body button:not(.graph-option),body :is(.next-lesson,.expand-button,.lesson-navigation a,.lesson-tabs a,.chapter-nav a,.step-nav a,.tile,.review-link,.question-link){border-bottom:4px solid #8cb0c4;box-shadow:0 3px 5px #17314c1c;transition:transform .12s ease,box-shadow .12s ease;touch-action:manipulation}body button:not(.graph-option):not(:disabled):active,body :is(.next-lesson,.lesson-navigation a,.lesson-tabs a,.chapter-nav a,.step-nav a,.tile,.review-link,.question-link):active{transform:translateY(3px);box-shadow:0 0 1px #17314c20}body button:disabled{box-shadow:none}body :is(button,a,input,select):focus-visible{outline:3px solid #df922d;outline-offset:3px}.graph-column{min-width:0}.graph-column .controls{width:100%;margin-top:10px}body .question-link,body .review-link{display:inline-block;padding:12px 16px;border-radius:8px;background:#e4f2fa;color:#155e84;text-decoration:none;line-height:1.6}.question-list{list-style:none;padding:0;display:grid;gap:12px}.question-list a{display:block}.question-list small{display:block;color:#587185}.practice-navigation{margin:16px 0}.practice-navigation summary{cursor:pointer;font-weight:700;padding:12px;background:#eaf4fa;border-radius:8px}.review-row{padding:16px;border:1px solid #d9e7ee;border-radius:10px;margin:12px 0}.review-row p{margin:5px 0 12px}.review-link{margin-top:8px}.lesson-grid>*{min-width:0}@media(prefers-reduced-motion:reduce){body button,body a{transition:none!important}}
/* 講義サイトの再生ボタンに合わせたブルーの立体感。背景色は各画面の設定を維持する */
body button:not(.graph-option),body :is(.next-lesson,.expand-button,.lesson-navigation a,.lesson-tabs a,.chapter-nav a,.step-nav a,.review-link,.question-link){background-image:linear-gradient(to bottom,rgba(255,255,255,.42),rgba(255,255,255,.09) 48%,rgba(10,76,142,.12));border-top:1px solid rgba(255,255,255,.75);border-left:1px solid rgba(255,255,255,.35);border-right:1px solid rgba(16,87,145,.28);border-bottom:3px solid rgba(12,84,145,.45);box-shadow:0 4px 7px rgba(13,71,161,.20),inset 0 1px 0 rgba(255,255,255,.5);transition:transform .12s ease,box-shadow .12s ease,filter .12s ease;touch-action:manipulation}
body button:not(.graph-option):not(:disabled):hover,body :is(.next-lesson,.expand-button,.lesson-navigation a,.lesson-tabs a,.chapter-nav a,.step-nav a,.review-link,.question-link):hover{filter:brightness(1.06)}
body button:not(.graph-option):not(:disabled):active,body :is(.next-lesson,.expand-button,.lesson-navigation a,.lesson-tabs a,.chapter-nav a,.step-nav a,.review-link,.question-link):active{transform:translateY(2px);box-shadow:0 1px 2px rgba(13,71,161,.17),inset 0 2px 4px rgba(8,65,119,.16);border-bottom-width:1px}
body button:disabled{box-shadow:none;filter:saturate(.6)}
@media(prefers-reduced-motion:reduce){body button,body a{transition:none!important}}


/* 2026-10-21: all back/next controls match powers_square.html. */
body nav.lesson-pagination{display:flex;align-items:center;justify-content:flex-start;flex-wrap:wrap;gap:6px}
body .lesson-pagination .lesson-step:is(.step-back,.step-next){display:inline-flex;flex:0 0 auto;align-items:center;justify-content:center;box-sizing:border-box;min-width:70px;min-height:35px;padding:7px 11px;border-radius:9px;font:700 .85rem/1.35 Meiryo,"Yu Gothic",sans-serif;text-align:center;text-decoration:none;letter-spacing:normal;cursor:pointer;box-shadow:0 2px 4px #17314c22;transition:transform .12s ease,box-shadow .12s ease,filter .12s ease;touch-action:manipulation}
body .lesson-pagination .lesson-step.step-back{background:linear-gradient(#f9fcff,#dbe9f4);color:#30536b;border:1px solid #9fb9cd}
body .lesson-pagination .lesson-step.step-next{background:linear-gradient(#4cadd4,#177eaf);color:#fff;border:1px solid #176b94}
body .lesson-pagination .lesson-step small{display:none}
body .lesson-pagination .lesson-step[hidden]{display:none!important}
body .lesson-pagination .lesson-step:not(:disabled):hover{filter:brightness(1.05)}
body .lesson-pagination .lesson-step:not(:disabled):active{transform:translateY(2px);box-shadow:0 1px 2px rgba(13,71,161,.17),inset 0 2px 4px rgba(8,65,119,.16);border-bottom-width:1px}
body .lesson-pagination .lesson-step:focus-visible{outline:3px solid #dd8b28;outline-offset:3px}