.lesson-source { margin: 26px 0; padding-block: 20px; border-block: 1px solid var(--line); }
.lesson-source > h3 { margin-top: 0; }
.lesson-source > :last-child { margin-bottom: 0; }
.lesson-deck { display: grid; grid-template-columns: repeat(2,minmax(0,1fr)); gap: 18px; list-style: none; margin: 26px 0; padding: 0 !important; }
.lesson-deck > li { min-width: 0; margin: 0 !important; }
.lesson-slide { display: flex; flex-direction: column; gap: 12px; min-height: 260px; height: 100%; padding: 22px; border: 1px solid var(--line); border-radius: 12px; background: var(--paper-bright); color: var(--ink); }
.marketing-article .lesson-slide h3 { margin: 0; font-size: 24px; line-height: 1.25; letter-spacing: -.025em; text-wrap: balance; }
.marketing-article .lesson-slide-main { margin: 0; font-size: 19px; font-weight: 700; line-height: 1.4; font-variant-numeric: tabular-nums; }
.marketing-article .lesson-slide-note { margin: 0; color: var(--ink-soft); font-size: 14px; line-height: 1.5; }
.lesson-slide-number { margin-top: auto; align-self: flex-end; color: var(--ink-soft); font-size: 12px; font-variant-numeric: tabular-nums; }
.lesson-vote-bar { height: 10px; overflow: hidden; background: var(--line); border-radius: 3px; }
.lesson-vote-bar span { display: block; height: 100%; width: 45%; background: var(--orange-dark); }
.lesson-calculation { display: grid; grid-template-columns: repeat(3,minmax(0,1fr)); gap: 18px; margin: 22px 0; font-variant-numeric: tabular-nums; }
.lesson-calculation > div { min-width: 0; padding-top: 14px; border-top: 1px solid var(--line); }
.lesson-calculation span { display: block; font-size: 14px; line-height: 1.5; color: var(--ink-soft); }
.lesson-calculation strong { display: block; margin-block: 8px; font-size: 25px; line-height: 1.3; white-space: nowrap; }
.marketing-article .lesson-calculation p { margin: 0; font-size: 14px; line-height: 1.55; }
.lesson-answer { margin-top: 18px; }
.lesson-answer > summary { min-height: 44px; align-content: center; cursor: pointer; font-weight: 700; color: var(--orange-dark); }
.lesson-answer > summary:focus-visible { outline: 2px solid var(--orange-dark); outline-offset: 4px; }
@media(max-width:640px) {
 .lesson-deck { grid-template-columns: 1fr; gap: 14px; }
 .lesson-slide { min-height: 220px; padding: 20px; gap: 10px; }
 .marketing-article .lesson-slide h3 { font-size: 23px; }
 .lesson-source { margin-block: 22px; padding-block: 17px; }
 .lesson-calculation { grid-template-columns: 1fr; gap: 16px; }
 .lesson-calculation > div { display: grid; grid-template-columns: minmax(0,1fr) auto; align-items: center; gap: 6px 12px; }
 .lesson-calculation strong { margin: 0; font-size: 24px; }
 .lesson-calculation p { grid-column: 1 / -1; }
}