.b3-story-panel{margin:24px 0;background:white;border:1px solid #c7dade;border-radius:16px;text-align:left;overflow:hidden}.b3-story-panel summary{font-weight:700;color:#0f4c5c;padding:18px;cursor:pointer;font-size:1.05rem}.b3-story{padding:24px 30px;max-width:800px;margin:auto;text-align:left;background:#fff;border-radius:16px}.b3-story h2{font-size:1.6rem}.b3-story p{font-size:1.1rem;line-height:1.8;margin:16px 0;white-space:pre-line}.b3-diagram{display:block;max-width:100%;width:700px;height:auto;margin:24px auto;border-radius:14px;background:#fff}.b3-diagram-options .b3-diagram{width:100%;margin:0 auto;min-height:90px}.b3-class .b3-order{display:flex;flex-direction:column;gap:10px;text-align:left;counter-reset:step}.b3-class .b3-order li{display:flex;justify-content:space-between;align-items:center;gap:20px;width:100%;counter-increment:step}.b3-class .b3-order strong{font-size:1.05rem;line-height:1.5;margin:0}.b3-class .b3-order strong:before{content:counter(step) '. ';color:#0f4c5c}.b3-context{font-size:1.2rem;line-height:1.65;padding:20px;border-left:4px solid #ff8b7e;background:#fff8e9;text-align:left;margin:24px 0;white-space:pre-line}.b3-class .b2-classify{grid-template-columns:repeat(2,minmax(0,1fr))}.b3-class .b2-classify select{font-size:1rem}.b3-class .feedback p{white-space:pre-line}.b3-lesson-stage{font-weight:700;letter-spacing:.05em;color:#0f4c5c}.b3-detail .detail-block p,.b3-detail .detail-block li{font-size:1rem}.b3-class textarea{min-height:150px}@media(max-width:640px){.b3-story{padding:18px}.b3-story p{font-size:1rem}.b3-class .b3-order li{flex-direction:column;align-items:stretch;gap:12px}.b3-class .b3-order li>span{justify-content:flex-end}.b3-diagram-options{grid-template-columns:1fr}.b3-class .b2-classify{grid-template-columns:1fr}.b3-diagram{border-radius:8px}.b3-class .b2-options{grid-template-columns:1fr}}

/* Comparable mathematical wholes keep the same physical scale inside and outside choices. */
.b3-class{--b3-plot-width:min(520px,calc(100vw - 100px))}.b3-class .b3-diagram{width:var(--b3-plot-width);max-width:100%;height:auto}.b3-class .b3-diagram-options{grid-template-columns:1fr}.b3-class .b3-diagram-options .b3-diagram{width:var(--b3-plot-width)}.b3-class h1{white-space:pre-line}

.b3-class .b3-water{width:100%;max-width:850px}