.hero h1 {
  font-size: clamp(52px, 6vw, 96px);
  line-height: .96;
}

.hero h1 em {
  -webkit-text-stroke-width: 1.35px;
  display: inline-block;
}

.equation-card {
  align-self: center;
  border: 1px solid var(--line);
  padding: 25px 28px;
  background: rgba(250, 250, 244, .62);
  display: grid;
  grid-template-columns: 1fr 1px 1fr;
  gap: 24px;
  align-items: center;
  position: relative;
  font: inherit;
}

.equation-card math {
  font-size: clamp(24px, 2.2vw, 38px);
  margin: 5px 0;
  text-align: center;
}

.eq-label {
  position: absolute;
  left: 16px;
  top: -8px;
  background: var(--paper);
  padding: 0 8px;
  font: 9px "DM Mono";
  letter-spacing: .13em;
  color: var(--muted);
}

.eq-divider { height: 60px; background: var(--line); }

.eq-note {
  grid-column: 1 / -1;
  text-align: center;
  border-top: 1px solid var(--line);
  padding-top: 13px;
  font: 10px "DM Mono";
  color: var(--muted);
}

.boundary {
  padding: 14px 15px;
  display: grid;
  grid-template-columns: auto 1fr;
  align-items: start;
  gap: 14px;
}

.boundary span { white-space: nowrap; }
.boundary math { font-size: 11px; justify-self: end; margin: 0; }

.theory {
  padding: 105px 0 120px;
  border-top: 1px solid var(--line);
}

.theory-head {
  display: grid;
  grid-template-columns: .4fr 1.15fr .75fr;
  gap: 50px;
  align-items: start;
  margin-bottom: 65px;
}

.theory-head h2 {
  font-size: clamp(32px, 4vw, 62px);
  line-height: 1.08;
  letter-spacing: -.055em;
  margin: 0;
}

.theory-head > p {
  font-size: 13px;
  color: var(--muted);
  line-height: 1.9;
  margin: 5px 0 0;
}

.section-index {
  font: 10px "DM Mono";
  display: block;
  margin-bottom: 22px;
  color: #95a099;
}

.formula-flow {
  display: grid;
  grid-template-columns: 1fr auto 1fr auto 1fr;
  align-items: stretch;
  border-top: 1px solid var(--line);
  border-bottom: 1px solid var(--line);
}

.formula-flow article { padding: 35px 28px; min-height: 240px; }

.formula-flow article math {
  font-size: clamp(19px, 1.7vw, 27px);
  min-height: 75px;
  display: grid;
  place-items: center;
  margin: 15px 0;
}

.formula-flow article p {
  font-size: 11px;
  line-height: 1.8;
  color: var(--muted);
  margin: 25px 0 0;
}

.formula-no {
  font: 9px "DM Mono";
  letter-spacing: .12em;
  color: #78857e;
}

.featured-formula { background: var(--ink); color: white; }
.featured-formula .formula-no, .featured-formula p { color: #acb9b2 !important; }
.featured-formula math { color: var(--acid); }
.flow-arrow { display: grid; place-items: center; color: #9da7a1; font: 22px "DM Mono"; }

.error-law {
  margin-top: 28px;
  padding: 24px 30px;
  background: var(--acid);
  display: grid;
  grid-template-columns: .45fr 1fr .6fr;
  align-items: center;
  gap: 35px;
}

.error-law > span { font: 9px "DM Mono"; letter-spacing: .13em; }
.error-law math { font-size: 25px; }
.error-law p { font-size: 11px; text-align: right; margin: 0; }

@media (max-width: 1000px) {
  .theory-head { grid-template-columns: 1fr; }
  .formula-flow { grid-template-columns: 1fr; }
  .flow-arrow { padding: 8px; transform: rotate(90deg); }
  .error-law { grid-template-columns: 1fr; }
  .error-law p { text-align: left; }
}