/* Палитра по мотивам rfs.ru: тёмно-синий градиент, синий #0b4c89, серый фон, акцент #fe4817 */
:root{
  --navy-0:#040325; --navy-1:#110f45; --blue-0:#044679; --blue-1:#0b4c89;
  --grad:linear-gradient(90deg,var(--navy-0) 0%,var(--navy-1) 50%,var(--navy-0) 100%);
  --grad-hover:linear-gradient(90deg,var(--blue-0) 0%,var(--blue-1) 50%,var(--blue-0) 100%);
  --bg:#edf1f4; --card:#ffffff; --ink:#444444; --head:#110f45; --muted:#5f6770; --line:#e7e7e7;
  --link:#0b4c89; --soft:#eef3f9; --hot:#fe4817;
  --ok:#1e7d45; --ok-bg:#e6f4ec; --bad:#c62f2b; --bad-bg:#fbe9e8;
  --shadow:0 1px 3px rgba(4,3,37,.06),0 10px 30px rgba(4,3,37,.06);
}
@media (prefers-color-scheme:dark){:root{
  --bg:#08072a; --card:#121040; --ink:#d9dcea; --head:#ffffff; --muted:#9aa0bd; --line:#23215a;
  --link:#7fb2ea; --soft:#1a1856; --hot:#ff6a3d;
  --ok:#5fcf8c; --ok-bg:#133a2a; --bad:#ff8a80; --bad-bg:#40182a;
  --shadow:none;
}}
*{box-sizing:border-box}
html{-webkit-text-size-adjust:100%}
body{margin:0;background:var(--bg);color:var(--ink);
  font:17px/1.55 Roboto,-apple-system,BlinkMacSystemFont,"Segoe UI","Helvetica Neue",Arial,sans-serif}
h1,h2,.brand,.btn,.meta,.ring b{font-family:"Roboto Condensed",Roboto,"Arial Narrow",sans-serif}

/* шапка */
.top{background:var(--grad);color:#fff;border-bottom:3px solid var(--hot)}
.top-in{max-width:720px;margin:0 auto;padding:14px 16px;display:flex;justify-content:space-between;align-items:center;gap:12px}
.brand{font-weight:700;font-size:19px;letter-spacing:.3px;text-transform:uppercase;display:flex;align-items:center;gap:10px}
.brand .ball{font-style:normal;font-size:20px}
.brand span{font-weight:500;text-transform:none;opacity:.65;font-size:16px;letter-spacing:0}
.who{color:rgba(255,255,255,.8);font-size:15px;white-space:nowrap;overflow:hidden;text-overflow:ellipsis}

.wrap{max-width:720px;margin:0 auto;padding:24px 16px 48px}
.card{background:var(--card);border:1px solid var(--line);border-radius:6px;padding:28px;box-shadow:var(--shadow);animation:fade .25s ease}
@keyframes fade{from{opacity:0;transform:translateY(4px)}to{opacity:1;transform:none}}
h1{color:var(--head);font-size:28px;line-height:1.2;font-weight:700;margin:0 0 8px;text-transform:uppercase;letter-spacing:.3px}
h2{color:var(--head);font-size:21px;line-height:1.4;font-weight:500;margin:14px 0 20px}
.muted{color:var(--muted)} .small{font-size:14px}
.field{display:block;margin:22px 0}
.field>span{display:block;font-size:14px;color:var(--muted);margin-bottom:8px}
input{width:100%;font:inherit;color:inherit;background:var(--card);border:1px solid #c6c6c6;border-radius:4px;padding:12px 14px;outline:none;transition:border-color .15s,box-shadow .15s}
@media (prefers-color-scheme:dark){input{border-color:var(--line)}}
input:focus{border-color:var(--link);box-shadow:0 0 0 3px color-mix(in srgb,var(--link) 20%,transparent)}
.chips{display:flex;flex-wrap:wrap;gap:8px;margin-bottom:10px}
.chip{font:inherit;font-size:15px;color:var(--link);background:var(--card);border:1px solid var(--line);border-radius:4px;padding:7px 16px;cursor:pointer;transition:border-color .15s}
.chip:hover{border-color:var(--link)}
.chip.on{background:var(--grad);border-color:var(--navy-1);color:#fff}
.btn{font-size:16px;font-weight:700;text-transform:uppercase;letter-spacing:.5px;border:1px solid var(--line);background:var(--card);color:var(--link);border-radius:4px;padding:13px 24px;cursor:pointer;transition:background .2s,border-color .2s}
.btn:hover{border-color:var(--link)}
.btn:active{transform:translateY(1px)}
.btn.primary{background:var(--grad);border-color:var(--navy-1);color:#fff}
.btn.primary:hover{background:var(--grad-hover);border-color:var(--blue-1)}
@media (prefers-color-scheme:dark){.btn.primary,.chip.on{background:var(--grad-hover);border-color:var(--blue-1)}.btn.primary:hover{filter:brightness(1.15)}}
.btn.link{background:none;border:none;color:var(--muted);padding:12px 4px;font-weight:500;text-transform:none;letter-spacing:0;font-family:Roboto,sans-serif}
.btn.link:hover{color:var(--link)}
.meta{display:flex;justify-content:space-between;font-size:15px;color:var(--muted);text-transform:uppercase;letter-spacing:.4px}
.meta #score{color:var(--link)}
.bar{height:4px;background:var(--line);border-radius:2px;margin-top:10px;overflow:hidden}
.bar i{display:block;height:100%;width:0;background:var(--hot);transition:width .3s ease}
.opts{display:grid;gap:10px}
.opt{display:flex;gap:12px;align-items:flex-start;text-align:left;width:100%;font:inherit;font-size:16px;line-height:1.5;color:var(--ink);
  background:var(--card);border:1px solid var(--line);border-left:3px solid var(--line);border-radius:4px;padding:14px 16px;cursor:pointer;transition:border-color .15s,background .15s}
.opt:hover:not(:disabled){border-color:var(--link);background:var(--soft)}
.opt:disabled{cursor:default}
.opt .k{flex:none;width:26px;height:26px;border-radius:3px;background:var(--soft);display:grid;place-items:center;font-size:13px;font-weight:700;color:var(--link);margin-top:1px}
.opt.ok{border-color:var(--ok);background:var(--ok-bg)}
.opt.ok .k{background:var(--ok);color:#fff}
.opt.bad{border-color:var(--bad);background:var(--bad-bg)}
.opt.bad .k{background:var(--bad);color:#fff}
.opt.dim{opacity:.55}
.explain{margin-top:16px;padding:14px 16px;border-radius:4px;border-left:3px solid var(--link);background:var(--soft);font-size:15px}
.explain b{display:block;margin-bottom:4px;color:var(--head)}
.actions{display:flex;justify-content:space-between;align-items:center;margin-top:22px;gap:10px;flex-wrap:wrap}
.actions.center{justify-content:center}
#result{text-align:center}
.ring{position:relative;width:136px;height:136px;margin:4px auto 14px}
.ring svg{width:100%;height:100%;transform:rotate(-90deg)}
.ring circle{fill:none;stroke:var(--line);stroke-width:10}
.ring #ringArc{stroke:var(--hot);stroke-linecap:round;stroke-dasharray:326.7;stroke-dashoffset:326.7;transition:stroke-dashoffset .9s ease}
.ring b{position:absolute;inset:0;display:grid;place-items:center;font-size:32px;font-weight:700;color:var(--head)}
.verdict{font-size:18px;margin:6px 0 4px}
details{margin-top:26px;text-align:left;border-top:1px solid var(--line);padding-top:14px}
summary{cursor:pointer;color:var(--link);font-weight:500}
#mistakes{padding-left:22px}
#mistakes li{margin:16px 0}
#mistakes .q{font-weight:500;color:var(--head)}
#mistakes .y{color:var(--bad)} #mistakes .c{color:var(--ok)}
#mistakes .e{color:var(--muted);font-size:15px}
.err{color:var(--bad)}
@media (max-width:520px){
  body{font-size:16px}
  .card{padding:20px 18px}
  .brand{font-size:17px} .brand span{display:none}
  h1{font-size:24px} h2{font-size:19px}
  .actions .btn.primary{flex:1}
  .actions.center .btn{flex:1;white-space:nowrap;padding:12px 10px}
}