<div class="container">
  <div class="flex__container flex__container--margin" data-gutter="margin">
    <div class="flex__item"></div>
    <div class="flex__item"></div>
    <div class="flex__item"></div>
    <div class="flex__item"></div>
    <div class="flex__item"></div>
    <div class="flex__item"></div>
    <div class="flex__item"></div>
    <div class="flex__item"></div>
  </div>
</div>
<div class="container">
  <div class="flex__container flex__container--gap" data-gutter="gap">
    <div class="flex__item"></div>
    <div class="flex__item"></div>
    <div class="flex__item"></div>
    <div class="flex__item"></div>
    <div class="flex__item"></div>
    <div class="flex__item"></div>
    <div class="flex__item"></div>
    <div class="flex__item"></div>
  </div>
</div>

@import url("https://fonts.googleapis.com/css?family=Gochi+Hand");

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

body {
  width: 100vw;
  min-height: 100vh;
  margin: 0;
  background-color: #291642;
  font-family: "Gochi Hand", sans-serif;
  font-size: 100%;
  letter-spacing: 0.1rem;
  color: #fff;
  display: flex;
  justify-content: center;
  align-items: center;
}


.forms {
  height: 100vh;
  overflow-y: auto;
  border-left: 4px solid rgba(255,255,0,.1);
  display: flex;
  flex-direction: column;
  padding: 10px;
  position: relative;
  z-index: 2;
  background-color: rgba(0,0,0,.2);
}
.controls {
  background-color: rgba(0,0,0,.1);
  padding: 5px;
  border-radius: .5em;
  border: 1px solid rgba(0,0,0,.2);
  margin: 5px;
}

.controls select {
  font-size: .9em;
  max-width: 100px;
  min-width: 100px;
}

:root {
  --writingMode: horizontal-tb;
  --direction: ltr;
  --flexDirection: row;
  --flexWrap: wrap;
  --alignContent: flex-start;
  --justifyContent: flex-start;
  --gap: 20px;
}

.container {
  writing-mode: var(--writingMode);
  direction: var(--direction);
  
  display: flex;
  justify-content: center;
  align-items: center;
  width: calc(48vh + var(--gap) * 3 + 2px);
  border: 1px dashed #fff;
  background-color: rgba(255, 55, 120, .2);
  margin: 20px;
}

.flex__container {
  display: inline-flex;
  flex-flow:var(--flexDirection) var(--flexWrap);
  place-content: var(--alignContent) var(--justifyContent);
  position: relative;
  counter-reset: listCounter;
}

.flex__item {
  display: flex;
  justify-content: center;
  align-items: center;
  inline-size: 12vh;
  block-size: 12vh;
  counter-increment: listCounter;
}

.flex__item::before {
  content:  "[" counter(listCounter) "]";
  font-size: 2rem;
  background: rgba(0,0,0,.65);
  padding: 4px;
  border-radius: 4px;
}

.flex__item:nth-child(1) {
  background-color: #f36;
}

.flex__item:nth-child(2) {
  background-color: #CDDC39;
}

.flex__item:nth-child(3) {
  background-color: #2196F3;
}

.flex__item:nth-child(4) {
  background-color: #FF5722;
}

.flex__item:nth-child(5) {
  background-color: #F22;
}

.flex__item:nth-child(6) {
  background-color: #722;
}

.flex__item:nth-child(7) {
  background-color: #FF5;
}

.flex__item:nth-child(8) {
  background-color: #9f9f9f;
}

.flex__container--margin {
  margin: calc(-1 * var(--gap)) 0 0 calc(-1 * var(--gap));
  width: calc(100% + var(--gap));
}

.flex__container--margin > .flex__item {
  margin: var(--gap) 0 0 var(--gap);
}

.flex__container--gap {
  gap: var(--gap);
}

.flex__container::after {
  content: attr(data-gutter);
  position: absolute;
  left: 50%;
  transform: translate(-50%, 0);
  top: calc(100% + 10px);
  font-size: 2rem;
}