test-container-styles.css

/* Override QUnit's default styles that place #qunit-fixture outside the viewport */
#qunit-fixture {
  position: relative;
  left: auto;
  top: auto;
  width: auto;
  height: auto;
}

#ember-testing-container {
  position: fixed;

  background-color: #fff;
  background-image:
    linear-gradient(45deg, #eee 25%, transparent 25%, transparent 75%, #eee 75%, #eee),
    linear-gradient(45deg, #eee 25%, transparent 25%, transparent 75%, #eee 75%, #eee);
  background-position: 0 0, 10px 10px;
  background-size: 20px 20px;

  bottom: 0;
  right: 0;
  width: 640px;
  height: 384px;
  overflow: auto;
  z-index: 98;
  border: 1px solid #ccc;
  margin: 0 auto;

  /* Prevent leaking position fixed elements outside the testing container */
  transform: translateZ(0);
}

#ember-testing-container.ember-testing-container-full-screen {
  width: 100%;
  height: 100%;
  overflow: auto;
  z-index: 98;
  border: none;
  right: 0;
}

#ember-testing-container.ember-testing-container-hidden {
  opacity: 0;
  pointer-events: none;
}

#ember-testing {
  width: 200%;
  height: 200%;
  transform: scale(0.5);
  transform-origin: top left;
}

.ember-testing-container-full-screen #ember-testing {
  position: absolute;
  width: 100%;
  height: 100%;
  transform: scale(1);
}

#qunit-tests > li:last-child {
  margin-bottom: 384px;
}

@supports (display: flex) or (display: -webkit-box) {
  @media (min-height: 500px) {
    #qunit-tests {
      overflow: auto;
    }

    #ember-testing-container {
      right: 30px;
    }
  }
}