/*table, th, td {*/
th, td {
    border: 1px solid black;
    padding: 0;
}
    td {
        overflow: hidden;
    }
th {
    padding: 3px;
    background-color: #ccc;
    /* https://stackoverflow.com/questions/41882616/why-border-is-not-visible-with-position-sticky-when-background-color-exists */
    background-clip: padding-box;
}
    th:after{
        content:'';
        position:absolute;
        left: 0;
        bottom: 0;
        width:100%;
        border-bottom: 1px solid black;
    }
tr:first-child {
    position: sticky;
    top: -1px;
    border: 1px solid #000;
    z-index: 100;
}
tr > td:first-child {
    padding-left: 2px;
    padding-right: 2px;
    background-color: #ccc;
}

td.has-task {
    padding: 3px;
    background-color: #aaa;
    position: relative;
    background-clip: padding-box;
}
    td.tag-busy {
        background-color: red;
    }
    td.tag-tentative {
        /* https://www.quackit.com/css/codes/patterns/css_background_stripes.cfm */
        background-image: repeating-linear-gradient(165deg, #ccc, #ccc 10px, #dbdbdb 10px, #dbdbdb 20px);
    }
    td.tag-rough {
        border-style: dashed;
        border-width: 2px;
    }
    td.tag-join-me {
        background-color: #2a2;
    }
    td.tag-self {
        background-color: #22aa9d6e;
    }
td a {
    display: block;
    text-decoration: none;
    color: inherit;
    padding: 0;
    overflow-y: auto;
    position: absolute;
    top: 0;
    height: 100%;
    width: 100%;
}

li:target {
    background-color: #aeb;
}