/*
 * Both schemes are defined as tokens on :root and swapped under prefers-color-scheme, so the page
 * follows the operating system without any script and without a flash on load.
 */
:root {
  --surface: #ffffff;
  --surface-sunken: #f4f5f7;
  --surface-raised: #ffffff;
  --border: #d8dbe0;
  --text: #16181d;
  --text-dim: #5c6270;
  --accent: #1c5fd6;
  --danger: #b3261e;
  --danger-surface: #fce8e6;
  --ok: #146c2e;
  --request: #1c5fd6;
  --response: #146c2e;

  color-scheme: light dark;
  font-family: ui-sans-serif, system-ui, -apple-system, "Segoe UI", sans-serif;
  line-height: 1.5;
}

@media (prefers-color-scheme: dark) {
  :root {
    --surface: #16181d;
    --surface-sunken: #101216;
    --surface-raised: #1e2128;
    --border: #333944;
    --text: #e8eaee;
    --text-dim: #9aa2b1;
    --accent: #79a9ff;
    --danger: #f2837c;
    --danger-surface: #3a1d1b;
    --ok: #6ed08a;
    --request: #79a9ff;
    --response: #6ed08a;
  }
}

*,
*::before,
*::after {
  box-sizing: border-box;
}

body {
  margin: 0;
  background: var(--surface-sunken);
  color: var(--text);
}

main {
  max-width: 80rem;
  margin-inline: auto;
  padding: 1.5rem 1rem 4rem;
}

h1 {
  font-size: 1.5rem;
  margin-block: 0 0.25rem;
}

h2 {
  font-size: 1.15rem;
  margin-block: 0;
}

h3 {
  font-size: 1rem;
  margin-block: 0 0.25rem;
}

h4 {
  font-size: 0.9rem;
  text-transform: uppercase;
  letter-spacing: 0.04em;
  color: var(--text-dim);
  margin-block: 1.5rem 0.5rem;
}

a {
  color: var(--accent);
}

code,
.bytes,
.address {
  font-family: ui-monospace, "SF Mono", "Cascadia Mono", Menlo, monospace;
  font-size: 0.85em;
}

.masthead {
  margin-block-end: 1.5rem;
}

.hint {
  color: var(--text-dim);
  font-size: 0.85rem;
}

p.hint {
  margin-block: 0.25rem;
}

.value {
  font-weight: 600;
}

.name {
  font-weight: 500;
}

.empty {
  color: var(--text-dim);
  background: var(--surface-raised);
  border: 1px dashed var(--border);
  border-radius: 0.5rem;
  padding: 1rem 1.25rem;
}

.notice,
.port {
  background: var(--surface-raised);
  border: 1px solid var(--border);
  border-radius: 0.5rem;
  padding: 1rem 1.25rem;
  margin-block-end: 1rem;
}

.panel-header {
  display: flex;
  gap: 1rem;
  align-items: start;
  justify-content: space-between;
  flex-wrap: wrap;
  margin-block-end: 0.75rem;
}

.panel-header .actions {
  display: flex;
  gap: 0.5rem;
}

/* -------------------------------------------------------------------------- */
/* Controls                                                                   */
/* -------------------------------------------------------------------------- */

.controls {
  display: flex;
  flex-wrap: wrap;
  align-items: end;
  gap: 0.75rem 1rem;
  margin-block-end: 0.75rem;
  border: 0;
  padding: 0;
}

/*
 * Each label stays with the control it names. Without this the row wraps between them and a
 * "Parity" label ends up sitting above somebody else's select.
 */
.control {
  display: flex;
  flex-direction: column;
  gap: 0.15rem;
}

fieldset.controls {
  border: 1px solid var(--border);
  border-radius: 0.375rem;
  padding: 0.75rem 1rem;
}

fieldset.controls legend {
  font-size: 0.8rem;
  color: var(--text-dim);
  padding-inline: 0.35rem;
}

fieldset:disabled {
  opacity: 0.6;
}

label {
  font-size: 0.85rem;
  color: var(--text-dim);
}

button,
select,
input {
  font: inherit;
  font-size: 0.9rem;
  color: var(--text);
  background: var(--surface);
  border: 1px solid var(--border);
  border-radius: 0.375rem;
  padding: 0.35rem 0.6rem;
}

button {
  cursor: pointer;
}

button:hover:not(:disabled) {
  border-color: var(--accent);
}

button:disabled {
  cursor: not-allowed;
  opacity: 0.55;
}

:is(button, select, input):focus-visible {
  outline: 2px solid var(--accent);
  outline-offset: 1px;
}

.tabs {
  display: flex;
  gap: 0.25rem;
  margin-block: 1rem 0.5rem;
  border-block-end: 1px solid var(--border);
}

.tabs button[aria-pressed="true"] {
  border-color: var(--accent);
  color: var(--accent);
  font-weight: 600;
}

/* -------------------------------------------------------------------------- */
/* Validation                                                                 */
/* -------------------------------------------------------------------------- */

/*
 * :user-invalid rather than :invalid, so a register write field is not flagged red the moment it
 * is empty or half-typed — only once the field has been left or a submit attempted. Baseline
 * since 2023, so no fallback is carried.
 *
 * The bounds themselves come from the register definition and are set as real min/max/step
 * attributes, which is what makes the browser's own validation the source of truth here.
 */
input:user-invalid {
  border-color: var(--danger);
  background: var(--danger-surface);
}

input:user-valid {
  border-color: var(--ok);
}

.error-msg {
  display: none;
  color: var(--danger);
  font-size: 0.8rem;
}

/* Revealed by the browser's own judgement, not by a signal */
input:user-invalid ~ .error-msg,
.error-msg.shown {
  display: block;
}

.field {
  display: flex;
  align-items: center;
  gap: 0.35rem;
  flex-wrap: wrap;
}

.field input[type="number"] {
  width: 7rem;
}

/* -------------------------------------------------------------------------- */
/* Tables                                                                     */
/* -------------------------------------------------------------------------- */

/* Wide content scrolls inside its own box rather than pushing the page sideways */
.table-scroll {
  overflow-x: auto;
  border: 1px solid var(--border);
  border-radius: 0.375rem;
  max-block-size: 34rem;
  overflow-y: auto;
}

table {
  border-collapse: collapse;
  inline-size: 100%;
  font-size: 0.85rem;
}

thead th {
  position: sticky;
  inset-block-start: 0;
  background: var(--surface-raised);
  text-align: start;
  font-weight: 600;
  color: var(--text-dim);
  padding: 0.4rem 0.6rem;
  border-block-end: 1px solid var(--border);
  z-index: 1;
}

td {
  padding: 0.35rem 0.6rem;
  border-block-end: 1px solid var(--border);
  vertical-align: top;
}

tbody tr:last-child td {
  border-block-end: 0;
}

/*
 * The monitor keeps hundreds of rows and only a screenful is ever in view. content-visibility lets
 * the browser skip layout and paint for the rest; contain-intrinsic-size keeps the scrollbar from
 * jumping as those rows are realised, and `auto` lets it remember each row's real height once
 * measured.
 */
.frames tbody .row {
  content-visibility: auto;
  contain-intrinsic-size: auto none auto 1.9rem;
}

.frames .row.request td:nth-child(2) {
  color: var(--request);
  font-weight: 600;
}

.frames .row.response td:nth-child(2) {
  color: var(--response);
  font-weight: 600;
}

.frames .row.noise {
  color: var(--text-dim);
  background: var(--surface-sunken);
}

.registers .address {
  white-space: nowrap;
}

@media (max-width: 40rem) {
  .panel-header {
    flex-direction: column;
  }
}