@import "https://fonts.googleapis.com/css2?family=Shippori+Mincho:wght@400;500;600;700;800&display=swap";
@import "https://fonts.googleapis.com/css2?family=Noto+Sans+JP:wght@400;500;700&display=swap";
:root{--background:#f3eee6;--foreground:#594335;--primary-color:#594335;--text-main:#594335;--text-color:#594335;--text-light:#8c7e75;--accent-red:#d91e18;--accent-yellow:#f2a900;--card-bg:#fff6;--border-color:#dcd3c9;--font-main:"Shippori Mincho",serif;--font-heading:"Shippori Mincho",serif}*{box-sizing:border-box;margin:0;padding:0}body{background-color:var(--background);color:var(--foreground);font-family:var(--font-main);letter-spacing:.05em;min-height:100vh;line-height:1.8;position:relative;overflow-x:hidden}body:before{content:"";pointer-events:none;z-index:-1;filter:blur(40px);background:radial-gradient(circle at 10% 20%,#d91e1808 0%,#0000 40%),radial-gradient(circle at 90% 80%,#f2a90008 0%,#0000 40%),radial-gradient(circle,#59433505 0%,#0000 60%);width:100%;height:100%;position:fixed;top:0;left:0}body:after{content:"";z-index:-2;pointer-events:none;border:1px solid #5943350d;border-radius:50%;width:50vw;height:50vw;position:fixed;top:-10%;left:-10%}.container{max-width:1200px;margin:0 auto;padding:2rem}h1,h2,h3,h4,h5,h6{font-family:var(--font-heading);letter-spacing:.1em;font-weight:700}.textbook-grid{grid-template-columns:repeat(1,1fr);gap:2rem;display:grid}@media (min-width:600px){.textbook-grid{grid-template-columns:repeat(2,1fr)}}@media (min-width:900px){.textbook-grid{grid-template-columns:repeat(3,1fr)}}@media (min-width:1200px){.textbook-grid{grid-template-columns:repeat(4,1fr)}}@media (min-width:600px){.textbook-grid>:nth-child(2n){transform:translateY(30px)}}.animate-fade-in{animation:.4s ease-out forwards fadeIn}@keyframes fadeIn{0%{opacity:0}to{opacity:1}}@keyframes slideDownFade{0%{opacity:0;transform:translateY(-10px)}to{opacity:1;transform:translateY(0)}}::-webkit-scrollbar{width:8px}::-webkit-scrollbar-track{background:0 0}::-webkit-scrollbar-thumb{background:var(--text-light);opacity:.5;border-radius:4px}.hide-ruby rt{visibility:hidden}.fade-in{animation:.5s ease-in fadeIn}.vertical-text{writing-mode:vertical-rl;text-orientation:upright;letter-spacing:.3em}rt{opacity:.9;font-size:.7em;font-weight:700}.child-level-btn:hover{background-color:var(--text-main)!important;color:#fff!important;border:1px solid var(--text-main)!important}.hover-tooltip{-webkit-text-decoration:underline dotted var(--accent-red)2px;text-decoration:underline dotted var(--accent-red)2px;text-underline-offset:5px;cursor:help;display:inline;position:relative}.hover-tooltip:after{content:attr(data-tooltip);background-color:var(--text-main);color:#fff;white-space:nowrap;opacity:0;pointer-events:none;z-index:100;border-radius:4px;padding:4px 8px;font-size:.8rem;transition:opacity .2s;position:absolute;bottom:150%;left:50%;transform:translate(-50%);box-shadow:0 2px 4px #0003}.hover-tooltip:hover:after{opacity:1}