/* ============================================================
   Sourav Kundu — personal site
   Plain CSS, no build step. Mobile-first, responsive, accessible.
   ============================================================ */

:root {
  --bg: #fbfaf8;
  --surface: #ffffff;
  --surface-alt: #f3f0ea;
  --ink: #1d1c1a;
  --ink-soft: #4a4742;
  --ink-faint: #6f6b64;
  --accent: #2f5d62;
  --accent-strong: #244a4e;
  --accent-tint: #e3ebe9;
  --border: #e6e1d8;
  --max-width: 1080px;
  --measure: 940px;
  --radius: 14px;
  --radius-lg: 20px;
  --shadow: 0 12px 30px rgba(31, 28, 24, 0.08);
  --shadow-sm: 0 4px 14px rgba(31, 28, 24, 0.06);
  --font-sans: "Inter", -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto,
    Helvetica, Arial, sans-serif;
  --font-display: "Fraunces", Georgia, "Times New Roman", serif;
  --nav-h: 60px;
}

@media (prefers-color-scheme: dark) {
  :root {
    --bg: #16181a;
    --surface: #1e2123;
    --surface-alt: #22262a;
    --ink: #f1efe9;
    --ink-soft: #c3c0b9;
    --ink-faint: #9a968e;
    --accent: #7fb3b2;
    --accent-strong: #9cc6c5;
    --accent-tint: #243033;
    --border: #2f3438;
    --shadow: 0 12px 30px rgba(0, 0, 0, 0.4);
    --shadow-sm: 0 4px 14px rgba(0, 0, 0, 0.35);
  }
}

*,
*::before,
*::after { box-sizing: border-box; }

html {
  scroll-behavior: smooth;
  scroll-padding-top: calc(var(--nav-h) + 12px);
}

body {
  margin: 0;
  background: var(--bg);
  color: var(--ink);
  font-family: var(--font-sans);
  font-size: 1.0625rem;
  line-height: 1.65;
  -webkit-font-smoothing: antialiased;
  text-rendering: optimizeLegibility;
}

@media (prefers-reduced-motion: reduce) {
  html { scroll-behavior: auto; }
}

.container {
  width: 100%;
  max-width: var(--max-width);
  margin-inline: auto;
  padding-inline: 1.5rem;
}

/* ---------- Skip link ---------- */
.skip-link {
  position: absolute;
  left: -9999px;
  top: 0;
  background: var(--accent);
  color: #fff;
  padding: 0.6rem 1rem;
  border-radius: 0 0 var(--radius) 0;
  z-index: 200;
}
.skip-link:focus { left: 0; }

/* ---------- Links ---------- */
a {
  color: var(--accent-strong);
  text-decoration-thickness: 1px;
  text-underline-offset: 2px;
}
a:hover { color: var(--accent); }

:focus-visible {
  outline: 3px solid var(--accent);
  outline-offset: 2px;
  border-radius: 4px;
}

/* ---------- Sticky nav ---------- */
.nav {
  position: sticky;
  top: 0;
  z-index: 100;
  background: color-mix(in srgb, var(--bg) 88%, transparent);
  -webkit-backdrop-filter: saturate(180%) blur(12px);
  backdrop-filter: saturate(180%) blur(12px);
  border-bottom: 1px solid var(--border);
}
.nav__inner {
  display: flex;
  align-items: center;
  justify-content: space-between;
  min-height: var(--nav-h);
  gap: 1rem;
}
.nav__brand {
  font-family: var(--font-display);
  font-weight: 600;
  font-size: 1.15rem;
  letter-spacing: -0.01em;
  text-decoration: none;
  color: var(--ink);
}
.nav__menu {
  display: flex;
  align-items: center;
  gap: 1.4rem;
}
.nav__menu a {
  font-size: 0.95rem;
  font-weight: 500;
  text-decoration: none;
  color: var(--ink-soft);
}
.nav__menu a:hover { color: var(--accent); }
.nav__cta {
  background: var(--accent);
  color: #fff !important;
  padding: 0.4rem 0.9rem;
  border-radius: 999px;
}
.nav__cta:hover { background: var(--accent-strong); }

.nav__toggle {
  display: none;
  flex-direction: column;
  justify-content: center;
  gap: 5px;
  width: 42px;
  height: 42px;
  padding: 0;
  background: none;
  border: 1px solid var(--border);
  border-radius: 10px;
  cursor: pointer;
}
.nav__toggle span {
  display: block;
  width: 20px;
  height: 2px;
  margin-inline: auto;
  background: var(--ink);
  border-radius: 2px;
}

@media (max-width: 760px) {
  .nav__toggle { display: flex; }
  .nav__menu {
    position: absolute;
    top: var(--nav-h);
    left: 0;
    right: 0;
    flex-direction: column;
    align-items: stretch;
    gap: 0;
    background: var(--bg);
    border-bottom: 1px solid var(--border);
    padding: 0.5rem 1.5rem 1rem;
    box-shadow: var(--shadow);
    display: none;
  }
  .nav__menu.is-open { display: flex; }
  .nav__menu a { padding: 0.7rem 0; border-bottom: 1px solid var(--border); }
  .nav__cta { text-align: center; margin-top: 0.6rem; border-bottom: 0 !important; }
}

/* ---------- Hero ---------- */
.hero {
  background: linear-gradient(180deg, var(--accent-tint), var(--bg));
  padding-block: clamp(2.75rem, 6vw, 5rem);
  border-bottom: 1px solid var(--border);
}
.hero__inner {
  display: flex;
  flex-wrap: wrap;
  align-items: center;
  gap: 2.5rem;
}
.hero__text { flex: 1 1 340px; min-width: 0; }
.hero__media { flex: 0 0 auto; order: 2; margin-inline-start: auto; }

.hero__eyebrow {
  margin: 0 0 0.6rem;
  font-size: 0.85rem;
  font-weight: 600;
  letter-spacing: 0.04em;
  text-transform: uppercase;
  color: var(--accent-strong);
}
.hero__title {
  margin: 0 0 0.85rem;
  font-family: var(--font-display);
  font-weight: 600;
  font-size: clamp(2.1rem, 5.2vw, 3.25rem);
  line-height: 1.08;
  letter-spacing: -0.015em;
}
.hero__tagline {
  margin: 0;
  font-size: clamp(1.1rem, 2.4vw, 1.35rem);
  color: var(--ink-soft);
  max-width: 46ch;
}
.hero__actions {
  display: flex;
  flex-wrap: wrap;
  gap: 0.75rem;
  margin-top: 1.6rem;
}
.hero__meta {
  list-style: none;
  margin: 1.7rem 0 0;
  padding: 0;
  display: flex;
  flex-wrap: wrap;
  gap: 0.5rem 1.4rem;
  font-size: 0.92rem;
  color: var(--ink-faint);
}
.hero__meta li { position: relative; padding-left: 1rem; }
.hero__meta li::before {
  content: "";
  position: absolute;
  left: 0;
  top: 0.62em;
  width: 6px; height: 6px;
  border-radius: 50%;
  background: var(--accent);
}

.avatar {
  display: block;
  width: clamp(150px, 30vw, 240px);
  height: auto;
  aspect-ratio: 1 / 1;
  border-radius: 50%;
  object-fit: cover;
  border: 5px solid var(--surface);
  box-shadow: var(--shadow);
  background: var(--surface);
}

@media (max-width: 640px) {
  .hero__inner { flex-direction: column; align-items: flex-start; }
  .hero__media { order: -1; margin-inline-start: 0; }
}

/* ---------- Buttons ---------- */
.btn {
  display: inline-block;
  padding: 0.65rem 1.25rem;
  border-radius: 999px;
  font-weight: 600;
  font-size: 0.95rem;
  text-decoration: none;
  transition: transform 0.12s ease, background 0.12s ease, color 0.12s ease;
}
.btn:active { transform: translateY(1px); }
.btn--primary { background: var(--accent); color: #fff; }
.btn--primary:hover { background: var(--accent-strong); color: #fff; }
.btn--ghost { border: 1.5px solid var(--accent); color: var(--accent-strong); }
.btn--ghost:hover { background: var(--accent-tint); }

/* ---------- Sections ---------- */
.section { padding-block: clamp(2.75rem, 6vw, 4.5rem); }
.section--alt {
  background: var(--surface-alt);
  border-block: 1px solid var(--border);
}
.section__eyebrow {
  margin: 0 0 0.5rem;
  font-size: 0.8rem;
  font-weight: 600;
  letter-spacing: 0.08em;
  text-transform: uppercase;
  color: var(--accent-strong);
}
.section__heading {
  font-family: var(--font-display);
  font-weight: 600;
  font-size: clamp(1.55rem, 3.4vw, 2.2rem);
  line-height: 1.15;
  letter-spacing: -0.015em;
  margin: 0 0 1.1rem;
  max-width: 22ch;
}
.section__intro,
.section__intro p {
  color: var(--ink-soft);
  max-width: 60ch;
  margin: 0 0 2rem;
}

/* ---------- Prose ---------- */
.prose p {
  margin: 0 0 1.15rem;
  color: var(--ink-soft);
  max-width: 66ch;
}
.prose p:last-child { margin-bottom: 0; }
.prose strong { color: var(--ink); }
.prose--lead p { font-size: 1.1rem; }

/* ---------- Stat strip ---------- */
.stats {
  background: var(--accent);
  color: #fff;
  padding-block: clamp(1.75rem, 4vw, 2.5rem);
}
.stats__grid {
  display: grid;
  grid-template-columns: repeat(4, 1fr);
  gap: 1.5rem;
}
.stat { text-align: left; }
.stat__num {
  display: block;
  font-family: var(--font-display);
  font-weight: 700;
  font-size: clamp(1.6rem, 3.2vw, 2.3rem);
  line-height: 1;
  margin-bottom: 0.45rem;
}
.stat__label {
  display: block;
  font-size: 0.9rem;
  line-height: 1.45;
  color: rgba(255, 255, 255, 0.85);
}
@media (max-width: 820px) {
  .stats__grid { grid-template-columns: repeat(2, 1fr); gap: 1.5rem 1.25rem; }
}
@media (max-width: 440px) {
  .stats__grid { grid-template-columns: 1fr; }
}

/* ---------- Cards ---------- */
.cards {
  display: grid;
  grid-template-columns: repeat(2, 1fr);
  gap: 1.25rem;
}
.cards--soft { grid-template-columns: repeat(2, 1fr); }
@media (max-width: 760px) {
  .cards, .cards--soft { grid-template-columns: 1fr; }
}
.card {
  background: var(--surface);
  border: 1px solid var(--border);
  border-radius: var(--radius-lg);
  padding: 1.5rem 1.6rem;
  box-shadow: var(--shadow-sm);
}
.card--accent {
  border-color: var(--accent);
  background: linear-gradient(180deg, var(--accent-tint), var(--surface));
}
.card__title {
  font-family: var(--font-display);
  font-weight: 600;
  font-size: 1.2rem;
  line-height: 1.25;
  margin: 0 0 0.35rem;
  letter-spacing: -0.01em;
}
.card__kicker {
  margin: 0 0 0.85rem;
  font-size: 0.82rem;
  font-weight: 600;
  letter-spacing: 0.03em;
  text-transform: uppercase;
  color: var(--accent-strong);
}
.card__body { margin: 0; color: var(--ink-soft); font-size: 0.98rem; }
.card__metrics {
  list-style: none;
  margin: 1.1rem 0 0;
  padding: 0.9rem 0 0;
  border-top: 1px solid var(--border);
  display: grid;
  gap: 0.45rem;
}
.card__metrics li {
  position: relative;
  padding-left: 1.4rem;
  font-size: 0.92rem;
  font-weight: 500;
  color: var(--ink);
}
.card__metrics li::before {
  content: "";
  position: absolute;
  left: 0; top: 0.55em;
  width: 0.55rem; height: 0.55rem;
  border-radius: 50%;
  background: var(--accent);
}

/* ---------- Principles ---------- */
.principles {
  display: grid;
  grid-template-columns: repeat(2, 1fr);
  gap: 1.4rem 2rem;
}
@media (max-width: 760px) { .principles { grid-template-columns: 1fr; } }
.principle h3 {
  font-family: var(--font-display);
  font-weight: 600;
  font-size: 1.15rem;
  margin: 0 0 0.5rem;
  letter-spacing: -0.01em;
}
.principle p { margin: 0; color: var(--ink-soft); font-size: 0.98rem; }

/* ---------- Timeline ---------- */
.timeline {
  list-style: none;
  margin: 0;
  padding: 0;
  max-width: var(--measure);
}
.timeline__item {
  position: relative;
  padding: 0 0 1.9rem 1.9rem;
  border-left: 2px solid var(--border);
}
.timeline__item:last-child { padding-bottom: 0; }
.timeline__item::before {
  content: "";
  position: absolute;
  left: -7px; top: 0.3rem;
  width: 12px; height: 12px;
  border-radius: 50%;
  background: var(--accent);
  border: 2px solid var(--bg);
}
.timeline__when {
  display: block;
  font-size: 0.82rem;
  font-weight: 600;
  letter-spacing: 0.03em;
  text-transform: uppercase;
  color: var(--accent-strong);
  margin-bottom: 0.25rem;
}
.timeline__what {
  font-family: var(--font-display);
  font-weight: 600;
  font-size: 1.18rem;
  margin: 0 0 0.4rem;
  letter-spacing: -0.01em;
}
.timeline__item p { margin: 0; color: var(--ink-soft); font-size: 0.98rem; max-width: 64ch; }

/* ---------- Writing ---------- */
.writing__cta {
  display: flex;
  flex-wrap: wrap;
  align-items: center;
  gap: 1rem 1.25rem;
  margin-top: 1.5rem;
}
.writing__soon {
  font-size: 0.9rem;
  font-weight: 600;
  letter-spacing: 0.03em;
  text-transform: uppercase;
  color: var(--ink-faint);
}

/* ---------- Footer ---------- */
.footer {
  background: var(--surface);
  border-top: 1px solid var(--border);
  padding-block: clamp(2.5rem, 5vw, 3.75rem);
}
.footer__lead {
  color: var(--ink-soft);
  max-width: 56ch;
  margin: 0 0 1.6rem;
}
.contact-links {
  list-style: none;
  margin: 0 0 1.75rem;
  padding: 0;
  display: flex;
  flex-wrap: wrap;
  gap: 0.75rem 1.75rem;
}
.contact-links a { font-weight: 600; }
.footer__note { margin: 0; font-size: 0.9rem; color: var(--ink-faint); }