.delta-hero {
  position: relative;
  overflow: hidden;
  margin-bottom: 2rem;
  padding: clamp(1.4rem, 4vw, 3rem);
  border-radius: 1.25rem;
  color: #fff;
  background: linear-gradient(135deg, #073b66 0%, #0867a8 58%, #07966f 100%);
  box-shadow: 0 1rem 2.5rem rgba(5, 55, 91, .18);
}

.delta-hero::after {
  content: "Δ";
  position: absolute;
  right: 3%;
  bottom: -3.8rem;
  color: rgba(255, 255, 255, .09);
  font: 700 clamp(10rem, 25vw, 20rem)/1 Georgia, serif;
  pointer-events: none;
}

.delta-hero h1 { max-width: 850px; margin-bottom: .75rem; font-weight: 800; }
.delta-hero .lead { position: relative; z-index: 1; max-width: 820px; margin-bottom: 1.25rem; }
.delta-hero .breadcrumb-item, .delta-hero .breadcrumb-item::before { color: rgba(255,255,255,.72); }
.delta-hero .breadcrumb a { color: #fff; }
.delta-eyebrow { display: block; margin-bottom: .4rem; color: #a8f4d9; font-size: .78rem; font-weight: 800; letter-spacing: .09em; text-transform: uppercase; }
.delta-hero-formula { position: relative; z-index: 1; display: inline-block; padding: .55rem 1rem; border: 1px solid rgba(255,255,255,.35); border-radius: .75rem; background: rgba(0,0,0,.15); font: 700 1.35rem Georgia, serif; }

.formula-display { margin: 1.25rem 0; padding: .9rem 1rem; border-left: .3rem solid #0879c9; border-radius: .35rem; background: #eef7fd; color: #073b66; text-align: center; font-size: clamp(1.25rem, 3vw, 1.65rem); }

.delta-calculator .card-header { display: flex; align-items: center; justify-content: space-between; gap: 1rem; padding: 1rem 1.25rem; border: 0; color: #fff; background: #0b496d; }
.delta-calculator .card-header small { color: #9ee8cf; font-weight: 700; letter-spacing: .06em; }
.delta-equation-badge { flex: 0 0 auto; padding: .45rem .7rem; border-radius: .6rem; background: rgba(255,255,255,.13); font-family: Georgia, serif; }
.delta-calculator .form-label { font-weight: 700; }
.delta-result { padding: 1rem; border: 1px solid #b8cad8; border-left-width: .35rem; border-radius: .65rem; background: #f7fafc; }
.delta-result.result-positive { border-left-color: #16835d; background: #eefaf5; }
.delta-result.result-zero { border-left-color: #d18b00; background: #fff8e8; }
.delta-result.result-negative { border-left-color: #7259b5; background: #f5f1ff; }
.delta-result.result-error { border-left-color: #c93847; background: #fff1f2; }
.delta-result .result-value { font-size: 1.25rem; font-weight: 800; }
.delta-result code { color: inherit; font-size: 1em; }

.delta-cases, .delta-steps { display: grid; grid-template-columns: repeat(3, minmax(0, 1fr)); gap: 1rem; }
.delta-case, .delta-steps article { padding: 1rem; border: 1px solid #dce4ea; border-top: .3rem solid #16835d; border-radius: .75rem; background: #fff; box-shadow: 0 .35rem 1rem rgba(30,55,70,.06); }
.delta-case > span { display: inline-block; margin-bottom: .5rem; font-size: 1.25rem; font-weight: 800; }
.delta-case h4, .delta-steps h3 { margin-bottom: .35rem; font-size: 1.05rem; }
.delta-case p, .delta-steps p { margin: 0; }
.delta-case-zero { border-top-color: #d18b00; }
.delta-case-negative { border-top-color: #7259b5; }

.delta-section { margin: 2.2rem 0; }
.delta-steps { grid-template-columns: repeat(4, minmax(0, 1fr)); }
.delta-steps article { border-top-color: #0879c9; }
.delta-steps article > span { display: grid; width: 2rem; height: 2rem; margin-bottom: .65rem; border-radius: 50%; place-items: center; color: #fff; background: #0879c9; font-weight: 800; }
.delta-checklist { padding-left: 0; list-style: none; }
.delta-checklist li { position: relative; margin-bottom: .55rem; padding-left: 1.75rem; }
.delta-checklist li::before { content: "✓"; position: absolute; left: 0; color: #16835d; font-weight: 900; }
.physics-legend { margin: 1.25rem 0; border: 1px solid #cbdce8; border-radius: .65rem; background: #f8fbfd; }
.physics-legend h5 { margin: 0; padding: .8rem 1rem; border-bottom: 1px solid #cbdce8; color: #fff; background: #0b496d; }
.physics-legend th:first-child { min-width: 5rem; color: #075f43; font-size: 1.05rem; }
.physics-legend td, .physics-legend th { padding: .7rem .8rem; }
.physics-notes { padding-left: 1.25rem; }
.physics-notes li { margin-bottom: .4rem; }
.physics-coefficients { display: grid; grid-template-columns: repeat(3,minmax(0,1fr)); gap: .75rem; margin: 1rem 0; }
.physics-coefficients > div { padding: .8rem; border-left: 4px solid #0879c9; background: #eef7fd; }
.physics-coefficients span, .physics-coefficients strong, .physics-coefficients small { display: block; }
.physics-coefficients span { color: #546b7b; font-weight: 800; text-transform: uppercase; }
.physics-coefficients strong { color: #073b66; font-size: 1.35rem; }
.physics-roots { display: grid; grid-template-columns: repeat(2,minmax(0,1fr)); gap: .8rem; margin: 1rem 0; }
.physics-roots > div { padding: 1rem; border: 1px solid #d5e0e7; border-radius: .55rem; background: #fff; }
.physics-roots span, .physics-roots strong { display: block; }
.physics-roots span { color: #607483; font-size: .75rem; font-weight: 800; text-transform: uppercase; }
.physics-roots strong { margin: .25rem 0; color: #075f43; font-size: 1.25rem; }
.physics-roots p { margin: 0; }
.physics-conclusion { padding: 1rem; border-left: 5px solid #16835d; background: #eefaf5; color: #174f3d; }
.wp-caption { margin: 1.5rem auto; }
.wp-caption img { max-width: 100%; height: auto; border-radius: .8rem; }
.wp-caption-text { padding-top: .45rem; color: #66727b; font-size: .875rem; text-align: center; }
.delta-faq .accordion-button { font-weight: 700; }

@media (max-width: 991.98px) {
  .delta-steps { grid-template-columns: repeat(2, minmax(0, 1fr)); }
}

@media (max-width: 767.98px) {
  .delta-cases, .delta-steps { grid-template-columns: 1fr; }
  .physics-coefficients, .physics-roots { grid-template-columns: 1fr; }
  .delta-calculator .card-header { align-items: flex-start; flex-direction: column; }
}