/*
  Visual identity: a quiet lab-instrument look, built around an oscilloscope
  trace. Near-black background, a phosphor-green accent for the primary
  signal (sine/play state), and a warm amber accent reserved for the
  resonant/percussive synth section (bells, organ). Monospace is used for
  numeric readouts to read like a real instrument display; the body face is
  the platform's own UI font for plain labels and paragraphs.
*/

:root {
  --bg: #0b0e12;
  --surface: #141a20;
  --surface-raised: #1a222a;
  --border: #26323d;
  --text: #e7eef0;
  --text-muted: #9fb0b8;
  --accent: #4dff9f;
  --accent-warm: #ffb454;
  --danger: #ff6a6a;
  --focus-ring: #7be8ff;

  --font-body: -apple-system, "Segoe UI", Roboto, "Helvetica Neue", Arial, sans-serif;
  --font-mono: ui-monospace, "SF Mono", "Cascadia Code", "Roboto Mono", Consolas, monospace;
}

* {
  box-sizing: border-box;
}

html {
  color-scheme: dark;
}

body {
  margin: 0;
  background: var(--bg);
  color: var(--text);
  font-family: var(--font-body);
  line-height: 1.55;
}

main {
  max-width: 760px;
  margin: 0 auto;
  padding: 0 1.25rem 4rem;
}

header {
  max-width: 760px;
  margin: 0 auto;
  padding: 2rem 1.25rem 1rem;
}

h1 {
  font-family: var(--font-mono);
  letter-spacing: 0.02em;
  font-size: 1.9rem;
  margin: 0 0 0.25rem;
  background: linear-gradient(90deg, var(--accent), var(--focus-ring));
  -webkit-background-clip: text;
  background-clip: text;
  color: transparent;
}

.tagline {
  color: var(--text-muted);
  margin: 0 0 1rem;
}

h2 {
  font-family: var(--font-mono);
  font-size: 1.15rem;
  letter-spacing: 0.01em;
  margin-top: 0;
  border-bottom: 1px solid var(--border);
  padding-bottom: 0.5rem;
}

h3 {
  font-family: var(--font-mono);
  font-size: 1rem;
}

p {
  max-width: 62ch;
}

.skip-link {
  position: absolute;
  left: -999px;
  top: 0;
  background: var(--accent);
  color: #04140c;
  padding: 0.5rem 1rem;
  font-family: var(--font-mono);
  z-index: 10;
}

.skip-link:focus {
  left: 0.5rem;
  top: 0.5rem;
}

nav[aria-label="Sections"] {
  max-width: 760px;
  margin: 0 auto 1.5rem;
  padding: 0 1.25rem;
}

nav[aria-label="Sections"] ul {
  list-style: none;
  display: flex;
  flex-wrap: wrap;
  gap: 0.75rem 1rem;
  margin: 0;
  padding: 0;
}

nav[aria-label="Sections"] a {
  color: var(--accent);
  text-decoration: none;
  font-family: var(--font-mono);
  font-size: 0.9rem;
  border-bottom: 1px dashed transparent;
}

nav[aria-label="Sections"] a:hover,
nav[aria-label="Sections"] a:focus-visible {
  border-bottom-color: var(--accent);
}

.panel {
  background: var(--surface);
  border: 1px solid var(--border);
  border-left: 3px solid var(--accent);
  border-radius: 6px;
  padding: 1.25rem 1.25rem 1.5rem;
  margin-bottom: 1.5rem;
}

#synth.panel {
  border-left-color: var(--accent-warm);
}

#help.panel {
  border-left-color: var(--text-muted);
}

.field {
  display: flex;
  flex-direction: column;
  gap: 0.35rem;
  margin: 0.9rem 0;
  max-width: 30rem;
}

.checkbox-field {
  flex-direction: row;
  align-items: center;
  gap: 0.6rem;
}

.field-row {
  display: flex;
  flex-wrap: wrap;
  gap: 1.5rem;
}

label {
  font-weight: 600;
  font-size: 0.95rem;
}

input,
select,
textarea,
button {
  font-family: inherit;
  font-size: 1rem;
  color: var(--text);
}

input[type="text"],
input[type="number"],
select,
textarea {
  background: var(--bg);
  border: 1px solid var(--border);
  border-radius: 4px;
  padding: 0.5rem 0.6rem;
}

textarea {
  font-family: var(--font-mono);
  font-size: 0.85rem;
  resize: vertical;
}

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

output {
  font-family: var(--font-mono);
  color: var(--accent);
  background: var(--bg);
  border: 1px solid var(--border);
  border-radius: 4px;
  padding: 0.15rem 0.5rem;
  display: inline-block;
  width: fit-content;
}

button {
  background: var(--surface-raised);
  border: 1px solid var(--border);
  border-radius: 5px;
  padding: 0.6rem 1.1rem;
  cursor: pointer;
  margin: 0.3rem 0.3rem 0.3rem 0;
}

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

button[aria-pressed="true"] {
  background: var(--accent);
  color: #04140c;
  border-color: var(--accent);
}

button.danger {
  border-color: var(--danger);
  color: var(--danger);
}

button.danger:hover {
  background: var(--danger);
  color: #1a0606;
}

:focus-visible {
  outline: 3px solid var(--focus-ring);
  outline-offset: 2px;
}

fieldset {
  border: 1px solid var(--border);
  border-radius: 6px;
  margin: 1rem 0;
  padding: 0.75rem 1rem 1rem;
}

legend {
  font-family: var(--font-mono);
  font-size: 0.85rem;
  color: var(--text-muted);
  padding: 0 0.4rem;
}

.hint {
  font-size: 0.88rem;
  color: var(--text-muted);
  border-top: 1px dashed var(--border);
  padding-top: 0.75rem;
}

dialog {
  background: var(--surface-raised);
  color: var(--text);
  border: 1px solid var(--accent);
  border-radius: 8px;
  max-width: 32rem;
  padding: 1.5rem;
}

dialog::backdrop {
  background: rgba(0, 0, 0, 0.6);
}

dl {
  display: grid;
  grid-template-columns: auto 1fr;
  gap: 0.4rem 1rem;
}

dt {
  font-family: var(--font-mono);
  color: var(--accent);
}

dd {
  margin: 0;
}

footer {
  max-width: 760px;
  margin: 0 auto;
  padding: 1rem 1.25rem 3rem;
  color: var(--text-muted);
  font-size: 0.85rem;
}

.visually-hidden {
  position: absolute;
  width: 1px;
  height: 1px;
  overflow: hidden;
  clip: rect(0 0 0 0);
  white-space: nowrap;
}

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