.calendar {
    display: grid;
    grid-template-columns: repeat(7, 1fr);
    gap: 8px;
}
.day {
    font-size: 0.8em;
    border: 1px solid #ccc;
    padding: 4px;
}
.p_month {
    border: 1px solid #ccc;
    background-color: #888;
    /* padding: 8px; */
}
.event {
    position: relative;
    border: 1px solid #888;
    background-color: #F2F3F6;
    border-radius: 4px; /* 角を丸くする */
    cursor: pointer;
    /* margin-top: 5px; */
    /* padding: 5px; */
}
.arrow {
    color: blue;
}
h2 {
    display: inline;
    background: linear-gradient(transparent 70%, lightblue 70%);
    padding-top: 0.7em;
    margin-right: 1.0em;
}
h3 {
    display: inline;
    /* background: linear-gradient(transparent 70%, lightblue 70%); */
    padding-top: 0.7em;
    margin-right: 1.0em;
}
.top_bar {
    margin-bottom: 0.5em;
    text-align: center;
}
button {
    font-size: 0.6em;
}        
ul {
    border: solid 2px #3fb0ff;
    padding: 0.2em;
    position: relative;
    margin-top: 1em;
}
ul li {
    line-height: 1.5;
    /* padding: 0.5em 0; */
    list-style-type: none!important;
}
.tooltiptext {
    visibility: hidden;
    width: 180px;
    background-color: #555;
    color: #fff;
    border-radius: 6px;
    padding: 0.5em;
    position: absolute;
    z-index: 1;
    bottom: 125%; /* ツールチップの位置 */
    left: 50%;
    margin-left: -60px;
    opacity: 0;
    transition: opacity 0.3s;
}
.event:hover .tooltiptext {
    visibility: visible;
    opacity: 1;
}
.error {
    animation: blinking 1s ease-in-out infinite alternate;
    visibility: visible;
    color:red;
}
@keyframes blinking {
    0% {
        opacity: 0;
    }
    100% {
        opacity: 1;
    }
}