/* =========================================================
   Apple-inspired portfolio — Yeluru Sreenivasulu
   Light/dark alternating, big type, generous whitespace.
   ========================================================= */

:root {
  --bg: #ffffff;
  --bg-grey: #f5f5f7;
  --bg-dark: #000000;
  --bg-dark-2: #1d1d1f;
  --ink: #1d1d1f;
  --ink-soft: #6e6e73;
  --ink-light: #f5f5f7;
  --ink-light-soft: #a1a1a6;
  --link: #0071e3;
  --link-hover: #0077ed;
  --border: rgba(0, 0, 0, 0.08);
  --border-light: rgba(255, 255, 255, 0.12);
  --radius: 18px;
  --radius-lg: 28px;
  --max: 1200px;
  --pad: clamp(1.25rem, 4vw, 2.5rem);
  --ease: cubic-bezier(0.4, 0, 0.2, 1);
}

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

html {
  scroll-behavior: smooth;
  -webkit-text-size-adjust: 100%;
}

body {
  font-family: 'SF Pro Display', 'SF Pro Text', -apple-system, BlinkMacSystemFont,
               'Helvetica Neue', Helvetica, Arial, sans-serif;
  font-weight: 400;
  color: var(--ink);
  background: var(--bg);
  line-height: 1.47;
  letter-spacing: -0.003em;
  -webkit-font-smoothing: antialiased;
  -moz-osx-font-smoothing: grayscale;
}

a { color: var(--link); text-decoration: none; transition: color .2s var(--ease); }
a:hover { color: var(--link-hover); }

/* =====================================================
   TOP BAR — translucent, sticky, blur, Apple style
   ===================================================== */
.topbar {
  position: sticky; top: 0; z-index: 100;
  background: rgba(255, 255, 255, 0.72);
  backdrop-filter: saturate(180%) blur(20px);
  -webkit-backdrop-filter: saturate(180%) blur(20px);
  border-bottom: 1px solid var(--border);
}
.topbar-inner {
  max-width: var(--max);
  margin: 0 auto;
  padding: 0 var(--pad);
  height: 52px;
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 1rem;
}
.brand {
  font-size: 0.95rem;
  font-weight: 600;
  color: var(--ink);
  letter-spacing: -0.01em;
}
.brand:hover { color: var(--ink); opacity: 0.65; }
.topbar-links {
  display: flex; gap: 2rem;
  list-style: none;
}
.topbar-links a {
  color: var(--ink); opacity: 0.85;
  font-size: 0.82rem;
  font-weight: 400;
  letter-spacing: -0.005em;
}
.topbar-links a:hover { opacity: 1; color: var(--ink); }
.topbar-cta {
  font-size: 0.82rem;
  color: var(--link);
  font-weight: 400;
}

/* Mobile menu button — hidden on desktop */
.menu-toggle {
  display: none;
  width: 36px; height: 36px;
  background: transparent;
  border: none;
  cursor: pointer;
  padding: 8px;
  flex-direction: column;
  justify-content: space-between;
  align-items: stretch;
}
.menu-toggle span {
  display: block;
  height: 1.5px;
  background: var(--ink);
  border-radius: 2px;
  transition: transform 0.3s var(--ease), opacity 0.2s var(--ease);
}
.menu-toggle[aria-expanded="true"] span:nth-child(1) { transform: translateY(8px) rotate(45deg); }
.menu-toggle[aria-expanded="true"] span:nth-child(2) { opacity: 0; }
.menu-toggle[aria-expanded="true"] span:nth-child(3) { transform: translateY(-8px) rotate(-45deg); }

/* =====================================================
   GLOBAL SECTIONS
   ===================================================== */
.section {
  padding: clamp(4rem, 10vw, 8rem) var(--pad);
  max-width: var(--max);
  margin: 0 auto;
}
.section-light { background: var(--bg); color: var(--ink); }
.section-grey  { background: var(--bg-grey); color: var(--ink); max-width: none; padding-left: 0; padding-right: 0; }
.section-grey > .section-head,
.section-grey > .exp-grid { max-width: var(--max); margin-left: auto; margin-right: auto; padding-left: var(--pad); padding-right: var(--pad); }

.eyebrow {
  font-size: 0.78rem;
  font-weight: 500;
  text-transform: uppercase;
  letter-spacing: 0.12em;
  color: var(--ink-soft);
  margin-bottom: 1rem;
}
.eyebrow-light { color: var(--ink-light-soft); }

.section-head { margin-bottom: clamp(2.5rem, 5vw, 4.5rem); }

.section-headline {
  font-size: clamp(2.2rem, 5.5vw, 4rem);
  font-weight: 600;
  letter-spacing: -0.025em;
  line-height: 1.07;
  color: var(--ink);
  max-width: 16ch;
}

/* =====================================================
   HERO
   ===================================================== */
.hero {
  max-width: var(--max);
  margin: 0 auto;
  padding: clamp(5rem, 12vw, 9rem) var(--pad) clamp(4rem, 8vw, 7rem);
  text-align: left;
}
.display {
  font-size: clamp(3rem, 8.5vw, 6.5rem);
  font-weight: 600;
  letter-spacing: -0.035em;
  line-height: 1.02;
  color: var(--ink);
  margin-bottom: 1.5rem;
}
.display-sub {
  display: block;
  font-size: clamp(1.4rem, 3.5vw, 2.6rem);
  font-weight: 500;
  color: var(--ink-soft);
  letter-spacing: -0.02em;
  line-height: 1.15;
  margin-top: 0.75rem;
}
.hero-lede {
  font-size: clamp(1.05rem, 1.4vw, 1.25rem);
  color: var(--ink-soft);
  max-width: 56ch;
  margin: 1.5rem 0 2.5rem;
  line-height: 1.5;
}

.cta-row {
  display: flex; flex-wrap: wrap;
  gap: 1.25rem 2rem;
  align-items: center;
}

/* Pill buttons — Apple style */
.pill {
  display: inline-flex; align-items: center; justify-content: center;
  padding: 0.65rem 1.4rem;
  font-size: 0.95rem;
  font-weight: 400;
  border-radius: 980px;
  border: 1px solid transparent;
  transition: all 0.2s var(--ease);
  cursor: pointer;
  font-family: inherit;
  white-space: nowrap;
}
.pill-primary {
  background: var(--link);
  color: white;
}
.pill-primary:hover { background: var(--link-hover); color: white; }
.pill-link {
  font-size: 0.95rem;
  color: var(--link);
  font-weight: 400;
}
.pill-link:hover { color: var(--link-hover); }
.pill-link span { margin-left: .15rem; transition: margin .2s var(--ease); }
.pill-link:hover span { margin-left: .35rem; }
.pill-link-light { color: #2997ff; }
.pill-link-light:hover { color: #5cb3ff; }

/* Hero stats row */
.hero-stats {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(170px, 1fr));
  gap: 1.5rem;
  margin-top: clamp(3rem, 6vw, 5rem);
  padding-top: clamp(2rem, 4vw, 3rem);
  border-top: 1px solid var(--border);
}
.hero-stats > div {
  display: flex; flex-direction: column;
  gap: 0.35rem;
}
.hero-stats strong {
  font-size: clamp(2rem, 3.5vw, 2.8rem);
  font-weight: 600;
  letter-spacing: -0.03em;
  color: var(--ink);
  line-height: 1;
}
.hero-stats span {
  font-size: 0.92rem;
  color: var(--ink-soft);
}

/* =====================================================
   BANNER (dark full-width statement section)
   ===================================================== */
.banner {
  padding: clamp(5rem, 10vw, 9rem) var(--pad);
}
.banner-dark {
  background: var(--bg-dark);
  color: var(--ink-light);
}
.banner-contact {
  background: var(--bg-grey);
  color: var(--ink);
  text-align: center;
}
.banner-inner {
  max-width: var(--max);
  margin: 0 auto;
}
.banner-headline {
  font-size: clamp(2.4rem, 6vw, 4.8rem);
  font-weight: 600;
  letter-spacing: -0.03em;
  line-height: 1.05;
  margin-bottom: 1.75rem;
  max-width: 22ch;
}
.banner-dark .banner-headline { color: white; }
.banner-headline .muted {
  display: block;
  color: var(--ink-light-soft);
  font-weight: 600;
}
.banner-contact .banner-headline { margin-left: auto; margin-right: auto; }
.banner-contact .banner-headline .muted { color: var(--ink-soft); }
.banner-body {
  font-size: clamp(1.05rem, 1.4vw, 1.25rem);
  color: var(--ink-light-soft);
  max-width: 60ch;
  margin-bottom: 2.25rem;
  line-height: 1.5;
}
.banner-contact .banner-body {
  color: var(--ink-soft);
  margin-left: auto; margin-right: auto;
}
.banner-row { display: flex; flex-wrap: wrap; gap: 1.5rem 2.25rem; }

/* =====================================================
   BENTO GRID — expertise cards
   ===================================================== */
.bento {
  display: grid;
  grid-template-columns: repeat(3, 1fr);
  gap: 1rem;
}
.bento-card {
  background: var(--bg-grey);
  border-radius: var(--radius-lg);
  padding: clamp(1.5rem, 2.5vw, 2.25rem);
  transition: transform 0.4s var(--ease), background 0.3s var(--ease);
  display: flex; flex-direction: column;
  gap: 0.6rem;
  min-height: 220px;
}
.bento-card:hover {
  transform: translateY(-4px);
  background: #ececef;
}
.bento-wide { grid-column: span 2; }
.bento-card h3 {
  font-size: 1.25rem;
  font-weight: 600;
  letter-spacing: -0.015em;
  color: var(--ink);
  margin-bottom: 0.15rem;
}
.bento-body {
  font-size: 1rem;
  color: var(--ink-soft);
  line-height: 1.5;
}
.bento-tag {
  margin-top: auto;
  font-size: 0.82rem;
  text-transform: uppercase;
  letter-spacing: 0.15em;
  color: var(--ink-soft);
  font-weight: 500;
}

/* =====================================================
   PROJECTS GRID
   ===================================================== */
.projects-grid {
  display: grid;
  grid-template-columns: repeat(2, 1fr);
  gap: 1.25rem;
}
.project-card {
  background: var(--bg-grey);
  border-radius: var(--radius-lg);
  padding: clamp(1.75rem, 3vw, 2.5rem);
  display: flex; flex-direction: column;
  gap: 0.85rem;
  transition: transform 0.4s var(--ease), background 0.3s var(--ease);
}
.project-card:hover {
  transform: translateY(-4px);
  background: #ececef;
}
.project-tag {
  font-size: 0.78rem;
  text-transform: uppercase;
  letter-spacing: 0.12em;
  color: var(--link);
  font-weight: 500;
  margin-bottom: 0.35rem;
}
.project-card h3 {
  font-size: clamp(1.4rem, 2.2vw, 1.85rem);
  font-weight: 600;
  letter-spacing: -0.02em;
  color: var(--ink);
  line-height: 1.15;
}
.project-body {
  color: var(--ink-soft);
  font-size: 1rem;
  line-height: 1.55;
}
.project-meta {
  list-style: none;
  display: flex; flex-direction: column;
  gap: 0.4rem;
  margin-top: 1rem;
  padding-top: 1.25rem;
  border-top: 1px solid var(--border);
}
.project-meta li {
  display: flex; justify-content: space-between;
  gap: 1rem;
  font-size: 0.92rem;
}
.project-meta li span { color: var(--ink-soft); }
.project-meta li strong { color: var(--ink); font-weight: 500; text-align: right; }
.projects-foot {
  margin-top: 2.5rem;
  text-align: center;
}

/* =====================================================
   EXPERIENCE
   ===================================================== */
.exp-grid {
  display: grid;
  grid-template-columns: 1fr 1fr;
  gap: 1.5rem;
}
.exp-card {
  background: white;
  border-radius: var(--radius-lg);
  padding: clamp(2rem, 3vw, 2.75rem);
  box-shadow: 0 1px 2px rgba(0, 0, 0, 0.04), 0 4px 14px rgba(0, 0, 0, 0.05);
}
.exp-time {
  font-size: 0.82rem;
  text-transform: uppercase;
  letter-spacing: 0.12em;
  color: var(--ink-soft);
  margin-bottom: 1rem;
  font-weight: 500;
}
.exp-card h3 {
  font-size: clamp(1.3rem, 2vw, 1.6rem);
  font-weight: 600;
  letter-spacing: -0.015em;
  color: var(--ink);
  margin-bottom: 0.4rem;
  line-height: 1.2;
}
.exp-company {
  color: var(--link);
  font-size: 0.98rem;
  margin-bottom: 1.5rem;
}
.exp-points {
  list-style: none;
  display: flex; flex-direction: column;
  gap: 0.85rem;
}
.exp-points li {
  font-size: 0.98rem;
  color: var(--ink-soft);
  padding-left: 1.1rem;
  position: relative;
  line-height: 1.55;
}
.exp-points li::before {
  content: "";
  position: absolute;
  left: 0; top: 0.7em;
  width: 5px; height: 5px;
  border-radius: 50%;
  background: var(--ink-soft);
}
.exp-points strong { color: var(--ink); font-weight: 600; }

/* =====================================================
   IMPACT — big numbers on dark
   ===================================================== */
.impact-grid {
  max-width: var(--max);
  margin: clamp(2.5rem, 5vw, 4rem) auto 0;
  display: grid;
  grid-template-columns: repeat(3, 1fr);
  gap: 1px;
  background: var(--border-light);
  border-radius: var(--radius-lg);
  overflow: hidden;
  border: 1px solid var(--border-light);
}
.impact-card {
  background: var(--bg-dark);
  padding: clamp(2rem, 3vw, 3rem);
  display: flex; flex-direction: column;
  gap: 0.85rem;
  min-height: 220px;
}
.impact-card strong {
  font-size: clamp(2.6rem, 5vw, 4.5rem);
  font-weight: 600;
  letter-spacing: -0.035em;
  color: white;
  line-height: 1;
}
.impact-card p {
  color: var(--ink-light-soft);
  font-size: 1rem;
  line-height: 1.5;
  max-width: 32ch;
}

/* =====================================================
   EDUCATION & CERTS
   ===================================================== */
.edu-split {
  display: grid;
  grid-template-columns: 1fr 1fr;
  gap: 1.5rem;
}
.edu-block {
  background: var(--bg-grey);
  border-radius: var(--radius-lg);
  padding: clamp(2rem, 3vw, 2.75rem);
}
.edu-block h3 {
  font-size: 1.4rem;
  font-weight: 600;
  letter-spacing: -0.015em;
  color: var(--ink);
  margin-bottom: 0.6rem;
}
.edu-school {
  color: var(--link);
  font-size: 1rem;
  margin-bottom: 0.4rem;
}
.edu-meta {
  color: var(--ink-soft);
  font-size: 0.95rem;
}
.cert-list {
  list-style: none;
  display: flex; flex-direction: column;
  gap: 0.65rem;
  margin-top: 0.4rem;
}
.cert-list li {
  color: var(--ink-soft);
  font-size: 1rem;
  padding-left: 1.4rem;
  position: relative;
  line-height: 1.5;
}
.cert-list li::before {
  content: "";
  position: absolute;
  left: 0; top: 0.55em;
  width: 8px; height: 8px;
  border-radius: 50%;
  background: var(--link);
}

/* =====================================================
   CONTACT
   ===================================================== */
.contact-inner { text-align: center; max-width: 720px; }
.contact-actions {
  display: inline-flex; flex-wrap: wrap; gap: 1.25rem 2rem;
  align-items: center;
  margin-bottom: 2rem;
}
.contact-socials {
  font-size: 0.95rem;
  color: var(--ink-soft);
  display: inline-flex; gap: 0.7rem;
  flex-wrap: wrap;
  justify-content: center;
}
.contact-socials span { color: var(--ink-light-soft); }

/* =====================================================
   FOOTER
   ===================================================== */
.footer {
  background: var(--bg-grey);
  border-top: 1px solid var(--border);
  padding: 2rem var(--pad);
  font-size: 0.78rem;
  color: var(--ink-soft);
}
.footer-inner {
  max-width: var(--max);
  margin: 0 auto;
  display: flex; flex-wrap: wrap;
  justify-content: space-between;
  gap: 0.5rem;
}
.footer-line a { color: var(--ink-soft); text-decoration: underline; }
.footer-line a:hover { color: var(--link); }

/* =====================================================
   REVEAL ANIMATIONS
   ===================================================== */
.reveal {
  opacity: 0;
  transform: translateY(28px);
  transition: opacity 0.9s var(--ease), transform 0.9s var(--ease);
}
.reveal.is-visible {
  opacity: 1;
  transform: translateY(0);
}
@media (prefers-reduced-motion: reduce) {
  .reveal { opacity: 1; transform: none; transition: none; }
  html { scroll-behavior: auto; }
}

/* =====================================================
   RESPONSIVE
   ===================================================== */
@media (max-width: 900px) {
  /* Mobile burger menu */
  .menu-toggle { display: flex; }
  .topbar nav {
    position: absolute;
    top: 52px;
    left: 0; right: 0;
    background: rgba(255, 255, 255, 0.96);
    backdrop-filter: saturate(180%) blur(20px);
    -webkit-backdrop-filter: saturate(180%) blur(20px);
    border-bottom: 1px solid var(--border);
    max-height: 0;
    overflow: hidden;
    transition: max-height 0.35s var(--ease);
  }
  .topbar nav[data-open="true"] { max-height: 500px; }
  .topbar-links {
    display: flex; flex-direction: column;
    gap: 0;
    padding: 0.5rem 0;
  }
  .topbar-links li { width: 100%; }
  .topbar-links a {
    display: block;
    padding: 0.85rem var(--pad);
    font-size: 1.05rem;
    border-bottom: 1px solid var(--border);
  }
  .topbar-links li:last-child a { border-bottom: none; }

  .bento { grid-template-columns: repeat(2, 1fr); }
  .bento-wide { grid-column: span 2; }
  .projects-grid { grid-template-columns: 1fr; }
  .impact-grid { grid-template-columns: repeat(2, 1fr); }
  .exp-grid, .edu-split { grid-template-columns: 1fr; }
}
@media (max-width: 600px) {
  .bento, .impact-grid { grid-template-columns: 1fr; }
  .bento-wide { grid-column: auto; }
  .display-sub { font-size: 1.5rem; }
  .hero-stats { grid-template-columns: repeat(2, 1fr); }
  .footer-inner { flex-direction: column; }
  .topbar-cta { display: none; }
}