:root {
  --bg: #f5f7f6; --card: #ffffff; --ink: #1d2b33; --muted: #5b6b74; --line: #d9e1e4;
  --accent: #1f6f78; --accent-ink: #ffffff; --accent-soft: #e3f1f2; --warm: #b7791f; --warm-soft: #fbf3e4; --bad: #a33a3a;
  --radius: 12px;
}
* { box-sizing: border-box; }
html { font-size: 19px; }
body { margin: 0; background: var(--bg); color: var(--ink); font-family: "Segoe UI", system-ui, -apple-system, Roboto, sans-serif; line-height: 1.5; }
header.top { display: flex; align-items: center; gap: 12px; padding: 14px 28px; background: var(--card); border-bottom: 1px solid var(--line); }
header.top h1 { font-size: 1.25rem; margin: 0; font-weight: 650; letter-spacing: .1px; }
header.top a { color: inherit; text-decoration: none; }
.tag { font-size: .65rem; text-transform: uppercase; letter-spacing: .08em; background: var(--accent-soft); color: var(--accent); padding: 3px 8px; border-radius: 99px; font-weight: 700; }
header.top .right { margin-left: auto; color: var(--muted); font-size: .8rem; }
main { max-width: 1180px; margin: 0 auto; padding: 24px 28px 80px; }
main.narrow { max-width: 760px; }
h2 { font-size: 1.5rem; margin: 0 0 .4rem; }
h3 { font-size: 1.1rem; margin: 0 0 .4rem; color: var(--accent); text-transform: uppercase; letter-spacing: .06em; }
p { margin: .4rem 0 .8rem; }
.muted { color: var(--muted); }
.card { background: var(--card); border: 1px solid var(--line); border-radius: var(--radius); padding: 20px 24px; margin: 0 0 18px; }
.card.warm { background: var(--warm-soft); border-color: #ead9b3; }
.card.warm h3 { color: var(--warm); }
.situation { font-size: 1.35rem; line-height: 1.55; }
.big-code { font-family: ui-monospace, Consolas, monospace; font-size: 6rem; font-weight: 700; letter-spacing: .18em; line-height: 1; color: var(--accent); }
.code-row { display: flex; align-items: center; gap: 32px; flex-wrap: wrap; }
.stage-title { font-size: 2rem; margin: 0 0 .3rem; }
ul.plain { margin: 0; padding-left: 1.2rem; } ul.plain li { margin: .25rem 0; }
.chips { display: flex; flex-wrap: wrap; gap: 8px; } .chip { background: var(--accent-soft); color: var(--accent); border-radius: 99px; padding: 4px 12px; font-size: .9rem; }
.reveal { border-left: 5px solid var(--accent); padding: 2px 0 2px 16px; margin: 0 0 14px; }
.reveal b { color: var(--accent); }

button, .btn { font: inherit; font-weight: 600; border: 1px solid var(--accent); background: var(--accent); color: var(--accent-ink); padding: 10px 18px; border-radius: 10px; cursor: pointer; text-decoration: none; display: inline-block; }
button:hover:not(:disabled) { filter: brightness(1.08); }
button:disabled { opacity: .4; cursor: not-allowed; }
button.ghost { background: var(--card); color: var(--accent); }
button.on { background: var(--warm); border-color: var(--warm); }
button.danger { background: var(--card); color: var(--bad); border-color: var(--bad); }
button.small { padding: 5px 12px; font-size: .85rem; }
.bar { position: sticky; top: 0; z-index: 5; background: var(--card); border-bottom: 1px solid var(--line); padding: 10px 28px; display: flex; flex-wrap: wrap; gap: 8px; align-items: center; }
.bar .sep { width: 1px; height: 28px; background: var(--line); margin: 0 4px; }

label { display: block; font-weight: 600; margin: 14px 0 4px; }
label small { font-weight: 400; color: var(--muted); }
input[type=text], input[type=password], input[type=number], textarea, select { width: 100%; font: inherit; padding: 10px 12px; border: 1px solid #b9c6cb; border-radius: 10px; background: #fff; color: var(--ink); }
textarea { min-height: 96px; resize: vertical; }
input:focus, textarea:focus, select:focus, button:focus-visible { outline: 3px solid #8cc7cd; outline-offset: 1px; }
.seg { display: inline-flex; gap: 4px; }
.seg button { background: var(--card); color: var(--ink); border: 1px solid #b9c6cb; padding: 6px 14px; min-width: 44px; }
.seg button.sel { background: var(--accent); color: #fff; border-color: var(--accent); }
.crit { display: flex; align-items: center; justify-content: space-between; gap: 12px; padding: 10px 0; border-top: 1px solid var(--line); flex-wrap: wrap; }
.crit:first-child { border-top: 0; }
.crit .name { font-weight: 600; flex: 1 1 260px; }
.levels { font-size: .85rem; color: var(--muted); font-weight: 400; display: block; }
.msg { padding: 10px 14px; border-radius: 10px; margin: 10px 0; background: var(--accent-soft); }
.msg.err { background: #f8e3e3; color: var(--bad); }
table { width: 100%; border-collapse: collapse; } th, td { text-align: left; padding: 10px 12px; border-bottom: 1px solid var(--line); }
th { color: var(--muted); font-size: .8rem; text-transform: uppercase; letter-spacing: .06em; }
td.num, th.num { text-align: right; font-variant-numeric: tabular-nums; }
.board td:first-child { width: 3rem; color: var(--muted); } .board tr:first-child td { font-weight: 700; font-size: 1.2em; }
.grid2 { display: grid; grid-template-columns: 1fr 1fr; gap: 18px; } @media (max-width: 860px) { .grid2 { grid-template-columns: 1fr; } .big-code { font-size: 4.2rem; } }
.answer { background: #f7fafa; border: 1px solid var(--line); border-radius: 10px; padding: 12px 16px; margin: 8px 0; }
.answer b { display: block; font-size: .8rem; color: var(--muted); text-transform: uppercase; letter-spacing: .05em; margin-top: 8px; } .answer b:first-child { margin-top: 0; }
.hide-notes .notes { display: none; }
.hint { font-size: .85rem; color: var(--muted); }
@media (max-width: 700px) { html { font-size: 17px; } main { padding: 16px 14px 60px; } header.top, .bar { padding-left: 14px; padding-right: 14px; } }
@media (min-width: 1500px) { html { font-size: 22px; } main { max-width: 1400px; } }