/* A continuous blue–aqua palette, with generous chapter spacing. */
body { background: #f4f8fa; }
.masthead {
  padding-bottom: 76px;
  background:
    radial-gradient(ellipse at 12% 8%, #bcebdd 0, transparent 48%),
    radial-gradient(ellipse at 92% 30%, #c9e2fb 0, transparent 48%),
    linear-gradient(160deg, #f5fbf9, #e8f2f9);
  border-bottom: 0;
}
.hero { padding-top: 92px; padding-bottom: 58px; }
.teaser { background: #ffffffb8; border-color: #c0d8ce; box-shadow: 0 18px 55px #163d3510; }
.tldr { margin-top: 20px; border: 0; padding: 26px 30px; background: #ffffffb3; border-radius: 10px; }
.chapter, .results-band { position: relative; border-top: 0; }
.chapter::before, .results-band::before { content: ''; position: absolute; top: 0; left: 50%; transform: translateX(-50%); width: min(1100px, calc(100% - 64px)); height: 2px; background: #91b7bd; border-radius: 2px; }
.chapter::after, .results-band::after { content: ''; position: absolute; top: -1px; left: 50%; transform: translateX(-50%); width: 56px; height: 4px; background: #548e96; border-radius: 3px; }
.chapter .section { padding-top: 112px; padding-bottom: 112px; }
.chapter .eyebrow, .results-band .eyebrow { display: flex; align-items: center; gap: 14px; margin-bottom: 23px; }
.chapter .eyebrow::before, .results-band .eyebrow::before { content: ''; width: 34px; height: 3px; background: currentColor; flex-shrink: 0; }
.abstract-band { background: linear-gradient(180deg, #e8f2f9, #f4faf9); border-top: 0; }
.abstract-band .lead { border-left: 3px solid #2d8877; padding-left: 24px; margin-block: 34px; }
.abstract-band .note { margin-bottom: 0; }
.overview-band { background: linear-gradient(180deg, #f4faf9, #e8f3f9); }
.overview-band .section-heading { margin-bottom: 25px; }
.overview-band .eyebrow { color: #2c6096; }
.principles { gap: 26px; }
.principles article { padding: 30px 27px; background: #ffffffc9; border: 1px solid #cedfe5; border-top: 3px solid #8ab6c5; border-radius: 10px; }
.principles .index { color: #2c6096; }
.principles p { margin-bottom: 0; }
.method-band { background: linear-gradient(180deg, #e8f3f9, #e4f4ef); color: var(--ink); }
.method-band .eyebrow { color: #326b70; }
.method-band .section > h2 { margin-bottom: 48px; }
.method-band .section p { color: #536b73; }
.method-aside { background: #ffffffb3; border: 1px solid #c7dedb; border-top: 3px solid #8bc7b9; padding: 32px; }
.method-aside h3 { color: #274c53; }
.method-aside p:last-child { margin-bottom: 0; }
.method-list li { padding-bottom: 38px; border-color: #b8d5d3; }
.method-list li::before { background: #d7ede7; border-color: #99c7bd; color: #2e625b; }
.method-list h3 { color: #274c53; }
.results-band { margin-top: 0; padding-bottom: 0; background: linear-gradient(180deg, #e4f4ef, #eaf3f9 65%, #f4f8fa); border: 0; }
.flow .accent-node { background: linear-gradient(135deg, #d0eee3, #d6e9f7); border-color: #a9cec5; color: #274c53; }
.accent-node .step, .accent-node p { color: #426b6b; }
.results-band .section { padding-top: 112px; padding-bottom: 100px; }
.results-band .section-heading { margin-bottom: 24px; }
.chart, .figure { border-color: #c4dad1; box-shadow: 0 12px 35px #17453708; }
.results-band details { padding: 20px 24px; background: #ffffffb5; border: 1px solid #c4dad1; border-radius: 10px; }
footer { padding-block: 42px; }
@media (max-width: 760px) {
  .hero { padding-top: 64px; padding-bottom: 42px; }
  .masthead { padding-bottom: 48px; }
  .tldr { padding: 22px 20px; }
  .chapter .section, .results-band .section { padding-top: 72px; padding-bottom: 72px; }
  .abstract-band .lead { padding-left: 18px; }
  .principles { gap: 22px; }
  .principles article { padding: 25px; }
  .method-band .section > h2 { margin-bottom: 32px; }
  .method-aside { padding: 25px; }
  .results-band details { padding: 18px; }
}