/* ============================================================
   Daniel Bobritski — personal researcher site
   ============================================================ */

:root {
  /* Brand & accent */
  --primary:        #0070d1;
  --primary-press:  #0064b7;
  --on-primary:     #ffffff;
  --link-light:     #0064b7;
  --link-dark:      #53b1ff;

  /* Surfaces */
  --canvas-dark:    #000000;
  --dark-elevated:  #121314;
  --dark-card:      #181818;
  --canvas-light:   #ffffff;
  --surface-soft:   #f3f3f3;
  --surface-card:   #f5f7fa;

  /* Ink */
  --ink:            #000000;
  --body-light:     rgba(0,0,0,0.6);
  --mute-light:     #6b6b6b;
  --on-dark:        #ffffff;
  --body-dark:      rgba(255,255,255,0.7);
  --mute-dark:      rgba(229,229,229,0.55);

  /* Hairlines */
  --hairline-light: #e9e9e9;
  --hairline-dark:  rgba(229,229,229,0.2);

  /* Shape */
  --r-sm: 4px;
  --r-md: 8px;
  --r-full: 9999px;

  /* Spacing */
  --sp-xs: 8px;
  --sp-sm: 12px;
  --sp-md: 16px;
  --sp-lg: 24px;
  --sp-xl: 32px;
  --sp-xxl: 48px;
  --sp-section: 96px;

  --maxw: 1200px;
  --font: "Inter", "Helvetica Neue", Arial, sans-serif;
}

/* ---------- reset-ish ---------- */
* { box-sizing: border-box; }
html { scroll-behavior: smooth; -webkit-text-size-adjust: 100%; }
body {
  margin: 0;
  font-family: var(--font);
  font-size: 18px;
  line-height: 1.5;
  -webkit-font-smoothing: antialiased;
  text-rendering: optimizeLegibility;
  background: var(--canvas-dark);
  overflow-x: hidden;               /* never scroll sideways on mobile */
}
img { max-width: 100%; display: block; }
a { text-decoration: none; color: inherit; }

/* ============================================================
   TYPOGRAPHY  (display tier at weight 300 — the brand voice)
   ============================================================ */
.display-xl {
  font-size: clamp(2rem, 6vw, 54px);
  font-weight: 300;
  line-height: 1.15;
  letter-spacing: -0.5px;
  margin: 0 0 var(--sp-lg);
}
.display-md {
  font-size: clamp(1.6rem, 4vw, 35px);
  font-weight: 300;
  line-height: 1.2;
  letter-spacing: 0;
  margin: 0 0 var(--sp-sm);
}
.heading-md {
  font-size: 20px;
  font-weight: 600;
  line-height: 1.2;
  margin: 0 0 var(--sp-xs);
}
.body    { font-size: 18px; font-weight: 400; line-height: 1.6; }
.body-sm { font-size: 15px; font-weight: 400; line-height: 1.55; }

.eyebrow {
  font-size: 13px;
  font-weight: 600;
  letter-spacing: 1.5px;
  text-transform: uppercase;
  color: var(--link-dark);
  margin: 0 0 var(--sp-md);
}
.lede {
  font-size: clamp(1.05rem, 2.2vw, 22px);
  font-weight: 300;
  line-height: 1.5;
  color: var(--body-dark);
  max-width: 42ch;
  margin: 0 0 var(--sp-xl);
}
.lede--blue { color: rgba(255,255,255,0.85); }
.lede strong { font-weight: 600; color: var(--on-dark); }

.section-lede {
  font-size: 18px;
  color: var(--body-light);
  margin: 0 0 var(--sp-xxl);
}
.section-lede--dark { color: var(--body-dark); }

/* ============================================================
   BANDS  (full-bleed alternating chapters)
   ============================================================ */
.band { width: 100%; }
.band__inner {
  max-width: var(--maxw);
  margin: 0 auto;
  padding: var(--sp-section) var(--sp-lg);
}
.band--dark  { background: var(--canvas-dark);  color: var(--on-dark); }
.band--light { background: var(--canvas-light); color: var(--ink); }
.band--blue  { background: var(--primary);      color: var(--on-primary); }

/* ============================================================
   NAV  (sticky dark bar)
   ============================================================ */
.nav {
  position: sticky;
  top: 0;
  z-index: 50;
  background: rgba(0,0,0,0.85);
  backdrop-filter: saturate(160%) blur(10px);
  border-bottom: 1px solid var(--hairline-dark);
}
.nav__inner {
  max-width: var(--maxw);
  margin: 0 auto;
  height: 56px;
  padding: 0 var(--sp-lg);
  display: flex;
  align-items: center;
  justify-content: space-between;
}
.nav__brand { display: flex; align-items: center; gap: var(--sp-sm); color: var(--on-dark); }
.nav__monogram {
  display: grid;
  place-items: center;
  width: 32px; height: 32px;
  border-radius: var(--r-full);
  background: var(--primary);
  color: #fff;
  font-weight: 700;
  font-size: 13px;
  letter-spacing: 0.5px;
}
.nav__name { font-weight: 600; font-size: 15px; }
.nav__links { display: flex; gap: var(--sp-lg); }
.nav__links a {
  color: var(--body-dark);
  font-size: 15px;
  font-weight: 500;
  transition: color .15s ease;
}
.nav__links a:hover { color: var(--on-dark); }

/* ============================================================
   HERO
   ============================================================ */
.hero__inner {
  display: grid;
  grid-template-columns: 1.2fr 0.8fr;
  gap: var(--sp-xxl);
  align-items: center;
}
.hero__meta {
  font-size: 15px;
  color: var(--body-dark);
  margin: 0 0 var(--sp-xl);
}
.hero__meta a { color: var(--on-dark); border-bottom: 1px solid rgba(255,255,255,0.4); padding-bottom: 1px; }
.hero__meta a:hover { border-color: #fff; }

.hero__cta { display: flex; flex-wrap: wrap; gap: var(--sp-md); }

.portrait {
  position: relative;
  width: 100%;
  max-width: 320px;
  aspect-ratio: 1 / 1;
  margin-left: auto;
  border-radius: var(--r-md);
  overflow: hidden;
  background: var(--dark-card);
}
.portrait img { width: 100%; height: 100%; object-fit: cover; }
.portrait__fallback {
  display: flex;               /* shown only if the img fails to load */
  align-items: center;
  justify-content: center;
  width: 100%; height: 100%;
  font-size: 72px;
  font-weight: 300;
  letter-spacing: 2px;
  color: var(--mute-dark);
  background: linear-gradient(160deg, var(--dark-elevated), var(--canvas-dark));
}
.portrait img + .portrait__fallback { display: none; }

/* ============================================================
   BUTTONS  (fully-rounded pills)
   ============================================================ */
.btn {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  height: 48px;
  padding: 0 28px;
  border-radius: var(--r-full);
  font-size: 16px;
  font-weight: 700;
  letter-spacing: 0.45px;
  border: 1px solid transparent;
  cursor: pointer;
  transition: background .15s ease, transform .1s ease, border-color .15s ease;
}
.btn:active { transform: translateY(1px); }
.btn--primary { background: var(--primary); color: var(--on-primary); }
.btn--primary:hover { background: var(--primary-press); }
.btn--ghost-dark {
  background: transparent;
  color: var(--on-dark);
  border-color: var(--hairline-dark);
}
.btn--ghost-dark:hover { border-color: rgba(255,255,255,0.55); }
.btn--light { background: #fff; color: var(--primary); }
.btn--light:hover { background: rgba(255,255,255,0.9); }

/* ============================================================
   CARD GRIDS
   ============================================================ */
.card-grid { display: grid; gap: var(--sp-lg); }
.card-grid--3 { grid-template-columns: repeat(3, 1fr); }

/* Feature cards (light canvas) */
.feature-card {
  background: var(--surface-card);
  border: 1px solid var(--hairline-light);
  border-radius: var(--r-md);
  padding: var(--sp-xl);
}
.feature-card__tag {
  display: inline-block;
  font-size: 13px;
  font-weight: 700;
  letter-spacing: 1px;
  color: var(--primary);
  margin-bottom: var(--sp-md);
}
.feature-card .body { color: var(--body-light); font-size: 16px; }

/* Project tiles (dark canvas) */
.tile {
  display: flex;
  flex-direction: column;
  background: var(--dark-card);
  border-radius: var(--r-md);
  overflow: hidden;
  color: var(--on-dark);
  transition: transform .18s ease, box-shadow .18s ease;
}
.tile:hover {
  transform: translateY(-4px);
  box-shadow: 0 12px 32px rgba(0,0,0,0.45);
}
.tile__media {
  aspect-ratio: 16 / 9;
  background: var(--dark-elevated);
}
.tile__media img { width: 100%; height: 100%; object-fit: cover; }
.tile__video { position: absolute; inset: 0; width: 100%; height: 100%; object-fit: cover; display: block; }
/* Designed gradient headers (used in place of project imagery) */
.tile__media--a { background: linear-gradient(135deg, #0a2a4d 0%, #0070d1 100%); }
.tile__media--b { background: linear-gradient(135deg, #101014 0%, #004d8d 100%); }
.tile__media--c { background: linear-gradient(135deg, #0070d1 0%, #101014 100%); }
.tile__media { position: relative; }
.tile__body { padding: var(--sp-lg); }
.tile__body .body-sm { color: var(--body-dark); margin: var(--sp-xs) 0 0; }

.badge {
  display: inline-block;
  background: var(--primary);
  color: var(--on-primary);
  font-size: 11px;
  font-weight: 600;
  letter-spacing: 0.4px;
  padding: 4px 10px;
  border-radius: var(--r-full);
  margin-bottom: var(--sp-sm);
}

/* ============================================================
   ABOUT (narrow prose)
   ============================================================ */
.prose { max-width: 720px; }
.prose .body { color: var(--body-light); margin: 0 0 var(--sp-lg); }
.link { color: var(--link-light); font-weight: 500; }
.link:hover { text-decoration: underline; }

/* ============================================================
   FOOTER (blue chapter)
   ============================================================ */
.footer__inner {
  display: flex;
  flex-wrap: wrap;
  gap: var(--sp-xxl);
  justify-content: space-between;
  align-items: flex-start;
}
.footer__lead .btn { margin-top: var(--sp-lg); }
.footer__lead .lede--blue { margin-bottom: 0; }
.footer__links {
  list-style: none;
  margin: 0;
  padding: 0;
  display: grid;
  gap: var(--sp-sm);
  min-width: 200px;
}
.footer__links a {
  color: #fff;
  font-weight: 500;
  border-bottom: 1px solid rgba(255,255,255,0.35);
  padding-bottom: 2px;
  transition: border-color .15s ease;
}
.footer__links a:hover { border-color: #fff; }
.footer__fine {
  max-width: var(--maxw);
  margin: 0 auto;
  padding: var(--sp-lg) var(--sp-lg) var(--sp-xxl);
  display: flex;
  flex-wrap: wrap;
  gap: var(--sp-md);
  justify-content: space-between;
  font-size: 13px;
  color: rgba(255,255,255,0.8);
  border-top: 1px solid rgba(255,255,255,0.25);
}

/* ============================================================
   RESPONSIVE
   ============================================================ */

/* Tablet */
@media (max-width: 900px) {
  .band__inner { padding: 64px var(--sp-lg); }
  .card-grid--3 { grid-template-columns: 1fr 1fr; }
  .hero__inner {
    grid-template-columns: 1fr;
    text-align: center;
    gap: var(--sp-xl);
  }
  .hero__portrait { order: -1; }
  .portrait { margin: 0 auto; }
  .lede, .hero__meta { margin-left: auto; margin-right: auto; }
  .hero__cta { justify-content: center; }
}

/* Phone */
@media (max-width: 620px) {
  .card-grid--3 { grid-template-columns: 1fr; }
  .nav__inner { padding: 0 var(--sp-md); }
  .nav__name { display: none; }
  .nav__links { gap: var(--sp-md); }
  .nav__links a { font-size: 14px; }
  .band__inner { padding: 56px var(--sp-md); }
  .portrait { max-width: 220px; }

  /* Full-width, thumb-friendly buttons */
  .hero__cta { flex-direction: column; align-items: stretch; gap: var(--sp-sm); }
  .hero__cta .btn { width: 100%; }
  .footer__lead .btn { width: 100%; }

  .footer__inner { gap: var(--sp-xl); }
  .footer__links { min-width: 0; width: 100%; }
  .footer__fine { flex-direction: column; gap: var(--sp-xs); text-align: center; }
}

/* Small phone */
@media (max-width: 380px) {
  .band__inner { padding: 44px var(--sp-md); }
  .nav__links { gap: var(--sp-sm); }
}

/* Respect reduced-motion preferences */
@media (prefers-reduced-motion: reduce) {
  html { scroll-behavior: auto; }
  * { transition: none !important; }
}