wr_1 여분필드에 들어갑니다. 

 <span class="write_sv"> 일정</span>

          <!-- <input> 요소 추가 -->

  <div class="write_div" style="text-align: right;">

    <label for="wr_1" class="sound_only">날짜<strong>필수</strong></label>

    <input type="text" name="wr_1" id="wr_1" value="<?php echo $wr_1 ?>" required class="frm_input full_input required" maxlength="20" placeholder="날짜"  readonly>

  </div>

        <div class="calendar" id="calendar">

            <div class="calendar_list">

    <!-- 이전 달 버튼 -->

    <button class="prev" id="prevMonth" type="button">◁ </button>

    <!-- 현재 월 표시 -->

    <span class="current-month" id="currentMonth"></span>

    <!-- 다음 달 버튼 -->

    <button class="next" id="nextMonth" type="button">▷</button>

        </div>

    <div class="days-header">

      <span class="day-name">일</span>

      <span class="day-name">월</span>

      <span class="day-name">화</span>

      <span class="day-name">수</span>

      <span class="day-name">목</span>

      <span class="day-name">금</span>

      <span class="day-name">토</span>

    </div>

    <div id="calendarBody"></div>

  </div>

  <script>

    const calendarBody = document.getElementById("calendarBody");

    const today = new Date();

    const inputElement = document.getElementById("wr_1");

    const currentMonthLabel = document.getElementById("currentMonth");

    function createCalendar(year, month) {

      calendarBody.innerHTML = "";

      const firstDay = new Date(year, month, 1);

      const lastDay = new Date(year, month + 1, 0);

      const daysInMonth = lastDay.getDate();

      const startingDay = firstDay.getDay();

      for (let i = 0; i < startingDay; i++) {

        const dayElement = document.createElement("div");

        dayElement.classList.add("day", "empty");

        calendarBody.appendChild(dayElement);

      }

      for (let day = 1; day <= daysInMonth; day++) {

        const dayElement = document.createElement("div");

        dayElement.textContent = day;

        dayElement.classList.add("day");

        if (year === today.getFullYear() && month === today.getMonth() && day === today.getDate()) {

          dayElement.classList.add("today");

        }

        dayElement.addEventListener("click", () => {

          const selectedDay = document.querySelector(".day.selected");

          if (selectedDay) {

            selectedDay.classList.remove("selected");

          }

          dayElement.classList.add("selected");

          // 선택한 날짜를 <input> 요소에 할당

          inputElement.value = `${year}-${month + 1}-${day}`;

        });

        calendarBody.appendChild(dayElement);

      }

    }

    function updateCurrentMonthLabel(year, month) {

      const monthNames = ["1월", "2월", "3월", "4월", "5월", "6월", "7월", "8월", "9월", "10월", "11월", "12월"];

      currentMonthLabel.textContent = `${year}년 ${monthNames[month]}`;

    }

    createCalendar(today.getFullYear(), today.getMonth());

    updateCurrentMonthLabel(today.getFullYear(), today.getMonth());

    // 이전 달 버튼 클릭 이벤트 처리

    document.getElementById("prevMonth").addEventListener("click", () => {

      const currentYear = today.getFullYear();

      const currentMonth = today.getMonth();

      if (currentMonth === 0) {

        today.setFullYear(currentYear - 1, 11);

      } else {

        today.setMonth(currentMonth - 1);

      }

      createCalendar(today.getFullYear(), today.getMonth());

      updateCurrentMonthLabel(today.getFullYear(), today.getMonth());

    });

    // 다음 달 버튼 클릭 이벤트 처리

    document.getElementById("nextMonth").addEventListener("click", () => {

      const currentYear = today.getFullYear();

      const currentMonth = today.getMonth();

      if (currentMonth === 11) {

        today.setFullYear(currentYear + 1, 0);

      } else {

        today.setMonth(currentMonth + 1);

      }

      createCalendar(today.getFullYear(), today.getMonth());

      updateCurrentMonthLabel(today.getFullYear(), today.getMonth());

    });

  </script>

스타일시트 

/* Default styling for larger screens */
.calendar {
    width: 100%;
    margin: 0 auto;
    background-color: #f9f9f9;
    padding: 10px;
    display: flex;
    flex-direction: column;
  }
  
  .calendar-header {
    display: flex;
    justify-content: space-between;
    align-items: center;
    margin-bottom: 10px;
  }
  
  .calendar-header button {
    background: none;
    border: none;
    font-size: 24px;
    cursor: pointer;
  }
  
  .current-month {
    font-size: 18px;
    font-weight: bold;padding: 0 50px;
  }
  
  .days-header {
    display: flex;
    justify-content: space-between;
    background-color: rgb(95, 0, 128);
    color: #fff;
    font-weight: bold;
    text-align: center;
    }
  
  .day-name {
    flex: 1;
    padding: 10px;
    font-size: 14px; /* Adjust the font size for day names as needed */
  }
  
  .day {
    display: inline-block;
    width: 13.7%;
    line-height: 30px;
    text-align: center;
    cursor: pointer;
    margin: 5px 2px;
    font-size: 1.2rem;
    flex: 1;
    }
  
  .day.empty {
    visibility: hidden;
  }
  
  .day.selected {
    background-color: rgb(95, 0, 128);
    color: #fff;
    }
  
  .day.today {
    color: #3a8afd;
    }