.equation-page {
    --eq-blue: #1e3a5f;
    --eq-purple: #7457c8;
    --eq-teal: #15979a;
    --eq-yellow: #f4b942;
    --eq-orange: #ef8354;
    --eq-green: #36a269;
    --eq-red: #c94b55;
    --eq-ink: #19324d;
    --eq-muted: #60758b;
    --eq-border: #d8e4eb;
}

.equation-page h1,
.equation-page h2,
.equation-page p { color: var(--eq-ink); }
.equation-page .memory-section__card h2 { color: #fff; }

.equation-progress { margin: 1.25rem 0 2rem; padding: 1rem 1.25rem; background: #fff; border: 1px solid var(--eq-border); border-radius: 18px; box-shadow: 0 10px 30px rgba(30, 58, 95, .07); }
.equation-progress__text { display: flex; justify-content: space-between; gap: 1rem; margin-bottom: .7rem; color: var(--eq-muted); font-size: .92rem; }
.equation-progress__text strong { color: var(--eq-blue); }
.equation-progress__track { height: 10px; overflow: hidden; background: #e8eef2; border-radius: 999px; }
.equation-progress__fill { display: block; height: 100%; background: linear-gradient(90deg, var(--eq-purple), var(--eq-yellow)); border-radius: inherit; }
.equation-progress__fill--1 { width: 8.333%; }
.equation-progress__fill--2 { width: 16.666%; }
.equation-progress__fill--3 { width: 25%; }
.equation-progress__fill--4 { width: 33.333%; }
.equation-progress__fill--5 { width: 41.666%; }
.equation-progress__fill--6 { width: 50%; }
.equation-progress__fill--7 { width: 58.333%; }
.equation-progress__fill--8 { width: 66.666%; }
.equation-progress__fill--9 { width: 75%; }
.equation-progress__fill--10 { width: 83.333%; }
.equation-progress__fill--11 { width: 91.666%; }
.equation-progress__fill--12 { width: 100%; }

.equation-hero { display: grid; grid-template-columns: 1.1fr .9fr; align-items: center; gap: clamp(2rem, 5vw, 4rem); padding: clamp(2rem, 5vw, 4rem); background: linear-gradient(135deg, #f4f0ff, #ecfbf8); border: 1px solid #ddd6f4; border-radius: 30px; }
.equation-heading { max-width: 860px; margin: 2.5rem auto; text-align: center; }
.equation-heading h1,
.equation-hero h1 { margin: .25rem 0 1rem; color: var(--eq-blue); font-size: clamp(2rem, 5vw, 3.35rem); line-height: 1.08; }
.equation-lead { font-size: clamp(1.08rem, 2vw, 1.3rem); line-height: 1.65; }
.equation-callout,
.equation-warning { display: flex; align-items: flex-start; gap: .9rem; margin-top: 1.4rem; padding: 1rem 1.2rem; background: #fff; border-left: 5px solid var(--eq-yellow); border-radius: 12px; }
.equation-callout span,
.equation-warning span { font-size: 1.55rem; }
.equation-callout p,
.equation-warning p { margin: 0; }

.mystery-box { display: grid; place-items: center; min-height: 280px; }
.mystery-box__card { display: grid; place-items: center; width: 190px; height: 190px; color: #fff; background: linear-gradient(135deg, var(--eq-purple), #9578e6); border-radius: 34px; box-shadow: 0 22px 45px rgba(116, 87, 200, .25); transform: rotate(3deg); }
.mystery-box__card strong { font-size: 6rem; line-height: 1; }
.mystery-box__card span { font-weight: 800; }

.equation-card-grid,
.equation-method-grid,
.equation-traps { display: grid; grid-template-columns: repeat(2, minmax(0, 1fr)); gap: 1.2rem; margin: 2rem 0; }
.equation-card-grid article,
.equation-method-grid article,
.equation-traps article { padding: 1.7rem; }
.equation-card-grid h2,
.equation-method-grid h2,
.equation-traps h2 { margin: .5rem 0; }
.equation-icon { font-size: 2rem; }

.equation-anatomy { display: grid; grid-template-columns: 1fr auto 1fr; align-items: center; gap: 1rem; max-width: 820px; margin: 2rem auto; }
.equation-anatomy__member { padding: 1.8rem; background: #fff; border: 2px solid var(--eq-border); border-radius: 20px; text-align: center; }
.equation-anatomy__member strong { display: block; color: var(--eq-purple); font-size: clamp(2rem, 5vw, 3rem); }
.equation-anatomy__member span { color: var(--eq-muted); font-weight: 750; }
.equation-anatomy__equal { color: var(--eq-orange); font-size: 3rem; font-weight: 900; }

.equation-balance { max-width: 900px; margin: 2rem auto; padding: clamp(1.5rem, 5vw, 3rem); background: linear-gradient(180deg, #f4f0ff, #fff); border: 2px solid #d9cff5; border-radius: 28px; }
.equation-balance__pans { display: grid; grid-template-columns: 1fr auto 1fr; align-items: end; gap: 1.2rem; }
.equation-balance__pan { display: grid; place-items: center; min-height: 145px; padding: 1rem; background: #fff; border: 5px solid var(--eq-purple); border-radius: 15px 15px 45px 45px; box-shadow: 0 12px 25px rgba(30, 58, 95, .1); }
.equation-balance__pan strong { color: var(--eq-blue); font-size: clamp(2rem, 5vw, 3rem); }
.equation-balance__pivot { display: grid; place-items: center; width: 80px; height: 80px; color: #fff; background: var(--eq-purple); border-radius: 50%; font-size: 2.6rem; font-weight: 900; }
.equation-balance__beam { height: 12px; margin: -7px 6% 0; background: var(--eq-blue); border-radius: 999px; transform: rotate(0deg); transition: transform .3s ease; }
.equation-balance__base { width: 0; height: 0; margin: auto; border-right: 60px solid transparent; border-bottom: 95px solid var(--eq-blue); border-left: 60px solid transparent; }
.equation-balance__action { margin-top: 1.5rem; text-align: center; }
.equation-balance__action button.is-used { color: #155b36; background: #e8f8ef; border-color: var(--eq-green); }
.equation-balance__message { margin-top: 1rem; padding: .9rem 1rem; color: #155b36; background: #e8f8ef; border-left: 5px solid var(--eq-green); border-radius: 12px; font-weight: 750; }

.equation-rule { display: grid; grid-template-columns: auto 1fr; align-items: center; gap: 1.2rem; max-width: 820px; margin: 2rem auto; padding: 1.5rem; background: #fff; border: 1px solid var(--eq-border); border-radius: 20px; }
.equation-rule__operation { display: grid; place-items: center; min-width: 105px; min-height: 105px; color: #fff; background: linear-gradient(135deg, var(--eq-purple), #9274df); border-radius: 22px; font-size: 1.6rem; font-weight: 900; }
.equation-rule h2,
.equation-rule p { margin: .2rem 0; }
.equation-calculation { display: flex; flex-wrap: wrap; justify-content: center; align-items: center; gap: .8rem; margin-top: 1rem; color: var(--eq-blue); font-size: clamp(1.25rem, 3vw, 1.8rem); font-weight: 900; }
.equation-calculation span { padding: .5rem .8rem; background: #f2effb; border-radius: 10px; }

.equation-page .interactive-lesson { margin-top: 2.5rem; }
.equation-question-list { display: grid; gap: 1.1rem; }
.equation-question { padding: clamp(1.35rem, 4vw, 2.25rem); background: #fff; border: 2px solid var(--eq-border); border-radius: 20px; transition: border-color .2s ease, box-shadow .2s ease; }
.equation-question.is-complete { border-color: #7bcf9c; box-shadow: 0 10px 25px rgba(54, 162, 105, .1); }
.equation-question h2 { font-size: 1.2rem; }
.equation-question__number { margin: 0 0 .25rem; color: var(--eq-purple) !important; font-size: .8rem; font-weight: 800; text-transform: uppercase; letter-spacing: .08em; }
.equation-choices { display: grid; grid-template-columns: repeat(auto-fit, minmax(160px, 1fr)); gap: .8rem; margin-top: 1.2rem; }
.equation-choices--small { grid-template-columns: repeat(2, minmax(160px, 260px)); }
.equation-choices button { min-height: 58px; padding: .85rem 1rem; color: var(--eq-blue); background: #f8fafd; border: 2px solid #cfdce5; border-radius: 14px; font: inherit; font-weight: 750; cursor: pointer; transition: transform .15s ease, border-color .15s ease, background .15s ease; }
.equation-choices button:hover:not(:disabled),
.equation-choices button:focus-visible { transform: translateY(-2px); border-color: var(--eq-purple); background: #f1edff; }
.equation-choices button.is-wrong { border-color: var(--eq-red); background: #fff0f1; animation: equation-shake .25s linear; }
.equation-choices button.is-correct { color: #155b36; border-color: var(--eq-green); background: #e8f8ef; }
.equation-choices button:disabled { cursor: default; opacity: .72; }
.equation-choices button.is-correct:disabled { opacity: 1; }
.activity-feedback { margin-top: 1rem; padding: .9rem 1rem; border-radius: 12px; font-weight: 750; }
.activity-feedback.is-success { color: #155b36; background: #e8f8ef; border-left: 5px solid var(--eq-green); }
.activity-feedback.is-error { color: #8d2530; background: #fff0f1; border-left: 5px solid var(--eq-red); }

.equation-input-label { display: flex; flex-wrap: wrap; align-items: center; gap: .7rem; margin-bottom: 1rem; color: var(--eq-blue); font-size: 1.08rem; font-weight: 800; }
.equation-number-input { width: 120px; padding: .7rem .85rem; color: var(--eq-blue); background: #fff; border: 2px solid #b9ced7; border-radius: 10px; font: inherit; font-size: 1.1rem; }
.equation-number-input:focus { outline: 3px solid rgba(116, 87, 200, .18); border-color: var(--eq-purple); }
.equation-number-input.is-wrong { border-color: var(--eq-red); background: #fff5f5; }
.equation-number-input.is-correct { border-color: var(--eq-green); background: #eefbf3; }

.equation-steps { display: grid; gap: 1rem; max-width: 840px; margin: 2rem auto; }
.equation-steps article { display: flex; align-items: center; gap: 1.2rem; padding: 1.3rem 1.5rem; background: #fff; border: 1px solid var(--eq-border); border-radius: 18px; }
.equation-steps article > span { display: grid; flex: 0 0 46px; width: 46px; height: 46px; place-items: center; color: #fff; background: var(--eq-purple); border-radius: 50%; font-weight: 900; }
.equation-steps h2,
.equation-steps p { margin: 0; }

.verification-table { max-width: 700px; margin: 2rem auto; padding: 1.7rem; background: #fff; border: 1px solid var(--eq-border); border-radius: 20px; }
.verification-table__line { display: flex; justify-content: space-between; gap: 1rem; padding: .75rem; border-bottom: 1px solid var(--eq-border); }
.verification-table__line:last-child { border-bottom: 0; }
.verification-table__line strong { color: var(--eq-purple); }
.equation-traps .is-wrong-example { border-top: 5px solid var(--eq-red); }
.equation-traps .is-right-example { border-top: 5px solid var(--eq-green); }

.equation-problem { margin: 2rem 0; padding: clamp(1.5rem, 5vw, 3rem); border-top: 6px solid var(--eq-yellow); }
.equation-problem h2 { max-width: 800px; margin: 1rem 0; }
.equation-problem li { margin: .6rem 0; color: var(--eq-ink); }
.equation-score { display: flex; align-items: center; gap: 1rem; margin: 1.5rem 0; padding: 1.2rem 1.5rem; color: #fff; background: linear-gradient(135deg, var(--eq-blue), var(--eq-purple)); border-radius: 18px; }
.equation-score > span { font-size: 2.2rem; }
.equation-score p { margin: 0; color: #eee9ff; }
.equation-score strong { font-size: 1.2rem; }
.equation-score.is-complete { background: linear-gradient(135deg, #247a4b, var(--eq-green)); }
.equation-correction { margin-top: 1.5rem; padding: 1.25rem 1.5rem; }
.equation-correction summary { color: var(--eq-blue); font-size: 1.1rem; font-weight: 800; cursor: pointer; }
.equation-correction details div { padding-top: .7rem; }
.equation-navigation { display: flex; justify-content: space-between; gap: 1rem; margin: 3rem 0 1rem; padding-top: 1.5rem; border-top: 1px solid var(--eq-border); }

@keyframes equation-shake { 25% { transform: translateX(-4px); } 75% { transform: translateX(4px); } }

@media (max-width: 800px) {
    .equation-hero { grid-template-columns: 1fr; }
    .equation-card-grid,
    .equation-method-grid,
    .equation-traps { grid-template-columns: 1fr; }
    .equation-balance__pans { grid-template-columns: 1fr; }
    .equation-balance__pivot,
    .equation-balance__beam,
    .equation-balance__base { display: none; }
}

@media (max-width: 560px) {
    .equation-progress__text { display: grid; gap: .2rem; }
    .equation-hero { padding: 1.5rem; }
    .equation-anatomy { grid-template-columns: 1fr; }
    .equation-anatomy__equal { text-align: center; }
    .equation-choices,
    .equation-choices--small { grid-template-columns: 1fr; }
    .equation-rule { grid-template-columns: 1fr; text-align: center; }
    .equation-navigation { flex-direction: column-reverse; }
    .equation-navigation .btn { width: 100%; text-align: center; }
}

@media (prefers-reduced-motion: reduce) {
    .equation-page *,
    .equation-page *::before,
    .equation-page *::after { transition: none !important; animation: none !important; }
}