/* net-cat — сайт курсов. Стиль макетов автора: тёмный HUD, циан → фиолет, гранж-заголовки, рубленые углы. */
:root {
  --bg: #03050c;
  --panel: rgba(6, 10, 24, .78);
  --panel-2: rgba(10, 16, 38, .86);
  --line: rgba(92, 170, 255, .38);
  --line-hi: rgba(120, 220, 255, .9);
  --cyan: #3fe3ff;
  --blue: #4f86ff;
  --violet: #9b5cff;
  --pink: #d36bff;
  --ink: #eaf3ff;
  --dim: #94a8d0;
  --mute: #5f7299;
  --ok: #41f0a8;
  --bad: #ff5c8a;
  --grad: linear-gradient(90deg, var(--cyan), var(--blue) 48%, var(--violet));
  --f-head: "Unbounded", "Exo 2", sans-serif;
  --f-body: "Exo 2", "Segoe UI", sans-serif;
  --cut: 14px;
  --ease: cubic-bezier(.16, 1, .3, 1);
  color-scheme: dark;
}
* { box-sizing: border-box; }
html, body { margin: 0; min-height: 100%; }
body {
  background: var(--bg) url(../img/bg-a.webp) center / cover fixed no-repeat;
  color: var(--ink);
  font: 400 17px/1.45 var(--f-body);
  -webkit-font-smoothing: antialiased;
  overflow-x: hidden;
}
body.bg-b { background-image: url(../img/bg-b.webp); }
a { color: inherit; }
button, input { font: inherit; color: inherit; }
:focus-visible { outline: 2px solid var(--cyan); outline-offset: 3px; }

/* ---------- фон: бегущие 0/1 ---------- */
#matrix { position: fixed; inset: 0; width: 100%; height: 100%; z-index: 0; display: block; }
.vignette { position: fixed; inset: 0; z-index: 0; pointer-events: none;
  background: radial-gradient(120% 90% at 50% 45%, transparent 55%, rgba(0, 0, 0, .55)); }
.page { position: relative; z-index: 1; min-height: 100vh; pointer-events: none; }
.page > * { pointer-events: auto; }

/* ---------- гранж-заголовки ---------- */
.grunge {
  font: 900 clamp(34px, 6.4vw, 104px)/.92 var(--f-head);
  letter-spacing: .01em;
  text-transform: uppercase;
  margin: 0;
  background: linear-gradient(180deg, #f2fbff 0%, #bfe9ff 35%, #79b8ff 70%, #a98bff 100%);
  -webkit-background-clip: text; background-clip: text; color: transparent;
  -webkit-mask: url("data:image/svg+xml,%3Csvg xmlns='http://www.w3.org/2000/svg' width='220' height='220'%3E%3Cfilter id='n'%3E%3CfeTurbulence type='fractalNoise' baseFrequency='.9' numOctaves='2' seed='7'/%3E%3CfeColorMatrix values='0 0 0 0 1 0 0 0 0 1 0 0 0 0 1 0 0 0 -2.6 2.05'/%3E%3C/filter%3E%3Crect width='100%25' height='100%25' filter='url(%23n)'/%3E%3C/svg%3E");
          mask: url("data:image/svg+xml,%3Csvg xmlns='http://www.w3.org/2000/svg' width='220' height='220'%3E%3Cfilter id='n'%3E%3CfeTurbulence type='fractalNoise' baseFrequency='.9' numOctaves='2' seed='7'/%3E%3CfeColorMatrix values='0 0 0 0 1 0 0 0 0 1 0 0 0 0 1 0 0 0 -2.6 2.05'/%3E%3C/filter%3E%3Crect width='100%25' height='100%25' filter='url(%23n)'/%3E%3C/svg%3E");
  filter: drop-shadow(0 0 18px rgba(63, 160, 255, .35));
}
.grunge.sm { font-size: clamp(22px, 3.2vw, 46px); }
.kicker { font: 800 clamp(20px, 2.6vw, 40px)/1.05 var(--f-head); margin: 4px 0 0;
  background: linear-gradient(90deg, #9ff0ff, #8fb4ff 60%, #b99bff); -webkit-background-clip: text; background-clip: text; color: transparent; }
.hatch { display: inline-block; width: 92px; height: 12px; vertical-align: middle;
  background: repeating-linear-gradient(-55deg, var(--cyan) 0 5px, transparent 5px 11px); opacity: .85; }
.hatch.v { background: repeating-linear-gradient(-55deg, var(--violet) 0 5px, transparent 5px 11px); }

/* ---------- панели с рублеными углами ---------- */
.hud {
  position: relative; background: var(--panel);
  clip-path: polygon(var(--cut) 0, 100% 0, 100% calc(100% - var(--cut)), calc(100% - var(--cut)) 100%, 0 100%, 0 var(--cut));
  backdrop-filter: blur(3px);
}
.hud::before { /* контур поверх clip-path */
  content: ""; position: absolute; inset: 0; pointer-events: none; padding: 1.5px;
  background: linear-gradient(135deg, var(--line-hi), var(--line) 30%, rgba(155, 92, 255, .55) 75%, var(--line-hi));
  clip-path: inherit;
  -webkit-mask: linear-gradient(#000 0 0) content-box, linear-gradient(#000 0 0); -webkit-mask-composite: xor;
          mask: linear-gradient(#000 0 0) content-box exclude, linear-gradient(#000 0 0);
}

/* ---------- верхняя полоса ---------- */
.bar { display: flex; align-items: center; gap: 14px; justify-content: flex-end; flex-wrap: wrap;
  padding: 18px clamp(16px, 3vw, 44px) 0; font-size: 14px; color: var(--dim); }
.bar .id { font: 700 15px/1 var(--f-head); color: var(--ink); letter-spacing: .04em; padding: 9px 14px; }
.bar .id b { color: var(--cyan); }
.bar a, .bar button { background: none; border: 0; cursor: pointer; color: var(--dim); text-decoration: none; padding: 8px 4px;
  border-bottom: 1px solid transparent; transition: color .2s, border-color .2s; }
.bar a:hover, .bar button:hover { color: var(--ink); border-color: var(--cyan); }
.crumbs { margin-right: auto; display: flex; gap: 10px; align-items: center; font-size: 15px; }
.crumbs a { color: var(--dim); }
.crumbs span { color: var(--mute); }

/* ---------- кнопки ---------- */
.btn {
  --c: var(--cyan);
  display: inline-flex; align-items: center; gap: 12px; justify-content: space-between;
  min-height: 52px; padding: 0 18px; border: 0; cursor: pointer; text-decoration: none;
  font: 600 17px/1.1 var(--f-body); color: var(--ink);
  background: linear-gradient(90deg, color-mix(in srgb, var(--c) 16%, transparent), color-mix(in srgb, var(--c) 4%, transparent));
  clip-path: polygon(8px 0, 100% 0, 100% calc(100% - 8px), calc(100% - 8px) 100%, 0 100%, 0 8px);
  box-shadow: inset 0 0 0 1.5px color-mix(in srgb, var(--c) 75%, transparent);
  transition: transform .25s var(--ease), background .25s, box-shadow .25s;
}
.btn svg { width: 24px; height: 24px; flex: none; stroke: var(--c); }
.btn .chev { margin-left: auto; width: 16px; height: 16px; opacity: .8; transition: transform .25s var(--ease); }
.btn:hover { background: linear-gradient(90deg, color-mix(in srgb, var(--c) 34%, transparent), color-mix(in srgb, var(--c) 10%, transparent));
  box-shadow: inset 0 0 0 1.5px var(--c), 0 0 22px color-mix(in srgb, var(--c) 45%, transparent); }
.btn:hover .chev { transform: translateX(4px); }
.btn:active { transform: translateY(1px) scale(.99); }
.btn.lab { --c: var(--cyan); }
.btn.practice { --c: var(--blue); }
.btn.test { --c: var(--pink); }
.btn.lecture { --c: #7fd9ff; }
.btn.big {
  width: 100%; min-height: 64px; justify-content: center; position: relative;
  font: 900 22px/1 var(--f-head); letter-spacing: .08em; color: #06091a;
  background: linear-gradient(90deg, #7ff3ff, #4fa9ff 55%, #a477ff);
  box-shadow: 0 0 34px rgba(80, 170, 255, .45);
}
.btn.big:hover { box-shadow: 0 0 46px rgba(120, 200, 255, .7); filter: brightness(1.08); }
.btn.big .arr { position: absolute; right: 22px; stroke: #06091a; }
.btn[disabled] { opacity: .6; cursor: progress; }

/* ---------- героиня ---------- */
.heroine { position: fixed; bottom: 0; z-index: 0; pointer-events: none; height: min(92vh, 980px); width: auto;
  -webkit-mask: linear-gradient(180deg, #000 72%, transparent 99%); mask: linear-gradient(180deg, #000 72%, transparent 99%);
  filter: drop-shadow(0 0 30px rgba(80, 140, 255, .25)); }
.heroine.left { left: max(-60px, calc(50vw - 900px)); }
.heroine.right { right: max(-80px, calc(50vw - 960px)); transform: scaleX(-1); }

@media (prefers-reduced-motion: reduce) { * { transition: none !important; animation: none !important; } }
@media (max-width: 980px) { .heroine { display: none; } }