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

:root {
  --bg:       #0f0e0c;
  --surface:  #181612;
  --surface2: #211f19;
  --border:   #3a3730;
  --text:     #f0ece5;
  --muted:    #a09890;
  --accent:   #d4863a;
  --add-fg:   #55c26a;
  --del-fg:   #d95858;
  --r:        2px;
  --mono: ui-monospace, 'Cascadia Code', 'JetBrains Mono', 'Fira Mono', monospace;
  --sans: -apple-system, BlinkMacSystemFont, 'Inter', system-ui, sans-serif;
}

body {
  background: var(--bg);
  color: var(--text);
  font-family: var(--sans);
  font-size: 14px;
  min-height: 100vh;
  display: flex;
  flex-direction: column;
  line-height: 1.5;
  -webkit-font-smoothing: antialiased;
}

.container {
  width: 100%;
  max-width: 1240px;
  margin-inline: auto;
  padding-inline: 1.75rem;
}

/* ── Header ── */

.site-header {
  padding-block: 2.25rem 1.75rem;
  border-bottom: 1px solid var(--border);
}

.site-header h1 {
  font-size: 1.5rem;
  font-weight: 800;
  letter-spacing: -0.03em;
  font-family: var(--sans);
  line-height: 1;
}

.word-diff {
  color: var(--accent);
}

/* ── Main ── */

main {
  flex: 1;
  padding-block: 1.5rem 3rem;
}

.editors-grid {
  display: grid;
  grid-template-columns: 1fr 1fr;
  border: 1px solid var(--border);
  border-radius: var(--r);
  overflow: hidden;
}

.editor-pane { display: flex; flex-direction: column; }
.editor-pane + .editor-pane { border-left: 1px solid var(--border); }

@media (max-width: 640px) {
  .editors-grid        { grid-template-columns: 1fr; }
  .editor-pane + .editor-pane { border-left: none; border-top: 1px solid var(--border); }
}

.pane-header {
  padding: 0.45rem 0.875rem;
  background: var(--surface2);
  border-bottom: 1px solid var(--border);
  display: flex;
  align-items: center;
  gap: 0.5rem;
}

.pane-label {
  font-family: var(--mono);
  font-size: 0.68rem;
  font-weight: 500;
  color: var(--muted);
  letter-spacing: 0.06em;
  text-transform: uppercase;
}

textarea {
  width: 100%;
  height: 200px;
  padding: 0.875rem 1rem;
  background: var(--surface);
  color: var(--text);
  border: none;
  border-bottom: 2px solid transparent;
  resize: none;
  font-family: var(--mono);
  font-size: 0.8rem;
  line-height: 1.7;
  outline: none;
  tab-size: 2;
  transition: border-color 0.15s, background 0.15s;
}

textarea:focus {
  background: var(--bg);
  border-bottom-color: var(--accent);
}

textarea::placeholder {
  color: var(--muted);
  opacity: 0.45;
}

/* ── Toolbar ── */

.toolbar {
  display: flex;
  align-items: center;
  gap: 0.5rem;
  margin-block: 0.875rem;
}

.btn {
  cursor: pointer;
  border-radius: var(--r);
  font-family: var(--mono);
  font-size: 0.775rem;
  font-weight: 500;
  padding: 0.4rem 0.9rem;
  border: 1px solid transparent;
  letter-spacing: 0.02em;
  transition: all 0.1s;
}

.btn-primary {
  background: var(--accent);
  color: #0f0e0c;
  border-color: var(--accent);
}
.btn-primary:hover  { background: #e09545; border-color: #e09545; }
.btn-primary:active { opacity: 0.75; }

.btn-ghost {
  background: transparent;
  color: var(--muted);
  border-color: var(--border);
}
.btn-ghost:hover {
  background: var(--surface2);
  color: var(--text);
  border-color: var(--muted);
}