.sbk-lesson {
  --sbk-ink: #151816;
  --sbk-line: #b9b4aa;
  --sbk-paper: #f3eee4;
  --sbk-card: #faf8f2;
  --sbk-accent: #e88c1f;
  max-width: 1180px;
  margin: 0 auto;
  padding: 0 28px 100px;
  color: var(--sbk-ink);
}
.sbk-course-bar {
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 24px;
  margin: 0 -28px;
  padding: 18px 28px;
  border-bottom: 4px solid var(--sbk-accent);
  background: #f8f4eb;
}
.sbk-course-brand {
  color: var(--sbk-ink);
  font-size: 1.05rem;
  font-weight: 900;
  text-decoration: none;
}
.sbk-course-nav {
  display: flex;
  align-items: center;
  gap: 28px;
}
.sbk-course-nav a {
  padding: 8px 0;
  border-bottom: 2px solid transparent;
  color: var(--sbk-ink);
  font-weight: 800;
  text-decoration: none;
}
.sbk-course-nav a.active { border-color: var(--sbk-ink); }
.sbk-hero {
  padding: clamp(58px, 8vw, 100px) 0 40px;
  border-bottom: 1px solid #d2ccc1;
}
.sbk-meta,
.sbk-kicker {
  margin: 0;
  font-size: .78rem;
  font-weight: 900;
  letter-spacing: .13em;
  text-transform: uppercase;
}
.sbk-hero h1 {
  max-width: 960px;
  margin: 28px 0 0;
  font-size: clamp(2.2rem, 4.8vw, 4rem);
  line-height: 1.13;
  letter-spacing: -.055em;
  word-break: keep-all;
}
.sbk-subtitle {
  max-width: 900px;
  margin: 24px 0 0;
  font-size: clamp(1.15rem, 2.1vw, 1.55rem);
  line-height: 1.6;
  word-break: keep-all;
}
.sbk-goal {
  display: grid;
  grid-template-columns: 120px minmax(0, 1fr) auto;
  gap: 24px;
  align-items: start;
  margin-top: 38px;
  padding: 22px 0 0;
  border-top: 1px solid #d2ccc1;
}
.sbk-goal p { margin: 0; line-height: 1.7; }
.sbk-goal span {
  padding: 7px 11px;
  border: 1px solid var(--sbk-line);
  border-radius: 999px;
  font-size: .78rem;
  font-weight: 800;
  white-space: nowrap;
}
.sbk-step-nav {
  display: grid;
  grid-template-columns: repeat(4, 1fr);
  margin-top: 32px;
  border: 1px solid #262826;
}
.sbk-step-nav a {
  min-height: 96px;
  padding: 22px 16px 16px;
  border-right: 1px solid #c8c2b8;
  border-bottom: 1px solid #c8c2b8;
  background: rgba(255, 255, 255, .28);
  color: var(--sbk-ink);
  text-decoration: none;
}
.sbk-step-nav a:nth-child(4n) { border-right: 0; }
.sbk-step-nav a:nth-child(n+5) { border-bottom: 0; }
.sbk-step-nav span {
  display: block;
  margin-bottom: 8px;
  color: var(--sbk-accent);
  font-family: Georgia, serif;
  font-size: 1.55rem;
  font-weight: 900;
}
.sbk-step-nav b { font-size: .92rem; }
.sbk-step-nav a:hover,
.sbk-step-nav a.active { background: #fff; }
.sbk-body { padding-top: 48px; }
.sbk-step {
  scroll-margin-top: 28px;
  margin-top: 42px;
  padding: clamp(34px, 5vw, 62px);
  border: 1px solid #d2ccc1;
  background: rgba(255, 255, 255, .5);
}
.sbk-step:first-child { margin-top: 0; }
.sbk-step-head { margin-bottom: 30px; }
.sbk-kicker { color: #a94f20; }
.sbk-step-head h2 {
  max-width: 930px;
  margin: 13px 0 0;
  font-size: clamp(1.7rem, 3vw, 2.6rem);
  line-height: 1.25;
  letter-spacing: -.04em;
  word-break: keep-all;
}
.sbk-step-intro { margin: -10px 0 28px; line-height: 1.75; }
.sbk-today-card {
  padding: clamp(28px, 5vw, 52px);
  border-top: 4px solid var(--sbk-accent);
  background: #fff;
}
.sbk-today-card h3 {
  max-width: 920px;
  margin: 0;
  font-size: clamp(1.65rem, 3.4vw, 2.75rem);
  line-height: 1.35;
  letter-spacing: -.04em;
  word-break: keep-all;
}
.sbk-today-card > p { margin: 22px 0 0; font-size: 1.05rem; line-height: 1.75; }
.sbk-start-example {
  display: grid;
  grid-template-columns: 120px 1fr;
  gap: 20px;
  margin-top: 28px;
  padding: 22px;
  background: #f3eee4;
}
.sbk-start-example p { margin: 0; line-height: 1.65; }
.sbk-card-grid { display: grid; gap: 18px; }
.sbk-content-card {
  padding: 26px 28px;
  border: 1px solid #d2ccc1;
  background: #fff;
}
.sbk-card-head { display: flex; align-items: baseline; gap: 14px; margin-bottom: 15px; }
.sbk-card-head span { color: var(--sbk-accent); font-weight: 900; }
.sbk-card-head h3 { margin: 0; font-size: 1.18rem; line-height: 1.45; }
.sbk-detail-row {
  display: grid;
  grid-template-columns: minmax(140px, 230px) 1fr;
  gap: 20px;
  padding: 10px 0;
  border-top: 1px solid #ece7de;
}
.sbk-detail-row:first-of-type { border-top: 0; }
.sbk-detail-row--full { grid-template-columns: minmax(0, 1fr); }
.sbk-detail-row b { font-size: .9rem; }
.sbk-detail-row p { margin: 0; line-height: 1.7; }
.sbk-answer { margin-top: 18px; border: 1px solid #c7c1b6; }
.sbk-answer summary {
  padding: 15px 18px;
  background: #f1eee6;
  font-weight: 900;
  cursor: pointer;
  list-style-position: inside;
}
.sbk-answer[open] summary { border-bottom: 1px solid #d5cfc4; }
.sbk-answer-body { padding: 12px 18px 16px; }
.sbk-change-grid .sbk-content-card { border-left: 5px solid #187969; }
.sbk-change-grid .sbk-detail-row p { font-size: 1.02rem; }
.sbk-reading-divider {
  margin: 16px 0 0;
  padding: 18px 0 4px;
  border-top: 3px solid var(--sbk-accent);
  font-size: 1.35rem;
}
.sbk-word-grid { display: grid; grid-template-columns: repeat(2, minmax(0, 1fr)); gap: 18px; }
.sbk-word-card,
.sbk-word-empty {
  min-width: 0;
  padding: 26px 28px;
  border: 1px solid #d2ccc1;
  background: #fff;
}
.sbk-word-head { display: flex; align-items: baseline; gap: 10px; }
.sbk-word-head span { color: var(--sbk-accent); font-weight: 900; }
.sbk-word-head h3 { margin: 0; font-size: 1.4rem; }
.sbk-word-head em { margin-left: auto; color: #686d68; font-size: .8rem; font-style: normal; }
.sbk-word-surface,
.sbk-word-definition,
.sbk-word-note,
.sbk-word-example { margin: 13px 0 0; line-height: 1.65; }
.sbk-word-note { color: #5c625e; }
.sbk-word-example { padding: 13px 15px; background: #f4f0e8; }
.sbk-word-card small { display: inline-block; margin-top: 12px; color: #a94f20; font-weight: 800; }
.sbk-loading { grid-column: 1 / -1; padding: 35px; text-align: center; background: #fff; }
.sbk-close {
  display: flex;
  justify-content: space-between;
  gap: 26px;
  margin-top: 42px;
  padding: 28px 0 0;
  border-top: 1px solid #cfc9be;
}
.sbk-close p { max-width: 720px; margin: 0; color: #606560; }
@media (max-width: 760px) {
  .sbk-lesson { padding: 0 14px 70px; }
  .sbk-course-bar { margin: 0 -14px; padding: 15px 14px; }
  .sbk-course-nav { gap: 14px; }
  .sbk-hero { padding-top: 48px; }
  .sbk-goal,
  .sbk-start-example,
  .sbk-detail-row { grid-template-columns: 1fr; gap: 7px; }
  .sbk-goal span { justify-self: start; }
  .sbk-step-nav { grid-template-columns: repeat(2, 1fr); }
  .sbk-step-nav a:nth-child(2n) { border-right: 0; }
  .sbk-step-nav a:nth-child(4) { border-right: 0; border-bottom: 1px solid #c8c2b8; }
  .sbk-step-nav a:nth-child(5),
  .sbk-step-nav a:nth-child(6) { border-bottom: 1px solid #c8c2b8; }
  .sbk-step { margin-top: 24px; padding: 28px 18px; }
  .sbk-content-card,
  .sbk-word-card { padding: 22px 18px; }
  .sbk-word-grid { grid-template-columns: 1fr; }
  .sbk-close { display: block; }
  .sbk-close p { margin-top: 8px; }
}