/* =========================================================
   Varshith Chennuru — portfolio
   Minimal, monochrome, academic. Monospace meta accents.
   ========================================================= */

:root {
  --bg: #fbfbf8;
  --surface: #ffffff;
  --text: #16161a;
  --muted: #595962;
  --faint: #8a8a93;
  --border: #e6e3da;
  --rule: #ece9e0;
  --accent: #1d4ed8;
  --accent-soft: #eef2ff;
  --code-bg: #f3f1ea;
  --maxw: 760px;
  --mono: ui-monospace, "SF Mono", "JetBrains Mono", "Cascadia Code",
    "Fira Code", Menlo, Consolas, monospace;
  --sans: -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, Helvetica,
    Arial, sans-serif;
}

@media (prefers-color-scheme: dark) {
  :root {
    --bg: #0e0e10;
    --surface: #17171a;
    --text: #ecece8;
    --muted: #a3a3ac;
    --faint: #6c6c75;
    --border: #26262b;
    --rule: #232328;
    --accent: #8ab0ff;
    --accent-soft: #1a2233;
    --code-bg: #1b1b1f;
  }
}

* {
  box-sizing: border-box;
}

html {
  scroll-behavior: smooth;
}

body {
  margin: 0;
  font-family: var(--sans);
  font-size: 16.5px;
  line-height: 1.72;
  background: var(--bg);
  color: var(--text);
  -webkit-font-smoothing: antialiased;
  text-rendering: optimizeLegibility;
}

a {
  color: var(--accent);
  text-decoration: none;
}
a:hover {
  text-decoration: underline;
  text-underline-offset: 3px;
}

::selection {
  background: var(--accent-soft);
}

a:focus-visible,
button:focus-visible {
  outline: 2px solid var(--accent);
  outline-offset: 3px;
  border-radius: 2px;
}

.container {
  width: min(100% - 2.5rem, var(--maxw));
  margin: 0 auto;
}

/* ---------- Header ---------- */
.site-header {
  position: sticky;
  top: 0;
  z-index: 20;
  background: color-mix(in srgb, var(--bg) 88%, transparent);
  backdrop-filter: saturate(160%) blur(10px);
  border-bottom: 1px solid var(--rule);
}
.nav-wrap {
  display: flex;
  justify-content: space-between;
  align-items: center;
  gap: 1rem;
  padding: 0.85rem 0;
}
.brand {
  font-weight: 650;
  letter-spacing: -0.01em;
  color: var(--text);
}
.nav-links {
  display: flex;
  gap: 1.25rem;
  list-style: none;
  margin: 0;
  padding: 0;
}
.nav-links a {
  font-family: var(--mono);
  font-size: 0.78rem;
  color: var(--muted);
}
.nav-links a:hover {
  color: var(--text);
  text-decoration: none;
}

/* ---------- Headings ---------- */
h1,
h2,
h3 {
  line-height: 1.16;
  letter-spacing: -0.018em;
  margin: 0;
  color: var(--text);
}
h1 {
  font-size: clamp(1.9rem, 4.4vw, 2.85rem);
  font-weight: 680;
}
h2 {
  font-size: 1.28rem;
  font-weight: 650;
  margin-bottom: 0.25rem;
}
h3 {
  font-size: 1.06rem;
  font-weight: 620;
}

.section-label {
  font-family: var(--mono);
  font-size: 0.72rem;
  letter-spacing: 0.14em;
  text-transform: uppercase;
  color: var(--faint);
  margin: 0 0 0.35rem;
}

/* ---------- Hero ---------- */
.hero {
  padding: 4.8rem 0 2.8rem;
  border-bottom: 1px solid var(--rule);
}
.hero .eyebrow {
  font-family: var(--mono);
  font-size: 0.78rem;
  letter-spacing: 0.04em;
  color: var(--accent);
  margin: 0 0 1rem;
}
.hero h1 {
  max-width: 18ch;
  margin-bottom: 1.15rem;
}
.hero h1 .accent {
  color: var(--accent);
}
.hero-summary {
  max-width: 60ch;
  font-size: 1.08rem;
  color: var(--muted);
  margin: 0 0 1.6rem;
}
.hero-actions {
  display: flex;
  flex-wrap: wrap;
  gap: 0.6rem;
  margin-top: 1.4rem;
}
.button {
  display: inline-flex;
  align-items: center;
  gap: 0.45rem;
  padding: 0.6rem 1rem;
  border: 1px solid var(--border);
  border-radius: 8px;
  font-size: 0.9rem;
  font-weight: 550;
  color: var(--text);
  background: var(--surface);
  transition: border-color 0.15s ease, transform 0.15s ease;
}
.button:hover {
  text-decoration: none;
  border-color: var(--accent);
}
.button.primary {
  background: var(--text);
  color: var(--bg);
  border-color: var(--text);
}
.button.primary:hover {
  opacity: 0.88;
}

/* ---------- Sections ---------- */
.section {
  padding: 2.6rem 0;
  border-bottom: 1px solid var(--rule);
}
.section:last-of-type {
  border-bottom: none;
}
.section-head {
  display: flex;
  align-items: baseline;
  justify-content: space-between;
  gap: 1rem;
  margin-bottom: 1.3rem;
}
.lede {
  font-size: 1.04rem;
  color: var(--muted);
  max-width: 62ch;
}
.lede + .lede {
  margin-top: 0.9rem;
}

/* ---------- About ---------- */
.focus-grid {
  display: grid;
  grid-template-columns: repeat(2, minmax(0, 1fr));
  gap: 0.7rem;
  margin-top: 1.5rem;
}
.focus-item {
  border: 1px solid var(--border);
  background: var(--surface);
  border-radius: 10px;
  padding: 0.9rem 1rem;
}
.focus-item h4 {
  margin: 0 0 0.2rem;
  font-size: 0.95rem;
  font-weight: 620;
}
.focus-item p {
  margin: 0;
  font-size: 0.88rem;
  color: var(--muted);
}

/* ---------- Timeline (experience) ---------- */
.timeline {
  position: relative;
  margin-top: 0.4rem;
}
.timeline::before {
  content: "";
  position: absolute;
  left: 7px;
  top: 6px;
  bottom: 6px;
  width: 1px;
  background: var(--rule);
}
.tl-item {
  position: relative;
  padding: 0.4rem 0 1.6rem 2.1rem;
}
.tl-item:last-child {
  padding-bottom: 0.4rem;
}
.tl-item::before {
  content: "";
  position: absolute;
  left: 3px;
  top: 9px;
  width: 9px;
  height: 9px;
  border-radius: 50%;
  background: var(--bg);
  border: 2px solid var(--accent);
}
.tl-head {
  display: flex;
  flex-wrap: wrap;
  align-items: baseline;
  justify-content: space-between;
  gap: 0.4rem 1rem;
}
.tl-head h3 {
  margin: 0;
}
.tl-head .org {
  color: var(--muted);
  font-weight: 500;
}
.tl-date {
  font-family: var(--mono);
  font-size: 0.76rem;
  color: var(--faint);
  white-space: nowrap;
}
.tl-bullets {
  margin: 0.55rem 0 0;
  padding: 0;
  list-style: none;
}
.tl-bullets li {
  position: relative;
  padding-left: 1.15rem;
  margin: 0.35rem 0;
  color: var(--muted);
  font-size: 0.97rem;
}
.tl-bullets li::before {
  content: "→";
  position: absolute;
  left: 0;
  color: var(--faint);
}
.tl-bullets li b {
  color: var(--text);
  font-weight: 620;
}

/* ---------- Projects ---------- */
.proj-card {
  border: 1px solid var(--border);
  border-radius: 12px;
  background: var(--surface);
  padding: 1.2rem 1.25rem;
  margin-bottom: 1rem;
  transition: border-color 0.18s ease, transform 0.18s ease;
}
.proj-card:hover {
  border-color: var(--accent);
  transform: translateY(-2px);
}
.proj-head {
  display: flex;
  flex-wrap: wrap;
  align-items: baseline;
  justify-content: space-between;
  gap: 0.3rem 1rem;
  margin-bottom: 0.45rem;
}
.proj-head h3 {
  font-size: 1.08rem;
}
.proj-date {
  font-family: var(--mono);
  font-size: 0.75rem;
  color: var(--faint);
}
.proj-tag {
  display: inline-block;
  font-family: var(--mono);
  font-size: 0.68rem;
  letter-spacing: 0.04em;
  text-transform: uppercase;
  color: var(--accent);
  background: var(--accent-soft);
  border-radius: 999px;
  padding: 0.12rem 0.55rem;
  margin-bottom: 0.6rem;
}
.proj-desc {
  color: var(--muted);
  margin: 0.2rem 0 0.8rem;
  font-size: 0.97rem;
}
.stack {
  display: flex;
  flex-wrap: wrap;
  gap: 0.4rem;
}
.stack span {
  font-family: var(--mono);
  font-size: 0.72rem;
  color: var(--muted);
  background: var(--code-bg);
  border-radius: 5px;
  padding: 0.16rem 0.5rem;
  border: 1px solid var(--rule);
}

/* ---------- Skills ---------- */
.skill-group {
  margin-bottom: 1.1rem;
}
.skill-group h4 {
  margin: 0 0 0.45rem;
  font-size: 0.95rem;
  font-weight: 620;
}
.skill-group p {
  margin: 0;
  color: var(--muted);
  font-size: 0.95rem;
}

/* ---------- Education / certs ---------- */
.split {
  display: grid;
  grid-template-columns: 1fr 1fr;
  gap: 1.5rem;
}
.edu-item {
  margin-bottom: 0.9rem;
}
.edu-item .deg {
  font-weight: 620;
}
.edu-item .school {
  color: var(--muted);
  font-size: 0.92rem;
}
.edu-item .when {
  font-family: var(--mono);
  font-size: 0.76rem;
  color: var(--faint);
}
.cert-list {
  list-style: none;
  margin: 0;
  padding: 0;
}
.cert-list li {
  color: var(--muted);
  margin: 0.3rem 0;
  font-size: 0.95rem;
}

/* ---------- Contact ---------- */
.contact-box {
  text-align: center;
  padding: 1.5rem 0 0.5rem;
}
.contact-box .big {
  font-size: 1.4rem;
  font-weight: 660;
  letter-spacing: -0.01em;
  margin-bottom: 0.4rem;
}
.contact-links {
  display: flex;
  flex-wrap: wrap;
  gap: 1rem;
  justify-content: center;
  margin-top: 0.9rem;
  font-family: var(--mono);
  font-size: 0.86rem;
}

/* ---------- Footer ---------- */
.site-footer {
  padding: 2.2rem 0 3rem;
  text-align: center;
  color: var(--faint);
  font-size: 0.82rem;
  font-family: var(--mono);
}

/* ---------- Responsive ---------- */
@media (max-width: 620px) {
  body {
    font-size: 16px;
  }
  .nav-wrap {
    flex-direction: column;
    align-items: flex-start;
    gap: 0.5rem;
    padding: 0.7rem 0;
  }
  .nav-links {
    gap: 0.9rem;
  }
  .hero {
    padding: 3.2rem 0 2.2rem;
  }
  .focus-grid,
  .split {
    grid-template-columns: 1fr;
  }
  .tl-head {
    flex-direction: column;
    align-items: flex-start;
    gap: 0.15rem;
  }
}