/* ============================================================
   Tokens
   ============================================================ */

:root {
  --bg: #f3f5f9;
  --surface: #ffffff;
  --surface-2: #f7f9fc;
  --border: #e1e7f0;
  --border-strong: #cbd5e1;
  --text: #0f172a;
  --muted: #62718a;
  --accent: #2563eb;
  --accent-hover: #1d4ed8;
  --accent-soft: #e8effd;
  --net: #2563eb;
  --host: #a8b4c6;
  --danger: #dc2626;
  --danger-soft: #fef2f2;
  --shadow: 0 1px 2px rgba(15, 23, 42, .05), 0 10px 28px rgba(15, 23, 42, .07);
  --radius: 14px;
  --mono: ui-monospace, SFMono-Regular, "SF Mono", Menlo, Consolas, "Liberation Mono", monospace;
  --sans: system-ui, -apple-system, "Segoe UI", Roboto, "Helvetica Neue", Arial, sans-serif;
  color-scheme: light;
}

:root[data-theme="dark"] {
  --bg: #0a0e15;
  --surface: #121a26;
  --surface-2: #0e141e;
  --border: #24303f;
  --border-strong: #33415a;
  --text: #e5edf9;
  --muted: #8a9ab3;
  --accent: #5b9dff;
  --accent-hover: #7db0ff;
  --accent-soft: #16273f;
  --net: #5b9dff;
  --host: #47566d;
  --danger: #f87171;
  --danger-soft: #2a1517;
  --shadow: 0 1px 2px rgba(0, 0, 0, .5), 0 12px 32px rgba(0, 0, 0, .45);
  color-scheme: dark;
}

/* ============================================================
   Base
   ============================================================ */

* { box-sizing: border-box; }

html { -webkit-text-size-adjust: 100%; }

body {
  margin: 0;
  padding: 2.5rem 1.25rem 3rem;
  background: var(--bg);
  color: var(--text);
  font-family: var(--sans);
  font-size: 16px;
  line-height: 1.55;
  transition: background-color .2s ease, color .2s ease;
}

.page {
  max-width: 780px;
  margin: 0 auto;
}

/* ============================================================
   Masthead
   ============================================================ */

.masthead {
  display: flex;
  align-items: flex-start;
  justify-content: space-between;
  gap: 1rem;
  margin-bottom: 1.5rem;
}

.masthead h1 {
  margin: 0;
  font-size: 1.6rem;
  font-weight: 650;
  letter-spacing: -.02em;
}

.masthead p {
  margin: .3rem 0 0;
  color: var(--muted);
  font-size: .95rem;
}

.icon-button {
  flex: none;
  display: grid;
  place-items: center;
  width: 38px;
  height: 38px;
  padding: 0;
  border: 1px solid var(--border);
  border-radius: 10px;
  background: var(--surface);
  color: var(--muted);
  cursor: pointer;
  transition: color .15s ease, border-color .15s ease, background-color .15s ease;
}

.icon-button:hover {
  color: var(--accent);
  border-color: var(--border-strong);
  background: var(--surface-2);
}

.icon-button svg { grid-area: 1 / 1; }

.icon-button .icon-moon { display: none; }
:root[data-theme="dark"] .icon-button .icon-sun { display: none; }
:root[data-theme="dark"] .icon-button .icon-moon { display: block; }

:focus-visible {
  outline: 2px solid var(--accent);
  outline-offset: 2px;
}

/* ============================================================
   Cards
   ============================================================ */

.card {
  background: var(--surface);
  border: 1px solid var(--border);
  border-radius: var(--radius);
  box-shadow: var(--shadow);
}

.input-card { padding: 1.25rem; }

.field-label {
  display: block;
  margin-bottom: .5rem;
  font-size: .8rem;
  font-weight: 600;
  letter-spacing: .04em;
  text-transform: uppercase;
  color: var(--muted);
}

.input-row {
  display: flex;
  gap: .6rem;
}

.text-input {
  flex: 1 1 auto;
  min-width: 0;
  padding: .7rem .85rem;
  border: 1px solid var(--border-strong);
  border-radius: 10px;
  background: var(--surface-2);
  color: var(--text);
  font-family: var(--mono);
  font-size: .95rem;
  transition: border-color .15s ease, box-shadow .15s ease;
}

.text-input::placeholder { color: var(--host); }

.text-input:focus {
  outline: none;
  border-color: var(--accent);
  box-shadow: 0 0 0 3px var(--accent-soft);
}

.text-input[aria-invalid="true"] {
  border-color: var(--danger);
  box-shadow: 0 0 0 3px var(--danger-soft);
}

.button {
  flex: none;
  padding: .7rem 1.15rem;
  border: 1px solid transparent;
  border-radius: 10px;
  font-family: inherit;
  font-size: .92rem;
  font-weight: 600;
  cursor: pointer;
  transition: background-color .15s ease, border-color .15s ease, color .15s ease;
}

.button.primary {
  background: var(--accent);
  color: #fff;
}

.button.primary:hover { background: var(--accent-hover); }

.button.ghost {
  padding: .45rem .8rem;
  border-color: var(--border-strong);
  background: transparent;
  color: var(--muted);
  font-size: .82rem;
}

.button.ghost:hover {
  color: var(--accent);
  border-color: var(--accent);
  background: var(--accent-soft);
}

/* ============================================================
   Hints, errors, examples
   ============================================================ */

.hint {
  margin: .75rem 0 0;
  color: var(--muted);
  font-size: .84rem;
}

.hint code {
  font-family: var(--mono);
  font-size: .95em;
  padding: .1em .3em;
  border-radius: 4px;
  background: var(--surface-2);
  border: 1px solid var(--border);
  color: var(--text);
}

.error {
  margin: .75rem 0 0;
  padding: .6rem .75rem;
  border: 1px solid var(--danger);
  border-radius: 9px;
  background: var(--danger-soft);
  color: var(--danger);
  font-size: .86rem;
}

.examples {
  display: flex;
  flex-wrap: wrap;
  align-items: center;
  gap: .4rem;
  margin-top: 1rem;
  padding-top: 1rem;
  border-top: 1px solid var(--border);
}

.examples-label {
  font-size: .78rem;
  font-weight: 600;
  letter-spacing: .04em;
  text-transform: uppercase;
  color: var(--muted);
}

.chip {
  padding: .3rem .6rem;
  border: 1px solid var(--border-strong);
  border-radius: 999px;
  background: transparent;
  color: var(--muted);
  font-family: var(--mono);
  font-size: .78rem;
  cursor: pointer;
  transition: color .15s ease, border-color .15s ease, background-color .15s ease;
}

.chip:hover {
  color: var(--accent);
  border-color: var(--accent);
  background: var(--accent-soft);
}

/* ============================================================
   Results
   ============================================================ */

.results-card {
  margin-top: 1.25rem;
  padding: 1.25rem;
}

.results-head {
  display: flex;
  align-items: flex-start;
  justify-content: space-between;
  gap: 1rem;
  padding-bottom: 1rem;
  border-bottom: 1px solid var(--border);
}

.results-title {
  margin: 0;
  font-family: var(--mono);
  font-size: 1.05rem;
  font-weight: 600;
  word-break: break-all;
}

.results-sub {
  margin: .2rem 0 0;
  font-size: .8rem;
  color: var(--muted);
}

.result-grid { margin: 0; }

.row {
  display: flex;
  align-items: baseline;
  gap: 1rem;
  padding: .6rem 0;
  border-bottom: 1px dashed var(--border);
}

.row:last-child { border-bottom: 0; }

.row-label {
  flex: 0 0 38%;
  color: var(--muted);
  font-size: .87rem;
}

.row-value {
  display: flex;
  align-items: center;
  gap: .45rem;
  flex: 1 1 auto;
  min-width: 0;
  margin: 0;
}

.value-text {
  font-family: var(--mono);
  font-size: .92rem;
  font-weight: 500;
  word-break: break-all;
}

.tag {
  flex: none;
  padding: .1rem .45rem;
  border-radius: 5px;
  background: var(--accent-soft);
  color: var(--accent);
  font-size: .72rem;
  font-weight: 600;
  white-space: nowrap;
}

.copy {
  flex: none;
  display: grid;
  place-items: center;
  width: 26px;
  height: 26px;
  padding: 0;
  border: 0;
  border-radius: 6px;
  background: transparent;
  color: var(--host);
  cursor: pointer;
  opacity: 0;
  transition: opacity .15s ease, color .15s ease, background-color .15s ease;
}

.row:hover .copy,
.copy:focus-visible { opacity: 1; }

.copy:hover {
  color: var(--accent);
  background: var(--accent-soft);
}

.copy.done {
  color: var(--accent);
  opacity: 1;
}

/* ============================================================
   Bit breakdown
   ============================================================ */

.section-title {
  margin: 1.5rem 0 .4rem;
  font-size: .8rem;
  font-weight: 600;
  letter-spacing: .04em;
  text-transform: uppercase;
  color: var(--muted);
}

.breakdown-label {
  margin: 0 0 .5rem;
  font-family: var(--mono);
  font-size: .82rem;
  color: var(--muted);
  word-break: break-all;
}

.bit-scroll { overflow-x: auto; padding-bottom: .25rem; }

.bit-grid {
  display: grid;
  grid-template-columns: repeat(32, minmax(0, 1fr));
  gap: 2px;
  min-width: 360px;
  padding: .6rem;
  border: 1px solid var(--border);
  border-radius: 9px;
  background: var(--surface-2);
}

.bit {
  display: grid;
  place-items: center;
  padding: .3rem 0;
  border-radius: 3px;
  font-family: var(--mono);
  font-size: .7rem;
  font-weight: 600;
  text-transform: uppercase;
}

.bit.net { background: var(--net); color: #fff; }
.bit.host { background: var(--host); color: var(--surface); }
.bit.mix { color: #fff; text-shadow: 0 1px 1px rgba(0, 0, 0, .35); }

.bit.group-start { margin-left: 6px; }

.bit-legend {
  display: flex;
  flex-wrap: wrap;
  gap: .9rem;
  margin-top: .55rem;
  font-size: .78rem;
  color: var(--muted);
}

.bit-legend span {
  display: inline-flex;
  align-items: center;
  gap: .35rem;
}

.swatch {
  width: 10px;
  height: 10px;
  border-radius: 3px;
}

.swatch.net { background: var(--net); }
.swatch.host { background: var(--host); }

/* ============================================================
   Notes / empty / footer
   ============================================================ */

.notes {
  margin: 0;
  padding-left: 1.1rem;
  color: var(--muted);
  font-size: .86rem;
}

.notes li { margin-bottom: .35rem; }
.notes li:last-child { margin-bottom: 0; }

.empty-state {
  margin: 1.5rem 0 0;
  text-align: center;
  color: var(--muted);
  font-size: .9rem;
}

.footer {
  margin-top: 2rem;
  text-align: center;
  color: var(--muted);
  font-size: .8rem;
}

.footer p { margin: 0; }

/* ============================================================
   Responsive
   ============================================================ */

@media (max-width: 560px) {
  body { padding: 1.5rem .9rem 2rem; }

  .input-row { flex-wrap: wrap; }
  .text-input { flex: 1 1 100%; }
  .input-row .button { flex: 1 1 100%; }

  .row { flex-direction: column; gap: .2rem; }
  .row-label { flex: none; }
  .row-value { width: 100%; }
  .copy { opacity: 1; }

  .bit { font-size: .62rem; }
}

@media (prefers-reduced-motion: reduce) {
  * { transition: none !important; }
}