:root{--lightningcss-light:initial;--lightningcss-dark: ;color-scheme:light;--paper:#f7efe3;--ink:#17212b;--muted:#5a6872;--panel:#fffaf0;--white:#fff;--line:#d8cdbb;--blue:#246f9e;--blue-dark:#153b57;--green:#2b8b61;--coral:#df6044;--gold:#d49a23;--plum:#563f69;--shadow:0 22px 60px #37251729}*{box-sizing:border-box}body{min-width:320px;color:var(--ink);background:radial-gradient(circle at 9% 14%,#246f9e2e,#0000 26%),radial-gradient(circle at 88% 8%,#df604424,#0000 24%),linear-gradient(135deg,#f7efe3 0%,#f1e1c9 46%,#e9f1ed 100%);margin:0;font-family:Avenir Next,Trebuchet MS,Noto Sans CJK SC,Microsoft YaHei,sans-serif}button,a{font:inherit}button{cursor:pointer}.shell{min-height:100vh;padding:24px}.lesson-stage{flex-direction:column;gap:24px;width:min(1240px,100%);min-height:calc(100vh - 48px);margin:0 auto;display:flex}.stage-topbar{justify-content:space-between;align-items:flex-start;gap:18px;display:flex}.kicker{color:var(--coral);text-transform:uppercase;margin:0 0 8px;font-size:13px;font-weight:900}h1,h2,p{margin-top:0}h1{margin-bottom:0;font-size:46px;line-height:1.04}h2{margin-bottom:10px;font-size:29px;line-height:1.12}.doc-link{color:#fff;background:var(--blue-dark);min-height:42px;box-shadow:var(--shadow);border:1px solid #fff3;border-radius:8px;padding:10px 16px;font-weight:900;text-decoration:none}.lesson-layout{flex:1;grid-template-columns:minmax(0,1.35fr) minmax(330px,.65fr);gap:22px;display:grid}.board-panel,.guide-panel{box-shadow:var(--shadow);background:#fffaf0e6;border:1px solid #4a3b2a2e;border-radius:8px;position:relative;overflow:hidden}.board-panel{min-height:620px}.sky-strip{background:linear-gradient(#9ad3eed1,#ffeec49e 42%,#fffaf000 70%),repeating-linear-gradient(90deg,#ffffff38 0 1px,#0000 1px 34px);position:absolute;inset:0}.cloud{filter:blur(.2px);background:#ffffffc7;border-radius:999px;width:150px;height:42px;position:absolute}.cloud:before,.cloud:after{content:"";background:inherit;border-radius:50%;position:absolute}.cloud:before{width:58px;height:58px;bottom:8px;left:24px}.cloud:after{width:76px;height:76px;bottom:2px;right:18px}.cloud-a{animation:26s linear infinite cloud-drift;top:80px;left:6%}.cloud-b{animation:34s linear infinite reverse cloud-drift;top:170px;right:10%;transform:scale(.72)}.spark{background:var(--gold);clip-path:polygon(50% 0,60% 38%,100% 50%,60% 62%,50% 100%,40% 62%,0 50%,40% 38%);width:14px;height:14px;animation:2s ease-in-out infinite twinkle;position:absolute}.spark-a{top:38%;left:19%}.spark-b{animation-delay:-.8s;top:18%;right:25%}.lesson-board{z-index:1;height:100%;min-height:inherit;grid-template-columns:minmax(210px,.72fr) minmax(310px,1fr);align-items:center;gap:18px;padding:34px;display:grid;position:relative}.teacher{transform-origin:50% 75%;align-self:end;animation:4.8s ease-in-out infinite hover}.teacher img{filter:drop-shadow(0 20px 22px #37251738);width:min(100%,360px);height:auto;display:block}.teacher.think{animation-duration:6.2s}.teacher.point{transform:rotate(-2deg)}.teacher.celebrate{animation:1.5s ease-in-out infinite celebrate}.teacher.wrong{animation:1.2s ease-in-out infinite wrong-nod}.math-card{background-color:#fffdf6;background-image:linear-gradient(90deg,#3024180a 1px,#0000 1px),linear-gradient(#3024180a 1px,#0000 1px),none;background-position:0 0,0 0,0 0;background-repeat:repeat,repeat,repeat;background-size:24px 24px;background-attachment:scroll,scroll,scroll;background-origin:padding-box,padding-box,padding-box;background-clip:border-box,border-box,border-box;border:3px solid #302418;border-radius:8px;min-height:430px;padding:34px 30px 28px;position:relative;box-shadow:12px 14px #30241824}.formula-ribbon{color:#fff;background:var(--plum);text-align:center;border:2px solid #302418;border-radius:8px;min-width:118px;padding:8px 14px;font-size:18px;font-weight:900;position:absolute;top:-16px;left:24px}.grid-board{grid-template-columns:repeat(4,minmax(56px,1fr));gap:10px;margin-top:42px;display:grid}.cell{aspect-ratio:1;color:#0000;background:#f1cf79;border:2px solid #2f3a42;border-radius:8px;place-items:center;transition:transform .18s,background .18s,color .18s;display:grid;box-shadow:inset 0 -8px #84541c24}.cell.is-hot{color:#fff;background:var(--coral);transform:translateY(-4px)scale(1.04)}.cell.is-counted{color:#fff;background:var(--green);transform:scale(1.02)}.cell.is-miss{color:#fff;background:var(--blue)}.path-mark{width:100%;height:130px;margin-top:24px}.route{fill:none;stroke:var(--blue);stroke-width:7px;stroke-linecap:round;stroke-dasharray:18 14;animation:1.8s linear infinite dash}.route-dot{fill:var(--coral);animation:1.4s ease-in-out infinite pulse}.route-dot.delay{animation-delay:-.7s}.guide-panel{flex-direction:column;align-self:stretch;gap:22px;padding:28px;display:flex}.layer-pill{color:#fff;background:var(--green);border-radius:8px;width:max-content;margin-bottom:0;padding:6px 10px;font-size:13px;font-weight:900}.step-copy{min-height:92px;color:var(--muted);font-size:20px;line-height:1.58}.timeline{grid-template-columns:repeat(4,1fr);gap:8px;display:grid}.step-dot{border:2px solid var(--line);min-height:54px;color:var(--blue-dark);background:#fff;border-radius:8px;padding:7px 6px;font-weight:900}.step-dot.is-active{color:#fff;background:var(--blue);border-color:var(--blue-dark)}.controls{grid-template-columns:52px 1fr 52px 52px;gap:10px;display:grid}.icon-button,.primary-button,.answer{min-height:50px;color:var(--ink);background:#fff;border:2px solid #302418;border-radius:8px;font-weight:900;box-shadow:0 5px #30241833}.icon-button{font-size:26px}.primary-button{color:#fff;background:var(--coral)}.quiz-panel{background:#fff;border:2px dashed #30241847;border-radius:8px;margin-top:auto;padding:18px}.quiz-panel p{min-height:52px;color:var(--blue-dark);margin-bottom:12px;font-weight:900}.answer-row{grid-template-columns:repeat(3,1fr);gap:10px;display:grid}.answer{font-size:24px}.answer.is-picked{color:#fff;background:var(--plum)}button:focus-visible,a:focus-visible{outline-offset:3px;outline:4px solid #d49a23cc}@keyframes cloud-drift{0%{transform:translate(-18px)}50%{transform:translate(34px)}to{transform:translate(-18px)}}@keyframes twinkle{0%,to{opacity:.55;transform:scale(.78)rotate(0)}50%{opacity:1;transform:scale(1.22)rotate(35deg)}}@keyframes hover{0%,to{transform:translateY(0)rotate(-1deg)}50%{transform:translateY(-16px)rotate(1.5deg)}}@keyframes celebrate{0%,to{transform:translateY(0)rotate(-3deg)scale(1)}50%{transform:translateY(-22px)rotate(4deg)scale(1.04)}}@keyframes wrong-nod{0%,to{transform:rotate(-2deg)}50%{transform:rotate(3deg)}}@keyframes dash{to{stroke-dashoffset:-64px}}@keyframes pulse{0%,to{opacity:.7;transform:scale(1)}50%{opacity:1;transform:scale(1.35)}}@media (width<=980px){.lesson-layout,.lesson-board{grid-template-columns:1fr}.board-panel{min-height:auto}.teacher{justify-self:center;max-width:280px}.math-card{min-height:auto}}@media (width<=620px){.shell{padding:12px}.lesson-stage{min-height:calc(100vh - 24px)}.stage-topbar{flex-direction:column;align-items:stretch}h1{font-size:34px}h2{font-size:24px}.lesson-board,.guide-panel{padding:18px}.math-card{padding:28px 16px 18px}.grid-board{grid-template-columns:repeat(4,minmax(42px,1fr));gap:7px}.timeline{grid-template-columns:repeat(2,1fr)}.controls{grid-template-columns:48px 1fr 48px 48px}}