@import url('https://fonts.googleapis.com/css2?family=Noto+Sans+JP:wght@400;500;600;700;800&display=swap');
:root{--navy:#102e58;--blue:#1862da;--ink:#315575;--muted:#708b9e;--line:#d8e7ee;--green:#77a98a}*{box-sizing:border-box}html{scroll-behavior:smooth;scroll-padding-top:100px}body{margin:0;background:#f7fbfe;color:var(--ink);font-family:'Noto Sans JP',sans-serif;line-height:1.8;background-image:radial-gradient(ellipse at 0% 5%,#d7edf680,transparent 45%),radial-gradient(ellipse at 100% 35%,#e0efdd80,transparent 35%)}a{color:inherit;text-decoration:none}button,select,textarea{font:inherit}button,a,select{-webkit-tap-highlight-color:transparent}a:focus-visible,button:focus-visible,select:focus-visible,textarea:focus-visible,summary:focus-visible{outline:3px solid #e8a347;outline-offset:5px}header{position:sticky;top:0;z-index:10;display:flex;justify-content:space-between;align-items:center;padding:16px max(5vw,20px);background:#f8fcffdc;backdrop-filter:blur(20px);border-bottom:1px solid #ffffff}.brand{font-weight:800;color:var(--navy);letter-spacing:.08em;font-size:17px}.brand span{display:block;font-size:8px;letter-spacing:.24em;color:var(--muted);line-height:1.4}.shortcut{font-size:12px;border:1px solid #bed4e3;background:white;border-radius:30px;padding:9px 18px}.wrap{max-width:1080px;width:90%;margin:auto}.hero{padding-top:40px}.eyebrow{font-size:10px;letter-spacing:.19em;font-weight:700;color:var(--muted);margin:0 0 16px}.dot{display:inline-block;width:7px;height:7px;border-radius:50%;background:var(--green);margin-right:8px}.hero-image{width:100%;display:block;border-radius:20px;box-shadow:0 20px 60px #385f7520}.hero-bottom{display:flex;justify-content:space-between;align-items:center;padding:30px 0}.kicker{font-size:13px;color:var(--muted);margin:0 0 8px}h1{font-size:clamp(23px,3vw,34px);margin:0;color:var(--navy);letter-spacing:.03em}h2{font-size:clamp(24px,3.1vw,35px);line-height:1.6;letter-spacing:.03em;margin:0;color:var(--navy)}.date{font-size:32px;color:var(--green);font-weight:600;line-height:1.3}.date span{display:block;font-size:9px;letter-spacing:.18em;text-align:center}.jump{display:grid;grid-template-columns:repeat(3,1fr);border-top:1px solid var(--line);border-bottom:1px solid var(--line);margin-bottom:95px}.jump a{padding:20px 22px;font-size:14px;display:flex;gap:14px;align-items:center}.jump a+a{border-left:1px solid var(--line)}.jump b{font-size:11px;color:var(--green)}.jump span{margin-left:auto;color:var(--blue)}.jump a:hover{background:#e6f1fa}.section-head{display:flex;gap:22px;align-items:center;margin-bottom:28px}.number{font-size:52px;font-weight:400;color:#a0c4d1;line-height:1}.section-head .eyebrow{margin-bottom:5px}.video-box{aspect-ratio:16/9;border:8px solid white;border-radius:22px;overflow:hidden;box-shadow:0 16px 60px #30577615;background:#122e50}iframe{width:100%;height:100%;border:0}.under-video{display:flex;justify-content:space-between;gap:15px;font-size:12px;margin:14px 8px;color:var(--muted)}.under-video a{color:var(--blue)}#materials{padding:100px 0}.material-card{display:grid;grid-template-columns:1fr 1fr;gap:45px;align-items:center;background:#fff;border:1px solid white;border-radius:30px;padding:50px;box-shadow:0 20px 70px #3c6e7e0c}.book-visual{position:relative;min-height:290px;display:grid;place-items:center;background:radial-gradient(ellipse,#e6f2e3,transparent 70%)}.book{width:210px;height:260px;transform:rotate(-7deg);background:linear-gradient(135deg,#f2fcff,#daedff);border-left:12px solid #a5ccdf;border-radius:3px 12px 12px 3px;box-shadow:15px 20px 25px #36597726;display:flex;flex-direction:column;justify-content:space-between;padding:22px;color:var(--navy)}.book span{font-size:9px;letter-spacing:.15em}.book b{font-size:27px;line-height:1.6}.book i{font-size:8px;font-style:normal}.page-tag{position:absolute;bottom:0;right:5px;background:white;border:1px solid var(--line);border-radius:30px;padding:7px 16px;font-size:11px}.material-text p:not(.eyebrow){font-size:14px;margin:20px 0 25px}.primary,.secondary{display:inline-flex;align-items:center;justify-content:center;gap:20px;cursor:pointer;border:0;border-radius:12px;padding:16px 22px;font-weight:600;font-size:13px;transition:transform .2s,box-shadow .2s}.primary{background:var(--blue);color:white;box-shadow:0 6px 20px #1862da20}.primary:hover,.secondary:hover{transform:translateY(-2px)}.secondary{background:#f3f8fb;color:var(--ink);border:1px solid var(--line)}.work-section{padding:70px 0 80px;background:linear-gradient(180deg,#eaf4f380,#e5f0fa90)}.work-intro{font-size:13px;margin:0 0 28px}.steps{display:grid;grid-template-columns:repeat(5,1fr);gap:8px;position:relative;z-index:1}.steps button{border:1px solid #d6e5e9;border-radius:13px 13px 0 0;padding:16px 5px;background:#eef5f6;color:#7792a1;cursor:pointer;font-weight:600}.steps button span{display:block;font-size:9px;letter-spacing:.14em;font-weight:500;margin-bottom:4px}.steps button[aria-selected=true]{background:white;color:var(--blue);border-bottom-color:white;box-shadow:inset 0 3px var(--blue)}.work-panel{background:white;padding:40px 45px;border:1px solid var(--line);border-radius:0 0 25px 25px;margin-top:-1px;box-shadow:0 20px 60px #335f7810}.stage-top{display:flex;gap:22px;align-items:center;margin-bottom:25px}.stage-icon{width:84px;height:84px;flex-shrink:0;border-radius:22px;background:#edf6fa;display:grid;place-items:center}.stage-icon svg{width:53px;height:53px;stroke:#6097b1;stroke-width:2;fill:none;stroke-linecap:round;stroke-linejoin:round}.stage-label{margin:0 0 3px}h3{font-size:27px;line-height:1.5;margin:0;color:var(--navy)}.stage-subtitle{font-size:12px;margin:7px 0 0;color:var(--muted)}details{border-top:1px solid var(--line);border-bottom:1px solid var(--line);margin-bottom:30px}summary{cursor:pointer;list-style:none;font-size:13px;padding:16px 0;display:flex;justify-content:space-between}summary::-webkit-details-marker{display:none}.explanation{font-size:14px;line-height:2.1;padding:0 0 16px}.practice label{display:block;font-size:14px;font-weight:700;margin:0 0 12px}.practice small{font-weight:400;color:var(--muted);margin-left:10px;font-size:10px}select{width:100%;background:#f8fbfd;color:var(--ink);padding:14px 12px;border:1px solid #c5dce7;border-radius:10px;font-size:13px}.question-card{padding:24px 28px;background:linear-gradient(115deg,#ecf6fc,#f0f6ed);border-radius:18px;margin:20px 0 28px;position:relative}.question-card span{font-size:10px;color:var(--green);font-weight:600}.question-card p{font-size:20px;color:var(--navy);font-weight:600;margin:8px 0}textarea{width:100%;resize:vertical;padding:18px;border:1px solid #c5dce7;border-radius:12px;color:var(--ink);background:#fcfdfe;font-size:14px;line-height:1.9}textarea::placeholder{color:#9aafbd}.hint{font-size:11px;color:var(--muted);margin:7px 0 25px}.actions{display:flex;gap:12px;flex-wrap:wrap}.save-note{font-size:10px;color:var(--muted);margin-top:18px;line-height:1.9}#status{min-height:20px;font-size:12px;color:var(--blue)}.ending{text-align:center;padding:90px 0}.little-sun{color:#e4b35d;font-size:35px}.ending h2{margin:15px 0 22px}.ending p{font-size:14px;line-height:2;color:var(--muted)}.ending a{display:inline-block;font-size:12px;color:var(--blue);border-bottom:1px solid #a5c3e4;margin-top:20px}footer{border-top:1px solid var(--line);padding:25px 5%;display:flex;justify-content:space-between;font-size:11px;color:var(--muted)}.mobile{display:none}.reveal{opacity:0;transform:translateY(26px);transition:opacity .9s,transform .9s}.reveal.visible{opacity:1;transform:none}.switching{animation:slide .4s ease both}@keyframes slide{from{opacity:0;transform:translateX(18px)}to{opacity:1;transform:none}}
@media(max-width:650px){header{padding:12px 5%}.brand{font-size:14px}.shortcut{font-size:10px;padding:8px 13px}.hero{padding-top:25px}.hero-image{border-radius:12px}.hero-bottom{padding:24px 0}.kicker{font-size:10px}.date{font-size:24px}.jump{margin-bottom:60px}.jump a{padding:15px 6px;font-size:10px;gap:5px}.jump span{display:none}.jump b{font-size:9px}.section-head{gap:14px;margin-bottom:22px}.number{font-size:40px}.eyebrow{font-size:8px}.video-box{border:4px solid white;border-radius:12px}.under-video{font-size:9px}#materials{padding:65px 0}.material-card{grid-template-columns:1fr;gap:28px;padding:28px;border-radius:22px}.book-visual{min-height:220px}.book{width:170px;height:210px;padding:18px}.book b{font-size:22px}.material-text h2 br{display:none}.material-text p:not(.eyebrow){font-size:12px}.material-text .primary{width:100%}.work-section{padding:45px 0}.work-intro{font-size:10px}.steps{gap:3px}.steps button{font-size:11px;padding:12px 1px;border-radius:9px 9px 0 0}.steps button span{font-size:8px}.work-panel{padding:26px 19px}.stage-top{gap:14px;align-items:flex-start}.stage-icon{width:55px;height:55px;border-radius:15px}.stage-icon svg{width:37px;height:37px}h3{font-size:22px}.stage-subtitle{font-size:10px}.explanation{font-size:12px}.question-card{padding:20px}.question-card p{font-size:17px}select{font-size:12px}.actions{display:grid;grid-template-columns:1fr}.primary,.secondary{font-size:12px}.ending{padding:65px 0}footer{display:block;text-align:center}footer span{display:block;margin-top:6px}.mobile{display:block}}@media(prefers-reduced-motion:reduce){html{scroll-behavior:auto}.reveal{opacity:1;transform:none;transition:none}.switching{animation:none}*{transition:none!important}}
.learning-guide{background:#ffffffae;border-left:3px solid var(--green);padding:22px 26px;margin:0 0 30px;border-radius:0 16px 16px 0}.learning-guide strong{font-size:16px;color:var(--navy)}.learning-guide p{font-size:12px;margin:10px 0 0;color:var(--muted)}.knowledge{background:linear-gradient(110deg,#eaf4fc,#f1f7ef);padding:22px 26px;border-radius:16px;margin:20px 0 28px}.knowledge span{display:block;font-size:10px;letter-spacing:.08em;color:var(--muted)}.knowledge strong{display:block;font-size:20px;color:var(--navy);margin:7px 0}.knowledge p{font-size:12px;margin:5px 0 0}.explanation p{margin:0 0 20px}#references{display:flex;flex-wrap:wrap;gap:14px;margin:0 0 28px;font-size:11px;color:var(--blue)}.question-list{margin:12px 0 0}.question-list summary{font-size:12px}#all-questions{display:grid;gap:8px;padding-bottom:15px}#all-questions button{cursor:pointer;text-align:left;color:var(--ink);font-size:12px;background:#f5f9fb;border:1px solid var(--line);border-radius:8px;padding:13px 16px}#all-questions button:hover{background:#e8f2fb;border-color:#92b8dc}@media(max-width:650px){.learning-guide{padding:18px}.learning-guide strong{font-size:14px}.learning-guide p{font-size:11px}.knowledge{padding:18px}.knowledge strong{font-size:17px}.knowledge p{font-size:11px}#stage-title{font-size:20px}}