Adjustments on Markers: user can't post new marker if too close to another one + clicking the create button will create a "placeholder" marker to show where the marker will be posted

// WebKit-style focus

.tab-focus() {
  // Default
  outline: thin dotted;
  // WebKit
  outline: 5px auto -webkit-focus-ring-color;
  outline-offset: -2px;
}