:root {
  /* Default: follow the OS. Overridden by the theme toggle below. */
  color-scheme: light dark;

  --bg: light-dark(#f4f6fa, #0b1220);
  --surface: light-dark(#ffffff, #111a2c);
  --surface-2: light-dark(#f8fafc, #16213a);
  --text: light-dark(#0f172a, #e6edf6);
  --text-secondary: light-dark(#475569, #a3b2c7);
  --muted: light-dark(#64748b, #7d8ca3);
  --border: light-dark(#e2e8f0, #253248);
  --border-strong: light-dark(#cbd5e1, #34445f);
  --accent: light-dark(#2563eb, #60a5fa);
  --accent-hover: light-dark(#1d4ed8, #93c5fd);
  --accent-soft: light-dark(#eff6ff, #172a4a);
  --on-accent: light-dark(#ffffff, #0b1220);
  --error: light-dark(#dc2626, #f87171);
  --error-bg: light-dark(#fef2f2, #2c1518);
  --warning: light-dark(#b45309, #fbbf24);
  --warning-bg: light-dark(#fffbeb, #2a2110);
  --shadow:
    0 1px 2px light-dark(rgb(15 23 42 / 0.04), rgb(0 0 0 / 0.3)),
    0 5px 14px light-dark(rgb(15 23 42 / 0.06), rgb(0 0 0 / 0.35));
  --shadow-sm: 0 1px 2px light-dark(rgb(15 23 42 / 0.05), rgb(0 0 0 / 0.3));
  --radius: 10px;
  --radius-sm: 7px;
  --font-mono: ui-monospace, "SF Mono", "Cascadia Code", Menlo, Consolas, monospace;
}

:root[data-theme="light"] {
  color-scheme: light;
}

:root[data-theme="dark"] {
  color-scheme: dark;
}

* {
  box-sizing: border-box;
}

body {
  margin: 0;
  font-family: system-ui, -apple-system, "Segoe UI", sans-serif;
  font-size: 14px;
  line-height: 1.5;
  background: var(--bg);
  color: var(--text);
}

/* ---------- Header ---------- */

header {
  display: flex;
  align-items: center;
  gap: 2rem;
  padding: 0.75rem 1.5rem;
  border-bottom: 1px solid var(--border);
  position: sticky;
  top: 0;
  background: color-mix(in srgb, var(--surface) 85%, transparent);
  backdrop-filter: blur(10px);
  -webkit-backdrop-filter: blur(10px);
  z-index: 2;
}

h1 {
  font-size: 1.05rem;
  font-weight: 650;
  letter-spacing: -0.01em;
  margin: 0;
}

h1::before {
  content: "";
  display: inline-block;
  width: 0.6rem;
  height: 0.6rem;
  margin-right: 0.6rem;
  border-radius: 3px;
  background: linear-gradient(135deg, var(--accent), color-mix(in srgb, var(--accent) 55%, #14b8a6));
  vertical-align: baseline;
}

.type-picker {
  display: flex;
  align-items: center;
  gap: 0.6rem;
  font-weight: 550;
  color: var(--text-secondary);
}

.theme-toggle {
  margin-left: auto;
  display: inline-flex;
  align-items: center;
  justify-content: center;
  width: 2.25rem;
  height: 2.25rem;
  padding: 0;
  color: var(--text-secondary);
}

.theme-toggle svg {
  display: none;
  width: 1.1rem;
  height: 1.1rem;
}

.theme-toggle svg.active {
  display: block;
}

/* ---------- Layout ---------- */

main {
  display: grid;
  grid-template-columns: minmax(340px, 1fr) minmax(340px, 1fr);
  gap: 1.25rem;
  padding: 1.25rem 1.5rem 3rem;
  align-items: start;
  max-width: 1600px;
  margin: 0 auto;
}

@media (max-width: 900px) {
  main {
    grid-template-columns: 1fr;
    padding: 1rem;
  }
}

#form-panel,
#output-panel {
  background: var(--surface);
  border: 1px solid var(--border);
  border-radius: var(--radius);
  padding: 1.1rem 1.25rem;
  box-shadow: var(--shadow);
}

#output-panel {
  position: sticky;
  top: 4.25rem;
}

.muted {
  color: var(--muted);
}

/* ---------- Inputs & controls ---------- */

input[type="text"],
input[type="number"],
input[type="datetime-local"],
select,
textarea {
  font: inherit;
  color: var(--text);
  background: var(--surface-2);
  border: 1px solid var(--border-strong);
  border-radius: var(--radius-sm);
  transition: border-color 150ms ease, box-shadow 150ms ease, background 150ms ease;
}

input:focus-visible,
select:focus-visible,
textarea:focus-visible,
button:focus-visible,
summary:focus-visible {
  outline: none;
  border-color: var(--accent);
  box-shadow: 0 0 0 3px color-mix(in srgb, var(--accent) 25%, transparent);
}

summary:focus-visible {
  border-radius: var(--radius-sm);
}

select {
  padding: 0.4rem 0.5rem;
  cursor: pointer;
}

#import-box {
  margin-bottom: 1rem;
}

#import-input {
  width: 100%;
  margin-top: 0.6rem;
  padding: 0.6rem 0.7rem;
  font-size: 13px;
  resize: vertical;
}

#import-input::placeholder {
  color: var(--muted);
}

.import-controls {
  display: flex;
  align-items: center;
  justify-content: space-between;
  flex-wrap: wrap;
  gap: 0.75rem 1rem;
  margin-top: 0.6rem;
}

.firmware-toggle {
  display: flex;
  align-items: center;
  gap: 0.45rem;
  color: var(--text-secondary);
  cursor: pointer;
}

input[type="checkbox"] {
  accent-color: var(--accent);
  width: 1rem;
  height: 1rem;
  cursor: pointer;
}

/* ---------- Buttons ---------- */

button {
  padding: 0.35rem 0.85rem;
  font: inherit;
  font-weight: 550;
  border: 1px solid var(--border-strong);
  border-radius: var(--radius-sm);
  background: var(--surface);
  color: var(--text);
  cursor: pointer;
  box-shadow: var(--shadow-sm);
  transition: background 150ms ease, border-color 150ms ease, color 150ms ease, transform 100ms ease;
}

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

button:active {
  transform: scale(0.97);
}

#import-button,
#copy-hex {
  background: var(--accent);
  border-color: var(--accent);
  color: var(--on-accent);
}

#import-button:hover,
#copy-hex:hover {
  background: var(--accent-hover);
  border-color: var(--accent-hover);
  color: var(--on-accent);
}

/* ---------- Form fields ---------- */

.field {
  margin: 0.45rem 0;
}

.field > label {
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 1rem;
}

.field input[type="text"],
.field input[type="number"],
.field input[type="datetime-local"],
.field select {
  width: 60%;
  padding: 0.32rem 0.5rem;
}

.mono,
pre {
  font-family: var(--font-mono);
}

fieldset {
  border: 1px solid var(--border);
  border-radius: var(--radius-sm);
  background: var(--surface-2);
  margin: 0.6rem 0;
  padding: 0.5rem 0.75rem 0.65rem;
}

legend {
  font-weight: 600;
  padding: 0 0.45rem;
  color: var(--text-secondary);
  font-size: 13px;
  text-transform: none;
}

details {
  border: 1px solid var(--border);
  border-radius: var(--radius-sm);
  background: var(--surface-2);
  padding: 0.45rem 0.7rem;
}

details + details {
  margin-top: 0.5rem;
}

summary {
  cursor: pointer;
  font-weight: 600;
  color: var(--text-secondary);
  user-select: none;
  transition: color 150ms ease;
}

summary:hover {
  color: var(--accent);
}

details[open] > summary {
  margin-bottom: 0.4rem;
}

.nested {
  margin-top: 0.4rem;
  padding-left: 0.8rem;
  border-left: 2px solid var(--border-strong);
}

.checkbox-grid {
  display: grid;
  grid-template-columns: repeat(auto-fill, minmax(220px, 1fr));
  gap: 0.2rem 1rem;
  margin-top: 0.4rem;
}

.checkbox-grid label {
  font-weight: 400;
  white-space: nowrap;
  overflow: hidden;
  text-overflow: ellipsis;
  cursor: pointer;
}

.list-header {
  display: flex;
  align-items: center;
  justify-content: space-between;
  font-weight: 600;
}

.list-item {
  position: relative;
}

/* ---------- Output panel ---------- */

.output-header {
  display: flex;
  align-items: center;
  gap: 0.75rem;
  margin-bottom: 0.6rem;
}

.output-header h2 {
  font-size: 0.95rem;
  font-weight: 650;
  letter-spacing: -0.01em;
  margin: 0;
}

.output-header #copy-hex {
  margin-left: auto;
}

.hex {
  border: 1px solid var(--border);
  border-radius: var(--radius-sm);
  background: var(--surface-2);
  padding: 0.8rem 0.9rem;
  margin: 0 0 0.75rem;
  font-size: 13px;
  letter-spacing: 0.03em;
  white-space: pre-wrap;
  word-break: break-all;
  min-height: 3rem;
  user-select: all;
}

.error {
  color: var(--error);
  background: var(--error-bg);
  border: 1px solid color-mix(in srgb, var(--error) 35%, transparent);
  border-radius: var(--radius-sm);
  padding: 0.55rem 0.8rem;
  margin: 0.5rem 0;
}

.warnings {
  color: var(--warning);
  background: var(--warning-bg);
  border: 1px solid color-mix(in srgb, var(--warning) 35%, transparent);
  border-radius: var(--radius-sm);
  margin: 0.5rem 0;
  padding: 0.55rem 0.8rem 0.55rem 1.75rem;
}

details .warnings {
  border: none;
  background: transparent;
  padding: 0 0 0 1.25rem;
}

#dump-output,
#readable-output {
  overflow-x: auto;
  border: 1px solid var(--border);
  border-radius: var(--radius-sm);
  background: var(--surface);
  padding: 0.6rem 0.75rem;
  font-size: 12.5px;
}

/* ---------- Parse tree ---------- */

.tree {
  border: 1px solid var(--border);
  border-radius: var(--radius-sm);
  background: var(--surface);
  padding: 0.75rem;
  font-size: 13px;
  overflow-x: auto;
}

.tree-row {
  display: flex;
  gap: 0.75rem;
  padding: 0.12rem 0.3rem;
  border-radius: 4px;
}

.tree-row:hover {
  background: var(--accent-soft);
}

.tree-key {
  font-weight: 600;
  min-width: 14rem;
  color: var(--text-secondary);
}

.tree-value {
  word-break: break-all;
  font-family: var(--font-mono);
  font-size: 12.5px;
}

.tree details {
  border: none;
  background: transparent;
  padding: 0.1rem 0;
}

/* ---------- Motion ---------- */

@media (prefers-reduced-motion: reduce) {
  * {
    transition-duration: 0.01ms !important;
    animation-duration: 0.01ms !important;
  }
}