*,
*::before,
*::after {
  box-sizing: border-box;
  margin: 0;
  padding: 0;
}

/* Light theme (default) */
:root {
  --bg: #fafafa;
  --surface: #fff;
  --border: #ddd;
  --text: #1a1a1a;
  --text-secondary: #555;
  --accent: #0066cc;
  --accent-hover: #0052a3;
  --error-bg: #fef2f2;
  --error-text: #b91c1c;
  --warning-bg: #fffbeb;
  --warning-text: #92400e;
  --success-bg: #f0fdf4;
  --success-text: #166534;
  --radius: 6px;
}

/* Dark theme values */
[data-theme="dark"] {
  --bg: #111;
  --surface: #1a1a1a;
  --border: #333;
  --text: #e5e5e5;
  --text-secondary: #999;
  --accent: #4da3ff;
  --accent-hover: #7dbdff;
  --error-bg: #2d1515;
  --error-text: #f87171;
  --warning-bg: #2d2415;
  --warning-text: #fbbf24;
  --success-bg: #152d1a;
  --success-text: #4ade80;
}

/* System preference when no explicit choice */
@media (prefers-color-scheme: dark) {
  [data-theme="system"] {
    --bg: #111;
    --surface: #1a1a1a;
    --border: #333;
    --text: #e5e5e5;
    --text-secondary: #999;
    --accent: #4da3ff;
    --accent-hover: #7dbdff;
    --error-bg: #2d1515;
    --error-text: #f87171;
    --warning-bg: #2d2415;
    --warning-text: #fbbf24;
    --success-bg: #152d1a;
    --success-text: #4ade80;
  }
}

body {
  font-family: -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, Helvetica, Arial, sans-serif;
  background: var(--bg);
  color: var(--text);
  line-height: 1.5;
  min-height: 100vh;
}

main {
  max-width: 700px;
  margin: 0 auto;
  padding: 3rem 1rem;
}

/* Top bar */
.top-bar {
  display: flex;
  align-items: center;
  justify-content: space-between;
}

h1 {
  font-size: 1.8rem;
  font-weight: 700;
  margin-bottom: 0.25rem;
}

#theme-toggle {
  background: none;
  border: 1px solid var(--border);
  border-radius: var(--radius);
  color: var(--text-secondary);
  cursor: pointer;
  font-size: 1.1rem;
  width: 2.2rem;
  height: 2.2rem;
  display: flex;
  align-items: center;
  justify-content: center;
  padding: 0;
  line-height: 1;
}

#theme-toggle:hover {
  color: var(--text);
  border-color: var(--text-secondary);
}

.subtitle {
  color: var(--text-secondary);
  margin-bottom: 2rem;
  font-size: 0.95rem;
}

/* Explainer */
.explainer {
  margin-bottom: 1.5rem;
  font-size: 0.9rem;
  color: var(--text-secondary);
  line-height: 1.6;
}

.explainer p + p {
  margin-top: 0.5rem;
}

/* Tabs */
.tabs {
  display: flex;
  gap: 0;
  margin-bottom: 1.5rem;
  border-bottom: 2px solid var(--border);
}

.tab {
  background: none;
  border: none;
  padding: 0.6rem 1rem;
  font-size: 0.9rem;
  font-weight: 600;
  color: var(--text-secondary);
  cursor: pointer;
  border-bottom: 2px solid transparent;
  margin-bottom: -2px;
  transition: color 0.15s, border-color 0.15s;
}

.tab:hover {
  color: var(--text);
}

.tab.active {
  color: var(--accent);
  border-bottom-color: var(--accent);
}

/* Panels */
.panel {
  margin-bottom: 1rem;
}

/* Two-pane layout */
.two-pane {
  display: flex;
  gap: 0.75rem;
  align-items: stretch;
}

.pane {
  flex: 1;
}

.pane label {
  display: block;
  font-size: 0.85rem;
  font-weight: 600;
  color: var(--text-secondary);
  margin-bottom: 0.35rem;
}

.pane-header {
  display: flex;
  align-items: center;
  justify-content: space-between;
  margin-bottom: 0.35rem;
}

.pane-header label {
  margin-bottom: 0;
}

.pane-arrow {
  display: flex;
  align-items: center;
  color: var(--text-secondary);
  font-size: 1.2rem;
  padding-top: 1.2rem;
}

textarea {
  width: 100%;
  padding: 0.6rem 0.8rem;
  font-size: 0.9rem;
  font-family: monospace;
  border: 1px solid var(--border);
  border-radius: var(--radius);
  background: var(--surface);
  color: var(--text);
  outline: none;
  resize: vertical;
}

textarea:focus {
  border-color: var(--accent);
  box-shadow: 0 0 0 2px rgba(0, 102, 204, 0.2);
}

textarea[readonly] {
  background: var(--bg);
}

/* Codec options */
.codec-options {
  display: flex;
  gap: 1.5rem;
  margin-bottom: 1rem;
}

.radio-label {
  display: flex;
  align-items: center;
  gap: 0.4rem;
  font-size: 0.9rem;
  cursor: pointer;
}

.hint {
  color: var(--text-secondary);
  font-size: 0.8rem;
}

/* Input group */
.input-group {
  display: flex;
  gap: 0.5rem;
}

.input-group input {
  flex: 1;
  padding: 0.6rem 0.8rem;
  font-size: 1rem;
  border: 1px solid var(--border);
  border-radius: var(--radius);
  background: var(--surface);
  color: var(--text);
  outline: none;
}

.input-group input:focus {
  border-color: var(--accent);
  box-shadow: 0 0 0 2px rgba(0, 102, 204, 0.2);
}

.input-group button,
.btn-primary {
  padding: 0.6rem 1.2rem;
  font-size: 1rem;
  font-weight: 600;
  background: var(--accent);
  color: #fff;
  border: none;
  border-radius: var(--radius);
  cursor: pointer;
  white-space: nowrap;
}

.input-group button:hover,
.btn-primary:hover {
  background: var(--accent-hover);
}

/* Copy button */
.copy-btn {
  background: none;
  border: 1px solid var(--border);
  border-radius: var(--radius);
  color: var(--text-secondary);
  cursor: pointer;
  font-size: 0.75rem;
  padding: 0.2rem 0.5rem;
}

.copy-btn:hover {
  color: var(--text);
  border-color: var(--text-secondary);
}

/* Secondary button */
.btn-secondary {
  background: none;
  border: 1px solid var(--border);
  border-radius: var(--radius);
  color: var(--text-secondary);
  cursor: pointer;
  font-size: 0.85rem;
  padding: 0.4rem 0.8rem;
  margin-top: 0.5rem;
}

.btn-secondary:hover {
  color: var(--text);
  border-color: var(--text-secondary);
}

/* Warning / info messages */
.warning {
  margin-top: 0.75rem;
  padding: 0.6rem 0.8rem;
  background: var(--warning-bg);
  color: var(--warning-text);
  border-radius: var(--radius);
  font-size: 0.85rem;
}

.direction-hint {
  margin-top: 0.5rem;
  font-size: 0.8rem;
  color: var(--text-secondary);
}

/* Cards */
.card {
  background: var(--surface);
  border: 1px solid var(--border);
  border-radius: var(--radius);
  padding: 1.2rem;
  margin-top: 1rem;
}

.card h2 {
  font-size: 1rem;
  font-weight: 600;
  margin-bottom: 0.75rem;
  color: var(--text-secondary);
  text-transform: uppercase;
  letter-spacing: 0.03em;
}

/* Parse results */
#parse-list {
  display: grid;
  grid-template-columns: auto 1fr;
  gap: 0.4rem 1rem;
}

#parse-list dt {
  font-weight: 600;
  white-space: nowrap;
}

#parse-list dd {
  word-break: break-all;
  font-family: monospace;
  font-size: 0.9rem;
}

/* Params table */
#params-table {
  width: 100%;
  border-collapse: collapse;
  font-size: 0.9rem;
}

#params-table th {
  text-align: left;
  font-weight: 600;
  padding: 0.4rem 0.6rem;
  border-bottom: 2px solid var(--border);
  color: var(--text-secondary);
}

#params-table td {
  padding: 0.4rem 0.6rem;
  border-bottom: 1px solid var(--border);
  font-family: monospace;
  word-break: break-all;
}

#params-table tr:last-child td {
  border-bottom: none;
}

/* Build panel */
.build-base {
  margin-bottom: 1rem;
}

.build-base label {
  display: block;
  font-size: 0.85rem;
  font-weight: 600;
  color: var(--text-secondary);
  margin-bottom: 0.35rem;
}

.build-base input {
  width: 100%;
  padding: 0.6rem 0.8rem;
  font-size: 0.9rem;
  border: 1px solid var(--border);
  border-radius: var(--radius);
  background: var(--surface);
  color: var(--text);
  outline: none;
}

.build-base input:focus {
  border-color: var(--accent);
  box-shadow: 0 0 0 2px rgba(0, 102, 204, 0.2);
}

.build-pairs {
  margin-bottom: 1rem;
}

.build-pair-header {
  display: grid;
  grid-template-columns: 1fr 1fr 2rem;
  gap: 0.5rem;
  font-size: 0.8rem;
  font-weight: 600;
  color: var(--text-secondary);
  margin-bottom: 0.35rem;
}

.build-row {
  display: grid;
  grid-template-columns: 1fr 1fr 2rem;
  gap: 0.5rem;
  margin-bottom: 0.4rem;
}

.build-row input {
  width: 100%;
  padding: 0.4rem 0.6rem;
  font-size: 0.85rem;
  font-family: monospace;
  border: 1px solid var(--border);
  border-radius: var(--radius);
  background: var(--surface);
  color: var(--text);
  outline: none;
}

.build-row input:focus {
  border-color: var(--accent);
  box-shadow: 0 0 0 2px rgba(0, 102, 204, 0.2);
}

.build-remove {
  background: none;
  border: none;
  color: var(--text-secondary);
  cursor: pointer;
  font-size: 1.1rem;
  padding: 0;
  display: flex;
  align-items: center;
  justify-content: center;
}

.build-remove:hover {
  color: var(--error-text);
}

/* Footer */
footer {
  max-width: 700px;
  margin: 2rem auto 0;
  padding: 1rem 1rem;
  text-align: center;
  color: var(--text-secondary);
  font-size: 0.8rem;
  border-top: 1px solid var(--border);
}

footer a {
  color: var(--accent);
  text-decoration: none;
}

footer a:hover {
  text-decoration: underline;
}

/* Utility */
.hidden {
  display: none !important;
}

@media (max-width: 500px) {
  .two-pane {
    flex-direction: column;
  }

  .pane-arrow {
    transform: rotate(90deg);
    justify-content: center;
    padding-top: 0;
  }

  .input-group {
    flex-direction: column;
  }

  #parse-list {
    grid-template-columns: 1fr;
  }

  #parse-list dt {
    margin-top: 0.5rem;
  }

  .build-pair-header,
  .build-row {
    grid-template-columns: 1fr 1fr 2rem;
  }
}