:root{--bg: #f4f1ea;--card: #fffdf8;--ink: #2b2b2b;--muted: #8a857c;--line: #e7e2d6;--accent: #c0563f;--accent-soft: #f0d9d2;--r1: #d9534f;--r2: #e0922f;--r3: #4f9d69;--r4: #4a7fb5;--radius: 16px;font-family:-apple-system,Hiragino Sans,Hiragino Kaku Gothic ProN,Yu Gothic,Noto Sans JP,sans-serif}*{box-sizing:border-box}body{margin:0;background:var(--bg);color:var(--ink);-webkit-font-smoothing:antialiased}button{font-family:inherit;cursor:pointer}hr{border:none;border-top:1px solid var(--line);margin:18px 0}.center{min-height:100vh;display:flex;flex-direction:column;align-items:center;justify-content:center;gap:12px;padding:24px}.muted{color:var(--muted)}.small{font-size:.82rem}.big{font-size:1.6rem;font-weight:700}.card{background:var(--card);border:1px solid var(--line);border-radius:var(--radius);padding:22px;box-shadow:0 1px 2px #00000008,0 8px 24px #0000000a}.brand{font-weight:800;letter-spacing:.04em;font-size:1.25rem}.brand.big{font-size:2.2rem}.brand-sub{color:var(--accent);font-weight:600;font-size:.7em;letter-spacing:.18em;margin-left:6px}.app{max-width:720px;margin:0 auto;padding:0 16px 80px}.topbar{display:flex;align-items:center;justify-content:space-between;padding:18px 4px;position:sticky;top:0;background:var(--bg);z-index:5}.topbar nav{display:flex;gap:6px}.navbtn{border:none;background:transparent;color:var(--muted);padding:8px 14px;border-radius:999px;font-size:.95rem}.navbtn.active{background:var(--accent-soft);color:var(--accent);font-weight:600}.login{width:100%;max-width:360px;display:flex;flex-direction:column;gap:12px;align-items:stretch;text-align:center}.login input{padding:12px 14px;border:1px solid var(--line);border-radius:10px;font-size:1rem;background:#fff}.login button{padding:12px;border:none;border-radius:10px;background:var(--accent);color:#fff;font-size:1rem;font-weight:600}.login button:disabled{opacity:.6}.err{color:var(--r1);font-size:.85rem}.progress{margin:8px 0 18px}.progress-top{display:flex;justify-content:space-between;align-items:baseline;margin-bottom:8px}.deck-title{font-weight:700}.combo{font-weight:700;color:var(--accent)}.bar{position:relative;height:10px;background:var(--line);border-radius:999px;overflow:hidden}.bar-fill{height:100%;background:linear-gradient(90deg,#e0922f,var(--accent));transition:width .4s ease}.bar-mark{position:absolute;top:-3px;width:2px;height:16px;background:var(--ink);opacity:.35}.progress-sub{margin-top:6px;font-size:.8rem}.flashcard{min-height:320px}.face{display:flex;flex-direction:column}.label{font-size:.75rem;letter-spacing:.08em;color:var(--muted);margin-bottom:10px}.cloze{font-size:1.5rem;line-height:1.9}.cloze.small{font-size:1rem;line-height:1.7;margin-bottom:8px}.reveal{margin-top:22px;align-self:center;padding:12px 28px;border:1px solid var(--accent);color:var(--accent);background:#fff;border-radius:999px;font-size:1rem}.answer-kana{font-size:3rem;font-weight:800;text-align:center;letter-spacing:.04em;margin:6px 0;color:var(--ink)}.answer-surface{font-size:1.4rem;text-align:center;color:var(--muted);margin-bottom:4px}.sentence{font-size:1.3rem;line-height:2.2}.trans{font-size:.95rem;margin-top:6px}ruby rt{font-size:.55em;color:var(--accent);font-weight:600}.details{margin-top:16px;display:flex;flex-direction:column;gap:10px;font-size:.92rem}.details .row{display:grid;grid-template-columns:56px 1fr;gap:10px;align-items:start}.details .k{color:var(--muted);font-size:.8rem;padding-top:2px}.tag{display:inline-block;background:var(--accent-soft);color:var(--accent);border-radius:6px;padding:1px 7px;font-size:.72rem;margin-left:6px}.examples .ex{margin-bottom:8px}.ratings{display:grid;grid-template-columns:repeat(4,1fr);gap:8px;margin-top:22px}.rate{padding:14px 6px;border:none;border-radius:12px;color:#fff;font-size:.95rem;font-weight:600}.rate.r1{background:var(--r1)}.rate.r2{background:var(--r2)}.rate.r3{background:var(--r3)}.rate.r4{background:var(--r4)}.session-done{gap:12px}.session-done button{padding:10px 24px;border:1px solid var(--accent);color:var(--accent);background:#fff;border-radius:999px}.toast{position:fixed;left:50%;transform:translate(-50%);top:76px;background:var(--ink);color:#fff;padding:12px 22px;border-radius:999px;font-weight:600;z-index:20;box-shadow:0 8px 24px #0003;animation:pop .3s ease}@keyframes pop{0%{transform:translate(-50%,-8px);opacity:0}to{transform:translate(-50%);opacity:1}}.profile{display:flex;flex-direction:column;gap:14px}.profile .avatar{width:56px;height:56px;border-radius:50%;background:var(--accent);color:#fff;display:flex;align-items:center;justify-content:center;font-size:1.6rem;font-weight:700;margin-bottom:10px}.stat-grid{display:grid;grid-template-columns:repeat(3,1fr);text-align:center}.stat-num{font-size:1.8rem;font-weight:800}.deck-row{display:flex;justify-content:space-between;align-items:center;padding:10px 0;border-top:1px solid var(--line)}.deck-row:first-of-type{border-top:none}.deck-name{font-weight:600}.logout{align-self:center;margin-top:8px;padding:10px 24px;border:1px solid var(--line);background:#fff;color:var(--muted);border-radius:999px}