.course-preview-module__8hc9Fa__root{color:#24332f;overflow-wrap:anywhere;min-width:0;font:16px/1.85 system-ui,PingFang SC,Microsoft YaHei,sans-serif}.course-preview-module__8hc9Fa__header{background:#fff;border:1px solid #dde7e3;border-radius:12px;margin-bottom:20px;padding:24px}.course-preview-module__8hc9Fa__header h2{margin:6px 0 10px;font-size:24px;font-weight:650;line-height:1.5}.course-preview-module__8hc9Fa__header p{color:#63746f;margin:0 0 12px;font-size:15px}.course-preview-module__8hc9Fa__header small,.course-preview-module__8hc9Fa__label{color:#63746f;letter-spacing:0;font-size:13px}.course-preview-module__8hc9Fa__label{color:#246d66}.course-preview-module__8hc9Fa__layout{grid-template-columns:220px minmax(0,1fr);align-items:start;gap:20px;display:grid}.course-preview-module__8hc9Fa__directory{background:#fff;border:1px solid #dde7e3;border-radius:12px;max-height:calc(100dvh - 120px);padding:16px 10px;position:sticky;top:96px;overflow-y:auto}.course-preview-module__8hc9Fa__directory p{justify-content:space-between;gap:8px;margin:0 0 12px;padding:0 10px;font-size:14px;font-weight:600;display:flex}.course-preview-module__8hc9Fa__directory p span{color:#63746f;font-size:13px;font-weight:400}.course-preview-module__8hc9Fa__directory ol{margin:0;padding:0;list-style:none}.course-preview-module__8hc9Fa__directory button{text-align:left;color:#465a53;width:100%;font:inherit;cursor:pointer;background:0 0;border:0;border-radius:8px;align-items:baseline;gap:10px;padding:10px;font-size:14px;line-height:1.7;display:flex}.course-preview-module__8hc9Fa__directory button span{color:#63746f;flex:none;font-size:12px}.course-preview-module__8hc9Fa__directory button:hover{background:#f2f7f4}.course-preview-module__8hc9Fa__directory button[aria-current=step]{color:#246d66;background:#eaf5f0;font-weight:600}.course-preview-module__8hc9Fa__article{background:#fff;border:1px solid #dde7e3;border-radius:12px;min-width:0;padding:28px}.course-preview-module__8hc9Fa__chapterHeader{border-bottom:1px solid #dde7e3;margin-bottom:24px;padding-bottom:20px}.course-preview-module__8hc9Fa__chapterHeader>span{color:#63746f;font-size:13px}.course-preview-module__8hc9Fa__chapterHeader h3{margin:6px 0 8px;scroll-margin-top:100px;font-size:20px;font-weight:650;line-height:1.55}.course-preview-module__8hc9Fa__chapterHeader p{color:#63746f;margin:0;font-size:14px}.course-preview-module__8hc9Fa__body{min-width:0}.course-preview-module__8hc9Fa__root .course-preview-module__8hc9Fa__article .course-preview-module__8hc9Fa__body h1{font-size:24px}.course-preview-module__8hc9Fa__root .course-preview-module__8hc9Fa__article .course-preview-module__8hc9Fa__body h2{font-size:22px}.course-preview-module__8hc9Fa__root .course-preview-module__8hc9Fa__article .course-preview-module__8hc9Fa__body h3{font-size:19px}.course-preview-module__8hc9Fa__root .course-preview-module__8hc9Fa__article .course-preview-module__8hc9Fa__body h4{font-size:17px}.course-preview-module__8hc9Fa__root .course-preview-module__8hc9Fa__body h1,.course-preview-module__8hc9Fa__root .course-preview-module__8hc9Fa__body h2,.course-preview-module__8hc9Fa__root .course-preview-module__8hc9Fa__body h3,.course-preview-module__8hc9Fa__root .course-preview-module__8hc9Fa__body h4{letter-spacing:0;margin:20px 0 12px;font-style:normal;line-height:1.6}.course-preview-module__8hc9Fa__root .course-preview-module__8hc9Fa__body p,.course-preview-module__8hc9Fa__root .course-preview-module__8hc9Fa__body li,:is(.course-preview-module__8hc9Fa__body .markdown,.course-preview-module__8hc9Fa__body .rich-math){font-size:16px;line-height:1.85}.course-preview-module__8hc9Fa__body img,.course-preview-module__8hc9Fa__body svg,.course-preview-module__8hc9Fa__body iframe{max-width:100%}.course-preview-module__8hc9Fa__body .katex-display{max-width:100%;padding:4px 0;overflow:auto hidden}:is(.course-preview-module__8hc9Fa__body .teaching-activity,.course-preview-module__8hc9Fa__body .chain-content-section,.course-preview-module__8hc9Fa__body .chain-teachback){background:#fff;border:1px solid #dde7e3;border-radius:10px;margin:16px 0;padding:20px}.course-preview-module__8hc9Fa__body .chain-section-kicker{color:#63746f;letter-spacing:0;font-size:13px;font-style:normal}.course-preview-module__8hc9Fa__body .chain-opening{border:1px solid #dde7e3;border-radius:10px;grid-template-columns:minmax(0,1fr);padding:20px}.course-preview-module__8hc9Fa__body .chain-opening-question strong{font-size:17px}.course-preview-module__8hc9Fa__body .chain-opening-figure{max-width:480px;margin:20px auto 0}.course-preview-module__8hc9Fa__body .chain-lesson-goal{font-size:16px}.course-preview-module__8hc9Fa__body .chain-guiding-question{border-radius:10px;padding:16px}:is(.course-preview-module__8hc9Fa__body .chain-mini-practice,.course-preview-module__8hc9Fa__body .chain-activity,.course-preview-module__8hc9Fa__body .chain-lab){border-radius:10px;margin-block:20px;padding:20px}.course-preview-module__8hc9Fa__body .chain-lab-readout strong{font-size:20px}.course-preview-module__8hc9Fa__body textarea,.course-preview-module__8hc9Fa__body input{max-width:100%;font-size:15px}.course-preview-module__8hc9Fa__body .chain-teachback textarea{background:#fff;border:1px solid #cfdcd6;border-radius:8px;width:100%;margin-top:12px;padding:12px;display:block}.course-preview-module__8hc9Fa__pagination{border-top:1px solid #dde7e3;justify-content:space-between;align-items:center;gap:16px;margin-top:28px;padding-top:24px;display:flex}.course-preview-module__8hc9Fa__pagination span{color:#63746f;font-size:13px}.course-preview-module__8hc9Fa__pagination button{color:#246d66;min-height:44px;font:inherit;cursor:pointer;background:#fff;border:1px solid #dde7e3;border-radius:8px;padding:8px 16px;font-size:14px}.course-preview-module__8hc9Fa__pagination button:disabled{cursor:default;color:#9ba9a2;background:#f7f9f8}.course-preview-module__8hc9Fa__root button:focus-visible,.course-preview-module__8hc9Fa__root a:focus-visible{outline-offset:3px;outline:3px solid #246d66}@media (max-width:1100px){.course-preview-module__8hc9Fa__layout{grid-template-columns:minmax(0,1fr)}.course-preview-module__8hc9Fa__directory{max-height:240px;position:static}.course-preview-module__8hc9Fa__directory ol{grid-template-columns:repeat(2,minmax(0,1fr));display:grid}}@media (max-width:600px){.course-preview-module__8hc9Fa__header,.course-preview-module__8hc9Fa__article{padding:18px 16px}.course-preview-module__8hc9Fa__header h2{font-size:22px}.course-preview-module__8hc9Fa__directory ol{display:block}:is(.course-preview-module__8hc9Fa__body .teaching-activity,.course-preview-module__8hc9Fa__body .chain-content-section,.course-preview-module__8hc9Fa__body .chain-teachback,.course-preview-module__8hc9Fa__body .chain-opening,.course-preview-module__8hc9Fa__body .chain-mini-practice,.course-preview-module__8hc9Fa__body .chain-activity,.course-preview-module__8hc9Fa__body .chain-lab){padding:14px}}
.chain-course{--chain-ink:#273431;--chain-muted:#67736b;--chain-line:#deded1;--chain-paper:#fffefa;--chain-blue:#365c57;--chain-teal:#4b7464;--chain-amber:#a96f3d;min-height:100dvh;color:var(--chain-ink);background:#f5f3ed;padding-bottom:5.5rem;font-family:Noto Sans CJK SC,Microsoft YaHei,PingFang SC,system-ui,sans-serif;font-size:16px;line-height:1.7}.chain-course *,.chain-course :before,.chain-course :after{box-sizing:border-box}.chain-course button,.chain-ai-dialog button{font:inherit;cursor:pointer}.chain-course button,.chain-course a,.chain-course input,.chain-course textarea,.chain-ai-dialog button,.chain-ai-dialog textarea{touch-action:manipulation}.chain-course button:focus-visible,.chain-course textarea:focus-visible,.chain-course a:focus-visible,.chain-course input:focus-visible,.chain-ai-dialog button:focus-visible,.chain-ai-dialog textarea:focus-visible,.chain-ai-dialog a:focus-visible,.rich-math__table-scroll:focus-visible{outline-offset:3px;outline:3px solid #f1ad43}.chain-skip-link{z-index:60;color:var(--chain-blue);background:#fff;padding:.65rem .9rem;font-weight:800;position:fixed;top:.5rem;left:.5rem;transform:translateY(-150%)}.chain-skip-link:focus{transform:translateY(0)}.chain-topbar{border-bottom:1px solid var(--chain-line);background:#fbfaf6;justify-content:space-between;align-items:center;gap:1rem;min-height:4.25rem;padding:.75rem clamp(1rem,4vw,4rem);display:flex}.chain-brand{letter-spacing:.02em;align-items:center;gap:.7rem;font-weight:800;display:flex}.chain-brand-mark{background:var(--chain-blue);color:#fff;border-radius:50%;place-items:center;width:2rem;height:2rem;font-family:Georgia,serif;font-size:1.4rem;display:grid}.chain-topbar-meta{color:var(--chain-muted);font-size:.875rem}.chain-topbar-right,.chain-account{flex-wrap:wrap;align-items:center;gap:.5rem 1rem;display:flex}.chain-account{color:var(--chain-muted);font-size:.875rem}.chain-account .button--quiet,.chain-login-link,.chain-home-link{color:var(--chain-blue);letter-spacing:0;text-underline-offset:.2em;text-transform:none;font-size:.875rem;font-weight:800;text-decoration:underline}.chain-login-link,.chain-home-link{align-items:center;min-height:2.75rem;display:inline-flex}.chain-offline-notice{color:#563910;background:#fff3dc;border-left:4px solid #a96f3d;margin:1rem clamp(1rem,4vw,4rem) 0;padding:.75rem 1rem}.chain-local-banner{background:#fffefa;border:1px solid #b6c9c0;max-width:52rem;padding:1.5rem}.chain-local-banner p{margin:0 0 1rem}.chain-local-banner{max-width:none;margin:1rem clamp(1rem,4vw,4rem) 0}.chain-local-actions{flex-wrap:wrap;gap:.75rem;display:flex}.chain-local-actions button{border:1px solid var(--chain-blue);background:var(--chain-blue);color:#fff;min-height:2.75rem;padding:.5rem .85rem}.chain-local-actions button+button{color:var(--chain-blue);background:0 0}.chain-local-actions button:disabled{cursor:wait;opacity:.6}.chain-hero{border-bottom:1px solid var(--chain-line);background:linear-gradient(135deg,#fefbf5,#e9f0f1);grid-template-columns:minmax(0,1.15fr) minmax(17rem,.85fr);align-items:end;gap:clamp(2rem,5vw,5rem);padding:clamp(3rem,6vw,6rem) clamp(1rem,6vw,6rem);display:grid}.chain-eyebrow{color:var(--chain-teal);letter-spacing:.17em;text-transform:uppercase;margin:0 0 1rem;font-size:.78rem;font-weight:800}.chain-hero h1{letter-spacing:-.04em;margin:0;font-family:Noto Serif CJK SC,Songti SC,SimSun,serif;font-size:clamp(2.6rem,5vw,5rem);font-weight:700;line-height:1.18}.chain-hero-copy>p:last-child{max-width:46rem;color:var(--chain-muted);margin:1.5rem 0 0;font-size:1.05rem}.chain-hero-map{gap:.7rem;display:grid}.chain-hero-map>div{border-top:1px solid #9daeba;grid-template-columns:5.4rem 1fr;gap:1rem;padding:1rem 0;display:grid}.chain-hero-map strong{color:var(--chain-blue)}.chain-hero-map span{color:var(--chain-muted)}.chain-workspace{grid-template-columns:minmax(16rem,20rem) minmax(0,1fr);gap:clamp(1.5rem,3vw,3rem);max-width:98rem;margin:0 auto;padding:clamp(1.2rem,3vw,3rem);display:grid}.chain-sidebar{border:1px solid var(--chain-line);background:#fbfaf6;align-self:start;max-height:calc(100dvh - 2rem);padding:1.15rem;position:sticky;top:1rem;overflow-y:auto;box-shadow:0 .5rem 1.5rem #363e2c0a}.chain-tabs{grid-template-columns:1fr 1fr;gap:.4rem;display:grid}.chain-tabs button{border:1px solid var(--chain-line);min-height:3rem;color:var(--chain-muted);background:#f5f7fa;padding:.5rem;font-size:.9rem;font-weight:700}.chain-tabs button.is-current{border-color:var(--chain-blue);background:var(--chain-blue);color:#fff}.chain-sidebar-heading{justify-content:space-between;align-items:baseline;gap:.5rem;margin:1.4rem 0 .7rem;display:flex}.chain-sidebar-heading p{margin:0;font-weight:800}.chain-sidebar-heading small{color:var(--chain-muted);white-space:nowrap}.chain-progress{background:#e3e9ee;border-radius:999px;height:.45rem;margin:.5rem 0 1rem;overflow:hidden}.chain-progress span{border-radius:inherit;background:var(--chain-teal);height:100%;transition:width .18s ease-out;display:block}.chain-nav-toggle{border:1px solid var(--chain-blue);width:100%;min-height:2.75rem;color:var(--chain-blue);background:#fffefa;padding:.4rem .7rem;font-weight:800;display:none}.chain-lesson-search{color:var(--chain-muted);gap:.35rem;margin-bottom:.8rem;font-size:.78rem;font-weight:800;display:grid}.chain-lesson-search input{width:100%;min-height:2.75rem;color:var(--chain-ink);font:inherit;background:#fff;border:1px solid #8da0b1;border-radius:0;padding:.55rem .7rem}.chain-lesson-list{margin:0;padding:0;list-style:none}.chain-lesson-list li+li{border-top:1px solid var(--chain-line)}.chain-lesson-list button{width:100%;min-height:4.2rem;color:var(--chain-ink);text-align:left;background:0 0;border:0;grid-template-columns:2rem 1fr;column-gap:.5rem;padding:.65rem .35rem;display:grid}.chain-lesson-list button:hover,.chain-lesson-list button.is-current{background:#edf4f3}.chain-lesson-list button span{color:var(--chain-teal);font-weight:800}.chain-lesson-list button strong{font-size:.94rem;line-height:1.5}.chain-lesson-list button small{color:var(--chain-muted);grid-column:2;font-size:.74rem;line-height:1.45}.chain-lesson-list button em{color:var(--chain-teal);grid-column:2;font-size:.76rem;font-style:normal}.chain-search-empty{color:#68410f;background:#fff5e7;margin:.5rem 0;padding:.8rem;font-size:.84rem}.chain-sidebar-note{border-top:1px solid var(--chain-line);color:var(--chain-muted);margin:1.25rem 0 0;padding-top:1rem;font-size:.82rem}.chain-main{min-width:0;scroll-margin-top:1rem}.chain-path{color:var(--chain-muted);gap:.6rem;margin:0 0 1rem;font-size:.85rem;display:flex}.chain-bridge-overview{border:1px solid var(--chain-line);background:#fafbf8;margin:1.2rem 0 0}.chain-bridge-overview>summary{min-height:2.75rem;color:var(--chain-blue);cursor:pointer;padding:.85rem 1rem;font-size:.9rem;font-weight:700}.chain-bridge-overview>summary:focus-visible{outline:3px solid var(--chain-teal);outline-offset:3px}.chain-bridge-overview-body{padding:0 1rem 1rem}.chain-bridge-overview-body>p{color:#42534c;max-width:55rem;margin:.35rem 0 .85rem;font-size:.88rem}.chain-bridge-overview-body>.chain-bridge-swipe-hint{display:none}.chain-bridge-map{grid-template-columns:repeat(3,minmax(0,1fr));gap:.55rem;display:grid}.chain-bridge-map-item{background:#fffefa;border:1px solid #d3ded6;min-width:0;padding:.7rem .8rem}.chain-bridge-map-item.is-related{border-color:var(--chain-teal);box-shadow:inset .25rem 0 var(--chain-teal)}.chain-bridge-map-item>strong{margin-bottom:.35rem;font-size:.85rem;display:block}.chain-bridge-current{color:#805012;white-space:nowrap;margin-left:.45rem;font-size:.72rem}.chain-bridge-map-item>div{flex-wrap:wrap;align-items:center;gap:.15rem .5rem;display:flex}.chain-bridge-map-item button{min-height:2.5rem;color:var(--chain-blue);text-align:left;text-underline-offset:.18em;background:0 0;border:0;padding:.2rem 0;font-size:.8rem;font-weight:700;text-decoration:underline}.chain-bridge-map-item button[aria-current=page]{color:#75420e;text-decoration-thickness:2px}.chain-bridge-map-item span{color:var(--chain-teal);font-weight:800}.chain-cross-lesson{border:1px solid var(--chain-line);background:#f8faf7;margin:2rem 0 0;padding:clamp(1rem,2.5vw,1.6rem)}.chain-cross-lesson>h3{margin:0 0 1rem;font-family:Noto Serif CJK SC,Songti SC,SimSun,serif;font-size:clamp(1.25rem,2vw,1.55rem)}.chain-cross-lesson-item+.chain-cross-lesson-item{border-top:1px solid #b9c9c1;margin-top:1.4rem;padding-top:1.4rem}.chain-cross-more{border-top:1px solid #b9c9c1;margin-top:.85rem}.chain-cross-more>summary{color:var(--chain-blue);cursor:pointer;padding:.85rem 0;font-weight:700}.chain-cross-more>.chain-cross-lesson-item{padding:.25rem 0 1rem}.chain-cross-lesson-item h4{margin:0 0 .7rem;font-size:1.08rem}.chain-cross-roles{grid-template-columns:repeat(2,minmax(0,1fr));gap:.7rem;display:grid}.chain-cross-role{background:#fff;min-width:0;padding:.8rem}.chain-cross-role p{margin:0}.chain-cross-roles strong{color:var(--chain-teal);display:block}.chain-cross-example{border-left:3px solid var(--chain-teal);background:#fff;margin:.8rem 0;padding:.8rem 1rem}.chain-cross-example>span{color:var(--chain-teal);font-size:.78rem;font-weight:800}.chain-cross-example .rich-math p,.chain-cross-practice .rich-math p{margin:.35rem 0}.chain-cross-practice{background:#fffefa;border:1px solid #d3ded6;padding:.8rem 1rem}.chain-cross-practice>strong{color:#805012}.chain-cross-practice details{margin-top:.5rem}.chain-cross-practice summary{width:fit-content;min-height:2.5rem;color:var(--chain-blue);cursor:pointer;padding:.35rem 0;font-weight:800}.chain-cross-practice details .rich-math{border-left:3px solid var(--chain-amber);background:#fff7e9;margin-top:.4rem;padding:.5rem .8rem}.chain-cross-link{border:1px solid var(--chain-blue);background:var(--chain-blue);color:#fff;text-align:left;min-height:2.75rem;margin-top:.9rem;padding:.45rem .75rem;font-size:.88rem;font-weight:800}.chain-lesson{border:1px solid var(--chain-line);background:var(--chain-paper);min-width:0;padding:clamp(1.1rem,3vw,3rem);box-shadow:0 .8rem 2.2rem #363e2c0a}.chain-lesson-header{padding-bottom:.6rem}.chain-lesson-header h2{max-width:19ch;margin:0;font-family:Noto Serif CJK SC,Songti SC,SimSun,serif;font-size:clamp(2rem,4vw,3.45rem);line-height:1.22}.chain-lesson-goal{max-width:48rem;margin:0;font-size:1.04rem;font-weight:600}.chain-opening{background:#f4f5ed;border:1px solid #d8ded2;grid-template-columns:minmax(0,.95fr) minmax(0,1.05fr);align-items:stretch;gap:clamp(1.2rem,3vw,2.5rem);margin:1.1rem 0 1.5rem;padding:clamp(1rem,2.5vw,1.6rem);display:grid}.chain-opening-copy{flex-direction:column;justify-content:center;min-width:0;display:flex}.chain-opening h3{margin:0 0 1.1rem;font-family:Noto Serif CJK SC,Songti SC,SimSun,serif;font-size:clamp(1.4rem,2.3vw,2.1rem);line-height:1.35}.chain-opening-copy>p:not(.chain-section-kicker){margin:0 0 .8rem;font-size:.98rem}.chain-opening-question{border-left:3px solid var(--chain-amber);background:#fffdf8;gap:.2rem;margin:.5rem 0 .8rem;padding:.75rem .95rem;display:grid}.chain-opening-question span{color:#90613c;font-size:.76rem;font-weight:800}.chain-opening-question strong{font-size:.98rem;font-weight:700}.chain-opening-answer{border-top:1px solid #d8ded2;margin-top:.3rem}.chain-opening-answer summary{width:fit-content;min-height:2.5rem;color:var(--chain-blue);cursor:pointer;padding:.45rem 0;font-weight:800}.chain-opening-answer p{border-left:3px solid var(--chain-teal);background:#fff;margin:.2rem 0 0;padding:.7rem .9rem}.chain-opening-figure{background:#e7e4da;flex-direction:column;min-width:0;margin:0;display:flex}.chain-opening-figure img{object-fit:cover;aspect-ratio:3/2;flex:1;width:100%;height:auto;display:block}.chain-opening-figure figcaption{color:var(--chain-muted);text-align:right;background:#fbfaf6;padding:.4rem .6rem;font-size:.72rem}.chain-lesson-orientation{border-bottom:1px solid var(--chain-line);padding:1rem 0 1.5rem}.chain-lesson-orientation .chain-lesson-meta{margin-top:.65rem}.chain-lesson-meta{color:var(--chain-muted);flex-wrap:wrap;gap:.4rem 1.5rem;margin-top:1.35rem;font-size:.86rem;display:flex}.chain-guiding-question{border-left:.25rem solid var(--chain-amber);background:#faf3e9;margin:2rem 0;padding:1.1rem 1.5rem}.chain-guiding-question span{color:#805012;font-size:.78rem;font-weight:800;display:block}.chain-guiding-question p{margin:.35rem 0 0;font-family:Noto Serif CJK SC,SimSun,serif;font-size:1.25rem;font-weight:700}.chain-content-section{border-bottom:1px solid var(--chain-line);padding:2rem 0}.chain-section-kicker{color:var(--chain-teal);letter-spacing:.13em;margin-bottom:.9rem;font-size:.78rem;font-weight:800}.chain-error-section{background:#fffbf2;margin-inline:-.4rem;padding-inline:.4rem}.chain-content-section h2,.chain-activity h2,.chain-activity h3{margin:0 0 1.05rem;font-size:clamp(1.4rem,2.5vw,1.8rem);line-height:1.35}.rich-math{overflow-wrap:anywhere;min-width:0}.rich-math>p,.rich-math>ul,.rich-math>ol,.rich-math>blockquote{max-width:49rem}.rich-math p{margin:.75rem 0 1.1rem}.rich-math li{margin-bottom:.35rem;padding-left:.15rem}.rich-math h2{margin:0 0 1rem;font-size:clamp(1.35rem,2.4vw,1.8rem);line-height:1.35}.rich-math h3{margin:1.65rem 0 .65rem;font-size:1.15rem}.rich-math strong{color:#122e50}.rich-math blockquote{border-left:3px solid var(--chain-blue);background:#f3f6fb;margin:1.1rem 0;padding:.1rem 1rem}.rich-math .katex-display{max-width:100%;padding:.65rem 0;overflow:auto hidden}.rich-math__table-scroll,.chain-activity-table{max-width:100%;margin:1.2rem 0 1.5rem;overflow-x:auto}.rich-math table,.chain-activity-table table{border-collapse:collapse;background:#fff;width:100%;min-width:27rem;font-size:.93rem}.rich-math th,.rich-math td,.chain-activity-table th,.chain-activity-table td{border:1px solid var(--chain-line);vertical-align:top;text-align:left;padding:.75rem .8rem}.rich-math th,.chain-activity-table th{background:#eaf1f5;font-weight:800}.rich-math td p,.rich-math th p{margin:0}.chain-activity{background:#f0f7f5;border:1px solid #b4c9c7;margin:2rem 0;padding:1.5rem}.chain-activity-prompt{margin:0 0 1rem;font-weight:800}.chain-choices{gap:.55rem;display:grid}.chain-choices button{min-height:3.25rem;color:var(--chain-ink);text-align:left;background:#fff;border:1px solid #9caaa9;align-items:center;gap:.75rem;padding:.65rem .8rem;display:flex}.chain-choices button:hover,.chain-choices button.is-selected{border-color:var(--chain-teal);background:#e2f0ec}.chain-choices button span{background:var(--chain-teal);color:#fff;border-radius:50%;flex:0 0 1.65rem;place-items:center;height:1.65rem;font-size:.78rem;font-weight:800;display:grid}.chain-activity-actions{flex-wrap:wrap;gap:1rem;margin-top:1rem;display:flex}.chain-activity-actions button{min-height:2.75rem;color:var(--chain-blue);text-underline-offset:.2em;background:0 0;border:0;padding:.35rem 0;font-weight:800;text-decoration:underline}.chain-hint,.chain-feedback{background:#fff;margin:1rem 0 0;padding:.9rem 1rem}.chain-hint{border-left:4px solid var(--chain-amber)}.chain-feedback.is-correct{border-left:4px solid var(--chain-teal)}.chain-feedback.is-retry{border-left:4px solid var(--chain-amber)}.chain-feedback strong{display:block}.chain-feedback p:last-child{margin-bottom:0}.chain-mini-practice{background:#f6f7f1;border:1px solid #d8ded2;max-width:49rem;margin-top:1.7rem;padding:1.15rem}.chain-mini-practice-heading{justify-content:space-between;align-items:baseline;gap:.75rem;margin-bottom:.55rem;display:flex}.chain-mini-practice-heading span{color:var(--chain-teal);font-weight:800}.chain-mini-practice-heading small{color:var(--chain-muted)}.chain-mini-prompt{margin:0 0 .85rem;font-weight:700}.chain-mini-choices{grid-template-columns:repeat(3,minmax(0,1fr));gap:.5rem;display:grid}.chain-mini-choices button{min-height:3rem;color:var(--chain-ink);text-align:left;background:#fff;border:1px solid #aab9ad;align-items:center;gap:.45rem;padding:.5rem .6rem;font-size:.9rem;display:flex}.chain-mini-choices button:hover,.chain-mini-choices button.is-selected{border-color:var(--chain-teal);background:#e9f1e9}.chain-mini-choices button span{background:var(--chain-teal);color:#fff;border-radius:50%;flex:none;place-items:center;width:1.45rem;height:1.45rem;font-size:.74rem;font-weight:800;display:grid}.chain-mini-input{gap:.55rem;display:flex}.chain-mini-input input{min-width:0;min-height:3rem;color:var(--chain-ink);font:inherit;background:#fff;border:1px solid #9aaca1;flex:1;padding:.5rem .75rem}.chain-mini-input button{border:1px solid var(--chain-blue);background:var(--chain-blue);color:#fff;min-height:3rem;padding:.45rem .9rem;font-weight:800}.chain-mini-input button:disabled{opacity:.5;cursor:not-allowed}.chain-mini-actions{gap:1rem;margin-top:.6rem;display:flex}.chain-mini-actions button{min-height:2.5rem;color:var(--chain-blue);text-underline-offset:.2em;background:0 0;border:0;padding:.25rem 0;font-size:.83rem;font-weight:700;text-decoration:underline}.chain-mini-hint,.chain-mini-feedback{background:#fff;margin:.65rem 0 0;padding:.65rem .85rem}.chain-mini-hint{border-left:3px solid var(--chain-amber)}.chain-mini-feedback.is-correct{border-left:3px solid var(--chain-teal)}.chain-mini-feedback.is-retry{border-left:3px solid var(--chain-amber)}.chain-mini-feedback strong{display:block}.chain-mini-feedback p{margin:.2rem 0 0}.chain-lab{background:#fffaf0;border:1px solid #c6b78f;margin:2rem 0;padding:1.5rem}.chain-lab-heading{justify-content:space-between;align-items:flex-start;gap:1rem;margin-bottom:.8rem;display:flex}.chain-lab-heading h3{margin:0;font-size:clamp(1.35rem,2.4vw,1.75rem);line-height:1.35}.chain-lab-heading .chain-section-kicker{color:#8a4c0d;margin-bottom:.45rem}.chain-lab-badge{color:#7a4109;border:1px solid #c98a39;border-radius:50%;flex:none;place-items:center;min-width:3.1rem;min-height:3.1rem;font-size:.8rem;font-weight:800;display:grid}.chain-lab>p{max-width:49rem}.chain-lab button{min-height:2.75rem;color:var(--chain-ink);background:#fff;border:1px solid #9d875f;font-weight:700}.chain-lab button:hover,.chain-lab button[aria-pressed=true]{background:#f7e7c7;border-color:#8a4c0d}.chain-lab button:disabled{cursor:not-allowed;opacity:.55}.chain-lab-options,.chain-token-grid,.chain-angle-picker{flex-wrap:wrap;gap:.55rem;margin:1rem 0;display:flex}.chain-lab-options button,.chain-token-grid button,.chain-angle-picker button{padding:.55rem .9rem}.chain-angle-picker button{width:3.3rem;padding:.5rem}.chain-lab-result{border-left:4px solid var(--chain-amber);background:#fff;margin-top:1rem;padding:.9rem 1rem}.chain-lab-result.is-correct{border-left-color:var(--chain-teal)}.chain-lab-result strong{display:block}.chain-lab-result p{margin:.3rem 0 0}.chain-lab-actions{flex-wrap:wrap;gap:.6rem;margin-top:1rem;display:flex}.chain-lab-actions button,.chain-lab-check,.chain-lab-reset{padding:.5rem .85rem}.chain-lab-check{margin-top:1rem;color:#fff!important;background:#7a4109!important;border-color:#7a4109!important}.chain-lab-reset{margin-top:.75rem}.chain-lab-readout{background:#fff;margin:1rem 0 0;padding:.75rem .9rem;font-weight:650}.chain-lab-note{color:var(--chain-muted);border-left:3px solid #c98a39;margin:.9rem 0 0;padding-left:.9rem}.chain-lab-note.is-best{border-left-color:var(--chain-teal);color:var(--chain-teal);font-weight:800}.chain-walk-line{grid-template-columns:repeat(11,minmax(2.25rem,1fr));margin:1.4rem 0 .7rem;padding:1rem 0 .4rem;display:grid;overflow-x:auto}.chain-walk-arrow{color:#8a4c0d;width:fit-content;margin:.8rem auto -.5rem;font-size:1.1rem;font-weight:900}.chain-walk-line span{text-align:center;border-top:2px solid #637489;min-width:2.25rem;position:relative}.chain-walk-line span:before{content:"";border-left:2px solid #637489;height:.6rem;position:absolute;top:-.35rem;left:50%}.chain-walk-line span.is-origin{color:#a34d13;font-weight:800}.chain-walk-line span.is-current{color:var(--chain-teal);font-size:1.1rem;font-weight:900}.chain-lab-slider{gap:.55rem;margin:1rem 0;font-weight:700;display:grid}.chain-lab-slider input,.chain-double-slider input{width:100%;min-height:2.75rem;accent-color:var(--chain-teal)}.chain-canvas-legend{color:var(--chain-muted);margin:.8rem 0 .35rem;font-size:.86rem}.chain-lab-canvas{background:#fff;border:1px solid #c9d2dc;width:min(100%,40rem);height:auto;margin:0 auto 1rem;display:block}.chain-lab-metrics{grid-template-columns:repeat(auto-fit,minmax(10rem,1fr));gap:.6rem;margin:1rem 0;display:grid}.chain-lab-metrics span{color:var(--chain-muted);background:#fff;border:1px solid #dbcaa5;padding:.8rem;font-size:.82rem}.chain-lab-metrics strong{color:var(--chain-ink);margin-top:.2rem;font-size:1rem;display:block}.chain-builder-grid{grid-template-columns:repeat(2,minmax(0,1fr));gap:.8rem;display:grid}.chain-builder-grid fieldset{border:1px solid #dbcaa5;min-width:0;padding:.8rem}.chain-builder-grid legend{padding:0 .35rem;font-weight:800}.chain-builder-grid button{text-align:left;width:100%;margin-top:.45rem;padding:.45rem .65rem;display:block}.chain-inequality-line{border-top:3px solid #64748b;height:4rem;margin:1.3rem 1rem 0;position:relative}.chain-inequality-line:before{content:"";border:3px solid var(--chain-teal);z-index:1;background:#fff;border-radius:50%;width:.85rem;height:.85rem;position:absolute;top:-.55rem;left:50%;transform:translate(-50%)}.chain-inequality-line.is-closed:before{background:var(--chain-teal)}.chain-inequality-line:after{content:"";background:var(--chain-teal);width:50%;height:.75rem;position:absolute;top:-.48rem}.chain-inequality-line.is-left:after{clip-path:polygon(0 50%,10% 0,10% 28%,100% 28%,100% 72%,10% 72%,10% 100%);left:0}.chain-inequality-line.is-right:after{clip-path:polygon(0 28%,90% 28%,90% 0,100% 50%,90% 100%,90% 72%,0 72%);right:0}.chain-inequality-line span{font-weight:800;position:absolute;top:.8rem;left:50%;transform:translate(-50%)}.chain-sequence-built{gap:.45rem;margin:1rem 0;padding-left:2.2rem;display:grid}.chain-sequence-built li{border-left:4px solid var(--chain-teal);background:#fff;padding:.65rem .8rem}.chain-sequence-bank{gap:.55rem;display:grid}.chain-sequence-bank button{text-align:left;padding:.65rem .8rem}.chain-ruler{border-top:3px solid #64748b;height:2.4rem;margin:2.5rem 0 1rem;position:relative}.chain-ruler span{position:absolute;top:.55rem;transform:translate(-50%)}.chain-ruler span:first-of-type{transform:none}.chain-ruler span:last-of-type{transform:translate(-100%)}.chain-ruler span:before{content:"";border-left:2px solid #64748b;height:.8rem;position:absolute;top:-1rem;left:50%}.chain-ruler span:first-of-type:before{left:0}.chain-ruler span:last-of-type:before{left:100%}.chain-ruler i{z-index:1;background:var(--chain-teal);color:#fff;text-align:center;border-radius:1rem;min-width:1.7rem;padding:.1rem .35rem;font-style:normal;font-weight:800;position:absolute;top:-2.15rem;transform:translate(-50%)}.chain-double-slider{grid-template-columns:1fr 1fr;gap:1rem;margin:1rem 0;display:grid}.chain-double-slider label{gap:.35rem;display:grid}.chain-sort-cards{gap:.65rem;display:grid}.chain-sort-cards>div{background:#fff;border:1px solid #dbcaa5;padding:.8rem}.chain-sort-cards>div.is-correct{border-left:4px solid var(--chain-teal)}.chain-sort-cards>div.is-wrong{border-left:4px solid var(--chain-amber)}.chain-sort-cards p{margin:0 0 .6rem}.chain-sort-cards [role=group]{flex-wrap:wrap;gap:.4rem;display:flex}.chain-sort-cards button{min-height:2.5rem;padding:.35rem .65rem}.chain-sort-cards small{color:var(--chain-muted);margin-top:.55rem;display:block}.chain-sort-cards>div.is-correct small{color:var(--chain-teal);font-weight:800}.chain-sort-cards>div.is-wrong small{color:#8a4c0d}.chain-fraction-bars{gap:.8rem;margin:1.25rem 0;display:grid}.chain-fraction-bars>div{grid-template-columns:8rem minmax(0,1fr);align-items:center;gap:1rem;display:grid}.chain-fraction-bars strong{font-size:.88rem}.chain-fraction-bars div span{grid-template-columns:repeat(12,minmax(0,1fr));gap:.18rem;display:grid}.chain-fraction-bars i{background:#fff;border:1px solid #94b5af;height:1.5rem}.chain-fraction-bars i.is-filled{background:#58a498}.chain-number-line{grid-template-columns:repeat(17,minmax(2.2rem,1fr));max-width:100%;margin:1.25rem 0;padding-bottom:.25rem;display:grid;overflow-x:auto}.chain-number-line span{text-align:center;border-top:2px solid #607489;min-width:2.2rem;padding-top:.9rem;font-size:.8rem;position:relative}.chain-number-line span:before{content:"";border-left:2px solid #607489;height:.6rem;position:absolute;top:-.35rem;left:50%}.chain-number-line .is-start{color:#a34d13;font-weight:800}.chain-number-line .is-end{color:var(--chain-teal);font-weight:800}.chain-figure-gallery{grid-template-columns:repeat(auto-fit,minmax(min(100%,18rem),1fr));gap:.7rem;margin:1.25rem 0;display:grid}.chain-figure{border:1px solid var(--chain-line);background:#fff;min-width:0;margin:0;padding:.7rem}.chain-figure img{width:min(100%,42rem);height:auto;margin:auto;display:block}.chain-figure figcaption{color:var(--chain-muted);text-align:center;margin:.7rem 0 0;font-size:.85rem}.chain-figure figcaption a{min-height:2.75rem;color:var(--chain-blue);text-underline-offset:.15em;align-items:center;display:inline-flex}.chain-answer,.chain-source-note{border:1px solid var(--chain-line);background:#fff;margin:1.5rem 0 0}.chain-answer summary,.chain-source-note summary{min-height:3rem;color:var(--chain-blue);cursor:pointer;padding:.7rem 1rem;font-weight:800}.chain-answer>.rich-math,.chain-source-note>p{padding:0 1rem .5rem}.chain-teachback{background:#eaf1f5;margin-top:2rem;padding:1.5rem}.chain-teachback h3{margin:0 0 .5rem;font-size:1.6rem}.chain-teachback p{margin:0 0 1rem}.chain-teachback label{margin-bottom:.4rem;font-weight:800;display:block}.chain-teachback textarea{width:100%;min-height:8rem;color:var(--chain-ink);font:inherit;resize:vertical;background:#fff;border:1px solid #8295a5;padding:.8rem}.chain-save-note{color:var(--chain-muted);margin-top:.35rem;display:block}.chain-save-error{color:#9c2525;margin-top:.35rem;display:block}.chain-resources{border:1px solid var(--chain-line);background:#f8faf9;margin-top:2rem;padding:1.5rem}.chain-resources h3{margin:.3rem 0 1rem;font-size:1.4rem}.chain-resource-list{gap:.7rem;display:grid}.chain-resource-list details{border:1px solid var(--chain-line);background:#fff;padding:.8rem 1rem}.chain-resource-list summary{cursor:pointer;color:var(--chain-blue);justify-content:space-between;gap:1rem;display:flex}.chain-resource-list summary span{color:var(--chain-muted);font-size:.85rem}.chain-resource-list a{color:var(--chain-blue);margin-top:.6rem;display:inline-block}.chain-material-frame{border:1px solid var(--chain-line);background:#fff;width:100%;height:min(70vh,42rem);margin-top:.8rem;display:block}.chain-material-markdown{border:1px solid var(--chain-line);overflow-wrap:anywhere;margin-top:.8rem;padding:1rem}.chain-teacher-feedback{border-left:4px solid var(--chain-teal);background:#eaf4f0;margin-top:1.5rem;padding:1rem 1.2rem}.chain-teacher-feedback p{white-space:pre-wrap;margin:0}.chain-work-records{margin-top:1.5rem}.chain-work-records>div:last-child{grid-template-columns:repeat(auto-fill,minmax(min(100%,12rem),1fr));gap:.8rem;display:grid}.chain-work-records figure{border:1px solid var(--chain-line);background:#fff;margin:0}.chain-work-records img{object-fit:contain;width:100%;height:10rem;display:block}.chain-work-records figcaption{color:var(--chain-muted);overflow-wrap:anywhere;padding:.5rem}.chain-source-note{background:0 0}.chain-source-note p{color:var(--chain-muted);font-size:.86rem}.chain-lesson-footer{justify-content:space-between;gap:1rem;padding-top:2rem;display:flex}.chain-lesson-footer button{border:1px solid var(--chain-blue);min-height:3rem;color:var(--chain-blue);background:0 0;padding:.6rem 1rem;font-weight:800}.chain-lesson-footer .chain-next{background:var(--chain-blue);color:#fff}.chain-ai-launcher{z-index:20;right:max(1rem, env(safe-area-inset-right));bottom:max(1rem, env(safe-area-inset-bottom));color:#fff;background:#183d68;border:1px solid #142d4a;border-radius:999px;align-items:center;gap:.6rem;min-height:3.25rem;padding:.55rem .9rem;font-weight:800;display:flex;position:fixed;box-shadow:0 .4rem 1.4rem #14284142}.chain-ai-launcher span{color:#183d68;background:#fff;border-radius:50%;place-items:center;width:1.85rem;height:1.85rem;font-size:.72rem;display:grid}.chain-ai-dialog{width:100vw;max-width:none;height:100dvh;max-height:none;color:var(--chain-ink);background:#fff;border:0;margin:0;padding:0;position:fixed;inset:0}.chain-ai-dialog::backdrop{background:#0c192c8c}.chain-ai-shell{grid-template-rows:auto minmax(0,1fr) auto;height:100%;min-height:0;font-family:Microsoft YaHei,PingFang SC,system-ui,sans-serif;font-size:14.5px;line-height:1.5;display:grid}.chain-ai-header{border-bottom:1px solid var(--chain-line);justify-content:space-between;align-items:center;gap:1rem;min-height:3.5rem;padding:.45rem 1.25rem;display:flex}.chain-ai-header>div{align-items:baseline;gap:.75rem;min-width:0;display:flex}.chain-ai-header strong{color:var(--chain-blue);flex:none;font-size:.95rem}.chain-ai-header span{min-width:0;color:var(--chain-muted);text-overflow:ellipsis;white-space:nowrap;font-size:.78rem;font-weight:700;overflow:hidden}.chain-ai-header button{border:1px solid var(--chain-line);min-height:2.5rem;color:var(--chain-ink);background:#fff;padding:.25rem .7rem}.chain-ai-messages{background:#f7f9fa;min-height:0;padding:.75rem 1.2rem;overflow-y:auto}.chain-ai-thread{width:min(100%,72rem);margin-inline:auto}.chain-ai-question-picker{border:1px solid var(--chain-line);background:#fff;margin-bottom:1rem;padding:1rem}.chain-ai-form .chain-ai-question-picker{max-height:min(30dvh,14rem);margin:0 auto;overflow-y:auto}.chain-ai-question-picker-header{flex-wrap:wrap;justify-content:space-between;align-items:center;gap:.5rem;display:flex}.chain-ai-question-picker h3{margin:0;font-size:1.05rem}.chain-ai-question-picker-header button{border:1px solid var(--chain-blue);min-height:2.75rem;color:var(--chain-blue);background:#fff;padding:.35rem .7rem;font-size:.85rem;font-weight:700}.chain-ai-question-picker>p{color:var(--chain-muted);margin:.45rem 0 .8rem;font-size:.85rem}.chain-ai-question-list{grid-template-columns:repeat(2,minmax(0,1fr));gap:.5rem;display:grid}.chain-ai-question-list button{min-height:3.25rem;color:var(--chain-ink);text-align:left;background:#f6f9fb;border:1px solid #b7c7d5;align-items:flex-start;gap:.65rem;padding:.65rem .75rem;font-size:.88rem;line-height:1.5;display:flex}.chain-ai-question-list button[aria-pressed=true]{border-color:var(--chain-teal);background:#e6f3ef}.chain-ai-question-list button span{color:var(--chain-teal);flex:none;font-weight:800}.chain-ai-question-list button:disabled,.chain-ai-question-picker-header button:disabled{opacity:.6;cursor:not-allowed}.chain-ai-empty{border-left:4px solid var(--chain-teal);background:#fff;max-width:34rem;padding:.8rem 1rem}.chain-ai-empty p{color:var(--chain-muted);margin-bottom:0}.chain-ai-message{border:1px solid var(--chain-line);overflow-wrap:anywhere;background:#fff;max-width:min(42rem,100%);margin:0 0 .55rem;padding:.65rem .8rem}.chain-ai-message--user{background:#eaf1f5;margin-left:auto}.chain-ai-message>strong{color:var(--chain-blue);margin-bottom:.3rem;font-size:.76rem;display:block}.chain-ai-message p:last-child{margin-bottom:0}.chain-ai-status{color:var(--chain-muted)}.chain-ai-form{border-top:1px solid var(--chain-line);background:#fff;gap:.3rem;padding:.55rem 1.25rem;display:grid}.chain-ai-form>*{width:min(100%,72rem);margin-inline:auto}.chain-ai-form-heading{flex-wrap:wrap;justify-content:space-between;align-items:center;gap:.35rem;display:flex}.chain-ai-form label{font-size:.83rem;font-weight:800}.chain-ai-form-heading button{min-height:2.75rem;color:var(--chain-blue);text-underline-offset:.15em;background:0 0;border:0;padding:.25rem .5rem;font-size:.83rem;font-weight:700;text-decoration:underline}.chain-ai-compose-help{color:var(--chain-muted);margin:0;font-size:.8rem}.chain-ai-form textarea{width:100%;min-height:3.25rem;max-height:8rem;color:var(--chain-ink);font:inherit;resize:vertical;background:#fff;border:1px solid #8da0b1;padding:.5rem .65rem}.chain-ai-form-actions{justify-content:flex-end;gap:.5rem;display:flex}.chain-ai-form-actions button{border:1px solid var(--chain-blue);min-height:2.75rem;color:var(--chain-blue);background:#fff;padding:.45rem .95rem;font-weight:800}.chain-ai-form-actions button:last-child{background:var(--chain-blue);color:#fff}.chain-ai-form-actions button:disabled{opacity:.55;cursor:not-allowed}.chain-ai-error{color:#a52222;margin:0;font-size:.85rem}.chain-ai-error a{color:#a52222;text-decoration:underline}.chain-ai-dialog .rich-math h2{font-size:1.2rem}.chain-ai-dialog .rich-math h3{font-size:1.02rem}.chain-ai-dialog .rich-math table{min-width:25rem}@media (max-width:60rem){.chain-hero,.chain-workspace{grid-template-columns:1fr}.chain-sidebar{max-height:none;position:static}.chain-sidebar.is-open{max-height:58dvh}.chain-nav-toggle{display:block}.chain-sidebar:not(.is-open) .chain-lesson-search,.chain-sidebar:not(.is-open) .chain-lesson-list,.chain-sidebar:not(.is-open) .chain-search-empty,.chain-sidebar:not(.is-open) .chain-sidebar-note{display:none}.chain-lesson-list{grid-template-columns:repeat(2,minmax(0,1fr));gap:.4rem;display:grid}.chain-lesson-list li{border:1px solid var(--chain-line)!important}}@media (max-width:48rem){.chain-bridge-map{scroll-snap-type:x proximity;grid-template-columns:none;grid-auto-columns:minmax(15rem,78%);grid-auto-flow:column;padding-bottom:.45rem;overflow-x:auto}.chain-bridge-map-item{scroll-snap-align:start}.chain-cross-roles{grid-template-columns:1fr}.chain-bridge-overview-body>.chain-bridge-swipe-hint{color:var(--chain-teal);margin:0 0 .5rem;font-size:.78rem;font-weight:800;display:block}.chain-opening{grid-template-columns:1fr}.chain-opening-figure{order:-1}.chain-mini-choices{grid-template-columns:1fr}}@media (max-width:38rem){.chain-topbar{align-items:flex-start}.chain-topbar-meta{display:none}.chain-topbar-right,.chain-account{justify-content:flex-end}.chain-hero{padding:2.5rem 1rem}.chain-workspace{gap:1rem;padding:1rem .65rem}.chain-sidebar{padding:.8rem}.chain-lesson-list{grid-template-columns:1fr}.chain-lesson-list button{min-height:3.3rem}.chain-lesson{padding:1.1rem}.chain-opening{margin:1.25rem -.15rem;padding:.7rem}.chain-opening-copy{padding:.35rem}.chain-mini-input{flex-direction:column}.chain-guiding-question{padding:.9rem}.chain-activity,.chain-lab,.chain-teachback{padding:1rem}.chain-builder-grid,.chain-double-slider{grid-template-columns:1fr}.chain-fraction-bars>div{grid-template-columns:1fr;gap:.3rem}.chain-lesson-footer{flex-direction:column}.chain-lesson-footer button{width:100%}.chain-ai-launcher{right:.65rem;bottom:max(.65rem, env(safe-area-inset-bottom))}.chain-ai-launcher-label{display:none}.chain-ai-launcher{justify-content:center;width:3.25rem;padding:.55rem}.chain-ai-dialog{border:0;width:100vw;height:100dvh;margin:0}.chain-ai-header,.chain-ai-messages,.chain-ai-form{padding-left:.9rem;padding-right:.9rem}.chain-ai-shell{font-size:16px;line-height:1.55}.chain-ai-header>div{gap:0;display:grid}.chain-ai-question-list{grid-template-columns:1fr}}@media (prefers-reduced-motion:reduce){.chain-course *,.chain-ai-dialog *{scroll-behavior:auto!important;transition-duration:.01ms!important;animation-duration:.01ms!important}}.chain-course{--chain-ink:#202d29;--chain-muted:#60716a;--chain-line:#e0e7e2;--chain-paper:#fff;--chain-blue:#21644d;--chain-teal:#21644d;background:#f7f8f6}.chain-topbar{background:#f7f8f6}.chain-brand-mark{border-radius:7px;font-family:system-ui,sans-serif;font-size:20px}.chain-workspace{grid-template-columns:240px minmax(0,800px);gap:44px;max-width:1280px;padding:28px 24px}.chain-sidebar{box-shadow:none;background:0 0;border:0;border-right:1px solid #e0e7e2;padding:0 20px 0 0}.chain-lesson-list button{border-radius:6px}.chain-lesson-list button strong{font-size:13px;font-weight:550}.chain-lesson-list button small{font-size:11px}.chain-lesson-list button.is-current{background:#e8f2eb}.chain-lesson-header h2{font-family:var(--font-body);font-size:30px;line-height:1.4}.chain-lesson-header{margin-bottom:20px}.chain-eyebrow{letter-spacing:.03em}.chain-section-kicker{color:#21644d;letter-spacing:.03em;font-size:13px}.chain-lesson h3,.chain-lesson h4{font-family:var(--font-body)}.chain-opening{background:#fff;border:1px solid #dce7df;border-radius:12px;margin:24px 0;padding:24px;display:block}.chain-opening-copy h3{font-size:22px}.chain-opening-figure{display:none}.chain-opening-question{background:#edf5ef;border-color:#d7e7dc;border-radius:8px}.chain-opening-copy>p{font-size:15px}.chain-lesson-orientation{border-color:#dce7df;border-radius:8px}.chain-step-map{border-block:1px solid #e0e7e2;flex-wrap:wrap;gap:8px;padding:16px 0;display:flex}.chain-step-map a{color:#21644d;background:#edf5ef;border-radius:6px;min-height:36px;padding:6px 10px;font-size:12px;text-decoration:none}.chain-content-section,.chain-teachback{padding-block:32px;scroll-margin-top:24px}.chain-content-section h3{font-size:23px}.chain-error-section{background:#fffcf4;border-color:#e8dfc6;border-radius:8px}.chain-teachback{background:#fff;border-color:#dce7df;border-radius:10px}.chain-course .rich-math{line-height:1.85}.chain-lesson-search input{border-color:#dce5df;border-radius:7px}.chain-answer,.chain-opening-answer{border-radius:6px}@media (max-width:960px){.chain-workspace{grid-template-columns:210px minmax(0,1fr);gap:24px;padding:24px 16px}}@media (max-width:720px){.chain-workspace{padding:16px;display:block}.chain-sidebar{background:#fff;border:1px solid #e0e7e2;border-radius:10px;max-height:none;margin-bottom:24px;padding:16px;position:static}.chain-nav-toggle{border-radius:6px;display:block}.chain-lesson-list{display:none}.chain-sidebar.is-open .chain-lesson-list{max-height:400px;display:block;overflow:auto}.chain-sidebar-note{display:none}.chain-lesson-header h2{font-size:27px}.chain-opening{padding:20px}.chain-opening-copy h3{font-size:21px}.chain-step-map{gap:6px}.chain-step-map a{padding:6px;font-size:12px}.chain-topbar{padding:16px;display:block}.chain-topbar-right{margin-top:12px}.chain-topbar-meta{display:none}}@media (min-width:1100px){.chain-ai-dialog{border:0;border-left:1px solid #dce5df;width:390px;max-width:390px;height:100dvh;margin:0;inset:0 0 0 auto;box-shadow:-8px 0 32px #203b2b12}.chain-assistant-open .chain-course{margin-right:390px}.chain-assistant-open .chain-workspace{grid-template-columns:190px minmax(0,1fr);gap:24px;padding:24px 16px}.chain-ai-header strong{font-size:20px}.chain-ai-shell{min-height:100%}}
.course-source-workspace-module__R_bskG__root{min-width:0}.course-source-workspace-module__R_bskG__versionNote{margin-bottom:20px}.course-source-workspace-module__R_bskG__metadata{flex-wrap:wrap;align-items:center;gap:8px;margin-bottom:16px;display:flex}.course-source-workspace-module__R_bskG__metadata>span:last-child{color:#63746f;overflow-wrap:anywhere;font-size:13px}.course-source-workspace-module__R_bskG__files{grid-template-columns:minmax(0,1fr);gap:20px;display:grid}.course-source-workspace-module__R_bskG__files>*{min-width:0}.course-source-workspace-module__R_bskG__files code{overflow-wrap:anywhere;white-space:normal;font-size:13px}.course-source-workspace-module__R_bskG__files p{font-size:14px;line-height:1.8}.course-source-workspace-module__R_bskG__files small,.course-source-workspace-module__R_bskG__files .course-source-workspace-module__R_bskG__note{color:#63746f;font-size:13px}.course-source-workspace-module__R_bskG__files ul{columns:2;column-gap:32px;margin:0;padding-left:20px}.course-source-workspace-module__R_bskG__files li{break-inside:avoid;margin-bottom:8px}@media (max-width:700px){.course-source-workspace-module__R_bskG__files ul{columns:1}}