.lesson-hero { color: #fff; background: radial-gradient(circle at 76% 20%, rgba(188,243,108,.19), transparent 22rem), linear-gradient(135deg, var(--forest), #0b2d25 72%, #184d3c); }
.lesson-hero__grid { min-height: 610px; display: grid; grid-template-columns: 1.1fr .9fr; gap: clamp(2rem, 7vw, 6rem); align-items: center; padding-block: clamp(4rem, 8vw, 7rem); }
.lesson-hero h2 { color: #fff; font-size: clamp(3.2rem, 7vw, 6.7rem); }
.lesson-hero h2 span { color: var(--lime); }
.lesson-takeaway { margin-top: 2.2rem; padding-left: 1.2rem; border-left: 4px solid var(--lime); }
.lesson-takeaway span, .lesson-takeaway strong { display: block; }
.lesson-takeaway span { color: #b9c9c2; font-size: .76rem; font-weight: 800; letter-spacing: .14em; text-transform: uppercase; }
.lesson-takeaway strong { margin-top: .3rem; font-size: 1.3rem; line-height: 1.3; }
.energy-equation { display: grid; grid-template-columns: 1fr auto 1fr; gap: 1rem; align-items: center; padding: 2rem; border: 1px solid rgba(255,255,255,.16); border-radius: 30px; background: rgba(255,255,255,.08); box-shadow: 0 30px 70px rgba(0,0,0,.22); }
.energy-equation div { display: grid; place-items: center; min-height: 130px; padding: 1rem; border-radius: 20px; background: #fff; color: var(--ink); }
.energy-equation div:last-child { grid-column: 1 / -1; min-height: 150px; background: var(--lime); }
.energy-equation strong { font-size: clamp(2.5rem, 5vw, 4.2rem); line-height: 1; }
.energy-equation span { color: var(--muted); font-size: .8rem; font-weight: 800; letter-spacing: .1em; text-transform: uppercase; }
.energy-equation b { color: var(--lime); font-size: 2rem; }
.plain-definition { display: grid; gap: 1rem; margin-top: 2rem; }
.plain-definition article { display: grid; grid-template-columns: 105px 1fr; gap: 1.5rem; align-items: center; padding: 1.3rem; border: 1px solid var(--line); border-radius: 20px; }
.plain-definition h3, .plain-definition p { margin-bottom: .3rem; }
.unit-mark { display: grid; place-items: center; width: 105px; height: 105px; border-radius: 50%; background: var(--forest); color: var(--lime); font-size: 2rem; font-weight: 900; letter-spacing: -.05em; }
.unit-mark--energy { background: var(--lime); color: var(--forest); }
.power-visuals { display: grid; grid-template-columns: 1fr 1fr; gap: 1rem; }
.power-card { padding: 1.5rem; border-radius: 22px; background: #fff; box-shadow: var(--shadow); }
.power-card > p { margin: 1rem 0 0; text-align: center; font-size: 1.1rem; }
.power-chart { position: relative; height: 250px; padding: 25px 25px 40px 65px; border-left: 2px solid var(--ink); border-bottom: 2px solid var(--ink); }
.power-block { position: absolute; left: 65px; bottom: 40px; display: grid; place-items: center; width: calc(100% - 90px); height: 36%; background: var(--green); color: #fff; border-radius: 8px 8px 0 0; }
.power-block--high { width: calc(50% - 40px); height: 72%; background: var(--forest-2); }
.axis-y { position: absolute; left: 0; top: 50%; transform: translateY(-50%) rotate(-90deg); font-size: .75rem; font-weight: 800; letter-spacing: .1em; text-transform: uppercase; }
.axis-x { position: absolute; left: 65px; right: 20px; bottom: 8px; text-align: center; font-size: .8rem; font-weight: 800; }
.worked-sum { display: grid; grid-template-columns: repeat(5, auto); gap: .65rem; align-items: center; justify-content: center; padding: 2rem; border-radius: 26px; background: var(--forest); color: #fff; box-shadow: var(--shadow); }
.worked-sum span, .worked-sum strong { padding: .7rem; border-radius: 12px; background: rgba(255,255,255,.1); font-size: clamp(1.3rem, 3vw, 2.2rem); }
.worked-sum strong { background: var(--lime); color: var(--forest); }
.worked-sum b { color: var(--lime); font-size: 1.6rem; }
.worked-sum p { grid-column: 1 / -1; margin: .6rem 0 0; color: #cbd9d3; text-align: center; }
.myth-section blockquote { margin: 0; color: var(--lime); font-size: clamp(2rem, 4vw, 3.6rem); font-weight: 850; line-height: 1.12; letter-spacing: -.04em; }
.myth-section p { color: #cbd9d3; font-size: 1.12rem; }
.big-formula { display: flex; flex-wrap: wrap; gap: .7rem; align-items: center; margin: 2rem 0; font-size: clamp(1.4rem, 4vw, 2.4rem); font-weight: 850; }
.big-formula span, .big-formula strong { padding: .7rem 1rem; border-radius: 13px; background: #edf3ef; }
.big-formula strong { background: var(--lime); }
.safety-box { margin-top: 2rem; }
.safety-box .eyebrow { color: var(--danger); }
.safety-box h2 { font-size: clamp(1.7rem, 3vw, 2.5rem); }
.lesson-version { margin-top: 2rem; color: var(--muted); font-size: .8rem; text-align: center; }
.advanced-coming { display: grid; grid-template-columns: auto 1fr; gap: 1rem; align-items: start; margin-top: 1.5rem; padding: 1.1rem; border: 1px dashed #8fa79d; border-radius: 14px; background: #eef4f1; }
.advanced-coming > span { padding: .35rem .5rem; border-radius: 999px; background: #fff0c7; color: #714d00; font-size: .64rem; font-weight: 900; letter-spacing: .09em; white-space: nowrap; }
.advanced-coming h3 { margin: .1rem 0 .35rem; font-size: 1.05rem; }
.advanced-coming p { margin: 0; color: var(--muted); font-size: .92rem; }
.knowledge-gate { position: relative; overflow: hidden; padding: clamp(1.5rem, 4vw, 2.7rem); border: 1px solid #a9bbb3; border-radius: 24px; background: #f8fbf9; box-shadow: var(--shadow); }
.knowledge-gate::before { content: ""; position: absolute; right: -90px; top: -110px; width: 260px; height: 260px; border-radius: 50%; background: rgba(188,243,108,.22); }
.knowledge-gate__lock { position: relative; display: inline-flex; margin-bottom: 1rem; padding: .42rem .7rem; border-radius: 999px; background: var(--forest); color: var(--lime); font-size: .7rem; font-weight: 950; letter-spacing: .13em; }
.knowledge-gate > div { position: relative; }
.gate-steps { display: grid; gap: .75rem; margin-top: 1.7rem; }
.gate-steps article { display: grid; grid-template-columns: 42px 1fr; gap: 1rem; align-items: start; padding: 1rem; border: 1px solid var(--line); border-radius: 14px; background: #fff; }
.gate-steps article > span { display: grid; place-items: center; width: 42px; height: 42px; border-radius: 50%; background: var(--forest); color: var(--lime); font-weight: 900; }
.gate-steps h3 { margin: .12rem 0 .25rem; font-size: 1.04rem; }
.gate-steps p { margin: 0; color: var(--muted); font-size: .9rem; }
.gate-action { margin-top: 1.2rem; padding-top: 1.2rem; border-top: 1px solid var(--line); }
.gate-action .button:disabled { opacity: .62; cursor: not-allowed; }
.gate-action p { margin: .7rem 0 0; color: var(--muted); font-size: .82rem; }
.quiz { margin-top: 2rem; }
.quiz__meta { display: flex; flex-wrap: wrap; justify-content: space-between; gap: .5rem 1rem; margin-bottom: 1rem; padding: .85rem 1rem; border-radius: 12px; background: #edf3ef; color: var(--muted); font-size: .82rem; font-weight: 750; }
.quiz__questions { display: grid; gap: 1rem; }
.quiz-question { margin: 0; padding: 1.25rem; border: 1px solid var(--line); border-radius: 18px; background: #fff; }
.quiz-question legend { width: 100%; padding: 0; font-size: 1.05rem; font-weight: 850; line-height: 1.4; }
.quiz-question__top { display: flex; gap: .8rem; align-items: flex-start; margin-bottom: .9rem; }
.quiz-question__number { display: grid; place-items: center; flex: 0 0 38px; height: 38px; border-radius: 50%; background: var(--forest); color: var(--lime); font-weight: 900; }
.quiz-question__instruction { display: block; margin: .15rem 0 0 3rem; color: var(--muted); font-size: .78rem; font-weight: 700; }
.quiz-options { display: grid; gap: .6rem; margin-top: 1rem; }
.quiz-option { position: relative; display: grid; grid-template-columns: 24px 1fr; gap: .75rem; align-items: start; padding: .8rem .9rem; border: 1px solid var(--line); border-radius: 12px; cursor: pointer; transition: border-color .15s ease, background .15s ease; }
.quiz-option:hover { border-color: var(--green); background: #f7fbf9; }
.quiz-option input { width: 19px; height: 19px; margin: .12rem 0 0; accent-color: var(--green); }
.quiz-option span { line-height: 1.45; }
.quiz-question--missing { border-color: var(--danger); background: #fff7f5; }
.quiz-question--correct { border-color: var(--green); background: #f3fbf7; }
.quiz-question--wrong { border-color: var(--danger); background: #fff7f5; }
.quiz-feedback { margin: 1rem 0 0; padding: .85rem 1rem; border-radius: 10px; background: rgba(255,255,255,.8); font-size: .9rem; }
.quiz-feedback strong { display: block; margin-bottom: .25rem; }
.quiz-feedback p { margin: .35rem 0 0; }
.quiz-answer-list { margin: .35rem 0 0; padding-left: 1.2rem; }
.quiz__actions { display: flex; flex-wrap: wrap; gap: .7rem; margin-top: 1.25rem; }
.quiz__new { background: #fff; color: var(--ink); }
.quiz__actions .button:disabled { opacity: .48; cursor: not-allowed; transform: none; }
.quiz-result { margin-top: 1.25rem; padding: clamp(1.4rem, 4vw, 2.2rem); border-radius: 20px; background: var(--forest); color: #fff; outline: none; }
.quiz-result h3 { color: var(--lime); font-size: clamp(1.7rem, 4vw, 2.6rem); }
.quiz-result p { color: #d2dfd9; }
.quiz-result__score { display: block; margin-bottom: .35rem; color: #fff; font-size: clamp(2.2rem, 6vw, 4.3rem); font-weight: 950; line-height: 1; letter-spacing: -.05em; }
.topic-picker { padding-block: clamp(1.6rem, 4vw, 2.8rem); border-bottom: 1px solid var(--line); background: #fff; }
.topic-picker__heading { display: grid; grid-template-columns: minmax(0, .8fr) minmax(280px, 1.2fr); gap: 1.5rem; align-items: end; margin-bottom: 1.2rem; }
.topic-picker__heading h2, .topic-picker__heading p { margin-bottom: 0; }
.topic-picker__heading > p { color: var(--muted); }
.topic-picker__grid { display: grid; grid-template-columns: repeat(4, minmax(0, 1fr)); gap: .65rem; }
.topic-choice { position: relative; display: grid; grid-template-columns: 2.1rem 1fr; gap: .1rem .65rem; min-height: 82px; padding: .85rem; border: 1px solid var(--line); border-radius: 14px; background: #f8fbf9; color: var(--ink); text-decoration: none; }
a.topic-choice { transition: transform .15s ease, border-color .15s ease, box-shadow .15s ease; }
a.topic-choice:hover { transform: translateY(-2px); border-color: var(--green); box-shadow: 0 10px 24px rgba(8,46,37,.1); }
.topic-choice__number { grid-row: 1 / span 2; display: grid; place-items: center; align-self: start; width: 2.1rem; height: 2.1rem; border-radius: 50%; background: var(--forest); color: var(--lime); font-size: .78rem; font-weight: 900; }
.topic-choice__title { align-self: end; font-size: .88rem; font-weight: 850; line-height: 1.25; }
.topic-choice small { color: var(--muted); font-size: .7rem; font-weight: 750; }
.topic-choice--current { border-color: var(--green); background: var(--forest); color: #fff; box-shadow: 0 12px 30px rgba(8,46,37,.16); }
.topic-choice--current .topic-choice__number { background: var(--lime); color: var(--forest); }
.topic-choice--current small { color: #c8d8d1; }
.topic-choice--locked { opacity: .68; }
.lesson-hero--capacity { background: radial-gradient(circle at 77% 20%, rgba(247,184,65,.2), transparent 22rem), linear-gradient(135deg, var(--forest), #0b2d25 68%, #315f3c); }
.capacity-flow { display: grid; grid-template-columns: 1fr auto 1fr auto 1fr; gap: 1rem; align-items: center; }
.capacity-flow article { min-height: 245px; padding: 1.35rem; border: 1px solid var(--line); border-radius: 22px; background: #fff; box-shadow: var(--shadow); }
.capacity-flow article > span { display: grid; place-items: center; width: 34px; height: 34px; margin-bottom: 1.2rem; border-radius: 50%; background: var(--forest); color: var(--lime); font-weight: 900; }
.capacity-flow small, .capacity-flow strong { display: block; }
.capacity-flow small { color: var(--muted); font-weight: 800; letter-spacing: .07em; text-transform: uppercase; }
.capacity-flow strong { margin: .4rem 0 .8rem; color: var(--forest); font-size: clamp(1.5rem, 3vw, 2.35rem); line-height: 1; }
.capacity-flow p { margin: 0; color: var(--muted); }
.capacity-flow > b { color: var(--green); font-size: 2rem; }
.scenario-note { margin: 1.2rem 0 0; color: var(--muted); font-size: .88rem; text-align: center; }
.configuration-grid { display: grid; grid-template-columns: repeat(3, 1fr); gap: 1rem; margin: 2rem 0; }
.configuration-grid article { padding: 1.35rem; border-radius: 18px; background: var(--forest); color: #fff; text-align: center; }
.configuration-grid strong, .configuration-grid span { display: block; }
.configuration-grid strong { color: var(--lime); font-size: clamp(1.65rem, 3vw, 2.4rem); }
.configuration-grid span { margin-top: .35rem; color: #d2dfd9; }

@media (max-width: 850px) {
  .lesson-hero__grid, .power-visuals, .configuration-grid { grid-template-columns: 1fr; }
  .topic-picker__grid { grid-template-columns: repeat(2, minmax(0, 1fr)); }
  .energy-equation { max-width: 560px; }
  .capacity-flow { grid-template-columns: 1fr; }
  .capacity-flow article { min-height: auto; }
  .capacity-flow > b { transform: rotate(90deg); text-align: center; }
}

@media (max-width: 650px) {
  .lesson-hero__grid { min-height: auto; }
  .topic-picker__heading, .topic-picker__grid { grid-template-columns: 1fr; }
  .plain-definition article { grid-template-columns: 75px 1fr; gap: 1rem; }
  .unit-mark { width: 75px; height: 75px; font-size: 1.4rem; }
  .worked-sum { grid-template-columns: repeat(3, auto); }
  .worked-sum b:nth-of-type(2) { display: none; }
  .worked-sum strong { grid-column: 1 / -1; text-align: center; }
  .advanced-coming { grid-template-columns: 1fr; }
  .advanced-coming > span { justify-self: start; }
}