:root{color-scheme:light;--ink:#17342d;--muted:#566d63;--green:#176b5b;--dark:#0f4f43;--mint:#e9f5ee;--line:#d5e6dc;--paper:#f8faf7;--focus:#175cd3}
*{box-sizing:border-box}body{margin:0;background:var(--paper);color:var(--ink);font:17px/1.65 system-ui,-apple-system,"Hiragino Sans","Yu Gothic","Noto Sans JP",sans-serif}button{font:inherit;cursor:pointer}a{color:var(--green)}button:focus-visible,a:focus-visible{outline:3px solid var(--focus);outline-offset:3px}.skip-link{position:absolute;top:-5rem;left:1rem;background:#fff;padding:.6rem 1rem;z-index:10}.skip-link:focus{top:1rem}.wrap,.header-inner{width:min(1050px,calc(100% - 36px));margin:auto}.site-header{background:#fff;border-bottom:1px solid var(--line)}.header-inner{min-height:74px;display:flex;align-items:center;gap:25px}.brand{display:flex;align-items:center;gap:10px;text-decoration:none;color:var(--ink);white-space:nowrap}.brand-mark{display:grid;place-items:center;width:40px;height:40px;border-radius:11px;background:var(--green);color:#fff;font-weight:900}.brand strong,.brand small{display:block;line-height:1.2}.brand small{color:var(--muted);font-size:12px}.header-inner nav{margin-left:auto;display:flex;gap:20px}.header-inner nav a{font-size:14px;font-weight:800;text-decoration:none}.prototype-tag{border:1px solid var(--line);border-radius:999px;padding:4px 10px;color:var(--muted);font-size:11px;font-weight:900;white-space:nowrap}.eyebrow{margin:0 0 10px;font-size:12px;letter-spacing:.16em;color:var(--green);font-weight:900}.hero{background:radial-gradient(circle at 78% 20%,#cfe8da,transparent 42%),linear-gradient(110deg,#f5fbf5,#eaf5ed);border-bottom:1px solid var(--line);padding:54px 0}.hero h1{margin:0;font-size:clamp(33px,4.3vw,52px);line-height:1.28}.hero h1 em{color:var(--green);font-style:normal}.hero p:not(.eyebrow){max-width:690px}.hero-note{font-size:14px;color:var(--muted)}.practice{padding:48px 0}.practice-head{display:flex;justify-content:space-between;align-items:end;gap:15px}.practice-head h2{margin:0;font-size:29px}.practice-head strong{white-space:nowrap;color:var(--green)}.progress-track{height:9px;margin:21px 0;border-radius:99px;background:#e1ece5;overflow:hidden}.progress-track span{display:block;height:100%;width:0;background:var(--green);transition:width .2s}.practice-card{padding:30px;background:#fff;border:1px solid var(--line);border-radius:18px;box-shadow:0 18px 34px #193e3210}.pair-label{margin:0;color:var(--green);font-size:15px;font-weight:900}.instruction{margin:9px 0 20px;font-size:20px;font-weight:800}.listen-button,.next-button{min-height:51px;padding:10px 20px;border:0;border-radius:10px;background:var(--green);color:#fff;font-weight:900}.listen-button:hover,.next-button:hover{background:var(--dark)}.listen-status{margin:10px 0 18px;color:var(--muted);font-size:14px}.choices{display:grid;grid-template-columns:repeat(2,minmax(0,1fr));gap:10px}.choices button{min-height:68px;border:1px solid #bfd6c8;border-radius:11px;background:#fff;color:var(--ink);font-size:25px;font-weight:800}.choices button:not(:disabled):hover{background:var(--mint)}.choices button:disabled{cursor:default}.choices button.correct{background:#e3f4e8;border-color:var(--green)}.choices button.incorrect{background:#faece8;border-color:#c77b62}.feedback{min-height:48px;margin:17px 0 8px;color:var(--muted)}.feedback strong{display:block;color:var(--ink);font-size:19px}.feedback p{margin:7px 0}.compare{display:flex;flex-wrap:wrap;gap:8px;margin-top:15px}.compare button{min-height:44px;padding:8px 13px;border:1px solid var(--green);border-radius:8px;background:#fff;color:var(--green);font-size:15px;font-weight:800}.compare a{display:inline-flex;align-items:center;min-height:44px;padding:8px 13px;border:1px solid var(--line);border-radius:8px;text-decoration:none;font-size:14px;font-weight:800}.next-button{margin-top:9px}.practice-note{color:var(--muted);font-size:14px}.reference{padding:28px 0 64px}.reference h2{margin:0 0 8px;font-size:28px}.reference p:not(.eyebrow){color:var(--muted)}.reference div{display:flex;gap:12px;flex-wrap:wrap}.reference a{display:inline-flex;min-height:46px;align-items:center;border:1px solid var(--green);border-radius:8px;padding:8px 14px;text-decoration:none;font-size:15px;font-weight:800}footer{border-top:1px solid var(--line);padding:23px max(18px,calc((100% - 1050px)/2));display:flex;justify-content:space-between;gap:10px;color:var(--muted);font-size:13px}
@media(max-width:620px){.header-inner{gap:8px}.header-inner nav{display:block}.header-inner nav a{display:block;font-size:12px}.prototype-tag{display:none}.hero{padding:38px 0}.practice-card{padding:19px}.instruction{font-size:19px}.choices button{font-size:21px}.practice-head h2{font-size:24px}}@media(max-width:390px){.brand small{font-size:10px}.choices{gap:7px}.choices button{font-size:19px;padding:4px}footer{display:block}}@media(prefers-reduced-motion:reduce){.progress-track span{transition:none}}
.feedback>button{min-height:48px;padding:9px 16px;border:1px solid var(--green);border-radius:9px;background:var(--mint);color:var(--green);font-weight:800}