/* ============================================================
   δivergent Byte — main.css
   IBM Plex Serif (body/headings) + IBM Plex Mono (UI/labels)
   Palette: warm ink-on-parchment, accent dark navy
   ============================================================ */

/* --- Custom properties ------------------------------------ */
:root {
  --ink:        #0f0f0f;
  --ink-mid:    #3a3a3a;
  --ink-light:  #6a6a6a;
  --page:       #f5f1ea;
  --rule:       #ccc8be;
  --rule-light: #e2dfd8;
  --accent:     #1a1a2e;
  --code-bg:    #edeae2;
  --hero-text:  #e8e4da;
  --max:        760px;
  --wide:       1100px;
}

/* --- Reset ------------------------------------------------ */
*, *::before, *::after { box-sizing: border-box; margin: 0; padding: 0; }
html { scroll-behavior: smooth; -webkit-text-size-adjust: 100%; }

/* --- Base ------------------------------------------------- */
body {
  background: var(--page);
  color: var(--ink);
  font-family: 'IBM Plex Serif', Georgia, serif;
  font-size: 17px;
  line-height: 1.8;
}

img { max-width: 100%; display: block; }
a { color: inherit; }

/* --- Site header / navigation ----------------------------- */
.site-header {
  background: var(--accent);
  color: var(--hero-text);
  padding: 0 1.5rem;
  position: sticky;
  top: 0;
  z-index: 100;
  border-bottom: 1px solid rgba(255,255,255,0.07);
}

.site-header__inner {
  max-width: var(--wide);
  margin: 0 auto;
  display: flex;
  align-items: center;
  justify-content: space-between;
  height: 3.5rem;
}

.site-header__brand {
  font-family: 'IBM Plex Serif', serif;
  font-size: 1.05rem;
  font-weight: 600;
  text-decoration: none;
  color: var(--hero-text);
  letter-spacing: -0.01em;
}

.site-header__brand .brand-delta {
  color: #7ec8a0;
}

.site-nav {
  display: flex;
  align-items: center;
  gap: 2rem;
}

.site-nav__link {
  font-family: 'IBM Plex Mono', monospace;
  font-size: 0.68rem;
  letter-spacing: 0.1em;
  text-transform: uppercase;
  text-decoration: none;
  color: rgba(232, 228, 218, 0.65);
  transition: color 0.15s;
}

.site-nav__link:hover { color: var(--hero-text); }

.site-nav__link--cta {
  color: #7ec8a0;
  border: 1px solid rgba(126,200,160,0.4);
  padding: 0.3rem 0.8rem;
}

.site-nav__link--cta:hover {
  color: #7ec8a0;
  border-color: #7ec8a0;
}

/* --- Hero ------------------------------------------------- */
.hero {
  background: var(--accent);
  color: var(--hero-text);
  padding: 5rem 1.5rem 5rem;
  text-align: center;
}

.hero__inner { max-width: var(--max); margin: 0 auto; }

.hero__delta {
  font-family: 'IBM Plex Serif', serif;
  font-size: clamp(4rem, 12vw, 8rem);
  font-weight: 600;
  line-height: 1;
  color: #7ec8a0;
  letter-spacing: -0.03em;
  margin-bottom: 1.5rem;
  display: block;
}

.hero__brand {
  font-family: 'IBM Plex Serif', serif;
  font-size: clamp(1.4rem, 4vw, 2rem);
  font-weight: 300;
  letter-spacing: -0.01em;
  margin-bottom: 1.25rem;
  color: var(--hero-text);
}

.hero__tagline {
  font-family: 'IBM Plex Serif', serif;
  font-size: 1rem;
  font-weight: 300;
  font-style: italic;
  color: rgba(232,228,218,0.65);
  line-height: 1.6;
  margin-bottom: 0.5rem;
}

.hero__sub {
  font-family: 'IBM Plex Mono', monospace;
  font-size: 0.72rem;
  letter-spacing: 0.18em;
  text-transform: uppercase;
  color: #7ec8a0;
  margin-top: 1.75rem;
  margin-bottom: 2rem;
}

.hero__cta {
  display: inline-block;
  font-family: 'IBM Plex Mono', monospace;
  font-size: 0.72rem;
  letter-spacing: 0.12em;
  text-transform: uppercase;
  color: var(--accent);
  background: #7ec8a0;
  text-decoration: none;
  padding: 0.75rem 1.75rem;
  margin-top: 0.5rem;
  transition: background 0.15s;
}

.hero__cta:hover { background: #98d6b4; }

/* --- Page sections ---------------------------------------- */
.section {
  padding: 4rem 1.5rem;
}

.section--ruled {
  border-top: 1px solid var(--rule);
}

.section--dark {
  background: var(--code-bg);
}

.section__inner {
  max-width: var(--max);
  margin: 0 auto;
}

/* --- Section rule (Ballmer-piece style) ------------------- */
.section-rule {
  font-family: 'IBM Plex Mono', monospace;
  font-size: 0.65rem;
  letter-spacing: 0.18em;
  text-transform: uppercase;
  color: var(--ink-light);
  border-bottom: 1px solid var(--rule);
  padding-bottom: 0.4rem;
  margin: 3rem 0 1.5rem;
}

.section-rule:first-child { margin-top: 0; }

/* --- Kicker ----------------------------------------------- */
.kicker {
  font-family: 'IBM Plex Mono', monospace;
  font-size: 0.65rem;
  letter-spacing: 0.2em;
  text-transform: uppercase;
  color: var(--ink-light);
  margin-bottom: 1rem;
  display: flex;
  align-items: center;
  gap: 1rem;
}

.kicker::after {
  content: '';
  flex: 1;
  height: 1px;
  background: var(--rule);
}

/* --- Headings --------------------------------------------- */
h1, h2, h3, h4 {
  font-family: 'IBM Plex Serif', serif;
  font-weight: 600;
  line-height: 1.15;
  letter-spacing: -0.02em;
}

h1 { font-size: clamp(1.8rem, 5vw, 2.6rem); margin-bottom: 0.75rem; }
h2 { font-size: clamp(1.25rem, 3.5vw, 1.75rem); margin-bottom: 0.6rem; }
h3 { font-size: 1.1rem; margin-bottom: 0.5rem; }
h4 { font-size: 0.95rem; font-weight: 600; margin-bottom: 0.35rem; }

/* --- Body copy -------------------------------------------- */
p { margin-bottom: 1.3rem; }
p:last-child { margin-bottom: 0; }

.lede {
  font-size: 1.05rem;
  font-weight: 300;
  line-height: 1.75;
  margin-bottom: 1.5rem;
  color: var(--ink-mid);
}

strong { font-weight: 600; }
em { font-style: italic; }

/* --- Therefore block (Ballmer-piece style) ---------------- */
.therefore {
  font-family: 'IBM Plex Mono', monospace;
  font-size: 0.875rem;
  line-height: 1.6;
  color: var(--ink-mid);
  margin: 1.75rem 0;
  padding: 0.85rem 1rem;
  background: var(--code-bg);
  border-left: 3px solid var(--ink);
}

/* --- Product entries -------------------------------------- */
.product {
  margin-bottom: 2.5rem;
  padding-bottom: 2.5rem;
  border-bottom: 1px solid var(--rule-light);
}

.product:last-child {
  margin-bottom: 0;
  padding-bottom: 0;
  border-bottom: none;
}

.product__name {
  font-family: 'IBM Plex Mono', monospace;
  font-size: 0.68rem;
  letter-spacing: 0.18em;
  text-transform: uppercase;
  color: var(--ink-light);
  margin-bottom: 0.4rem;
}

.product__title {
  font-family: 'IBM Plex Serif', serif;
  font-size: 1.2rem;
  font-weight: 600;
  letter-spacing: -0.01em;
  margin-bottom: 0.6rem;
}

.product__body { color: var(--ink-mid); }

.product__link {
  display: inline-block;
  font-family: 'IBM Plex Mono', monospace;
  font-size: 0.68rem;
  letter-spacing: 0.1em;
  text-transform: uppercase;
  text-decoration: none;
  color: var(--ink);
  border-bottom: 1px solid var(--rule);
  margin-top: 0.75rem;
  padding-bottom: 0.1rem;
  transition: border-color 0.15s;
}

.product__link:hover { border-color: var(--ink); }

/* --- Essay list ------------------------------------------- */
.essay-list {
  list-style: none;
  margin: 1rem 0;
}

.essay-list li {
  padding: 0.6rem 0;
  border-bottom: 1px solid var(--rule-light);
  font-size: 0.95rem;
}

.essay-list li:last-child { border-bottom: none; }

.essay-list strong {
  display: block;
  margin-bottom: 0.15rem;
}

.essay-list span {
  font-size: 0.85rem;
  color: var(--ink-light);
  font-style: italic;
}

/* --- CTA block -------------------------------------------- */
.cta-block {
  border-top: 3px solid var(--ink);
  padding-top: 2rem;
  margin-top: 3rem;
  display: flex;
  align-items: baseline;
  justify-content: space-between;
  gap: 2rem;
  flex-wrap: wrap;
}

.cta-block__text {
  font-family: 'IBM Plex Serif', serif;
  font-size: 1.1rem;
  font-weight: 300;
  font-style: italic;
  color: var(--ink-mid);
  flex: 1;
  min-width: 200px;
}

.cta-block__link {
  font-family: 'IBM Plex Mono', monospace;
  font-size: 0.72rem;
  letter-spacing: 0.12em;
  text-transform: uppercase;
  text-decoration: none;
  color: var(--page);
  background: var(--ink);
  padding: 0.75rem 1.5rem;
  white-space: nowrap;
  transition: background 0.15s;
}

.cta-block__link:hover { background: var(--ink-mid); }

/* --- About page specific ---------------------------------- */
.about-grid {
  display: grid;
  gap: 0;
}

.byline {
  font-family: 'IBM Plex Mono', monospace;
  font-size: 0.7rem;
  color: var(--ink-light);
  letter-spacing: 0.06em;
  border-top: 1px solid var(--rule);
  padding-top: 0.75rem;
  margin-top: 1rem;
  margin-bottom: 0;
}

/* --- Footer ----------------------------------------------- */
.site-footer {
  background: var(--accent);
  color: rgba(232,228,218,0.5);
  padding: 3rem 1.5rem 2rem;
  margin-top: 0;
}

.site-footer__inner {
  max-width: var(--wide);
  margin: 0 auto;
  display: grid;
  grid-template-columns: 1fr 1fr;
  gap: 2rem;
}

.site-footer__brand {
  font-family: 'IBM Plex Serif', serif;
  font-size: 1rem;
  font-weight: 600;
  color: var(--hero-text);
  margin-bottom: 0.5rem;
  text-decoration: none;
}

.site-footer__brand .brand-delta { color: #7ec8a0; }

.site-footer__detail {
  font-family: 'IBM Plex Mono', monospace;
  font-size: 0.65rem;
  line-height: 2;
  letter-spacing: 0.05em;
}

.site-footer__detail a {
  color: rgba(232,228,218,0.5);
  text-decoration: none;
}

.site-footer__detail a:hover { color: var(--hero-text); }

.site-footer__nav {
  font-family: 'IBM Plex Mono', monospace;
  font-size: 0.65rem;
  line-height: 2;
  letter-spacing: 0.08em;
  text-transform: uppercase;
  text-align: right;
}

.site-footer__nav a {
  display: block;
  color: rgba(232,228,218,0.5);
  text-decoration: none;
}

.site-footer__nav a:hover { color: var(--hero-text); }

.site-footer__copy {
  max-width: var(--wide);
  margin: 2rem auto 0;
  padding-top: 1.5rem;
  border-top: 1px solid rgba(255,255,255,0.07);
  font-family: 'IBM Plex Mono', monospace;
  font-size: 0.62rem;
  color: rgba(232,228,218,0.3);
  letter-spacing: 0.05em;
  display: flex;
  justify-content: space-between;
  flex-wrap: wrap;
  gap: 0.5rem;
}

/* --- Utility ---------------------------------------------- */
.mono {
  font-family: 'IBM Plex Mono', monospace;
  font-size: 0.875em;
}

.dim { color: var(--ink-light); }

hr.rule {
  border: none;
  border-top: 1px solid var(--rule);
  margin: 2.5rem 0;
}

/* --- Comparison / pricing tables -------------------------- */
.compare-table {
  width: 100%;
  border-collapse: collapse;
  font-size: 0.875rem;
  margin: 1.75rem 0;
  font-family: 'IBM Plex Mono', monospace;
}

.compare-table th {
  font-size: 0.6rem;
  letter-spacing: 0.12em;
  text-transform: uppercase;
  color: var(--ink-light);
  border-bottom: 2px solid var(--ink);
  padding: 0.4rem 0.75rem;
  text-align: left;
  font-weight: 400;
}

.compare-table td {
  padding: 0.5rem 0.75rem;
  border-bottom: 1px solid var(--rule-light);
  vertical-align: top;
  line-height: 1.5;
  color: var(--ink-mid);
  font-size: 0.78rem;
}

.compare-table tr:last-child td { border-bottom: none; }
.compare-table td:first-child { color: var(--ink); font-weight: 500; }
.compare-table .highlight td { background: rgba(126,200,160,0.08); }

/* Pricing row */
.compare-table .total td {
  border-top: 2px solid var(--ink);
  color: var(--ink);
  font-weight: 500;
}

/* --- Essay layout ----------------------------------------- */
.essay-page {
  padding: 0 1.5rem 6rem;
}

.essay-masthead {
  max-width: var(--max);
  margin: 0 auto;
  padding: 3.5rem 0 2.5rem;
  border-bottom: 3px solid var(--ink);
  margin-bottom: 3rem;
}

.essay-masthead .kicker {
  margin-bottom: 1rem;
}

.essay-masthead h1 {
  font-family: 'IBM Plex Serif', serif;
  font-size: clamp(1.8rem, 5vw, 2.6rem);
  font-weight: 600;
  line-height: 1.1;
  letter-spacing: -0.02em;
  margin-bottom: 0.75rem;
}

.essay-masthead .deck {
  font-family: 'IBM Plex Serif', serif;
  font-size: 1.05rem;
  font-weight: 300;
  font-style: italic;
  color: var(--ink-mid);
  line-height: 1.5;
  margin-bottom: 1rem;
}

.essay-masthead .byline {
  font-family: 'IBM Plex Mono', monospace;
  font-size: 0.7rem;
  color: var(--ink-light);
  letter-spacing: 0.06em;
  border-top: 1px solid var(--rule);
  padding-top: 0.75rem;
  margin-top: 1rem;
}

.essay-body {
  max-width: var(--max);
  margin: 0 auto;
}

.essay-body p { margin-bottom: 1.3rem; }
.essay-body p:last-child { margin-bottom: 0; }

.essay-body blockquote {
  border-left: 3px solid var(--rule);
  padding-left: 1.25rem;
  margin: 1.5rem 0;
  color: var(--ink-mid);
  font-style: italic;
}

.essay-body pre {
  font-family: 'IBM Plex Mono', monospace;
  font-size: 0.82rem;
  line-height: 1.6;
  background: var(--code-bg);
  padding: 1.1rem 1.25rem;
  margin: 1.5rem 0;
  overflow-x: auto;
  border-left: 3px solid var(--rule);
}

.essay-body code {
  font-family: 'IBM Plex Mono', monospace;
  font-size: 0.85em;
  background: var(--code-bg);
  padding: 0.1em 0.35em;
  border-radius: 2px;
}

.essay-body pre code {
  background: none;
  padding: 0;
  font-size: 1em;
}

.essay-body .therefore {
  font-family: 'IBM Plex Mono', monospace;
  font-size: 0.875rem;
  line-height: 1.6;
  color: var(--ink-mid);
  margin: 1.75rem 0;
  padding: 0.85rem 1rem;
  background: var(--code-bg);
  border-left: 3px solid var(--ink);
}

.essay-body .section-rule {
  margin-top: 3rem;
}

.essay-body .closing {
  margin-top: 3rem;
  border-top: 3px solid var(--ink);
  padding-top: 1.5rem;
}

.essay-body .sig {
  font-family: 'IBM Plex Mono', monospace;
  font-size: 0.75rem;
  color: var(--ink-light);
  line-height: 1.9;
  margin-top: 2rem;
}

.essay-body .coda {
  font-family: 'IBM Plex Mono', monospace;
  font-size: 0.78rem;
  font-style: italic;
  color: var(--ink-light);
  margin-top: 0.75rem;
}

/* Essay footnotes */
.essay-body .footnotes {
  margin-top: 3rem;
  padding-top: 1.5rem;
  border-top: 1px solid var(--rule);
  font-family: 'IBM Plex Mono', monospace;
  font-size: 0.72rem;
  color: var(--ink-light);
  line-height: 1.7;
}

.essay-body .footnotes ol {
  padding-left: 1.5em;
}

.essay-body .footnotes li { margin-bottom: 0.4rem; }

/* Essay series badge */
.series-badge {
  display: inline-block;
  font-family: 'IBM Plex Mono', monospace;
  font-size: 0.6rem;
  letter-spacing: 0.15em;
  text-transform: uppercase;
  color: var(--page);
  background: var(--ink);
  padding: 0.2rem 0.5rem;
  margin-bottom: 0.5rem;
}

/* --- Essay index cards ------------------------------------ */
.essay-grid {
  display: grid;
  gap: 0;
  margin-top: 1.5rem;
}

.essay-card {
  padding: 1.5rem 0;
  border-bottom: 1px solid var(--rule-light);
  display: grid;
  grid-template-columns: 1fr auto;
  gap: 1rem;
  align-items: start;
  text-decoration: none;
  color: inherit;
}

.essay-card:first-child { border-top: 1px solid var(--rule-light); }

.essay-card:hover .essay-card__title { text-decoration: underline; }

.essay-card__title {
  font-family: 'IBM Plex Serif', serif;
  font-size: 1rem;
  font-weight: 600;
  letter-spacing: -0.01em;
  line-height: 1.3;
  margin-bottom: 0.3rem;
}

.essay-card__deck {
  font-size: 0.875rem;
  color: var(--ink-mid);
  font-style: italic;
  line-height: 1.5;
}

.essay-card__meta {
  font-family: 'IBM Plex Mono', monospace;
  font-size: 0.6rem;
  letter-spacing: 0.1em;
  text-transform: uppercase;
  color: var(--ink-light);
  white-space: nowrap;
  padding-top: 0.15rem;
}

/* --- Services index grid ---------------------------------- */
.services-grid {
  display: grid;
  grid-template-columns: 1fr 1fr;
  gap: 2px;
  margin-top: 2rem;
  background: var(--rule-light);
}

.service-tile {
  background: var(--page);
  padding: 2rem 1.75rem;
  text-decoration: none;
  color: inherit;
  display: block;
  transition: background 0.15s;
}

.service-tile:hover { background: var(--code-bg); }

.service-tile__label {
  font-family: 'IBM Plex Mono', monospace;
  font-size: 0.6rem;
  letter-spacing: 0.18em;
  text-transform: uppercase;
  color: var(--ink-light);
  margin-bottom: 0.5rem;
}

.service-tile__title {
  font-family: 'IBM Plex Serif', serif;
  font-size: 1.1rem;
  font-weight: 600;
  letter-spacing: -0.01em;
  line-height: 1.2;
  margin-bottom: 0.6rem;
}

.service-tile__body {
  font-size: 0.875rem;
  color: var(--ink-mid);
  line-height: 1.6;
}

.service-tile--full {
  grid-column: 1 / -1;
}

/* --- Back link -------------------------------------------- */
.back-link {
  display: inline-flex;
  align-items: center;
  gap: 0.5rem;
  font-family: 'IBM Plex Mono', monospace;
  font-size: 0.65rem;
  letter-spacing: 0.1em;
  text-transform: uppercase;
  text-decoration: none;
  color: var(--ink-light);
  margin-bottom: 2rem;
}

.back-link:hover { color: var(--ink); }

/* --- Responsive ------------------------------------------- */
@media (max-width: 640px) {
  body { font-size: 16px; }

  .hero { padding: 3.5rem 1.25rem 3.5rem; }

  .site-nav { gap: 1.25rem; }
  .site-nav__link--cta { display: none; }

  .cta-block { flex-direction: column; }
  .cta-block__link { text-align: center; }

  .site-footer__inner {
    grid-template-columns: 1fr;
  }

  .site-footer__nav { text-align: left; }
}

@media (max-width: 400px) {
  .site-nav { gap: 0.75rem; }
}