*{box-sizing:border-box}
html{-webkit-text-size-adjust:100%}
body{margin:0;background:#f6f6f4;color:#1b1b1b;font:17px/1.55 -apple-system,system-ui,sans-serif}
main{max-width:820px;margin:0 auto;padding:0 14px 90px}
.top{position:sticky;top:0;z-index:5;background:#f6f6f4;display:flex;align-items:center;gap:8px;padding:10px 0}
.top h1{font-size:19px;margin:0;margin-right:auto}
.top a,.btn{font:inherit;font-size:15px;padding:9px 14px;border-radius:11px;border:1px solid #d9d9d4;background:#fff;color:#1b1b1b;text-decoration:none;cursor:pointer;min-height:42px;display:inline-flex;align-items:center}
.top a.on,.btn.dark{background:#1b1b1b;color:#fff;border-color:#1b1b1b}
.btn:disabled{opacity:.4}
.chips{display:flex;gap:6px;overflow-x:auto;padding:2px 0 8px;-webkit-overflow-scrolling:touch}
.chip{flex:0 0 auto;font-size:14px;padding:7px 12px;border-radius:999px;border:1px solid #e0e0db;background:#fff;cursor:pointer;white-space:nowrap}
.chip.on{background:#1b1b1b;color:#fff;border-color:#1b1b1b}
.chip small{opacity:.65;margin-left:4px}
.card{background:#fff;border:1px solid #e4e4e0;border-radius:16px;padding:16px;margin:10px 0}
.tag{display:inline-block;font-size:12px;letter-spacing:.04em;text-transform:uppercase;color:#666;background:#f0f0ec;padding:3px 9px;border-radius:7px;margin-bottom:8px}
.q{font-weight:600;font-size:18px;margin-bottom:12px}
.expr{font:16px/1.6 ui-monospace,Menlo,monospace;background:#f3f3f0;border-radius:10px;padding:10px 12px;margin:10px 0;overflow-x:auto;font-weight:500;word-break:break-word}
.state{font-size:15px;background:#eef3fb;border-radius:10px;padding:10px 12px;margin:8px 0;font-weight:500}
.opt{display:flex;gap:10px;align-items:flex-start;width:100%;text-align:left;font:inherit;font-size:16px;padding:13px 14px;margin:8px 0;border:1.5px solid #e2e2dd;border-radius:13px;background:#fff;cursor:pointer;color:#1b1b1b}
.opt .k{flex:0 0 24px;height:24px;border-radius:7px;background:#f0f0ec;font-size:13px;display:flex;align-items:center;justify-content:center;font-weight:600}
.opt.right{border-color:#1a7f37;background:#eef8f1}.opt.right .k{background:#1a7f37;color:#fff}
.opt.wrong{border-color:#c0392b;background:#fdf1ef}.opt.wrong .k{background:#c0392b;color:#fff}
.why{background:#f5f5f2;border-radius:12px;padding:12px 14px;margin-top:10px;font-size:15px;overflow-x:auto}
.note{font-size:14px;color:#555;margin:6px 0}
.mono{font:14px/1.5 ui-monospace,Menlo,monospace;margin:3px 0;word-break:break-word}
.bar{display:flex;gap:8px;justify-content:flex-end;margin-top:12px;flex-wrap:wrap}
.stat{font-size:14px;color:#666;margin:2px 0 6px}
.bad{color:#c0392b}
/* K-map */
table.km{border-collapse:collapse;margin:10px auto;font:15px ui-monospace,Menlo,monospace}
.km th,.km td{border:1px solid #cfcfca;width:44px;height:40px;text-align:center;padding:0}
.km th{background:#f3f3f0;font-weight:600;color:#555;font-size:13px}
.km th.corner{position:relative;width:52px;background:linear-gradient(to top right,#f3f3f0 49%,#cfcfca 50%,#f3f3f0 51%)}
.km th.corner span:first-child{position:absolute;right:4px;top:2px;font-size:12px}
.km th.corner span:last-child{position:absolute;left:4px;bottom:2px;font-size:12px}
.km td.one{background:#eef8f1;color:#1a7f37;font-weight:700}
.km td.z0{background:#fde8e5;color:#c0392b}.km td.z1{background:#fff1d6;color:#b7791f}.km td.z2{background:#e8eefc;color:#2563eb}.km td.z3{background:#f1e8fb;color:#7c3aed}
.km td.hl{background:#fde68a;font-weight:700}
.km td.col{background:#e8eefc}.km td.col.bad,.km td.bad{background:#fde8e5;color:#c0392b;font-weight:700}
.km td.col:not(:empty){color:#1a7f37;font-weight:700}
/* DPLL table */
.tw{overflow-x:auto;margin:10px 0;-webkit-overflow-scrolling:touch}
table.tr{border-collapse:collapse;font:13px ui-monospace,Menlo,monospace;white-space:nowrap}
.tr th,.tr td{border:1px solid #e0e0db;padding:5px 7px;text-align:center}
.tr th{background:#f3f3f0;font-weight:600}
.tr td.v{font-weight:700}.tr td.v.q{color:#bbb;font-weight:400}
.tr td.t{color:#1a7f37;background:#f2faf4}.tr td.f{color:#fff;background:#c0392b;font-weight:700}
.tr td.act{text-align:left;font-family:-apple-system,system-ui;font-weight:600}
.act.unit{color:#2563eb}.act.pure{color:#7c3aed}.act.case{color:#b7791f}.act.conflict{color:#c0392b}.act.sat{color:#1a7f37}
.tr tr.cur td{box-shadow:inset 0 -2px 0 #1b1b1b}
.res{font-weight:700;background:#eef8f1;border-radius:10px;padding:10px 12px;margin:8px 0}
svg.tree{display:block;margin:8px auto;width:100%;height:auto}
.cl{display:inline-block;font:14px ui-monospace,Menlo,monospace;padding:4px 8px;border-radius:8px;margin:3px;border:1.5px solid}
.c0{background:#fde8e5;border-color:#e6a99f}.c1{background:#fff1d6;border-color:#e8c27a}.c2{background:#e8eefc;border-color:#9db5ef}.c3{background:#f1e8fb;border-color:#c5a8ee}.c4{background:#eef8f1;border-color:#8fcf9f}
.rule{background:#eef3fb;border-radius:12px;padding:12px 14px;margin:10px 0}
.warn{background:#fdf1ef;border-radius:12px;padding:12px 14px;margin:10px 0;font-size:15px}
.grid2{display:grid;grid-template-columns:1fr 1fr;gap:10px}
@media (max-width:560px){.grid2{grid-template-columns:1fr}.q{font-size:17px}.km th,.km td{width:38px;height:36px}}
input.txt{width:100%;font:16px ui-monospace,Menlo,monospace;padding:11px 12px;border:1.5px solid #d9d9d4;border-radius:11px}
.dots{display:flex;gap:5px;justify-content:center;margin:8px 0}
.dots i{width:8px;height:8px;border-radius:50%;background:#d9d9d4}.dots i.on{background:#1b1b1b}
.lessons{display:grid;gap:8px}
.lessons a{display:block;background:#fff;border:1px solid #e4e4e0;border-radius:14px;padding:13px 15px;color:#1b1b1b;text-decoration:none}
.lessons a b{display:block;font-size:17px}.lessons a span{font-size:14px;color:#666}
.lessons a.done{border-color:#8fcf9f}
.navbar{position:fixed;left:0;right:0;bottom:0;background:rgba(246,246,244,.96);border-top:1px solid #e4e4e0;padding:10px 14px calc(10px + env(safe-area-inset-bottom));display:flex;gap:8px;justify-content:center}
.navbar .btn{flex:1;max-width:200px;justify-content:center}
.legend{display:flex;flex-wrap:wrap;gap:4px 12px;font-size:12px;color:#777;margin:0 0 10px}.legend span{white-space:nowrap}