style.css

/* Definition of css variables at the root level so their scope is the entire document */
:root {
    --base: #32f2af;
    --spacing: 30px;
    --blur: 0px;
    --grayscale: 50%;
    --contrast: 100%;
}

/* set image property values with above defined variables */
img {
    padding: var(--spacing);
    background: var(--base);
    filter: blur(var(--blur)) grayscale(var(--grayscale)) contrast(var(--contrast));
}

.hl {
    color: var(--base);
}

body {
    text-align: center;
    background: #193549;
    color: white;
    font-family: 'helvetica neue', sans-serif;
    font-weight: 100;
    font-size: 50px;
  }

  .controls {
    margin-bottom: 50px;
  }

  input {
    width: 100px;
  }