(--space-lg);
  border: 1px solid var(--color-border);
  border-radius: var(--radius-md);
  background: var(--color-card-bg);
}

.education-card h3 {
  font-size: 1.05rem;
  margin-bottom: var(--space-xs);
}

.education-card .education-institution {
  color: var(--color-accent);
  font-size: 0.9rem;
  font-weight: 500;
  margin-bottom: var(--space-sm);
}

.education-card p {
  color: var(--color-text-secondary);
  font-size: 0.85rem;
  margin-bottom: 0;
}

.cert-list {
  display: flex;
  flex-wrap: wrap;
  gap: var(--space-sm);
  margin-top: var(--space-sm);
}

.cert-list .tag {
  font-family: var(--font-sans);
}

/* --- CTA Section --- */
.cta-section {
  padding: var(--space-3xl) 0;
  text-align: center;
  background: var(--color-bg-alt);
  border-top: 1px solid var(--color-border);
}

.cta-section h2 {
  font-size: 1.75rem;
  margin-bottom: var(--space-sm);
}

.cta-subtitle {
  color: var(--color-text-secondary);
  font-size: 1.05rem;
  margin-bottom: var(--space-xl);
  max-width: 520px;
  margin-left: auto;
  margin-right: auto;
}

.cta-buttons {
  display: flex;
  justify-content: center;
  gap: var(--space-md);
  flex-wrap: wrap;
}

.cta-btn {
  display: inline-flex;
  align-items: center;
  gap: var(--space-sm);
  padding: 0.75rem 1.5rem;
  border-radius: var(--radius-full);
  font-weight: 600;
  font-size: 0.95rem;
  transition: all 0.2s ease;
}

.cta-btn-primary {
  background: var(--color-accent);
  color: #ffffff;
  border: 1px solid var(--color-accent);
}

.cta-btn-primary:hover {
  background: var(--color-accent-hover);
  color: #ffffff;
}

.cta-btn-secondary {
  background: var(--color-bg);
  color: var(--color-text);
  border: 1px solid var(--color-border);
}

.cta-btn-secondary:hover {
  border-color: var(--color-accent);
  color: var(--color-accent);
}

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

.footer-links {
  display: flex;
  justify-content: center;
  gap: var(--space-lg);
  margin-bottom: var(--space-md);
}

.footer-links a {
  color: var(--color-text-secondary);
  font-size: 0.9rem;
  font-weight: 500;
}
.footer-links a:hover { color: var(--color-accent); }

.footer-copy {
  font-size: 0.8rem;
  color: var(--color-text-secondary);
}

.footer-analytics {
  font-size: 0.7rem;
  color: var(--color-text-secondary);
  opacity: 0.5;
  margin-top: var(--space-sm);
  margin-bottom: 0;
}

.visitor-counter {
  display: inline;
  font-weight: 600;
}

/* ═══════════════════════════════════════════
   Project Detail Pages
   ═══════════════════════════════════════════ */

.project-hero {
  padding-top: calc(var(--space-3xl) + 60px);
  padding-bottom: var(--space-2xl);
  border-bottom: 1px solid var(--color-border);
}

.project-back {
  display: inline-flex;
  align-items: center;
  gap: var(--space-xs);
  font-size: 0.85rem;
  font-weight: 500;
  color: var(--color-text-secondary);
  margin-bottom: var(--space-lg);
}
.project-back:hover { color: var(--color-accent); }

.project-hero h1 {
  font-size: 2.25rem;
  margin-bottom: var(--space-sm);
}

.project-hero .hero-subtitle {
  max-width: 640px;
}

.project-meta {
  display: flex;
  align-items: center;
  gap: var(--space-lg);
  margin-top: var(--space-lg);
}

.project-meta a {
  display: inline-flex;
  align-items: center;
  gap: 6px;
  font-size: 0.9rem;
  font-weight: 500;
  padding: var(--space-sm) var(--space-md);
  border: 1px solid var(--color-border);
  border-radius: var(--radius-full);
}
.project-meta a:hover {
  border-color: var(--color-accent);
  background: rgba(37, 99, 235, 0.04);
}

.project-body {
  padding: var(--space-2xl) 0;
}

.project-body h2 {
  font-size: 1.4rem;
  margin-bottom: var(--space-md);
  margin-top: var(--space-2xl);
}

.project-body h2:first-child {
  margin-top: 0;
}

.project-body p,
.project-body li {
  color: var(--color-text-secondary);
  font-size: 0.95rem;
  line-height: 1.8;
}

.project-body ul {
  padding-left: var(--space-lg);
  margin-bottom: var(--space-md);
}

.project-body li {
  margin-bottom: var(--space-sm);
}

.tech-stack-grid {
  display: grid;
  grid-template-columns: repeat(auto-fill, minmax(200px, 1fr));
  gap: var(--space-md);
  margin-bottom: var(--space-md);
}

.tech-item {
  padding: var(--space-md);
  border: 1px solid var(--color-border);
  border-radius: var(--radius-md);
  background: var(--color-bg-alt);
}

.tech-item strong {
  display: block;
  font-size: 0.85rem;
  color: var(--color-text);
  margin-bottom: var(--space-xs);
}

.tech-item span {
  font-size: 0.85rem;
  color: var(--color-text-secondary);
}

.architecture-block {
  background: var(--color-bg-alt);
  border: 1px solid var(--color-border);
  border-radius: var(--radius-md);
  padding: var(--space-lg);
  margin: var(--space-md) 0;
  font-family: var(--font-mono);
  font-size: 0.85rem;
  line-height: 1.8;
  overflow-x: auto;
  white-space: pre;
  color: var(--color-text-secondary);
}

/* --- Responsive --- */
@media (max-width: 768px) {
  h1 { font-size: 2rem; }
  .hero-title { font-size: 2.2rem; }
  section { padding: var(--space-2xl) 0; }

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

  .hero-photo {
    width: 140px;
    height: 140px;
  }

  .hero-links {
    justify-content: center;
    flex-wrap: wrap;
  }

  .experience-item {
    grid-template-columns: 1fr;
    gap: var(--space-xs);
  }

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

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

  .stats-row {
    grid-template-columns: repeat(2, 1fr);
    gap: var(--space-md);
  }

  .logos-row {
    gap: var(--space-lg);
  }

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

  .nav-links { display: none; }
  .nav-links.open {
    display: flex;
    flex-direction: column;
    position: absolute;
    top: 100%;
    left: 0;
    right: 0;
    background: var(--color-bg);
    border-bottom: 1px solid var(--color-border);
    padding: var(--space-md) var(--space-lg);
    gap: var(--space-md);
  }
  .nav-toggle { display: block; }

  .project-meta {
    flex-wrap: wrap;
  }
}

@media (max-width: 480px) {
  .hero-title { font-size: 1.8rem; }
  .container { padding: 0 var(--space-md); }
}