discourse/app/assets/stylesheets/mobile/search.scss

.search button.btn-primary, .search button.btn {
  float: none;
}

.search.row {
  margin-top: 5px;
}

.search.row input.search {
  height: 25px;
  width: 69%;
}

.fps-search-context {
  margin-bottom: 15px;
}

.fps-topic {
  max-width: 75%;
}