styles.css

:root {
  --border-color: rgba(255, 255, 255, .3);
  --border-color--alt: rgba(255, 255, 255, .2);
  --border-color--active: rgba(255, 255, 255, .8);
  --ui-animation-time: .2s;
  --panel-width: 290px;
}

* {
  box-sizing: border-box;
  margin: 0;
  padding: 0;
  border: 0;
}

body {
  background: radial-gradient(circle, rgb(10,10,10) 20%, rgb(20,20,20) 100%);
  font-family: Verdana, Geneva, Tahoma, sans-serif;
  overflow: hidden;
}

main {
  width: 100vw;
  height: 100vh;
  display: flex;
  justify-content: center;
  align-items: center;
}

canvas {
  display: block;
}

.is-hidden {
  display: none !important;
}

/****************************
  Canvas keyboard controls
*****************************/
#canvas-wrapper {
  position: relative;
  z-index: 0;
}

  #canvas-wrapper canvas:focus {
    outline-offset: 4px;
  }

/****************************
  UI
*****************************/
/** Panels are the highest-level wrapper. */
.panel {
  position: absolute;
  top: 0;
  width: var(--panel-width);
  height: 100%;
  z-index: 100;
  overflow-y: auto;
  padding-top: 10px;

  color: white;
  background-color: rgba(0,0,0,.95);
  box-shadow: 0 0 10px 3px rgba(0,0,0,.4);

  transition: left var(--ui-animation-time) linear,
              right var(--ui-animation-time) linear;
}

  .panel.is-docked-left  { left: 0;  border-right: 1px solid var(--border-color); }
  .panel.is-docked-right { right: 0; border-left: 1px solid var(--border-color);  }

  .panel.is-docked-left.is-offscreen { left: calc(var(--panel-width) * -1); }
  .panel.panel.is-docked-right.is-offscreen { right: calc(var(--panel-width) * -1); }


  /** Groups are sets of components with a heading at the top. */
  .panel .group {
    padding-bottom: 25px;
  }

    .panel .group.is-collapsed {
      padding-bottom: 0px;
    }

    .panel .group .heading {}

      .panel .group .heading button {
        display: block;
        width: 100%;
        margin-bottom: 10px;
        padding: 8px 15px 9px 15px;

        text-align: left;
        font-size: 14px;
        font-weight: 700;
        color: rgba(255,255,255,1);

        background-color: black;
        background: linear-gradient(180deg, rgba(255,255,255,.12) 0%, rgba(0,0,0,0) 80%);

        border: 0;
        border-top: 1px solid rgba(255,255,255,.22);
        border-bottom: 1px solid rgba(255,255,255,.15);

        cursor: pointer;
      }

        .panel .group .heading button[aria-expanded="false"] {
          margin-bottom: 2px;
        }

        .panel .group .heading button:hover,
        .panel .group .heading button:focus {
          border-top-color: rgba(255, 255, 255, .65);
          border-bottom-color: rgba(255, 255, 255, .6);
          background: linear-gradient(180deg, rgba(255,255,255,.16) 0%, rgba(0,0,0,0) 80%);
        }

          .panel .group .heading button:focus {
            outline-offset: -2px;
          }

        /** Caret icon */
        .panel .group .heading button span {
          float: right;
          opacity: .6;
        }

        .panel .group .heading button[aria-expanded="true"] span {
          transform: rotate(180deg);
        }

  /** <hr>s are used as seperators between Components */
  .panel hr {
    border-bottom: 1px solid var(--border-color--alt);
    margin: 10px 15px;
  }

  /** Rows are <div>s used for laying out components horizontally */
  .panel .row {
    display: flex;
    justify-content: space-between;
    align-items: flex-start;

    margin-top: 15px;
    padding: 3px 15px;
  }

    .panel .row .component {
      flex: 0 0 calc(50% - 5px);
      padding: 0;
    }

  /** Components are individual controls (sliders, dropdowns, etc). */
  .panel .component {
    font-size: 12px;
    color: rgba(255,255,255,.7);
    padding: 3px 15px;
    width: 100%;

    display: flex;
    align-items: flex-start;
  }

    .panel .component.is-indented:before {
      content: '';
      display: block;
      flex: 0 0 35%;
    }

    /** <label> tag */
    .panel .component label {
      flex: 0 0 35%;
    }

    /** <select> dropdowns */
    .panel .dropdown label {
      padding-top: 4px;
    }

      .panel .dropdown select {
        flex: 1 1 auto;
        background-color: rgb(255,255,255,.1);
        color: rgba(255,255,255,.7);
        padding: 5px;
        max-width: calc(100% - 84px);
        font-size: 12px;
        border: 1px solid var(--border-color);
      }

        .panel .dropdown select optgroup {
          background-color: rgb(50,50,50);
        }

        .panel .dropdown select option {
          background-color: rgba(0,0,0,.8);
          color: rgba(255,255,255,.7);
        }

        .panel .dropdown select:hover,
        .panel .dropdown select:focus {
          border: 1px solid var(--border-color--active);
          color: rgba(255,255,255,1);
        }

        .panel .dropdown select:focus {
          outline-offset: 3px;
        }

    /** Sliders (<input type="range" ...>) */
    .panel .slider input[type="range"] {
      flex: 1 1 auto;
      width: 100%;
      margin-top: 5px;
      margin-right: 10px;
      position: relative;
      background-color: transparent;
      -webkit-appearance: none;
    }

      .panel .slider input[type="range"][disabled] {
        opacity: .4;
        cursor: not-allowed;
      }

      .panel .slider input[type="range"]:before {
        position: absolute;
        top: 4px;

        content: '';
        display: block;
        width: 100%;
        height: 1px;
        background-color: var(--border-color);
      }

        .panel .slider input[type="range"]:not([disabled]):hover:before,
        .panel .slider input[type="range"]:not([disabled]):focus:before {
          background-color: var(--border-color--active);
        }

      .panel .slider input[type=range]::-webkit-slider-runnable-track {
        background: transparent;
        border: 0;
        width: 100%;
      }

      .panel .slider input[type=range]::-webkit-slider-thumb {
        width: 10px;
        height: 10px;
        background: #ffffff;
        -webkit-appearance: none;
      }

      .panel .slider input[type=range]::-moz-range-track {
        background: transparent;
        border: 0;
        width: 100%;
      }

      .panel .slider input[type=range]::-moz-range-thumb {
        width: 10px;
        height: 10px;
        background: #ffffff;
      }

      .panel .slider input[type=range]::-ms-track {
        background: transparent;
        border: 0;
        width: 100%;
      }

      .panel .slider input[type=range]::-ms-fill-lower {
        background: transparent;
        border: 0;
      }

      .panel .slider input[type=range]::-ms-fill-upper {
        background: transparent;
        border: 0;
      }

      .panel .slider input[type=range]::-ms-thumb {
        width: 10px;
        height: 10px;
        background: #ffffff;
        margin-top: 0px;
        /*Needed to keep the Edge thumb centred*/
      }

      .panel .slider input[type=range]:focus {
        outline-offset: 3px;
      }

    /** Text field with value of component. */
    .panel .slider .value {
      flex: 1 0 15%;
      width: 100%;
      padding: 2px;
      background-color: rgba(255,255,255,.1);
      border: 1px solid var(--border-color);
      color: rgba(255,255,255,.7);
      font-family: 'Courier New', Courier, monospace;
    }

      .panel .slider .value[disabled] {
        opacity: .5;
        cursor: not-allowed;
      }

      .panel .slider .value:not([disabled]):hover,
      .panel .slider .value:not([disabled]):focus {
        border: 1px solid var(--border-color--active);
        color: rgba(255,255,255,1);
      }

      .panel .slider .value:focus {
        outline-offset: 3px;
      }

    /** Buttons */
    .panel .button button {
      padding: 8px 12px;
      border-radius: 3px;
      background-color: rgb(255,255,255,.1);
      border: 1px solid var(--border-color);
      color: rgba(255,255,255,.7);
      font-size: 12px;
      cursor: pointer;
    }

      .panel .button button:hover,
      .panel .button button:focus {
        border: 1px solid var(--border-color--active);
        color: rgba(255,255,255,1);
      }

      .panel .button button:focus {
        outline-offset: 3px;
      }

    /** Checkboxes */
    .panel .checkbox input + .custom-checkbox {
      position: relative;
      content: '';
      width: 14px;
      height: 14px;

      background-color: black;
      border: 1px solid var(--border-color);
    }

      .panel .checkbox input:checked + .custom-checkbox {
        background-color: white;
      }

      .panel .checkbox input:checked + .custom-checkbox:after {
        position: absolute;
        left: 1px;
        top: 2px;

        content: '';
        width: 8px;
        height: 4px;
        margin-right: 8px;

        border-left: 2px solid black;
        border-bottom: 2px solid black;

        transform: rotate(-45deg);
      }

      .panel .checkbox:hover .custom-checkbox,
      .panel .checkbox input:focus + .custom-checkbox {
        border: 1px solid var(--border-color--active);
      }

      .panel .checkbox input:focus + .custom-checkbox {
        outline: 5px auto Highlight;
        outline: 5px auto -webkit-focus-ring-color;
        outline-offset: 3px;
      }

    /** Color picker */
    .panel .color-picker {
      align-items: center;
    }

      .panel .color-picker input:focus {
        outline-offset: 3px;
      }

    /** Text input */
    .panel .text-input {
      align-items: center;
    }

      .panel .text-input input {
        width: 100%;
        padding: 5px 10px;
        background-color: rgba(255,255,255,.1);
        border: 1px solid var(--border-color);
        color: rgba(255,255,255,.7);
        font-family: 'Courier New', Courier, monospace;
      }

        .panel .text-input input:hover,
        .panel .text-input input:focus {
          border: 1px solid var(--border-color--active);
          color: rgba(255,255,255,1);
        }

        .panel .text-input input:focus {
          outline-offset: 3px;
        }

    /** Textarea */
    .panel .textarea {}

      .panel .textarea textarea {
        width: 100%;
        padding: 5px 10px;
        background-color: rgba(255,255,255,.1);
        border: 1px solid var(--border-color);
        color: rgba(255,255,255,.7);
        font-family: 'Courier New', Courier, monospace;
      }

        .panel .textarea textarea:hover,
        .panel .textarea textarea:focus {
          border: 1px solid var(--border-color--active);
          color: rgba(255,255,255,1);
        }

        .panel .textarea textarea:focus {
          outline-offset: 3px;
        }

    /** Set of checkboxes for birth/survival counts */
    .panel .count-fieldset {
      display: flex;
      flex-direction: row;
      flex-wrap: wrap;
      justify-content: space-between;
      margin: 0 15px;
    }

      .panel .count-fieldset label {
        flex: 0 0 calc(100% / 9);
        padding: 6px 0 10px 0;
        text-align: center;

        border-radius: 2px;
        font-size: 12px;
        color: rgba(255,255,255,.8);
      }

        .panel .count-fieldset label:hover,
        .panel .count-fieldset label:focus-within {
          background-color: rgba(255,255,255,.05);
          color: white;
        }

        .panel .count-fieldset label .custom-checkbox {
          margin-bottom: 2px;
          display: inline-block;
        }

    /** Scrollable sections containing a variable of components. */
    .panel .is-scrollable {
      max-height: 150px;
      overflow-y: scroll;

      scrollbar-width: 5px;
      scrollbar-color: transparent rgba(255,255,255,.1);
    }

      .panel .is-scrollable::-webkit-scrollbar {
        width: 5px;
        margin-left: 10px;
      }

      .panel .is-scrollable::-webkit-scrollbar-track {
        background-color: rgb(255,255,255,.0);
        border-radius: 100px;
      }

      .panel .is-scrollable::-webkit-scrollbar-thumb {
        background-color: rgb(255,255,255,.7);
        border-radius: 10px;
      }

  /** Special styling for the Pause/Play and Restart buttons in the Controls section */
  .panel .component.button.is-control-button button {
    width: 100%;
    background: rgba(255, 255, 255, .05);
    border: 0;
    text-align: center;
    padding: 15px;
  }

    .panel .component.button.is-control-button button .fas {
      display: block;
      font-size: 36px;
      margin-bottom: 10px;
    }

      .panel .component.button.is-control-button button[aria-pressed="false"] .fas.fa-play,
      .panel .component.button.is-control-button button[aria-pressed="false"] .text.play { display: none; }

      .panel .component.button.is-control-button button[aria-pressed="true"] .fas.fa-pause,
      .panel .component.button.is-control-button button[aria-pressed="true"] .text.pause { display: none; }

    .panel .component.button.is-control-button button:hover .text,
    .panel .component.button.is-control-button button:focus .text {
      text-decoration: underline;
    }

  /** Text display components just show a string and a value with no interactive elements. */
  .panel .text-display {
    font-weight: bold;
    opacity: .9;
  }

    .panel .text-display .value {
      margin-left: 5px;
      font-weight: normal;
    }

/** Step controls row below Pause and Restart buttons in the Controls group */
.step-controls-row {
  justify-content: space-between;
}

  .step-controls-row .button button {
    border: 0;
    padding: 6px;
    background: none;
  }

    /** +1/10/100 buttons on the left */
    .step-controls-row .step-numbers {
      flex: 0 1 55%;
      display: flex;
      justify-content: space-around;
      align-items: center;
      border: 1px solid var(--border-color);
      padding: 0 10px;
      height: 30px;
    }

      .step-controls-row .step-numbers .button {
        flex: 1 1 auto;
      }

        .step-controls-row .step-numbers .button button {
          vertical-align: middle;
          width: 100%;
        }

          .step-controls-row .step-numbers .button button:hover,
          .step-controls-row .step-numbers .button button:focus {
            border: 0;
            background-color: rgba(255,255,255,.1);
          }

    /** Text input and Run button on the right */
    .step-controls-row .custom-steps {}

      /** Number of steps text field */
      .step-controls-row .custom-steps .text-input {
        display: inline;
      }

        .step-controls-row .custom-steps .text-input input {
          width: 55px;
          height: 30px;
          margin-left: 10px;
          border-color: var(--border-color);
        }

      /** Run button */
      .step-controls-row .custom-steps .button {
        display: inline;
      }

        .step-controls-row .custom-steps .button button {
          background-color: rgba(255,255,255,.05);
          border: 1px solid var(--border-color);
          border-left: 0;
          border-radius: 0;
          height: 30px;
          vertical-align: middle;
          padding: 0 10px;
        }

.swap-button {
  background: none;
  color: white;
}

/** Center buttons and links */
.center-controls {
  position: absolute;
  left: 10px;
  top: 10px;
  z-index: 100;
  transition: left var(--ui-animation-time) linear;
}

  .center-controls.has-left-indent {
    left: calc( var(--panel-width) + 20px);
  }

  .center-controls .toggle-ui-button {
    background: rgba(0,0,0,.4);
    border: 1px solid var(--border-color);
    padding: 5px 15px;
    border-radius: 100px;
    color: rgb(255,255,255,.7);
    cursor: pointer;
    vertical-align: middle;
  }

    .center-controls .toggle-ui-button:hover,
    .center-controls .toggle-ui-button:focus {
      background: black;
      border-color: var(--border-color--active);
      color: white;
    }

    .center-controls .toggle-ui-button:focus {
      outline-offset: 4px;
    }

    .center-controls .toggle-ui-button .fas { margin-right: 5px; }

    .center-controls .toggle-ui-button[aria-pressed="false"] .fas.fa-eye,
    .center-controls .toggle-ui-button[aria-pressed="false"] .show { display: none; }

    .center-controls .toggle-ui-button[aria-pressed="true"] .fas.fa-eye-slash,
    .center-controls .toggle-ui-button[aria-pressed="true"] .hide { display: none;}

  .center-controls .about-button {
    display: inline-block;
    width: 27px;
    height: 27px;
    background: rgba(0,0,0,.4);
    border: 1px solid var(--border-color);
    border-radius: 100px;
    color:rgba(255, 255, 255, .7);
    font-size: 12px;
    cursor: pointer;
    margin: 0 10px;
    padding: 0;
  }

    .center-controls .about-button:hover,
    .center-controls .about-button:focus {
      background: black;
      border-color: var(--border-color--active);
    }

    .center-controls .about-button:focus {
      outline-offset: 4px;
    }

  .center-controls .github-link {
    color: rgba(255, 255, 255, .7);
    font-size: 27px;
    vertical-align: middle;
    padding: 0;
    margin: 0;
  }

    .center-controls .about-button:hover,
    .center-controls .about-button:focus,
    .center-controls .github-link:hover,
    .center-controls .github-link:focus {
      color: white;
    }

/*******************
  Modal dialogs
********************/
.dialog {
  display: none;

  position: absolute;
  left: 0;
  top: 0;
  width: 100vw;
  height: 100vh;
  z-index: 200;
  background-color: rgba(0,0,0,.7);

  justify-content: center;
  align-items: center;
}

  .dialog.is-visible {
    display: flex;
  }

  .dialog .content {
    position: relative;
    padding: 20px 30px;
    max-width: 600px;
    max-height: 80vh;
    overflow-y: scroll;

    background-color: black;
    color: rgba(255,255,255,.8);
  }

    .dialog .content .close-button {
      position: absolute;
      top: 15px;
      right: 20px;

      background: none;
      border: 0;
      padding: 0;

      color: white;
      font-size: 24px;
      font-weight: bold;
      cursor: pointer;
      opacity: .6;
    }

    .dialog .content .close-button:hover,
    .dialog .content .close-button:focus {
      opacity: 1;
      outline-offset: 2px;
    }

    .dialog .content h1 {
      font-size: 20px;
      margin: 0;
    }

    .dialog .content a {
      color: white;
      font-weight: bold;
      text-decoration: underline;
    }

  /** Seizure warning dialog ****************/
  #seizure-warning-dialog .content {
    max-width: 550px;
  }

  #seizure-warning-dialog h1 {
    color: rgb(255,50,50);
    text-align: center;
    font-size: 28px;
  }

  #seizure-warning-dialog p {
    margin: 20px 0;
    color: rgb(255,255,255,.7);
    line-height: 24px;
  }

  #seizure-warning-dialog button {
    background: none;
    border: 1px solid var(--border-color);
    cursor: pointer;
    color: white;
    padding: 10px 20px;
    margin-top: 10px;
    margin-bottom: 10px;
    font-size: 16px;
    font-weight: bold;
  }

    #seizure-warning-dialog button:hover,
    #seizure-warning-dialog button:focus {
      background-color: white;
      color: black;
      font-weight: bold;
      border-color: white;
      outline-offset: 4px;
    }

  #seizure-warning-dialog label {
    margin-left: 20px;
  }

    #seizure-warning-dialog label input {
      vertical-align: middle;
    }

    #seizure-warning-dialog label span {
      margin-left: 5px;
      font-size: 14px;
      opacity: .7;
      vertical-align: middle;
    }

  /** About dialog *******************/
  #about-dialog .content {
    font-size: 14px;
    color:rgba(255, 255, 255, .7);
  }

  #about-dialog .content h1 {
    font-size: 22px;
    margin-bottom: 15px;
    color: white;
  }

  #about-dialog .content p {
    line-height: 20px;
    margin-bottom: 20px;
  }

  #about-dialog .content b {
    color: white;
  }

  #about-dialog .content .row {
    display: flex;
    justify-content: space-between;
    margin: 20px 0;
    border-top: 1px solid var(--border-color);
    border-bottom: 1px solid var(--border-color);
  }

    #about-dialog .content .row > div {
      flex: 0 0 48%;
      padding: 15px 5px;
    }

      #about-dialog .content .row > div:first-of-type {
        border-right: 1px solid var(--border-color);
        padding-right: 20px;
      }

    #about-dialog .content h2 {
      margin-bottom: 10px;
      font-size: 16px;
      text-decoration: underline;
      color: white;
    }

    #about-dialog .content ul {
      margin-left: 20px;
    }

      #about-dialog .content ul li {
        padding-left: 5px;
        margin-bottom: 10px;
      }

        #about-dialog .content ul li code {
          font-weight: bold;
          font-family: 'Courier New', Courier, monospace;
          background-color: rgba(255,255,255,.1);
          color: white;
          padding: 3px 7px;
        }

        #about-dialog .content ul li ul {
          margin-top: 8px;
        }

          #about-dialog .content ul li ul li {
            margin: 4px 0;
          }

  #about-dialog .content .credits {
    margin: 20px -10px 0 -10px;
    padding: 20px;
    background-color: rgba(255,255,255,.05);
  }