demo.css

body {
    font-family: Consolas, monospace;
}

/* This node is where React renders itself. */
#stage {
    background: #EEE;
    padding: 1em;
}

.demo-component {
    /* border-box is required in order to compensate for border and padding. */
    box-sizing: border-box;

    /* Without setting width and height to 100% the component will
     *   be centered in the window at the same dimensions as it was prior
     *   to entering fullscreen.
     */
    height: 100%;
    width: 100%;

    /* These rest of these rules just help with visualizing the component's behavior.
     * The border helps visually identify the edges of the component.
     *
     */
    border: 10px dotted #0074E4;
    color: #0074E4;
    padding: 1em;
    margin-bottom: 1em;
}

/* You will almost certainly want to be able to scroll the content inside
 * your component if it extends off screen (long text for example).
 */
.fullscreen .demo-component {
    overflow-y: scroll;
}

.demo-component button {
    background: #0074E4;
    color: #FFF;
    border: 1px solid #0074E4;
    border-radius: 3px;
    padding: 1em 2em;
}

.filler-content {
    height: 150vh;
    background: #EEE;
}

/* Fullscreenable root node classes.
 *
 * You can use these rules with the .fullscreenable wrapper. By default the
 * component sets the .fullscreenable div's height and width to 100% when
 * it reaches fullscreen and then removes it on exit. This is necessary
 * to allow the contained component to cover the entire screen.
 */
.fullscreenable {}

/* The fullscreen class is added when the component is in native fullscreen. */
.fullscreenable.fullscreen {
    /* At least in Firefox, native fullscreen requires a background color */
    background: #FFF;
}

/* Added when native fullscreen is disabled. */
.fullscreenable.fullscreen_disabled {}

/* Added when the component is in pseudo fullscreen. */
.fullscreenable.fullscreen_pseudo {
    /* A background color is required for pseudo-fullscreen, otherwise the
    page will be visible behind the fullscreen component's contents. */
    background: #FFF;
}