:root {
  --bg: #1e1f22;
  --fg: #d7d7d7;
  --panel: #2a2c31;
  --pane-bg: #1e1f22;
  --pane-title-bg: #25272b;
  --border: #33353a;
  --btn-bg: #3a3b40;
  --btn-hover: #44454a;
  --btn-border: #4a4b50;
  --btn-disabled-bg: #2a2b30;
  --btn-disabled-fg: #888;
  --primary-bg: #2e7d32;
  --primary-hover: #388e3c;
  --primary-active: #1b5e20;
  --primary-border: #1b5e20;
  --primary-fg: #fff;
  --danger-bg: #5a2b2b;
  --danger-hover: #6e3535;
  --danger-active: #4a2323;
  --danger-border: #7a3b3b;
  --danger-fg: #ffb4b4;
  --asm-fg: #c8e6c9;
  --bytes-fg: #90caf9;
  --err-bg: #3a1d1d;
  --err-fg: #ffb4b4;
  --err-border: #5a2b2b;
  --modal-backdrop: rgba(0, 0, 0, 0.55);
  --modal-shadow: 0 12px 32px rgba(0, 0, 0, 0.45);
  color-scheme: dark;
}

body.theme-light {
  --bg: #ffffff;
  --fg: #1f1f1f;
  --panel: #f3f3f3;
  --pane-bg: #ffffff;
  --pane-title-bg: #ececec;
  --border: #d0d0d0;
  --btn-bg: #ffffff;
  --btn-hover: #f0f0f0;
  --btn-border: #c6c6c6;
  --btn-disabled-bg: #f0f0f0;
  --btn-disabled-fg: #a0a0a0;
  --primary-bg: #2e7d32;
  --primary-hover: #388e3c;
  --primary-active: #1b5e20;
  --primary-border: #1b5e20;
  --primary-fg: #fff;
  --danger-bg: #ffeef0;
  --danger-hover: #ffdcdf;
  --danger-active: #f9aeb3;
  --danger-border: #f9aeb3;
  --danger-fg: #b31d28;
  --asm-fg: #1f5a23;
  --bytes-fg: #0b5fa5;
  --err-bg: #ffeef0;
  --err-fg: #b31d28;
  --err-border: #f9aeb3;
  --modal-backdrop: rgba(0, 0, 0, 0.35);
  --modal-shadow: 0 10px 40px rgba(0, 0, 0, 0.2);
  color-scheme: light;
}

* { box-sizing: border-box; }

html, body {
  margin: 0;
  height: 100%;
  font-family: ui-sans-serif, -apple-system, system-ui, sans-serif;
  background: var(--bg);
  color: var(--fg);
}

body {
  display: flex;
  flex-direction: column;
}

header {
  display: flex;
  align-items: baseline;
  justify-content: space-between;
  padding: 0.5rem 1rem;
  border-bottom: 1px solid var(--border);
  background: var(--panel);
}

h1 {
  font-size: 1.1rem;
  margin: 0;
  font-weight: 600;
}

.sub {
  font-weight: 400;
  opacity: 0.6;
  font-size: 0.85rem;
  margin-left: 0.5rem;
}

.toolbar {
  display: flex;
  align-items: center;
  gap: 0.75rem;
}

.status {
  font-family: ui-monospace, "SF Mono", Menlo, monospace;
  font-size: 0.8rem;
  opacity: 0.75;
}

button {
  font: inherit;
  font-size: 0.85rem;
  background: var(--btn-bg);
  color: var(--fg);
  border: 1px solid var(--btn-border);
  padding: 0.3rem 0.7rem;
  border-radius: 4px;
  cursor: pointer;
}

button:hover:not(:disabled) { background: var(--btn-hover); }

button.primary {
  background: var(--primary-bg);
  color: var(--primary-fg);
  border-color: var(--primary-border);
}

button.primary:hover:not(:disabled) { background: var(--primary-hover); }
button.primary:active:not(:disabled) { background: var(--primary-active); }

button:disabled,
button.primary:disabled {
  background: var(--btn-disabled-bg);
  color: var(--btn-disabled-fg);
  border-color: var(--btn-disabled-bg);
  cursor: not-allowed;
}

.toolbar select {
  font: inherit;
  font-size: 0.85rem;
  background: var(--pane-bg);
  color: var(--fg);
  border: 1px solid var(--btn-border);
  padding: 0.25rem 0.35rem;
  border-radius: 4px;
}

button.danger {
  background: var(--danger-bg);
  color: var(--danger-fg);
  border-color: var(--danger-border);
}
button.danger:hover:not(:disabled) { background: var(--danger-hover); }
button.danger:active:not(:disabled) { background: var(--danger-active); }

.modal {
  position: fixed;
  inset: 0;
  background: var(--modal-backdrop);
  z-index: 10;
}
.modal[hidden] { display: none; }

.modal-panel {
  position: absolute;
  top: 50%;
  left: 50%;
  transform: translate(-50%, -50%);
  background: var(--panel);
  border: 1px solid var(--btn-border);
  border-radius: 6px;
  padding: 1.2rem 1.5rem;
  min-width: 320px;
  max-width: 480px;
  box-shadow: var(--modal-shadow);
}

.modal-panel p {
  margin: 0 0 1rem 0;
  line-height: 1.4;
}

.modal-actions {
  display: flex;
  justify-content: flex-end;
  gap: 0.5rem;
}

main {
  flex: 1 1 auto;
  display: grid;
  grid-template-columns: 1fr 1fr;
  gap: 1px;
  background: var(--border);
  overflow: hidden;
  min-height: 0;
}

.pane {
  display: flex;
  flex-direction: column;
  background: var(--pane-bg);
  min-height: 0;
  overflow: hidden;
}

.pane-title {
  padding: 0.3rem 0.75rem;
  font-family: ui-monospace, "SF Mono", Menlo, monospace;
  font-size: 0.75rem;
  text-transform: uppercase;
  letter-spacing: 0.05em;
  opacity: 0.55;
  background: var(--pane-title-bg);
  border-bottom: 1px solid var(--border);
  flex: 0 0 auto;
}

.pane-title.secondary { margin-top: auto; }

#source {
  flex: 1 1 auto;
  width: 100%;
  padding: 0.75rem;
  background: var(--pane-bg);
  color: var(--fg);
  border: none;
  outline: none;
  resize: none;
  font-family: ui-monospace, "SF Mono", Menlo, monospace;
  font-size: 13px;
  line-height: 1.5;
  tab-size: 4;
}

#asm, #bytes {
  flex: 1 1 auto;
  margin: 0;
  padding: 0.75rem;
  overflow: auto;
  font-family: ui-monospace, "SF Mono", Menlo, monospace;
  font-size: 12.5px;
  line-height: 1.5;
  white-space: pre;
  color: var(--asm-fg);
}

#bytes {
  color: var(--bytes-fg);
  max-height: 30%;
  border-top: 1px solid var(--border);
  flex: 0 0 auto;
}

.error {
  padding: 0.5rem 0.75rem;
  margin: 0;
  background: var(--err-bg);
  color: var(--err-fg);
  font-family: ui-monospace, "SF Mono", Menlo, monospace;
  font-size: 12.5px;
  white-space: pre-wrap;
  border-top: 1px solid var(--err-border);
  flex: 0 0 auto;
}

footer {
  padding: 0.4rem 1rem;
  border-top: 1px solid var(--border);
  background: var(--panel);
  font-size: 0.75rem;
  opacity: 0.55;
  text-align: right;
}

footer a {
  color: inherit;
  text-decoration: none;
  border-bottom: 1px dotted currentColor;
}

footer a:hover { opacity: 0.9; }

@media (max-width: 720px) {
  main {
    grid-template-columns: 1fr;
    grid-template-rows: 1fr 1fr;
  }
}