/* ============================================================
   SIGNET design system — shadcn/ui dark (zinc) + cyber accents
   No external deps: system font stacks, pure CSS.
   ============================================================ */

:root {
  --bg: #09090b;            /* zinc-950 */
  --bg-elev: #101014;
  --card: #0f0f12;
  --card-hover: #131318;
  --fg: #fafafa;            /* zinc-50 */
  --fg-muted: #a1a1aa;      /* zinc-400 */
  --fg-dim: #71717a;        /* zinc-500 */
  --border: #27272a;        /* zinc-800 */
  --border-hi: #3f3f46;     /* zinc-700 */
  --primary: #10b981;       /* emerald-500 */
  --primary-hi: #34d399;    /* emerald-400 */
  --primary-dim: #064e3b;   /* emerald-950 */
  --primary-fg: #052e22;
  --danger: #ef4444;
  --danger-dim: #450a0a;
  --warn: #f59e0b;
  --info: #38bdf8;
  --radius: 10px;
  --mono: ui-monospace, "Cascadia Code", "JetBrains Mono", Consolas,
          "SF Mono", Menlo, monospace;
  --sans: -apple-system, BlinkMacSystemFont, "Segoe UI", Inter, Roboto,
          "Helvetica Neue", Arial, sans-serif;
}

* { box-sizing: border-box; }

html { color-scheme: dark; }

body {
  margin: 0;
  font-family: var(--sans);
  color: var(--fg);
  background:
    radial-gradient(ellipse 80% 50% at 50% -10%,
      rgba(16, 185, 129, 0.07), transparent 70%),
    linear-gradient(rgba(255, 255, 255, 0.022) 1px, transparent 1px),
    linear-gradient(90deg, rgba(255, 255, 255, 0.022) 1px, transparent 1px),
    var(--bg);
  background-size: auto, 36px 36px, 36px 36px, auto;
  min-height: 100vh;
  -webkit-font-smoothing: antialiased;
}

::selection { background: rgba(16, 185, 129, 0.35); }

a { color: var(--primary-hi); text-decoration: none; }
a:hover { text-decoration: underline; }

/* ---------------------------------------------------------------- header */

.site-header {
  position: sticky; top: 0; z-index: 40;
  display: flex; align-items: center; justify-content: space-between;
  padding: 12px 28px;
  background: rgba(9, 9, 11, 0.82);
  backdrop-filter: blur(10px);
  border-bottom: 1px solid var(--border);
}

.brand {
  display: flex; align-items: center; gap: 10px;
  font-weight: 700; letter-spacing: 0.14em; font-size: 15px;
}
.brand .seal {
  width: 26px; height: 26px; border-radius: 6px;
  border: 1px solid var(--primary);
  display: inline-flex; align-items: center; justify-content: center;
  color: var(--primary); font-family: var(--mono); font-size: 13px;
  box-shadow: 0 0 14px rgba(16, 185, 129, 0.35), inset 0 0 8px rgba(16, 185, 129, 0.15);
}
.brand .ver {
  font-family: var(--mono); font-size: 10px; color: var(--fg-dim);
  border: 1px solid var(--border); border-radius: 4px; padding: 1px 6px;
  letter-spacing: 0.05em;
}

.site-nav { display: flex; gap: 4px; }
.site-nav a {
  color: var(--fg-muted); font-size: 13.5px; padding: 6px 12px;
  border-radius: 6px; border: 1px solid transparent;
}
.site-nav a:hover {
  color: var(--fg); text-decoration: none;
  background: var(--card-hover); border-color: var(--border);
}
.site-nav a.active {
  color: var(--primary-hi); border-color: rgba(16, 185, 129, 0.3);
  background: rgba(16, 185, 129, 0.08);
}

/* ---------------------------------------------------------------- layout */

.wrap { max-width: 1060px; margin: 0 auto; padding: 0 24px; }
.wrap-narrow { max-width: 780px; margin: 0 auto; padding: 0 24px; }

/* ---------------------------------------------------------------- cards */

.card {
  background: var(--card);
  border: 1px solid var(--border);
  border-radius: var(--radius);
  padding: 20px 22px;
  transition: border-color .15s, background .15s;
}
.card.hoverable:hover { border-color: var(--border-hi); background: var(--card-hover); }
.card h3 { margin: 0 0 8px; font-size: 15px; letter-spacing: .02em; }
.card p { margin: 0; font-size: 13.5px; line-height: 1.65; color: var(--fg-muted); }

.grid-3 { display: grid; grid-template-columns: repeat(3, 1fr); gap: 16px; }
@media (max-width: 800px) { .grid-3 { grid-template-columns: 1fr; } }

/* -------------------------------------------------------------- badges */

.badge {
  display: inline-flex; align-items: center; gap: 6px;
  font-family: var(--mono); font-size: 10.5px; letter-spacing: .08em;
  padding: 2px 8px; border-radius: 999px;
  border: 1px solid var(--border-hi); color: var(--fg-muted);
  text-transform: uppercase; white-space: nowrap;
}
.badge::before {
  content: ""; width: 6px; height: 6px; border-radius: 50%;
  background: currentColor;
}
.badge.ok      { color: var(--primary-hi); border-color: rgba(16,185,129,.4); background: rgba(16,185,129,.08); }
.badge.fail    { color: #f87171; border-color: rgba(239,68,68,.4); background: rgba(239,68,68,.08); }
.badge.warn    { color: var(--warn); border-color: rgba(245,158,11,.4); background: rgba(245,158,11,.08); }
.badge.info    { color: var(--info); border-color: rgba(56,189,248,.4); background: rgba(56,189,248,.08); }

/* -------------------------------------------------------------- buttons */

.btn {
  display: inline-flex; align-items: center; gap: 8px;
  font-family: var(--sans); font-size: 13.5px; font-weight: 500;
  padding: 8px 16px; border-radius: 8px; cursor: pointer;
  border: 1px solid var(--border-hi);
  background: var(--card); color: var(--fg);
  transition: all .15s;
}
.btn:hover { background: var(--card-hover); border-color: #52525b; }
.btn:active { transform: translateY(1px); }
.btn-primary {
  background: var(--primary); color: var(--primary-fg);
  border-color: var(--primary); font-weight: 600;
  box-shadow: 0 0 18px rgba(16, 185, 129, 0.25);
}
.btn-primary:hover { background: var(--primary-hi); border-color: var(--primary-hi); }
.btn-sm { padding: 5px 12px; font-size: 12.5px; }

/* --------------------------------------------------------------- inputs */

.input, textarea.input {
  width: 100%; font-family: var(--mono); font-size: 13px;
  padding: 9px 12px; border-radius: 8px;
  background: #0c0c0f; color: var(--fg);
  border: 1px solid var(--border-hi); outline: none;
  transition: border-color .15s, box-shadow .15s;
}
.input:focus {
  border-color: var(--primary);
  box-shadow: 0 0 0 3px rgba(16, 185, 129, 0.15);
}
.input::placeholder { color: var(--fg-dim); }
label.lbl {
  display: block; font-size: 12.5px; color: var(--fg-muted);
  margin: 14px 0 6px; letter-spacing: .02em;
}

/* ------------------------------------------------------------ terminal */

.terminal {
  background: #050507;
  border: 1px solid var(--border);
  border-radius: var(--radius);
  overflow: hidden;
  box-shadow: 0 12px 40px rgba(0, 0, 0, 0.5), 0 0 30px rgba(16, 185, 129, 0.06);
}
.terminal-bar {
  display: flex; align-items: center; gap: 7px;
  padding: 9px 14px; background: #0d0d11;
  border-bottom: 1px solid var(--border);
}
.terminal-bar .dot { width: 10px; height: 10px; border-radius: 50%; opacity: .85; }
.terminal-bar .dot.r { background: #ff5f57; } .terminal-bar .dot.y { background: #febc2e; } .terminal-bar .dot.g { background: #28c840; }
.terminal-bar .title {
  margin-left: 8px; font-family: var(--mono); font-size: 11px;
  color: var(--fg-dim); letter-spacing: .1em;
}
.terminal-body {
  margin: 0; padding: 16px 18px;
  font-family: var(--mono); font-size: 12.5px; line-height: 1.75;
  color: #d1fae5; white-space: pre-wrap; word-break: break-word;
}
.terminal-body .p { color: var(--primary-hi); }        /* prompt */
.terminal-body .c { color: var(--fg-dim); }            /* comment */
.terminal-body .k { color: var(--info); }              /* key */
.terminal-body .v { color: #fbbf24; }                  /* value */
.terminal-body .err { color: #f87171; }
.cursor {
  display: inline-block; width: 8px; height: 15px;
  background: var(--primary); vertical-align: -2px;
  animation: blink 1.1s steps(1) infinite;
}
@keyframes blink { 50% { opacity: 0; } }

/* ---------------------------------------------------------------- code */

code {
  font-family: var(--mono); font-size: 12.5px;
  background: #101014; border: 1px solid var(--border);
  padding: 1.5px 6px; border-radius: 5px; color: #a7f3d0;
}
pre.codeblock {
  background: #050507; color: #d4d4d8;
  border: 1px solid var(--border); border-radius: var(--radius);
  padding: 15px 18px; overflow-x: auto;
  font-family: var(--mono); font-size: 12.5px; line-height: 1.6;
  margin: 12px 0;
}
pre.codeblock .cm { color: var(--fg-dim); }            /* comment */

/* --------------------------------------------------------------- tables */

.table { border-collapse: collapse; width: 100%; font-size: 13.5px; }
.table th, .table td {
  border: 1px solid var(--border); padding: 8px 12px; text-align: left;
  vertical-align: top;
}
.table th {
  background: #101014; color: var(--fg-muted);
  font-family: var(--mono); font-size: 11px; letter-spacing: .08em;
  text-transform: uppercase;
}
.table td code { white-space: nowrap; }

/* ---------------------------------------------------------------- hero */

.hero { padding: 84px 0 30px; text-align: center; }
.hero .kicker {
  display: inline-flex; gap: 8px; align-items: center;
  font-family: var(--mono); font-size: 11px; letter-spacing: .22em;
  color: var(--primary-hi); text-transform: uppercase;
  border: 1px solid rgba(16, 185, 129, 0.35); border-radius: 999px;
  padding: 4px 14px; background: rgba(16, 185, 129, 0.07);
}
.hero h1 {
  font-size: clamp(38px, 6vw, 58px); line-height: 1.05; margin: 22px 0 14px;
  font-weight: 800; letter-spacing: -0.02em;
}
.hero h1 .glow {
  color: var(--primary-hi);
  text-shadow: 0 0 24px rgba(16, 185, 129, 0.45);
}
.hero .sub {
  font-size: 16.5px; color: var(--fg-muted); max-width: 640px;
  margin: 0 auto 28px; line-height: 1.6;
}

/* ---------------------------------------------------------------- page */

.page-head { padding: 44px 0 8px; }
.page-head h1 {
  font-size: 30px; margin: 8px 0 6px; letter-spacing: -0.01em;
  display: flex; align-items: center; gap: 12px; flex-wrap: wrap;
}
.page-head .sub { color: var(--fg-muted); font-size: 14px; }

h2.section {
  color: var(--primary-hi); font-size: 19px; margin: 40px 0 12px;
  padding-bottom: 8px; border-bottom: 1px solid var(--border);
  letter-spacing: .01em;
}

/* ---------------------------------------------------------------- note */

.note {
  border-left: 3px solid var(--warn);
  background: rgba(245, 158, 11, 0.06);
  border-radius: 0 8px 8px 0;
  padding: 12px 16px; font-size: 13.5px; color: #fde68a;
  margin: 14px 0;
}
.note.green {
  border-left-color: var(--primary);
  background: rgba(16, 185, 129, 0.06); color: #a7f3d0;
}

/* ---------------------------------------------------------------- misc */

.mono { font-family: var(--mono); }
.muted { color: var(--fg-muted); }
.dim { color: var(--fg-dim); }
.small { font-size: 12.5px; }

.footer {
  text-align: center; padding: 42px 20px; color: var(--fg-dim);
  font-size: 12.5px; border-top: 1px solid var(--border); margin-top: 60px;
  font-family: var(--mono); letter-spacing: .05em;
}

.divider { border: 0; border-top: 1px solid var(--border); margin: 26px 0; }

/* scanline overlay (very subtle) */
body::after {
  content: ""; position: fixed; inset: 0; pointer-events: none; z-index: 50;
  background: repeating-linear-gradient(
    0deg, rgba(255, 255, 255, 0.012) 0 1px, transparent 1px 3px);
  mix-blend-mode: overlay;
}

/* console output panels */
pre.out {
  background: #050507; border: 1px solid var(--border); border-radius: 8px;
  color: #a7f3d0; padding: 13px 15px; font-family: var(--mono);
  font-size: 12px; overflow: auto; max-height: 420px; margin: 10px 0 0;
  white-space: pre-wrap; word-break: break-word;
}

/* tabs (login page) */
.tabs { display: flex; gap: 4px; margin-bottom: 18px; }
.tabs button {
  flex: 1; padding: 8px; font-size: 13px; cursor: pointer;
  background: transparent; color: var(--fg-muted);
  border: 1px solid var(--border); border-radius: 8px;
  font-family: var(--sans); font-weight: 500;
}
.tabs button.on {
  color: var(--primary-hi); border-color: rgba(16, 185, 129, 0.4);
  background: rgba(16, 185, 129, 0.08);
}

/* ============================================================
   GRIDLOCK platform additions (board, hints, leaderboard)
   ============================================================ */

.board { display: grid; grid-template-columns: repeat(3, 1fr); gap: 16px; margin: 24px 0; }
@media (max-width: 900px) { .board { grid-template-columns: 1fr 1fr; } }
@media (max-width: 640px) { .board { grid-template-columns: 1fr; } }

.chal-card { position: relative; display: block; color: inherit; }
.chal-card .cat { margin-bottom: 10px; }
.chal-card h3 { font-size: 15.5px; margin: 0 0 6px; }
.chal-card .meta { display: flex; gap: 10px; align-items: center; flex-wrap: wrap;
                   font-family: var(--mono); font-size: 11px; color: var(--fg-dim); }
.chal-card .pts { color: var(--primary-hi); }
.chal-card .solved-mark { position: absolute; top: 14px; right: 14px;
  color: var(--primary-hi); font-size: 16px; }
a.chal-card { text-decoration: none; }
a.chal-card:hover { text-decoration: none; }

.filter-row { display: flex; gap: 8px; flex-wrap: wrap; margin: 18px 0 4px; }
.filter-row .btn.on { border-color: rgba(16,185,129,.5); color: var(--primary-hi);
  background: rgba(16,185,129,.08); }

.hint { border: 1px solid var(--border); border-radius: 8px; padding: 12px 14px;
        margin: 10px 0; }
.hint .hint-head { display: flex; justify-content: space-between; align-items: center;
                   gap: 10px; }
.hint.locked .hint-body { color: var(--fg-dim); font-style: italic; }
.hint .hint-body { margin-top: 8px; font-size: 13.5px; line-height: 1.6; color: var(--fg); }

.lb-table td, .lb-table th { font-family: var(--mono); }
.lb-table .r1 { color: #ffd700; } .lb-table .r2 { color: #c0c0c0; } .lb-table .r3 { color: #cd7f32; }

.stat-row { display: flex; gap: 14px; flex-wrap: wrap; margin: 14px 0; }
.stat { background: var(--card); border: 1px solid var(--border); border-radius: 8px;
        padding: 10px 18px; min-width: 120px; }
.stat .v { font-family: var(--mono); font-size: 22px; color: var(--primary-hi); }
.stat .k { font-size: 11px; color: var(--fg-dim); letter-spacing: .1em; text-transform: uppercase; }

.solve-row { display: flex; justify-content: space-between; gap: 10px; padding: 9px 4px;
             border-bottom: 1px solid var(--border); font-size: 13.5px; }
.solve-row .mono { color: var(--fg-muted); }

/* ---- a11y additions ------------------------------------------------- */
:focus-visible {
  outline: 2px solid var(--primary-hi, #34d399);
  outline-offset: 2px;
}
.sr-only {
  position: absolute; width: 1px; height: 1px; padding: 0; margin: -1px;
  overflow: hidden; clip: rect(0 0 0 0); white-space: nowrap; border: 0;
}
@media (prefers-reduced-motion: reduce) {
  *, *::before, *::after {
    animation-duration: 0.01ms !important;
    animation-iteration-count: 1 !important;
    transition-duration: 0.01ms !important;
  }
}