:root {
  --bg: #f0f4f8;
  --panel-bg: #ffffff;
  --accent: #4caf50;
  --pivot: #e53935;
  --axis: #263238;
  --shadow: 0 2px 4px rgba(0, 0, 0, 0.1);
}

* {
  box-sizing: border-box;
}

body {
  margin: 0;
  font-family: system-ui, "Segoe UI", Roboto, sans-serif;
  background: var(--bg);
  color: var(--axis);
  display: flex;
  flex-direction: column;
  align-items: center;
  padding: 1.5rem;
  gap: 1.5rem;
}

h1 {
  font-size: 1.8rem;
  font-weight: 600;
}

/* --- layout --- */
.sim-container {
  display: flex;
  gap: 2rem;
  flex-wrap: wrap;
  justify-content: center;
  width: 100%;
  max-width: 1100px;
}

/* --- controls panel --- */
.panel {
  background: var(--panel-bg);
  padding: 1.25rem 1.5rem;
  border-radius: 0.75rem;
  box-shadow: var(--shadow);
  width: 320px;
  display: flex;
  flex-direction: column;
  gap: 1.25rem;
}

.panel h2 {
  font-size: 1.1rem;
  font-weight: 600;
  margin: 0 0 0.5rem 0;
}

.ctrl-row {
  display: flex;
  flex-direction: column;
  gap: 0.35rem;
}

.ctrl-row label {
  font-size: 0.9rem;
}

.slider-wrap {
  display: flex;
  align-items: center;
  gap: 0.5rem;
}

.slider-wrap input[type="number"] {
  width: 70px;
  padding: 0.25rem 0.35rem;
  font-size: 0.85rem;
}

input[type="range"] {
  flex: 1;
}

.panel button {
  background: var(--accent);
  color: #fff;
  border: none;
  padding: 0.5rem 0.75rem;
  font-size: 0.95rem;
  border-radius: 0.5rem;
  cursor: pointer;
  transition: transform 0.15s;
}
.panel button:active {
  transform: scale(0.97);
}

.panel button.secondary {
  background: #607d8b;
}

/* --- canvas --- */
#simCanvas {
  background: #fff;
  border: 1px solid #cfd8dc;
  border-radius: 0.5rem;
  box-shadow: var(--shadow);
  display: block; /* Prevents inline spacing issues */
  width: 600px; /* Enforce static width */
  height: 600px; /* Enforce static height */
}

/* --- readouts --- */
.readout {
  display: flex;
  flex-direction: column;
  gap: 0.25rem;
  font-size: 0.9rem;
}
.readout span.val {
  font-weight: 600;
  margin-left: 0.25rem;
}

@media (max-width: 700px) {
  .panel {
    width: 100%;
  }
}