/* ---------------------------------------------------------
   Vishnu E — portfolio
   Editorial-technical system: Fraunces (display) + Inter (body)
   + IBM Plex Mono (labels/meta). Warm paper ground, single
   restrained accent, hairline rules instead of shadows/gradients.
--------------------------------------------------------- */

:root {
  --bg: #F7F4EF;
  --bg-alt: #EFEBE3;
  --surface: #FFFFFF;
  --ink: #16191C;
  --ink-soft: #52585D;
  --ink-faint: #82898F;
  --line: rgba(22, 25, 28, 0.13);
  --line-strong: rgba(22, 25, 28, 0.28);
  --accent: #2F5D55;
  --accent-soft: #E4E9E4;
  --accent-ink: #FFFFFF;

  --font-display: "Fraunces", "Iowan Old Style", "Georgia", serif;
  --font-body: "Inter", -apple-system, BlinkMacSystemFont, "Segoe UI", sans-serif;
  --font-mono: "IBM Plex Mono", ui-monospace, SFMono-Regular, Menlo, monospace;

  --wrap: 1120px;
  --radius: 3px;

  color-scheme: light;
}

:root:not([data-theme="light"]) {
  @media (prefers-color-scheme: dark) {
    --bg: #14171A;
    --bg-alt: #1B1F22;
    --surface: #1D2225;
    --ink: #F3F1EC;
    --ink-soft: #C2C7CA;
    --ink-faint: #8B9195;
    --line: rgba(255, 255, 255, 0.12);
    --line-strong: rgba(255, 255, 255, 0.26);
    --accent: #7FBFAF;
    --accent-soft: #223330;
    --accent-ink: #10201B;
    color-scheme: dark;
  }
}

[data-theme="dark"] {
  --bg: #14171A;
  --bg-alt: #1B1F22;
  --surface: #1D2225;
  --ink: #F3F1EC;
  --ink-soft: #C2C7CA;
  --ink-faint: #8B9195;
  --line: rgba(255, 255, 255, 0.12);
  --line-strong: rgba(255, 255, 255, 0.26);
  --accent: #7FBFAF;
  --accent-soft: #223330;
  --accent-ink: #10201B;
  color-scheme: dark;
}

* { box-sizing: border-box; }
html { -webkit-text-size-adjust: 100%; scroll-behavior: smooth; }
@media (prefers-reduced-motion: reduce) {
  html { scroll-behavior: auto; }
}

body {
  margin: 0;
  background: var(--bg);
  color: var(--ink);
  font-family: var(--font-body);
  font-size: 16px;
  line-height: 1.6;
  -webkit-font-smoothing: antialiased;
  text-rendering: optimizeLegibility;
  transition: background-color 0.25s ease, color 0.25s ease;
}

.wrap {
  max-width: var(--wrap);
  margin: 0 auto;
  padding: 0 28px;
}

.skip-link {
  position: absolute;
  left: -999px;
  top: 0;
  background: var(--ink);
  color: var(--bg);
  padding: 10px 16px;
  z-index: 200;
}
.skip-link:focus { left: 12px; top: 12px; }

h1, h2, h3 {
  font-family: var(--font-display);
  font-weight: 500;
  color: var(--ink);
  margin: 0;
  letter-spacing: -0.01em;
}

a { color: inherit; }

p { margin: 0 0 1em; color: var(--ink-soft); }
p:last-child { margin-bottom: 0; }

/* ---------------- Header ---------------- */

.site-header {
  position: sticky;
  top: 0;
  z-index: 100;
  background: color-mix(in srgb, var(--bg) 88%, transparent);
  backdrop-filter: blur(10px);
  border-bottom: 1px solid var(--line);
}

.header-row {
  display: flex;
  align-items: center;
  gap: 24px;
  height: 68px;
}

.mark {
  font-family: var(--font-mono);
  font-weight: 500;
  font-size: 14px;
  letter-spacing: 0.04em;
  border: 1px solid var(--line-strong);
  border-radius: 50%;
  width: 34px;
  height: 34px;
  display: inline-flex;
  align-items: center;
  justify-content: center;
  text-decoration: none;
  flex: none;
}

.primary-nav {
  display: flex;
  gap: 28px;
  margin-left: 8px;
}
.primary-nav a {
  font-size: 14px;
  text-decoration: none;
  color: var(--ink-soft);
  position: relative;
  padding: 4px 0;
}
.primary-nav a:hover { color: var(--ink); }

.header-actions {
  margin-left: auto;
  display: flex;
  align-items: center;
  gap: 12px;
}

.theme-toggle {
  width: 34px;
  height: 34px;
  border-radius: 50%;
  border: 1px solid var(--line-strong);
  background: transparent;
  color: var(--ink);
  display: inline-flex;
  align-items: center;
  justify-content: center;
  cursor: pointer;
  padding: 0;
}
.theme-toggle svg {
  width: 16px;
  height: 16px;
  fill: none;
  stroke: currentColor;
  stroke-width: 1.6;
  stroke-linecap: round;
}
.theme-toggle .icon-moon { display: none; }
[data-theme="dark"] .theme-toggle .icon-sun { display: none; }
[data-theme="dark"] .theme-toggle .icon-moon { display: block; }
@media (prefers-color-scheme: dark) {
  :root:not([data-theme="light"]) .theme-toggle .icon-sun { display: none; }
  :root:not([data-theme="light"]) .theme-toggle .icon-moon { display: block; }
}

.menu-toggle {
  display: none;
  width: 34px;
  height: 34px;
  border: none;
  background: none;
  cursor: pointer;
  flex-direction: column;
  justify-content: center;
  gap: 5px;
  padding: 0;
}
.menu-toggle span {
  display: block;
  height: 1px;
  background: var(--ink);
  width: 100%;
}

.mobile-nav {
  display: none;
  flex-direction: column;
  padding: 8px 28px 22px;
  border-bottom: 1px solid var(--line);
}
.mobile-nav a {
  padding: 12px 0;
  text-decoration: none;
  color: var(--ink);
  border-bottom: 1px solid var(--line);
  font-size: 15px;
}
.mobile-nav a:last-child { border-bottom: none; color: var(--accent); }
.mobile-nav.open { display: flex; }

/* ---------------- Buttons ---------------- */

.btn {
  display: inline-flex;
  align-items: center;
  gap: 8px;
  font-size: 14px;
  font-weight: 500;
  text-decoration: none;
  padding: 11px 20px;
  border-radius: var(--radius);
  border: 1px solid transparent;
  white-space: nowrap;
  transition: background-color 0.15s ease, color 0.15s ease, border-color 0.15s ease;
}
.btn-solid {
  background: var(--ink);
  color: var(--bg);
}
.btn-solid:hover { background: var(--accent); color: var(--accent-ink); }

.btn-line {
  border-color: var(--line-strong);
  color: var(--ink);
}
.btn-line:hover { border-color: var(--ink); }

.btn-small { padding: 8px 14px; font-size: 13px; }

.resume-link { display: inline-flex; }

/* ---------------- Hero ---------------- */

.hero { padding: 84px 0 96px; }

.hero-grid {
  display: grid;
  grid-template-columns: 1.5fr 1fr;
  gap: 64px;
  align-items: start;
}

.eyebrow {
  font-family: var(--font-mono);
  font-size: 12.5px;
  letter-spacing: 0.09em;
  text-transform: uppercase;
  color: var(--accent);
  margin: 0 0 18px;
}

.hero h1 {
  font-size: clamp(2.6rem, 5.4vw, 4.2rem);
  line-height: 1.02;
  margin-bottom: 22px;
}

.hero-lede {
  font-size: 18px;
  max-width: 46ch;
  color: var(--ink-soft);
}

.hero-actions {
  display: flex;
  gap: 14px;
  margin: 30px 0 44px;
  flex-wrap: wrap;
}

.hero-facts {
  list-style: none;
  margin: 0;
  padding: 24px 0 0;
  border-top: 1px solid var(--line);
  display: flex;
  gap: 40px;
  flex-wrap: wrap;
}
.hero-facts li { display: flex; flex-direction: column; gap: 4px; }
.hero-facts .num {
  font-family: var(--font-display);
  font-size: 28px;
  color: var(--ink);
}
.hero-facts .label {
  font-size: 12.5px;
  color: var(--ink-faint);
  max-width: 14ch;
}

.hero-meta {
  display: flex;
  flex-direction: column;
  gap: 12px;
  padding-top: 8px;
}
.meta-card {
  border: 1px solid var(--line);
  border-radius: var(--radius);
  padding: 16px 18px;
  display: flex;
  align-items: baseline;
  gap: 12px;
  background: var(--surface);
}
.meta-index {
  font-family: var(--font-mono);
  font-size: 12px;
  color: var(--ink-faint);
}
.meta-line { font-size: 14px; color: var(--ink-soft); }
.meta-status {
  background: var(--accent-soft);
  border-color: transparent;
  color: var(--ink);
  font-size: 13.5px;
  font-weight: 500;
}
.meta-status .dot {
  width: 7px; height: 7px;
  border-radius: 50%;
  background: var(--accent);
  flex: none;
}

/* ---------------- Section shell ---------------- */

.section { padding: 88px 0; border-top: 1px solid var(--line); }
.section-alt { background: var(--bg-alt); }

.section-grid {
  display: grid;
  grid-template-columns: 240px 1fr;
  gap: 56px;
}

.section-head {
  position: sticky;
  top: 96px;
  align-self: start;
  display: flex;
  flex-direction: column;
  gap: 10px;
}
.section-num {
  font-family: var(--font-mono);
  font-size: 12.5px;
  color: var(--accent);
  letter-spacing: 0.06em;
}
.section-head h2 { font-size: 30px; }

.section-body { max-width: 720px; }
.section-body .lede { font-size: 18px; color: var(--ink-soft); }
.section-body p { font-size: 15.5px; }

/* ---------------- Timeline ---------------- */

.timeline { list-style: none; margin: 0; padding: 0; }
.timeline-item {
  display: grid;
  grid-template-columns: 170px 1fr;
  gap: 32px;
  padding: 26px 0;
  border-bottom: 1px solid var(--line);
}
.timeline-item:first-child { padding-top: 0; }
.timeline-item:last-child { border-bottom: none; padding-bottom: 0; }

.timeline-when .dates {
  font-family: var(--font-mono);
  font-size: 12.5px;
  color: var(--ink-faint);
}

.timeline-what h3 { font-size: 19px; margin-bottom: 4px; }
.timeline-what .org {
  font-size: 13.5px;
  color: var(--accent);
  margin: 0 0 10px;
  font-weight: 500;
}
.timeline-what p:not(.org) { font-size: 15px; }

/* ---------------- Case studies ---------------- */

.case {
  padding: 32px 0;
  border-bottom: 1px solid var(--line);
}
.case:first-of-type { padding-top: 0; }

.case-head {
  display: flex;
  align-items: baseline;
  justify-content: space-between;
  gap: 16px;
  flex-wrap: wrap;
  margin-bottom: 18px;
}
.case-head h3 { font-size: 21px; }
.case-tag {
  font-family: var(--font-mono);
  font-size: 12px;
  color: var(--ink-faint);
}

.case-grid {
  display: grid;
  grid-template-columns: repeat(3, 1fr);
  gap: 24px;
}
.case-label {
  font-family: var(--font-mono);
  font-size: 11.5px;
  letter-spacing: 0.07em;
  text-transform: uppercase;
  color: var(--accent);
  margin: 0 0 8px;
}
.case-col p:not(.case-label) { font-size: 14.5px; }

.case-link {
  display: inline-block;
  margin-top: 4px;
  color: var(--accent);
  text-decoration: none;
  font-weight: 500;
}
.case-link:hover { text-decoration: underline; }

.case-footnote {
  padding-top: 28px;
  font-size: 14px;
  color: var(--ink-faint);
  font-style: italic;
  max-width: 640px;
}

/* ---------------- Skills ---------------- */

.skill-group { margin-bottom: 30px; }
.skill-group h3 {
  font-size: 13px;
  font-family: var(--font-mono);
  font-weight: 500;
  letter-spacing: 0.03em;
  color: var(--ink-faint);
  margin-bottom: 12px;
  text-transform: uppercase;
}
.pill-list {
  list-style: none;
  margin: 0;
  padding: 0;
  display: flex;
  flex-wrap: wrap;
  gap: 8px;
}
.pill-list li {
  font-size: 13.5px;
  padding: 7px 13px;
  border: 1px solid var(--line);
  border-radius: 20px;
  color: var(--ink-soft);
  background: var(--surface);
}

.certs { margin-top: 44px; padding-top: 32px; border-top: 1px solid var(--line); }
.certs h3 {
  font-size: 13px;
  font-family: var(--font-mono);
  font-weight: 500;
  letter-spacing: 0.03em;
  color: var(--ink-faint);
  margin-bottom: 16px;
  text-transform: uppercase;
}
.cert-list { list-style: none; margin: 0; padding: 0; display: flex; flex-direction: column; gap: 14px; }
.cert-list li { display: flex; gap: 18px; align-items: baseline; }
.cert-name {
  font-family: var(--font-mono);
  font-size: 13px;
  color: var(--ink);
  min-width: 62px;
  flex: none;
}
.cert-detail { font-size: 14.5px; color: var(--ink-soft); }

/* ---------------- Contact ---------------- */

.contact-section { text-align: center; }
.contact-inner {
  display: flex;
  flex-direction: column;
  align-items: center;
  gap: 14px;
  max-width: 560px;
  margin: 0 auto;
}
.contact-inner .section-num { display: block; }
.contact-inner h2 { font-size: 36px; }
.contact-inner .lede { font-size: 17px; }
.contact-links {
  display: flex;
  gap: 14px;
  flex-wrap: wrap;
  justify-content: center;
  margin-top: 10px;
}

/* ---------------- Footer ---------------- */

.site-footer { border-top: 1px solid var(--line); padding: 26px 0 40px; }
.footer-row {
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 16px;
  flex-wrap: wrap;
}
.footer-row p { font-size: 13px; color: var(--ink-faint); margin: 0; }

/* ---------------- Reveal-on-scroll ---------------- */

.reveal {
  opacity: 0;
  transform: translateY(14px);
  transition: opacity 0.6s ease, transform 0.6s ease;
}
.reveal.is-visible { opacity: 1; transform: translateY(0); }
@media (prefers-reduced-motion: reduce) {
  .reveal { opacity: 1; transform: none; transition: none; }
}

/* ---------------- Responsive ---------------- */

@media (max-width: 880px) {
  .hero-grid { grid-template-columns: 1fr; gap: 40px; }
  .section-grid { grid-template-columns: 1fr; gap: 20px; }
  .section-head { position: static; flex-direction: row; align-items: baseline; gap: 12px; }
  .case-grid { grid-template-columns: 1fr; gap: 18px; }
  .primary-nav { display: none; }
  .menu-toggle { display: flex; }
  .resume-link { display: none; }
}

@media (max-width: 620px) {
  .wrap { padding: 0 20px; }
  .hero { padding: 56px 0 64px; }
  .section { padding: 64px 0; }
  .timeline-item { grid-template-columns: 1fr; gap: 8px; }
  .hero-facts { gap: 28px; }
  .footer-row { flex-direction: column; align-items: flex-start; }
}