1. HTML

<div class="form-group input-container">
              <label for="projectdeadline">Tanggal Posting</label>
              <input type="date" id="projectdeadline" name="projectdeadline" class="form-control" value="<?= date('Y-m-d') ?>" required>
          </div>

2. CSS

.input-container input {
            box-sizing: border-box;
            padding: .75rem;
            position: relative;
            width: 100%;
        }

        input[type="date"]::-webkit-calendar-picker-indicator {
            background: transparent;
            bottom: 0;
            color: transparent;
            cursor: pointer;
            height: auto;
            left: 0;
            position: absolute;
            right: 0;
            top: 0;
            width: auto;
        }