paper-calendar.css

:host {
  display: block;
  max-width: 200px;
}

.field {
  position: relative;
}

#date-input {
  padding: 6px;
}

#calendar {
  width: 320px;
  display: none;
  background-color: #eee;
  border-radius: 6px;
  position: absolute;
  margin-left: 10px;
  padding-bottom: 10px;
  top: -10px;
  text-align: center;
  font-size: 18px;
  font-weight: 200;
  line-height: 30px;
  font-family: "Helvetica Neue", Helvetica, Arial, sans-serif;
}

#calendar.show {
  display: block;
}

.calendar-head {
  background-color: #3794d1;
  color: #fff;
  border-radius: 6px 6px 0 0;
}

#content {
  margin: 0 10px 10px;
}

.header {
  text-align: center;
  cursor: pointer;
}

paper-icon-button {
  margin: 0 !important;
}

.days, .months, .years {
  height: 40px;
  line-height: 40px;
  cursor: pointer;
  -webkit-user-select: none;
  -moz-user-select: none;
  -ms-user-select: none; /* IE10+ */
  user-select: none;
}

.days:hover, .months:hover, .years:hover {
  background-color: #dadada;
}

.days {
  width: 40px;
  border-radius: 50%;
  margin: 3px 1px; /* for old browsers*/
  margin: 3px calc(10px / 7);
}

.days.fade {
  color: #c9c9c9;
}

.months {
  width: 100px;
  margin: 5px 0;
  border-radius: 4px;
}

.years {
  width: 60px;
  margin: 5px 0;
  border-radius: 4px;
}

.days.core-selected,
.months.core-selected,
.years.core-selected {
  background-color: #3794d1;
  color: #fff;
}

.today {
  background: #3794d1;
  color: #fff;
  padding: 8px 15px;
  border-radius: 4px;
  cursor: pointer;
  -webkit-user-select: none;
  -moz-user-select: none;
  -ms-user-select: none; /* IE10+ */
  user-select: none;
}