:root {
  --bg: #15171c;
  --box-bg: #1f2229;
  --border: #3a3f4b;
  --text: #e6e8ee;
  --muted: #9aa1b2;
}

body {
  margin: 0;
  padding: 24px;
  background: var(--bg);
  color: var(--text);
  font-family: system-ui, sans-serif;


  display: grid;
  
  /* fr is fractional unit - all 1fr is equal size */
  grid-template-columns: 1fr 1fr 1fr; 
  column-gap: 24px;
  align-items: center;
}


/* ---------- Left column ---------- */

.sidebar {
  align-self: start; 
  display: flex;
  flex-direction: column;
  gap: 16px;
  max-width: 340px;
}

.box {
  background: var(--box-bg);
  border: 1px solid var(--border);
  border-radius: 8px;
  padding: 12px 16px;
}

.box h2 {
  margin: 0 0 10px;
  font-size: 0.8rem;
  letter-spacing: 0.08em;
  text-transform: uppercase;
  color: var(--muted);
}

/* Function box */
#function-form label {
  display: block;
  margin-bottom: 6px;
}


#function-input {
  padding: 6px 8px;
  font: 1rem;
  color: var(--text);
  background: var(--bg);
  border: 1px solid var(--border);
  border-radius: 4px;
}

#output-description {
  font-size: 0.85rem;
  color: var(--muted);
  margin-bottom: 6px;
}

#output-value {
  font: 1.1rem;
  min-height: 1.4em;
}

/* Options box */
.button-row {
  display: flex;
  flex-wrap: wrap;
  gap: 8px;
}

button {
  padding: 6px 12px;
  color: var(--text);
  background: var(--bg);
  border: 1px solid var(--border);
  border-radius: 4px;
}



/* ---------- Middle column: canvas + domain labels ---------- */
.plot {
  display: grid;
  grid-template-columns: auto auto auto;
  grid-template-areas:
    ".    top    ."
    "left canvas right"
    ".    bottom .";
  align-items: center;
  justify-items: center;
  gap: 8px;
}

#canvas {
  grid-area: canvas;
  border: 2px solid var(--border);
}

.domain-label {
  font: 0.9rem ui-monospace, monospace;
  color: var(--muted);
}

#domain-top    { grid-area: top; }
#domain-bottom { grid-area: bottom; }
#domain-left   { grid-area: left; }
#domain-right  { grid-area: right; }