message: Marketmaker page demo: improve layout
diff: +section {
  + max-width: 700px;
  + margin: 0 auto;
  + padding: 2em 0;
  +}
  +
  +section + section {
  + border-top: 1px solid #{$color-brand}55;
  +}
  +
  +p {
  + margin-bottom: 0.5em;
  +}
  +
  +.section-title {
  + margin: 0 auto 0.8em;
  + max-width: 572px;
  + font-style: normal;
  + line-height: 1em;
  + font-size: 30px;
  + text-align: center;
  + @include ff-regular;
  +}
  +
  .how-to-earn {
  - opacity: 1;
  + padding-top: 0;
  }
  .select-mode {
  +
  + .modes {
  display: flex;
  - flex-direction: column;
  - align-items: center;
  - justify-content: center;
  +
  + .mode + .mode {
  + margin-left: 2em;
  + }
  +
  + @media (max-width: 820px) {
  + display: block;
  +
  + .mode + .mode {
  + margin-left: 0;
  + }
  + }
  + }
  .mode {
  - opacity: 1;
  + margin-bottom: 1.8em;
  + //border: 1px solid $color-brand;
  + box-shadow: rgba(0,0,0, 0.2) 0 4px 24px;
  + border-radius: 10px;
  + padding: 1.5em 1em;
  +
  + .mode-title {
  + color: #{$color-brand};
  + font-weight: 500;
  + }
  + .number {
  + font-weight: bold;
  + }
  + .mode-button {
  + margin: 1em auto 0;
  + min-width: 100px;
  + display: block;
  + }
  }
  }
  