:root {
  --bg: #000;
  --panel: #111;
  --muted: #9aa;
  --err: #f88;
  --accent: #7fd;
}

html,
body {
  height: 100%;
  margin: 0;
  background: var(--bg);
  color: #fff;
  font-family: system-ui, Segoe UI, Roboto, sans-serif;
}

body {
  display: flex;
  flex-direction: column;
  min-height: 100vh;
}

header {
  padding: .6rem;
  text-align: center;
  background: var(--panel);
  border-bottom: 1px solid #222;
}

#controls {
  display: flex;
  gap: .6rem;
  align-items: center;
  justify-content: center;
  padding: .6rem;
  background: #0e0e0e;
  border-bottom: 1px solid #222;
  flex-wrap: wrap;
}

select {
  background: #111;
  color: #fff;
  border: 1px solid #333;
  padding: .4rem .6rem;
  border-radius: 6px;
  font-size: 1rem;
  min-width: 200px;
}

button {
  padding: .35rem .6rem;
  border-radius: 6px;
  border: none;
  background: var(--accent);
  color: #000;
  cursor: pointer;
}

#message {
  color: var(--muted);
  font-size: .9rem;
  text-align: center;
  margin-top: .25rem;
}

#canvas-container {
  flex: 1 1 auto;               /* take remaining height */
  display: flex;
  flex-direction: column;
  align-items: center;
  justify-content: center;      /* or flex-start if you prefer */
  padding: .4rem;
  min-height: 0;                /* important so children can shrink */
}

canvas {
  width: 100%;
  max-width: 1100px;
  border: 1px solid #222;
  background: #000;
  display: block;
}

footer {
  padding: .4rem;
  text-align: center;
  color: #888;
  font-size: .8rem;
  margin-top: auto;   /* NEW: pushes footer to bottom of flex column */
}

/* Spectral slider container */
#spectral-slider-container {
  max-width: 600px;
  margin: 1rem auto;
  text-align: center;
}

#spectralSlider {
  width: 100%;
  appearance: none;
  background: #222;
  height: 6px;
  border-radius: 4px;
  outline: none;
  cursor: pointer;
}

/* Slider thumb */
#spectralSlider::-webkit-slider-thumb {
  appearance: none;
  width: 18px;
  height: 18px;
  border-radius: 50%;
  background: var(--accent);
  border: none;
  cursor: pointer;
}
#spectralSlider::-moz-range-thumb {
  width: 18px;
  height: 18px;
  border-radius: 50%;
  background: var(--accent);
  border: none;
  cursor: pointer;
}

#spectral-labels {
  display: flex;
  justify-content: space-between;
  font-weight: bold;
  margin-top: .4rem;
  padding: 0 .3rem;
  color: #ccc;
}

/*Star options that appear below slider */
#starOptions {
  margin-top: 1rem;
  display: flex;
  flex-wrap: wrap;
  gap: .4rem;
  justify-content: center;
}
#starOptions button {
  background: #111;
  color: #fff;
  padding: .4rem .6rem;
  border: 1px solid #333;
  border-radius: 6px;
  cursor: pointer;
}
#starOptions button:hover {
  background: #333;
}

#canvasRainbow {
  width: 100%;
  height: 120px;        /* increase this to taste */
  margin-top: 4px;
}

/* main spectrum fills the flex space */
#spectrumCanvas {
  flex: 1 1 auto;
  max-height: 550px;
}

/* rainbow gets a fixed height */
#canvasRainbow {
  width: 100%;
  max-width: 1100px;
  height: 120px;
  margin-top: 4px;
}

#spectrumCanvas, #canvasRainbow {
  touch-action: none;  /* disable panning on touch devices */
}

/* 📱 Small screens */
@media (max-width: 520px) {
  #controls {
    padding: .5rem;
    gap: .4rem;
  }
  select {
    min-width: unset;
    width: 100%;
  }
}