:root {
  color-scheme: dark;
  --bg: #0f1210;
  --surface: #171b16;
  --surface-2: #1e241c;
  --line: #343c30;
  --text: #f4f0e6;
  --muted: #c8c1b0;
  --faint: #9a9486;
  --accent: #dff25a;
  --accent-ink: #17200a;
  --host: #3c4634;
  --teal: #9ed0c2;
  --danger: #ffb4a6;
  --danger-bg: #2a1612;
  --danger-line: #6a3530;
  --shadow: 0 24px 60px rgba(0, 0, 0, 0.28);
  --sans: system-ui, -apple-system, "Segoe UI", Roboto, Helvetica, Arial, sans-serif;
  --mono: ui-monospace, "SFMono-Regular", "Cascadia Code", "Segoe UI Mono", Menlo, Consolas, monospace;
}

* { box-sizing: border-box; }

html { scroll-behavior: smooth; }

body {
  margin: 0;
  min-height: 100vh;
  color: var(--text);
  font-family: var(--sans);
  font-size: 1rem;
  line-height: 1.5;
  background-color: var(--bg);
  background-image:
    radial-gradient(ellipse 70% 45% at 0% -10%, rgba(223, 242, 90, 0.09), transparent 55%),
    radial-gradient(ellipse 40% 30% at 100% 0%, rgba(158, 208, 194, 0.07), transparent 50%),
    linear-gradient(rgba(255, 255, 255, 0.025) 1px, transparent 1px),
    linear-gradient(90deg, rgba(255, 255, 255, 0.025) 1px, transparent 1px);
  background-size: auto, auto, 28px 28px, 28px 28px;
}

a { color: inherit; }

.skip {
  position: absolute;
  left: 0.75rem;
  top: 0.75rem;
  transform: translateY(-150%);
  background: var(--accent);
  color: var(--accent-ink);
  padding: 0.55rem 0.8rem;
  border-radius: 0.4rem;
  z-index: 5;
  font-weight: 700;
  text-decoration: none;
}

.skip:focus { transform: none; }

.wrap {
  width: min(72rem, calc(100% - 2rem));
  margin: 0 auto;
  padding: 1.25rem 0 3rem;
  min-width: 0;
}

.site-header {
  display: flex;
  flex-wrap: wrap;
  align-items: center;
  justify-content: space-between;
  gap: 0.75rem 1.25rem;
  margin-bottom: 1.35rem;
}

.brand {
  font-family: var(--mono);
  font-size: 0.84rem;
  font-weight: 700;
  letter-spacing: 0.16em;
  text-transform: uppercase;
  color: var(--accent);
  text-decoration: none;
  min-height: 2.75rem;
  display: inline-flex;
  align-items: center;
}

.site-nav ul {
  display: flex;
  flex-wrap: wrap;
  gap: 0.4rem;
  list-style: none;
  margin: 0;
  padding: 0;
}

.site-nav a {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  min-height: 2.75rem;
  padding: 0.35rem 0.9rem;
  border-radius: 999px;
  border: 1px solid var(--line);
  background: var(--surface);
  color: var(--text);
  text-decoration: none;
  font-family: var(--mono);
  font-size: 0.86rem;
}

.site-nav a[aria-current="page"] {
  background: var(--accent);
  color: var(--accent-ink);
  border-color: transparent;
  font-weight: 700;
}

h1 {
  margin: 0;
  font-size: clamp(2rem, 4vw, 3.1rem);
  line-height: 1.05;
  letter-spacing: -0.035em;
  font-weight: 650;
}

.lede {
  max-width: 40rem;
  margin: 0.75rem 0 0;
  color: var(--muted);
  font-size: 1.05rem;
}

.top {
  display: grid;
  gap: 1rem;
  margin-top: 1.25rem;
}

@media (min-width: 900px) {
  .top { grid-template-columns: minmax(0, 1.55fr) minmax(16rem, 0.75fr); align-items: start; }
}

.card {
  background: rgba(23, 27, 22, 0.92);
  border: 1px solid var(--line);
  border-radius: 1rem;
  box-shadow: var(--shadow);
  padding: 1.1rem 1.15rem 1.2rem;
  min-width: 0;
}

.stack { display: grid; gap: 1rem; margin-top: 1.25rem; }

label, .label, legend {
  display: block;
  font-size: 0.82rem;
  font-weight: 650;
  letter-spacing: 0.04em;
  text-transform: uppercase;
  color: var(--muted);
  margin-bottom: 0.4rem;
}

fieldset {
  margin: 0;
  padding: 0;
  border: 0;
  min-width: 0;
}

.cidr-row, .prefix-row, .output-row {
  display: grid;
  gap: 0.6rem;
  min-width: 0;
}

@media (min-width: 720px) {
  .cidr-row, .output-row { grid-template-columns: minmax(0, 1fr) auto; align-items: end; }
}

input[type="text"], input[type="number"], input[type="search"] {
  width: 100%;
  max-width: 100%;
  min-width: 0;
  min-height: 3rem;
  border-radius: 0.7rem;
  border: 1px solid var(--line);
  background: var(--bg);
  color: var(--text);
  font-family: var(--mono);
  font-size: 1.05rem;
  padding: 0.65rem 0.8rem;
  appearance: none;
}

input[type="number"] { max-width: 6.5rem; }

.output-row input[type="text"] {
  font-size: clamp(1rem, 2.5vw, 1.35rem);
}

input::placeholder { color: var(--faint); }

input:focus-visible, button:focus-visible, summary:focus-visible, a:focus-visible {
  outline: 2px solid var(--accent);
  outline-offset: 2px;
}

input[aria-invalid="true"] { border-color: var(--danger); }

.help, .rules p, footer, .empty, .note, .hint { color: var(--muted); }

.help, .hint { margin: 0.55rem 0 0; font-size: 0.92rem; }

.prefix-block { margin-top: 1rem; }

.prefix-row {
  grid-template-columns: auto minmax(0, 1fr);
  align-items: center;
}

input[type="range"] {
  width: 100%;
  accent-color: var(--accent);
  min-height: 2.75rem;
}

.bits {
  display: flex;
  gap: 3px;
  margin-top: 0.35rem;
  min-height: 0.7rem;
  min-width: 0;
}

.bit {
  flex: 1 1 0;
  min-width: 0;
  height: 0.55rem;
  border-radius: 1px;
  background: var(--host);
}

.bit-net { background: var(--accent); }
.bit-gap { margin-left: 0.35rem; }

.samples, .actions {
  display: flex;
  flex-wrap: wrap;
  gap: 0.45rem;
}

.samples { margin-top: 1rem; }

button, .copy { font: inherit; cursor: pointer; }

.primary, .sample, .copy {
  border: 1px solid transparent;
  border-radius: 0.7rem;
  min-height: 2.75rem;
}

.primary {
  background: var(--accent);
  color: var(--accent-ink);
  font-weight: 750;
  padding: 0.65rem 1rem;
}

.primary:hover { filter: brightness(1.05); }

.sample, .copy {
  background: var(--surface-2);
  color: var(--text);
  border-color: var(--line);
  padding: 0.4rem 0.7rem;
  font-family: var(--mono);
  font-size: 0.86rem;
}

.sample:hover, .copy:hover, .site-nav a:hover { border-color: var(--accent); }

.choices { display: grid; gap: 0.65rem; }

.choice {
  display: flex;
  gap: 0.75rem;
  align-items: flex-start;
  min-height: 2.75rem;
  margin: 0;
  font-size: 1rem;
  font-weight: 400;
  letter-spacing: 0;
  text-transform: none;
  color: var(--text);
}

.choice input {
  width: 1.2rem;
  height: 1.2rem;
  margin-top: 0.15rem;
  accent-color: var(--accent);
  flex: 0 0 auto;
}

.choice span { display: grid; gap: 0.15rem; min-width: 0; }

.choice strong {
  font-size: 0.95rem;
  letter-spacing: 0;
  text-transform: none;
  color: var(--text);
  font-weight: 650;
}

.choice code {
  font-family: var(--mono);
  font-size: 0.86rem;
  color: var(--teal);
  overflow-wrap: anywhere;
}

.error {
  margin: 0.85rem 0 0;
  padding: 0.75rem 0.85rem;
  border-radius: 0.7rem;
  background: var(--danger-bg);
  color: var(--danger);
  border: 1px solid var(--danger-line);
}

.error:focus { outline: 2px solid var(--danger); outline-offset: 2px; }

.rules summary {
  cursor: pointer;
  font-weight: 700;
  color: var(--text);
}

.rules p { margin: 0.7rem 0 0; font-size: 0.95rem; }

#results { margin-top: 1rem; }

#results h2, .tool-title {
  margin: 0 0 0.8rem;
  font-family: var(--mono);
  font-size: clamp(1.35rem, 2.5vw, 1.8rem);
  letter-spacing: -0.03em;
  overflow-wrap: anywhere;
}

#results h2:focus, .tool-title:focus { outline: none; }

.hero { margin: 0 0 0.9rem; }

.hero-value {
  display: block;
  font-family: var(--mono);
  font-size: clamp(2rem, 6vw, 3.4rem);
  line-height: 1;
  letter-spacing: -0.04em;
  color: var(--accent);
  overflow-wrap: anywhere;
}

.hero-label {
  display: block;
  margin-top: 0.35rem;
  color: var(--muted);
  font-size: 0.92rem;
}

.note {
  margin: 0 0 0.9rem;
  padding: 0.75rem 0.85rem;
  border-left: 3px solid var(--teal);
  background: rgba(158, 208, 194, 0.08);
}

.facts { margin: 0; }

.fact {
  display: grid;
  grid-template-columns: minmax(7.5rem, 11rem) minmax(0, 1fr) auto;
  gap: 0.75rem;
  align-items: center;
  padding: 0.72rem 0;
  border-top: 1px solid var(--line);
  min-width: 0;
}

.fact dt { margin: 0; color: var(--muted); font-size: 0.92rem; }
.fact dd { margin: 0; min-width: 0; }

.value {
  font-family: var(--mono);
  font-size: 1rem;
  overflow-wrap: anywhere;
  user-select: all;
}

.binary { letter-spacing: 0.01em; }
.bit-on { color: var(--accent); }
.bit-off { color: var(--teal); }
.bit-dot { color: var(--faint); }
.result-actions { margin-top: 0.9rem; }
.empty { margin: 0; }

footer { margin-top: 1.4rem; font-size: 0.88rem; }
footer p { margin: 0; }

.sr-only, .offscreen {
  position: absolute;
  width: 1px;
  height: 1px;
  padding: 0;
  margin: -1px;
  overflow: hidden;
  clip: rect(0, 0, 0, 0);
  white-space: nowrap;
  border: 0;
}

@media (max-width: 640px) {
  .wrap { width: min(100% - 1.25rem, 72rem); }
  .fact {
    grid-template-columns: minmax(0, 1fr);
    gap: 0.15rem;
    padding: 0.5rem 0;
  }
  .fact dt { grid-area: auto; }
  .fact dd { grid-area: auto; }
  .primary, .copy { width: 100%; }
  .output-row .copy, .cidr-row .primary { width: 100%; }
  .output-row input[type="text"] { font-size: 0.95rem; }
  .hint { margin-top: 0.2rem; }
}

.toolbar {
  display: flex;
  flex-wrap: wrap;
  gap: 0.6rem;
  align-items: end;
}

.toolbar > div { flex: 1 1 16rem; min-width: 0; }

.header-list { margin: 0; }

.header-row {
  display: grid;
  grid-template-columns: minmax(11rem, 16rem) minmax(0, 1fr) auto;
  gap: 0.35rem 1rem;
  align-items: baseline;
  padding: 0.75rem 0;
  border-top: 1px solid var(--line);
}

.header-name {
  grid-column: 1;
  margin: 0;
  font-family: var(--mono);
  font-size: 1rem;
  font-weight: 650;
  line-height: 1.35;
  overflow-wrap: break-word;
  word-break: normal;
}

.header-value {
  grid-column: 2;
  margin: 0;
  min-width: 0;
  font-family: var(--mono);
  font-size: 0.95rem;
  line-height: 1.4;
  overflow-wrap: anywhere;
  user-select: all;
}

.header-row .pill { grid-column: 3; justify-self: end; white-space: nowrap; }

@media (max-width: 720px) {
  .header-row { grid-template-columns: minmax(0, 1fr) auto; }
  .header-name { grid-column: 1; grid-row: 1; }
  .header-row .pill { grid-column: 2; grid-row: 1; }
  .header-value { grid-column: 1 / -1; grid-row: 2; }
}

.pill {
  display: inline-block;
  border-radius: 999px;
  padding: 0.15rem 0.55rem;
  border: 1px solid var(--line);
  font-family: var(--mono);
  font-size: 0.78rem;
}

.pill-listed { color: var(--danger); border-color: var(--danger-line); }
.pill-clear { color: var(--teal); }
.pill-unknown { color: var(--muted); }

.disclosure {
  margin: 0;
  color: var(--muted);
  font-size: 0.95rem;
}

@media (prefers-reduced-motion: reduce) {
  html { scroll-behavior: auto; }
  *, *::before, *::after {
    transition: none !important;
    animation: none !important;
  }
}