:root {
  --space: 5vmin;  /* How big is the border */
  --scale: 2;      /* Stripe size */
  --y: #FFF400;  /* Yellow */
  --g: #00A33E;  /* Green */
  --r: #DD020A;  /* Red */
  --bg: var(--y);
  --fg: var(--r);
  --txt: black;
  --dir: column;   /* default flex */

  /* varying font size */
  --font: 100px;

  /* colour and direction of the arrow */
  --arrowsize: calc(calc(var(--font) /4));
  --arrowcols: var(--fg) transparent transparent transparent;
  --arrowtop: calc(100% + calc( var(--arrowsize) / 2));
  --arrowleft: calc(50% - var(--arrowsize));
}

/*
NB: All changes to layout are controlled through variables so
there are no surprise media queries to go hunting for at
the end of the stylesheet.
*/
@media (max-height: 50vw) {
  :root {
    --dir: row;
    --arrowcols: transparent transparent transparent var(--fg);
    --arrowtop: calc(50% - var(--space));
    --arrowleft: 104%;
  }
}

/* Reset */
* {
  padding: 0;
  margin: 0;
  box-sizing: border-box;
  transition: border 0.2s ease-in-out;
}

body {
  padding: 0;
  margin: 0;
  font-size: var(--font);
  text-transform: uppercase;
  font-family: "Source Sans Pro";
  line-height: 80%;
  text-align: center;
}

/*
The article has a stripey green and yellow background.
*/
article {
  z-index: 1;
  position: relative;
  padding: var(--space);
  width: 100vw;
  height: 100vh;
  background: repeating-linear-gradient(135deg, var(--fg), var(--fg) calc( var(--space) * var(--scale)), var(--bg) calc( var(--space) * var(--scale)), var(--bg) calc( var(--space) * var(--scale) * 2));
}

/*
The article's stripey green and yellow background is
repeated, but flipped using this pseudo element - this
is what forms the centred chevron effect.
*/
article::before {
  position: absolute;
  top: 0;
  right: 0;
  content: "";
  background: repeating-linear-gradient(225deg, var(--fg), var(--fg) calc( var(--space) * var(--scale)), var(--bg) calc( var(--space) * var(--scale)), var(--bg) calc( var(--space) * var(--scale) * 2));
  width: 50vw;
  height: 100vh;
  display: block;
  z-index: 1;
}

article::after {
  position: absolute;
  top: var(--space);
  right: var(--space);
  bottom: var(--space);
  left: var(--space);
  content: "";
  background: var(--bg);
  display: block;
  z-index: 2;
}

/* The section is yellow, which covers most of the stripes */
section {
  height: 100%;
  display: flex;
  flex-direction: var(--dir);
  justify-content: space-evenly;
  align-content: center;
  align-items: center;
  position: relative;
  z-index: 3;
}

p {
  flex: 0 0;
  position: relative;
  text-wrap: balance; /** hurry up CSS4! */
  max-width: 80vw;
  outline: none;
  border: solid transparent thick;
  margin: 0.1em;
  color: var(--txt);
}

/* hint to the user that they can click */
p:hover {
  border-color: var(--fg);
}

/* add arrows to each paragraph */
p::before {
  position: absolute;
  top: var(--arrowtop);
  left: var(--arrowleft);
  border: var(--arrowsize) solid transparent;

  border-color: var(--arrowcols);
  content: "";
}

/* add arrows to each paragraph... except the last one */
p:last-of-type::before {
  border: none;
}