.what-is-kiso {
  position: relative;
  margin: 42px 0 64px;
  border: 1px solid var(--pro-bd, var(--border));
  border-radius: clamp(26px, 4vw, 42px);
  background: var(--pro-sur, var(--surface));
  padding: clamp(26px, 6vw, 64px);
  box-shadow: var(--shadow, 0 22px 70px rgba(43, 65, 76, .10));
  overflow: hidden;
}

.what-is-kiso::before {
  content: "";
  position: absolute;
  width: 260px;
  height: 260px;
  top: -150px;
  right: -110px;
  border-radius: 50%;
  background: color-mix(in srgb, var(--pro-key, var(--key)) 18%, transparent);
  pointer-events: none;
}

.what-is-kiso > * { position: relative; }
.what-is-kiso .what-kicker {
  margin: 0 0 10px;
  color: var(--pro-key2, var(--green));
  font: 800 12px/1.4 var(--mono, var(--sans));
  letter-spacing: .14em;
  text-transform: uppercase;
}
.what-is-kiso h1,
.what-is-kiso h2,
.what-is-kiso h3 { color: var(--pro-tx, var(--text)); }
.what-is-kiso h1,
.what-is-kiso > h2 {
  max-width: 18ch;
  margin: 0 0 18px;
  font: 700 clamp(38px, 7vw, 68px)/1.06 var(--serif, Georgia, serif);
}
.what-is-kiso h3 {
  margin: 42px 0 14px;
  font: 700 clamp(25px, 4vw, 36px)/1.2 var(--serif, Georgia, serif);
}
.what-is-kiso p {
  max-width: 72ch;
  margin: 0 0 18px;
  color: var(--pro-tx2, var(--muted));
  font-size: clamp(16px, 2vw, 18px);
  line-height: 1.78;
}
.what-is-kiso .what-lede {
  color: var(--pro-tx, var(--text));
  font-size: clamp(20px, 3vw, 27px);
  line-height: 1.5;
}
.what-is-kiso .jp-example {
  margin: 24px 0;
  border-left: 4px solid var(--pro-key, var(--key));
  padding: 3px 0 3px 20px;
}
.what-is-kiso .jp-example strong { color: var(--pro-tx, var(--text)); }
.what-is-kiso .try-lesson1 {
  min-height: 50px;
  display: inline-flex;
  align-items: center;
  justify-content: center;
  margin: 8px 0 12px;
  border: 0;
  border-radius: 999px;
  background: var(--pro-cta, var(--key));
  padding: 12px 22px;
  color: var(--pro-cta-text, #fff);
  font: 800 15px/1.3 var(--sans, system-ui, sans-serif);
  cursor: pointer;
  text-decoration: none;
  box-shadow: 0 10px 28px color-mix(in srgb, var(--pro-cta, var(--key)) 25%, transparent);
}
.what-is-kiso .how-kiso {
  margin: 38px 0;
  border: 1px solid var(--pro-bd, var(--border));
  border-radius: 22px;
  background: var(--pro-sur2, var(--surface-soft));
  overflow: hidden;
}
.what-is-kiso .how-kiso summary {
  min-height: 60px;
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 18px;
  padding: 16px 20px;
  color: var(--pro-tx, var(--text));
  font: 800 clamp(18px, 3vw, 24px)/1.3 var(--serif, Georgia, serif);
  cursor: pointer;
  list-style: none;
}
.what-is-kiso .how-kiso summary::-webkit-details-marker { display: none; }
.what-is-kiso .how-kiso summary::after { content: "+"; font-family: var(--sans, sans-serif); font-size: 28px; }
.what-is-kiso .how-kiso[open] summary::after { content: "−"; }
.what-is-kiso .how-body { border-top: 1px solid var(--pro-bd, var(--border)); padding: 20px; }
.what-is-kiso .how-steps { display: grid; gap: 12px; margin-top: 22px; counter-reset: kiso-how; }
.what-is-kiso .how-step {
  counter-increment: kiso-how;
  display: grid;
  grid-template-columns: 44px minmax(0, 1fr);
  gap: 14px;
  border: 1px solid var(--pro-bd, var(--border));
  border-radius: 16px;
  background: var(--pro-sur, var(--surface));
  padding: 16px;
}
.what-is-kiso .how-step::before {
  content: counter(kiso-how);
  width: 40px;
  height: 40px;
  display: grid;
  place-items: center;
  border-radius: 50%;
  background: var(--pro-key, var(--key));
  color: var(--pro-sur, #fff);
  font-weight: 900;
}
.what-is-kiso .how-step p { margin: 0; font-size: 16px; }
.what-is-kiso .method-line {
  margin: 22px 0;
  border-radius: 16px;
  background: var(--pro-soft, var(--surface-soft));
  padding: 18px;
  color: var(--pro-tx, var(--text));
  font-weight: 800;
  letter-spacing: .025em;
}
.what-is-kiso .closing-line { color: var(--pro-tx, var(--text)); font-weight: 700; }
.what-is-kiso .what-share-link { display: inline-flex; min-height: 44px; align-items: center; margin-left: 12px; font-weight: 700; }

.public-what-page .what-is-kiso { margin-top: 18px; }
.public-what-page .what-is-kiso h1 { max-width: 18ch; }
.public-what-page .what-share-link { display: none; }

@media (max-width: 600px) {
  .what-is-kiso { margin: 26px 0 44px; padding: 24px 18px; border-radius: 24px; }
  .what-is-kiso .how-body { padding: 16px 12px; }
  .what-is-kiso .how-step { grid-template-columns: 38px minmax(0, 1fr); gap: 10px; padding: 14px 12px; }
  .what-is-kiso .how-step::before { width: 36px; height: 36px; }
  .what-is-kiso .try-lesson1 { width: 100%; }
  .what-is-kiso .what-share-link { width: 100%; justify-content: center; margin: 2px 0 0; }
}

@media (prefers-reduced-motion: reduce) {
  .what-is-kiso * { scroll-behavior: auto; }
}