:root {
  --bg: #0f1117;
  --panel: #171a23;
  --panel-2: #1e2230;
  --border: #272c3b;
  --text: #e7eaf3;
  --muted: #8b93a7;
  --accent: #7c9cff;
  --easy: #3fd48a;
  --medium: #f5c451;
  --hard: #ff6b7a;
  --radius: 12px;
}
* { box-sizing: border-box; }
html, body { margin: 0; background: var(--bg); color: var(--text); font: 15px/1.45 -apple-system, BlinkMacSystemFont, "Segoe UI", Inter, Roboto, sans-serif; }
button, input { font: inherit; color: inherit; }
button { cursor: pointer; }
a { color: var(--accent); text-decoration: none; }
a:hover { text-decoration: underline; }
.hidden { display: none !important; }
.muted { color: var(--muted); }
.small { font-size: 12.5px; }
.error { color: var(--hard); min-height: 1.2em; margin: 6px 0 0; font-size: 13px; }
h1 { margin: 0; font-size: 20px; letter-spacing: -0.01em; }

.screen { min-height: 100dvh; }
.card { background: var(--panel); border: 1px solid var(--border); border-radius: var(--radius); padding: 22px; }

/* Login */
#login { display: grid; place-items: center; padding: 24px; }
.login-card { width: min(380px, 100%); display: flex; flex-direction: column; gap: 12px; }
.login-card h1 { font-size: 28px; }
.login-card input { background: var(--panel-2); border: 1px solid var(--border); border-radius: 10px; padding: 12px 14px; outline: none; }
.login-card input:focus { border-color: var(--accent); }
.user-pick { display: grid; grid-template-columns: repeat(auto-fit, minmax(120px, 1fr)); gap: 8px; }
.user-pick button { background: var(--panel-2); border: 2px solid var(--border); border-radius: 10px; padding: 12px; font-weight: 600; display: flex; align-items: center; gap: 8px; justify-content: center; }
.user-pick button.on { border-color: var(--u, var(--accent)); background: color-mix(in srgb, var(--u, var(--accent)) 14%, var(--panel-2)); }
.dot { width: 10px; height: 10px; border-radius: 50%; background: var(--u, var(--accent)); display: inline-block; }

button.primary { background: var(--accent); color: #0b0e17; border: 0; border-radius: 10px; padding: 11px 16px; font-weight: 700; }
button.primary:hover { filter: brightness(1.08); }
button.ghost { background: transparent; border: 1px solid var(--border); border-radius: 8px; padding: 6px 10px; color: var(--muted); }
button.ghost:hover { color: var(--text); border-color: var(--muted); }
button.link { background: none; border: 0; padding: 0; color: var(--accent); }
.chip { background: var(--panel-2); border: 1px solid var(--border); border-radius: 999px; padding: 5px 12px; font-weight: 600; display: inline-flex; align-items: center; gap: 7px; }
.chip::before { content: ""; width: 9px; height: 9px; border-radius: 50%; background: var(--u, var(--accent)); }

/* App shell */
#app { max-width: 980px; margin: 0 auto; padding: 18px 16px 60px; display: flex; flex-direction: column; gap: 16px; }
.topbar { display: flex; justify-content: space-between; align-items: center; gap: 12px; flex-wrap: wrap; }
.brand { display: flex; align-items: center; gap: 12px; }
.logo { font-size: 28px; }
.me { display: flex; align-items: center; gap: 8px; }

/* Scoreboard */
.scoreboard { display: grid; grid-template-columns: repeat(auto-fit, minmax(260px, 1fr)); gap: 12px; }
.score { background: var(--panel); border: 1px solid var(--border); border-radius: var(--radius); padding: 14px 16px; display: flex; flex-direction: column; gap: 8px; position: relative; overflow: hidden; }
.score.me-card { border-color: color-mix(in srgb, var(--u) 50%, var(--border)); }
.score .head { display: flex; justify-content: space-between; align-items: baseline; gap: 8px; }
.score .name { font-weight: 700; display: flex; align-items: center; gap: 8px; }
.score .count { font-variant-numeric: tabular-nums; font-size: 22px; font-weight: 800; }
.score .count small { font-size: 13px; color: var(--muted); font-weight: 500; }
.bar { height: 8px; border-radius: 99px; background: var(--panel-2); overflow: hidden; }
.bar > i { display: block; height: 100%; background: var(--u); border-radius: 99px; transition: width .4s cubic-bezier(.2,.8,.2,1); }
.score .split { display: flex; gap: 12px; font-size: 12.5px; color: var(--muted); }
.score .split b { color: var(--text); font-weight: 600; }
.crown { font-size: 16px; line-height: 1; }
.streak-note { font-size: 12.5px; color: var(--muted); }

/* Toolbar */
.toolbar { display: flex; gap: 10px; flex-wrap: wrap; align-items: center; }
.toolbar input { flex: 1 1 220px; background: var(--panel); border: 1px solid var(--border); border-radius: 10px; padding: 9px 12px; outline: none; }
.toolbar input:focus { border-color: var(--accent); }
.seg { display: inline-flex; background: var(--panel); border: 1px solid var(--border); border-radius: 10px; padding: 3px; gap: 2px; }
.seg button { background: transparent; border: 0; border-radius: 7px; padding: 6px 11px; color: var(--muted); font-weight: 600; font-size: 13px; }
.seg button.on { background: var(--panel-2); color: var(--text); }
.seg button.easy.on { color: var(--easy); }
.seg button.medium.on { color: var(--medium); }
.seg button.hard.on { color: var(--hard); }

/* Categories */
.cats { display: flex; gap: 6px; flex-wrap: wrap; }
.cats button { background: var(--panel); border: 1px solid var(--border); border-radius: 999px; padding: 5px 11px; font-size: 13px; color: var(--muted); display: inline-flex; gap: 6px; align-items: center; }
.cats button.on { color: var(--text); border-color: var(--accent); background: color-mix(in srgb, var(--accent) 12%, var(--panel)); }
.cats button .n { font-size: 11px; background: var(--panel-2); border-radius: 99px; padding: 1px 6px; font-variant-numeric: tabular-nums; }
.cats button.all-done { border-color: color-mix(in srgb, var(--easy) 40%, var(--border)); }

/* List */
.list { display: flex; flex-direction: column; gap: 14px; }
.group h2 { font-size: 13px; text-transform: uppercase; letter-spacing: .08em; color: var(--muted); margin: 6px 0 8px 4px; display: flex; justify-content: space-between; }
.group .rows { background: var(--panel); border: 1px solid var(--border); border-radius: var(--radius); overflow: hidden; }
.row + .row { border-top: 1px solid var(--border); }
.row-main { width: 100%; display: grid; grid-template-columns: 48px 1fr auto auto 18px; align-items: center; gap: 12px; padding: 12px 14px; background: transparent; border: 0; text-align: left; }
.row-main:hover { background: var(--panel-2); }
.row.open .row-main { background: var(--panel-2); }
.num { color: var(--muted); font-variant-numeric: tabular-nums; font-size: 13px; }
.title { font-weight: 600; }
.row.mine-done .title { color: var(--muted); text-decoration: line-through; text-decoration-color: color-mix(in srgb, var(--muted) 60%, transparent); }
.diff { font-size: 11.5px; font-weight: 700; padding: 2px 8px; border-radius: 999px; }
.diff.Easy { color: var(--easy); background: color-mix(in srgb, var(--easy) 14%, transparent); }
.diff.Medium { color: var(--medium); background: color-mix(in srgb, var(--medium) 14%, transparent); }
.diff.Hard { color: var(--hard); background: color-mix(in srgb, var(--hard) 14%, transparent); }
.marks { display: inline-flex; gap: 6px; }
.mark { width: 22px; height: 22px; border-radius: 50%; border: 2px solid var(--u); display: inline-grid; place-items: center; font-size: 12px; color: #0b0e17; font-weight: 800; opacity: .35; }
.mark.done { background: var(--u); opacity: 1; }
.mark.me-mark { box-shadow: 0 0 0 2px var(--panel), 0 0 0 3px color-mix(in srgb, var(--u) 50%, transparent); }
.chev { color: var(--muted); transition: transform .2s; }
.row.open .chev { transform: rotate(90deg); }

.detail { padding: 4px 14px 16px 74px; display: flex; flex-direction: column; gap: 10px; border-top: 1px dashed var(--border); }
.detail .desc { margin: 10px 0 0; }
.detail .example { margin: 0; background: var(--bg); border: 1px solid var(--border); border-radius: 8px; padding: 10px 12px; font-size: 13px; white-space: pre-wrap; overflow-x: auto; }
.detail .idea { margin: 0; color: var(--muted); }
.detail .idea strong { color: var(--text); }
.links { display: flex; gap: 14px; align-items: center; flex-wrap: wrap; margin-top: 4px; }
.links .toggle { margin-left: auto; padding: 9px 14px; }
.links .toggle.undo { background: var(--panel-2); color: var(--text); border: 1px solid var(--border); }
.when { margin: 0; }

.empty { text-align: center; padding: 40px 16px; color: var(--muted); }
.foot { text-align: center; }

@media (max-width: 640px) {
  .row-main { grid-template-columns: 40px 1fr auto 18px; }
  .row-main .diff { display: none; }
  .detail { padding-left: 14px; }
}

/* Celebrate */
@keyframes pop { 0% { transform: scale(1); } 40% { transform: scale(1.25); } 100% { transform: scale(1); } }
.mark.pop { animation: pop .35s ease; }