:root {
    /* Active theme colours, overwritten by JS when the theme changes */
    --body-color: #00e64d;
    --head-color: #ccffd5;
    --ui: #7dffa8;
    --ui-dim: #2f7a4d;
  }

  * { box-sizing: border-box; }

  html, body {
    margin: 0;
    height: 100%;
    background: #000;
    overflow: hidden;
    font-family: ui-monospace, "Cascadia Code", "SF Mono", Consolas, "Liberation Mono", monospace;
  }

  /* The rain itself */
  #matrix {
    position: fixed;
    inset: 0;
    display: block;
    width: 100%;
    height: 100%;
  }

  /* Subtle CRT vignette to give the screen some depth */
  .vignette {
    position: fixed;
    inset: 0;
    pointer-events: none;
    background: radial-gradient(ellipse at center,
                rgba(0,0,0,0) 55%,
                rgba(0,0,0,0.55) 100%);
    z-index: 2;
  }

  /* Faint scanlines, CRT flavour */
  .scanlines {
    position: fixed;
    inset: 0;
    pointer-events: none;
    background: repeating-linear-gradient(
      to bottom,
      rgba(0,0,0,0) 0px,
      rgba(0,0,0,0) 2px,
      rgba(0,0,0,0.18) 3px,
      rgba(0,0,0,0) 4px
    );
    mix-blend-mode: multiply;
    opacity: 0.6;
    z-index: 3;
  }

  /* ---- Controls ---- */
  .toggle {
    position: fixed;
    right: 16px;
    bottom: 16px;
    z-index: 10;
    display: inline-flex;
    align-items: center;
    gap: 8px;
    padding: 9px 14px;
    background: rgba(0, 12, 5, 0.72);
    color: var(--ui);
    border: 1px solid var(--ui-dim);
    border-radius: 2px;
    font: inherit;
    font-size: 13px;
    letter-spacing: 0.02em;
    cursor: pointer;
    backdrop-filter: blur(3px);
    transition: border-color .18s ease, color .18s ease, opacity .4s ease;
  }
  .toggle::before {
    content: "";
    width: 8px; height: 8px;
    border-radius: 50%;
    background: var(--body-color);
    box-shadow: 0 0 8px var(--body-color);
  }
  .toggle:hover { border-color: var(--ui); }

  .panel {
    position: fixed;
    right: 16px;
    bottom: 62px;
    z-index: 10;
    width: 258px;
    max-width: calc(100vw - 32px);
    padding: 18px 18px 20px;
    background: rgba(0, 12, 5, 0.82);
    border: 1px solid var(--ui-dim);
    border-radius: 3px;
    color: var(--ui);
    backdrop-filter: blur(5px);
    transform-origin: bottom right;
    transition: opacity .2s ease, transform .2s ease;
  }
  .panel[hidden] {
    display: block;               /* keep it in flow so transition works */
    opacity: 0;
    transform: translateY(8px) scale(.98);
    pointer-events: none;
  }

  .panel h1 {
    margin: 0 0 14px;
    font-size: 13px;
    font-weight: 600;
    letter-spacing: 0.04em;
    color: var(--ui);
  }
  .panel h1 span { color: var(--ui-dim); font-weight: 400; }

  .row { margin-bottom: 14px; }
  .row:last-of-type { margin-bottom: 0; }
  .row label {
    display: block;
    font-size: 12px;
    color: var(--ui);
    margin-bottom: 6px;
    display: flex;
    justify-content: space-between;
  }
  .row label b { color: var(--ui-dim); font-weight: 400; }

  input[type="range"] {
    -webkit-appearance: none;
    appearance: none;
    width: 100%;
    height: 3px;
    background: var(--ui-dim);
    border-radius: 3px;
    outline-offset: 3px;
  }
  input[type="range"]::-webkit-slider-thumb {
    -webkit-appearance: none;
    width: 14px; height: 14px;
    border-radius: 50%;
    background: var(--body-color);
    box-shadow: 0 0 8px var(--body-color);
    cursor: pointer;
  }
  input[type="range"]::-moz-range-thumb {
    width: 14px; height: 14px; border: none;
    border-radius: 50%;
    background: var(--body-color);
    box-shadow: 0 0 8px var(--body-color);
    cursor: pointer;
  }

  .themes { display: flex; gap: 8px; }
  .themes button {
    flex: 1;
    height: 22px;
    border: 1px solid var(--ui-dim);
    border-radius: 2px;
    background: transparent;
    cursor: pointer;
    padding: 0;
  }
  .themes button i { display: block; height: 100%; border-radius: 1px; }
  .themes button[aria-pressed="true"] { border-color: var(--ui); }

  .switch {
    display: flex;
    align-items: center;
    justify-content: space-between;
    font-size: 12px;
    cursor: pointer;
    user-select: none;
  }
  .switch input { accent-color: var(--body-color); width: 15px; height: 15px; cursor: pointer; }

  .pause {
    width: 100%;
    margin-top: 4px;
    padding: 8px;
    background: transparent;
    color: var(--ui);
    border: 1px solid var(--ui-dim);
    border-radius: 2px;
    font: inherit;
    font-size: 12px;
    cursor: pointer;
    transition: border-color .18s ease;
  }
  .pause:hover { border-color: var(--ui); }

  .hint {
    position: fixed;
    left: 16px;
    bottom: 16px;
    z-index: 5;
    color: var(--ui-dim);
    font-size: 12px;
    letter-spacing: 0.02em;
    pointer-events: none;
    transition: opacity .6s ease;
  }

  :focus-visible { outline: 2px solid var(--ui); }

  @media (max-width: 480px) {
    .hint { display: none; }
  }