:root{--ink:#17221d;--green:#123a2c;--board:#267653;--board-dark:#123d2d;--cream:#f3efe5;--paper:#fbfaf6;--gold:#d8a841;--line:#d9d6cc;--shadow:0 24px 60px rgba(13,42,31,.18)}
*{box-sizing:border-box}html{scroll-behavior:smooth}body{margin:0;color:var(--ink);background:var(--paper);font-family:"Hiragino Kaku Gothic ProN","Yu Gothic",Meiryo,sans-serif;line-height:1.75}button{font:inherit;color:inherit}.site-header{height:72px;display:flex;align-items:center;justify-content:space-between;padding:0 clamp(20px,5vw,72px);background:#fff;border-bottom:1px solid #e9e6dd}.brand{display:inline-flex;gap:12px;align-items:center;color:var(--green);font:bold 17px/1 Georgia,serif;letter-spacing:.2em;text-decoration:none}.brand-mark{position:relative;width:34px;height:34px;display:inline-block;transform:rotate(-12deg)}.brand-mark i,.brand-mark b{position:absolute;width:24px;height:24px;border-radius:50%;border:2px solid var(--green)}.brand-mark i{left:0;top:1px;background:var(--green)}.brand-mark b{right:0;bottom:1px;background:var(--paper)}.howto-button{border:0;background:none;font-weight:700;cursor:pointer;padding:10px}.howto-button:before{content:"?";display:inline-grid;place-items:center;width:22px;height:22px;border:1px solid;border-radius:50%;margin-right:8px}.hero{padding:54px 24px 76px;background:radial-gradient(circle at 50% 25%,#fff 0,#f8f6ef 44%,#efeadf 100%);border-bottom:1px solid var(--line)}.intro{text-align:center}.eyebrow,.section-kicker{font:700 11px/1.2 Georgia,serif;letter-spacing:.24em;color:#b08027}.intro h1{font-family:Georgia,"Yu Mincho",serif;font-size:clamp(44px,7vw,72px);line-height:1;margin:12px 0 15px;color:var(--green);letter-spacing:.12em}.intro>p:last-child{margin:0;color:#66716b;font-size:14px}.mode-panel{max-width:660px;margin:35px auto 30px}.segmented{display:grid;grid-template-columns:1fr 1fr;background:#e6e2d8;border-radius:10px;padding:5px}.mode-button{border:0;background:transparent;border-radius:7px;padding:13px;cursor:pointer;font-weight:700;color:#68706c}.mode-button span{font-size:11px;margin-right:7px}.mode-button.active{background:var(--green);color:#fff;box-shadow:0 5px 12px rgba(18,58,44,.18)}.difficulty-row{display:flex;justify-content:center;align-items:center;gap:18px;margin-top:15px;font-size:12px;color:#626c67}.difficulty{display:flex;border:1px solid #d6d1c6;border-radius:6px;overflow:hidden}.difficulty button{border:0;border-left:1px solid #ddd8cd;background:#fff;padding:6px 16px;cursor:pointer}.difficulty button:first-child{border:0}.difficulty button.active{background:#dfd8c7;color:var(--green);font-weight:700}.game-layout{max-width:920px;margin:auto;display:grid;grid-template-columns:150px minmax(320px,520px) 150px;gap:26px;align-items:center}.score-card{background:#fff;border:1px solid #e1ded5;border-radius:10px;box-shadow:0 10px 24px rgba(16,46,35,.08);padding:18px;text-align:center;transition:.2s}.score-card.active{border-color:var(--gold);box-shadow:0 0 0 2px rgba(216,168,65,.22),0 10px 24px rgba(16,46,35,.1);transform:translateY(-3px)}.player-label{display:flex;align-items:center;gap:9px;text-align:left}.player-label small{display:block;font:9px Georgia;letter-spacing:.16em;color:#9a9e99}.player-label strong{font-size:14px}.disc{display:inline-block;border-radius:50%;width:28px;height:28px;box-shadow:inset -3px -4px 6px rgba(0,0,0,.22),0 2px 4px rgba(0,0,0,.25)}.disc.black{background:#151b18}.disc.white{background:#fff;border:1px solid #d5d4ce}.score-card output{display:block;font:48px/1.25 Georgia,serif;color:var(--green);margin:7px}.turn-tag{display:block;border-radius:20px;padding:4px;background:#ece9e1;font-size:11px;color:#777}.active .turn-tag{background:#e5d4a8;color:#604817;font-weight:700}.status{text-align:center;height:32px;font-size:14px;font-weight:700;color:var(--green)}.board-wrap{padding:12px;background:#bb8b4c;border-radius:8px;box-shadow:var(--shadow),inset 0 0 0 2px rgba(92,51,16,.3);aspect-ratio:1}.board{display:grid;grid-template-columns:repeat(8,1fr);width:100%;height:100%;background:var(--board);border:2px solid var(--board-dark)}.cell{position:relative;border:0;border-right:1px solid rgba(8,53,37,.66);border-bottom:1px solid rgba(8,53,37,.66);background:transparent;padding:0;cursor:default;display:grid;place-items:center}.cell.legal{cursor:pointer}.cell.legal:after{content:"";width:17%;height:17%;border-radius:50%;background:rgba(255,224,138,.85);box-shadow:0 0 0 4px rgba(255,224,138,.12)}.cell.legal:hover{background:rgba(255,255,255,.09)}.stone{width:78%;height:78%;border-radius:50%;box-shadow:inset -5px -7px 8px rgba(0,0,0,.22),0 3px 5px rgba(0,0,0,.35);animation:drop .18s ease-out}.stone.black{background:radial-gradient(circle at 35% 28%,#4e5551,#0c100e 63%)}.stone.white{background:radial-gradient(circle at 35% 28%,#fff,#dddcd6 70%);box-shadow:inset -4px -5px 7px rgba(0,0,0,.1),0 3px 5px rgba(0,0,0,.3)}@keyframes drop{from{transform:scale(.2) rotateY(90deg)}to{transform:scale(1) rotateY(0)}}.game-actions{display:flex;gap:10px;justify-content:center;margin-top:20px}.primary-action,.secondary-action{border-radius:6px;padding:10px 20px;font-weight:700;font-size:13px;cursor:pointer}.primary-action{border:0;background:var(--green);color:#fff;box-shadow:0 5px 12px rgba(18,58,44,.18)}.secondary-action{background:#fff;border:1px solid #d5d1c7}.secondary-action:disabled{opacity:.4;cursor:not-allowed}.guide{padding:80px 24px;max-width:1050px;margin:auto;text-align:center}.guide h2,.name-note h2,dialog h2{font:700 30px/1.4 Georgia,"Yu Mincho",serif;color:var(--green);margin:8px 0 35px}.rule-grid{display:grid;grid-template-columns:repeat(3,1fr);gap:26px}.rule-grid article{position:relative;padding:38px 28px 28px;background:#f4f0e7;border-top:3px solid var(--green);min-height:275px}.rule-number{position:absolute;left:14px;top:10px;font:italic 24px Georgia;color:#d3c5a9}.rule-grid h3{font:700 18px Georgia,"Yu Mincho",serif;color:var(--green);margin:18px 0 8px}.rule-grid p{font-size:13px;margin:0;color:#606963}.mini-board{width:80px;height:80px;margin:auto;background:repeating-linear-gradient(0deg,transparent 0 25%,rgba(0,0,0,.18) 25% 26%),repeating-linear-gradient(90deg,#2f7c59 0 25%,rgba(0,0,0,.18) 25% 26%);position:relative}.mini-board i,.flip-visual i{position:absolute;width:20px;height:20px;border-radius:50%}.mini-board .dark{background:#18201c;left:20px;top:20px}.mini-board .light{background:white;left:40px;top:20px}.mini-board .place{border:2px dashed var(--gold);left:60px;top:20px}.flip-visual{height:80px;display:flex;align-items:center;justify-content:center;gap:22px}.flip-visual i{position:static;width:45px;height:45px;box-shadow:0 3px 4px #999}.flip-visual .dark{background:#18201c}.flip-visual .light{background:#fff}.flip-visual b{color:var(--gold)}.count-visual{height:80px;display:flex;justify-content:center;align-items:center}.count-visual i{width:38px;height:38px;border-radius:50%;background:#18201c;margin-left:-8px;box-shadow:0 2px 4px #777}.count-visual i:nth-child(n+4){background:#fff}.name-note{max-width:1000px;margin:0 auto 90px;padding:45px 55px;background:var(--green);color:#e7eee9;display:grid;grid-template-columns:180px 1fr;gap:45px;align-items:center}.name-note h2{color:#fff;margin-bottom:15px}.name-note p:last-child{font-size:13px;margin:0}.note-mark{font:50px Georgia;color:#fff;text-align:center;letter-spacing:-8px}.note-mark span{display:inline-block;width:58px;height:58px;overflow:hidden;border-radius:50%;background:linear-gradient(90deg,#161d19 50%,#fff 50%);color:transparent;vertical-align:middle;margin:0 8px}footer{min-height:110px;background:#e9e4d9;display:flex;align-items:center;justify-content:space-between;padding:20px clamp(24px,8vw,100px);font-size:11px;color:#777}.footer-brand{font-size:13px}.footer-brand .brand-mark{transform:scale(.75) rotate(-12deg)}dialog{max-width:480px;border:0;border-radius:12px;padding:35px;box-shadow:0 20px 80px #0006;color:var(--ink)}dialog::backdrop{background:rgba(4,25,17,.68);backdrop-filter:blur(3px)}.dialog-close{position:absolute;right:15px;top:10px;border:0;background:none;font-size:28px;cursor:pointer}dialog h2{margin-bottom:10px}dialog .primary-action{margin-top:15px;width:100%}
@media(max-width:800px){.game-layout{grid-template-columns:1fr 1fr;max-width:540px}.board-column{grid-column:1/3;grid-row:2}.score-card{display:flex;align-items:center;justify-content:space-between;padding:10px 14px}.score-card output{font-size:30px;margin:0}.turn-tag{display:none}.name-note{margin:0 24px 60px;grid-template-columns:1fr;text-align:center;gap:15px}.rule-grid{grid-template-columns:1fr}.rule-grid article{min-height:auto}.guide{padding-top:60px}}@media(max-width:480px){.site-header{height:60px}.hero{padding:16px 12px 24px}.intro h1{font-size:46px}.mode-panel{margin:26px auto 20px}.difficulty-row{gap:8px}.difficulty button{padding:6px 9px}.game-layout{gap:10px}.board-wrap{padding:7px}.player-label .disc{width:22px;height:22px}.score-card{padding:8px}.score-card output{font-size:25px}.game-actions{margin-top:14px}.guide{padding-left:18px;padding-right:18px}.name-note{margin-left:12px;margin-right:12px;padding:35px 24px}footer{flex-direction:column;justify-content:center;gap:12px}.brand>span:last-child{font-size:14px}}
@media(prefers-reduced-motion:reduce){*{scroll-behavior:auto}.stone{animation:none}}

.adsbygoogle{margin: 16px 0}.site-header{height:62px}.hero{padding-top:16px;padding-bottom:24px}.intro h1{font-size:clamp(42px,6vw,64px);margin-top:7px;margin-bottom:10px}.mode-panel{margin-top:22px;margin-bottom:18px}.difficulty-row{margin-top:10px}.game-actions{margin-top:14px}.guide{padding-top:24px;padding-bottom:24px}.guide h2{margin-bottom:25px}.rule-grid article{padding-top:28px;padding-bottom:22px;min-height:245px}.name-note{margin-bottom:55px;padding-top:34px;padding-bottom:34px}.name-note h2{margin-bottom:12px}footer{min-height:84px;padding-top:14px;padding-bottom:14px}
.strategy{max-width:1050px;margin:0 auto;padding:24px 24px 40px;border-top:1px solid var(--line)}.strategy-heading{text-align:center;max-width:680px;margin:0 auto 26px}.strategy-heading h2{font:700 30px/1.4 Georgia,"Yu Mincho",serif;color:var(--green);margin:6px 0 18px}.strategy-heading>p:last-child{font-size:13px;color:#65706a;margin:0}.strategy-grid{display:grid;grid-template-columns:repeat(2,1fr);gap:12px}.strategy-grid article{display:grid;grid-template-columns:58px 1fr;gap:16px;padding:22px;background:#f4f0e7;border-radius:4px}.strategy-grid h3{font:700 17px Georgia,"Yu Mincho",serif;color:var(--green);margin:0 0 5px}.strategy-grid p{font-size:12px;line-height:1.8;color:#5e6862;margin:0}.tip-icon{width:52px;height:52px;border-radius:50%;display:grid;place-items:center;background:var(--green);color:#fff;font:bold 18px Georgia;position:relative}.corner-icon{border-radius:4px;background:linear-gradient(90deg,var(--board-dark) 49%,transparent 49%),linear-gradient(0deg,var(--board-dark) 49%,var(--board) 49%);border:3px solid #b88a4f}.corner-icon i{width:20px;height:20px;border-radius:50%;background:#fff;position:absolute;left:3px;top:3px}.choice-icon{box-shadow:inset 0 0 0 4px var(--board)}.quiet-icon{font-size:35px;color:var(--gold)}.edge-icon{border-radius:4px;background:var(--board);display:flex;padding-left:7px}.edge-icon i{width:17px;height:17px;border-radius:50%;background:#fff;margin-left:-5px}.edge-icon i:last-child{background:#161d19}.parity-icon{background:#b08027}.pass-icon{font-size:29px}
@media(max-width:800px){.strategy-grid{grid-template-columns:1fr}.name-note{margin-bottom:42px}.guide{padding-top:44px}}
@media(max-width:480px){.site-header{height:56px}.hero{padding-top:26px;padding-bottom:40px}.intro h1{font-size:44px}.mode-panel{margin-top:18px;margin-bottom:14px}.guide{padding-top:38px;padding-bottom:34px}.strategy{padding:36px 12px 40px}.strategy-grid article{grid-template-columns:48px 1fr;padding:17px 15px;gap:12px}.tip-icon{width:44px;height:44px}.name-note{padding-top:28px;padding-bottom:28px}footer{gap:8px}}
.stone{animation:none}.stone.animate{animation:drop .24s ease-out}.difficulty-row[hidden]{display:none!important}.header-actions{display:flex;align-items:center;gap:8px}.sound-button{border:1px solid #d8d4ca;background:#fff;border-radius:20px;padding:5px 11px;cursor:pointer;font-size:12px;font-weight:700;color:var(--green)}.sound-button[aria-pressed="false"]{color:#929994;background:#f0eee8;text-decoration:line-through}@media(max-width:480px){.header-actions{gap:2px}.sound-button span{display:none}.sound-button{width:34px;height:34px;padding:0}.howto-button{padding:7px}}
.color-row{display:flex;justify-content:center;align-items:center;gap:18px;margin-top:10px;font-size:12px;color:#626c67}.color-choice{display:flex;border:1px solid #d6d1c6;border-radius:6px;overflow:hidden}.color-choice button{border:0;border-left:1px solid #ddd8cd;background:#fff;padding:6px 16px;cursor:pointer}.color-choice button:first-child{border:0}.color-choice button.active{background:#dfd8c7;color:var(--green);font-weight:700}.color-row[hidden]{display:none!important}@media(max-width:480px){.color-row{gap:8px}.color-choice button{padding:6px 10px}}