ant-design/style/components/datepicker/MonthPanel.less

.@{prefixCalendarClass}-month-panel {
  left: 0px;
  top:0px;
  bottom: 0px;
  right: 0px;
  background: #ffffff;
  z-index: 10;
  position: absolute;
  outline: none;
}

.@{prefixCalendarClass}-month-panel-hidden {
  display: none;
}

.@{prefixCalendarClass}-month-panel-header {
  .calendarPanelHeader(~"@{prefixCalendarClass}-month-panel");
}

.@{prefixCalendarClass}-month-panel-table {
  table-layout: fixed;
  width: 100%;
  height: 248px;
  border-collapse: separate;
}

.@{prefixCalendarClass}-month-panel-cell {
  text-align: center;
}

.@{prefixCalendarClass}-month-panel-month {
  display: inline-block;
  margin: 0 auto;
  color: #666;
  background: transparent;
  text-align: center;
  height: 24px;
  line-height: 24px;
  padding: 0px 6px;
  border-radius: 4px;

  &:hover {
    background: #ebfaff;
    cursor: pointer;
  }
}

.@{prefixCalendarClass}-month-panel-selected-cell .@{prefixCalendarClass}-month-panel-month {
  background: #3fc7fa;
  color: #fff;

  &:hover {
    background: #3fc7fa;
    color: #fff;
  }
}