:root {
  --blue: #1D4BFF; --blue2: #6F8DFF; --sky: #9DB2FF;
  --text: #E6E8EE; --muted: #8C93A8; --line: #1A1F2E; --dim: #2A3045;
  --card: rgba(10, 14, 30, .6);
  --trap: #FF8A8A; --trap-bg: rgba(60, 10, 20, .35); --trap-line: #5A2A35;
  --ok: #7FE0A8;
  --f-head: 'Unbounded', 'Arial Black', system-ui, sans-serif;
  --f-body: 'Manrope', system-ui, -apple-system, 'Segoe UI', Roboto, sans-serif;
  --f-logo: 'Marck Script', 'Segoe Script', cursive;
}
* { box-sizing: border-box; }
html { -webkit-text-size-adjust: 100%; }
body {
  margin: 0; min-height: 100vh; background: #000; color: var(--text);
  font-family: var(--f-body); font-size: 17px; line-height: 1.7;
}
body::before {
  content: ""; position: fixed; inset: 0; z-index: -1; pointer-events: none;
  background: radial-gradient(60% 55% at 50% 118%, rgba(29, 75, 255, .85) 0%, rgba(18, 40, 200, .35) 45%, transparent 75%);
}
a { color: var(--sky); }
a:hover { color: #fff; }
:focus-visible { outline: 3px solid var(--blue2); outline-offset: 2px; border-radius: 4px; }
.skip { position: absolute; left: -999px; top: 0; background: var(--blue); color: #fff; padding: 8px 14px; z-index: 100; }
.skip:focus { left: 8px; top: 8px; }
.wrap { max-width: 980px; margin: 0 auto; padding: 0 16px; }
.wrap.narrow { max-width: 720px; }

/* навигация */
.nav { border-bottom: 1px solid var(--line); background: rgba(0, 0, 0, .55); position: sticky; top: 0; z-index: 20; backdrop-filter: blur(6px); }
.nav .wrap { display: flex; align-items: center; gap: 8px 18px; flex-wrap: wrap; padding-top: 8px; padding-bottom: 8px; }
.logo { font-family: var(--f-logo); font-size: 28px; color: #fff; text-decoration: none; line-height: 1; margin-right: auto; }
.logo b { color: var(--blue2); font-weight: 400; }
.nav-links { display: flex; gap: 2px 4px; flex-wrap: wrap; }
.nav-links a { color: var(--muted); text-decoration: none; font-weight: 600; font-size: 15px; padding: 8px 10px; border-radius: 8px; min-height: 40px; display: inline-flex; align-items: center; }
.nav-links a:hover { color: #fff; }
.nav-links a[aria-current="page"] { color: #fff; background: rgba(29, 75, 255, .35); }

/* типографика */
h1, h2, h3 { font-family: var(--f-head); text-transform: uppercase; line-height: 1.15; margin: 0 0 .5em; font-weight: 700; letter-spacing: .01em; }
h1 { font-size: clamp(26px, 6vw, 48px); font-weight: 900; }
h2 { font-size: clamp(20px, 4.4vw, 28px); }
h3 { font-size: clamp(16px, 3.4vw, 19px); }
p { margin: 0 0 1em; }
.cap { font-size: 12px; letter-spacing: .16em; text-transform: uppercase; color: var(--sky); font-weight: 800; }
.muted { color: var(--muted); }
.plate { display: inline-block; background: var(--blue); color: #fff; transform: skewX(-6deg); box-shadow: 0 0 clamp(14px, 3vw, 40px) rgba(29, 75, 255, .6); padding: .02em .3em; }
.plate > span { display: inline-block; transform: skewX(6deg); }

/* кнопки */
.btn { font: 800 16px/1.2 var(--f-body); border: 1px solid var(--dim); background: rgba(10, 14, 30, .8); color: var(--text); padding: 12px 18px; border-radius: 10px; cursor: pointer; min-height: 46px; text-decoration: none; display: inline-flex; align-items: center; justify-content: center; gap: 8px; }
.btn:hover { border-color: var(--blue2); color: #fff; }
.btn.primary { background: var(--blue); border-color: var(--blue); color: #fff; box-shadow: 0 0 22px rgba(29, 75, 255, .45); }
.btn.primary:hover { background: #3a60ff; }
.btn.small { min-height: 38px; padding: 8px 12px; font-size: 14px; }
.btn[disabled] { opacity: .45; cursor: not-allowed; }
.btn.on { background: rgba(29, 75, 255, .35); border-color: var(--blue2); color: #fff; }

/* карточки и блоки */
.card { border: 1px solid var(--line); background: var(--card); border-radius: 10px; padding: 16px 18px; }
.grid { display: grid; gap: 12px; }
.grid.cols { grid-template-columns: repeat(auto-fill, minmax(150px, 1fr)); }
.box { border-radius: 10px; padding: 14px 16px; margin: 0 0 14px; border: 1px solid var(--line); background: var(--card); }
.box > .cap { display: block; margin-bottom: 6px; }
.box ul { margin: 0; padding-left: 1.2em; }
.box li { margin-bottom: .45em; }
.box.trap { background: var(--trap-bg); border-color: var(--trap-line); }
.box.trap .cap { color: var(--trap); }
.box.trap li, .box.trap p { color: var(--trap); }
.box.example { border-left: 4px solid var(--blue); }
.box.tutor { border-color: var(--blue2); background: rgba(29, 75, 255, .12); }
.tag { display: inline-block; font-size: 12px; font-weight: 800; letter-spacing: .08em; text-transform: uppercase; padding: 2px 8px; border-radius: 99px; border: 1px solid var(--dim); color: var(--sky); margin-right: 6px; }
.tag.warn { color: var(--trap); border-color: var(--trap-line); }
.tag.ok { color: var(--ok); border-color: #1d4a35; }

/* бегущая строка */
.marquee { overflow: hidden; border-top: 1px solid var(--line); border-bottom: 1px solid var(--line); background: rgba(0, 0, 0, .5); white-space: nowrap; }
.marquee-track { display: inline-flex; animation: marq 38s linear infinite; padding: 10px 0; }
.marquee-track span { font-weight: 800; letter-spacing: .06em; text-transform: uppercase; font-size: 14px; color: var(--sky); padding: 0 22px; }
.marquee-track span::after { content: "/"; color: var(--blue2); margin-left: 44px; }
@keyframes marq { to { transform: translateX(-50%); } }
@media (prefers-reduced-motion: reduce) {
  .marquee { white-space: normal; }
  .marquee-track { animation: none; flex-wrap: wrap; }
  .marquee-track .dup { display: none; }
}

/* модальное окно / пароль */
.overlay { position: fixed; inset: 0; background: rgba(0, 0, 0, .75); z-index: 60; display: flex; align-items: center; justify-content: center; padding: 16px; }
.dialog { background: #060a18; border: 1px solid var(--blue2); border-radius: 12px; padding: 20px; max-width: 420px; width: 100%; }
.input { width: 100%; font: 600 17px var(--f-body); background: #000; color: #fff; border: 1px solid var(--dim); border-radius: 10px; padding: 12px 14px; min-height: 46px; }
.input:focus { border-color: var(--blue2); outline: none; box-shadow: 0 0 0 3px rgba(111, 141, 255, .35); }
.err { color: var(--trap); font-weight: 600; min-height: 1.5em; }
textarea.input { min-height: 180px; line-height: 1.6; resize: vertical; }

footer.foot { border-top: 1px solid var(--line); margin-top: 48px; padding: 20px 0 40px; color: var(--muted); font-size: 14px; }
.hidden { display: none !important; }
.sr { position: absolute; width: 1px; height: 1px; overflow: hidden; clip: rect(0 0 0 0); }
.tutor-bar { display: flex; gap: 10px; align-items: center; flex-wrap: wrap; }

@media (max-width: 520px) {
  body { font-size: 17px; }
  .logo { font-size: 25px; }
  .nav-links a { padding: 8px 8px; font-size: 14px; }
}