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 {
  padding: 0 10px;
  height: 34px;
  line-height: 30px;
  position: relative;
  text-align: center;
  user-select: none;
  -webkit-user-select: none;
  border-bottom: 1px solid #ccc;

  > a {
    font-weight: bold;
    display: inline-block;
    padding: 4px 5px;
    text-align: center;
    width: 30px;

    &:hover {
      cursor: pointer;
      color: #23c0fa;
    }
  }
}

.@{prefixCalendarClass}-month-panel-prev-year-btn, .@{prefixCalendarClass}-month-panel-next-year-btn {
  position: absolute;
  top: 0;
}

.@{prefixCalendarClass}-month-panel-prev-year-btn {
  user-select: none;
  left: 0;
}

.@{prefixCalendarClass}-month-panel .@{prefixCalendarClass}-month-panel-year-select {
  width: 180px;
}

.@{prefixCalendarClass}-month-panel-year-select-arrow {
  display: none;
}

.@{prefixCalendarClass}-month-panel-next-year-btn {
  user-select: none;
  right: 0;
}

.@{prefixCalendarClass}-month-panel-body {
  padding: 9px 10px 10px;
}

.@{prefixCalendarClass}-month-panel-table {
  table-layout: fixed;
  width: 100%;
  height:255px;
  border-collapse: separate;
}

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

.@{prefixCalendarClass}-month-panel-month {
  display: block;
  width: 46px;
  margin: 0 auto;
  color: #666;
  border-radius: 4px 4px;
  height: 36px;
  padding: 0;
  background: transparent;
  line-height: 36px;
  text-align: center;

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

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

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