style.css

/* 
    Copyright © 2019 Gallactica
    https://github.com/gallactica
*/

:root {
    --hl: #6E71C4;
    --color: #D5D5D5;
    --border: #50555F;
}

body {
    background: #282B33FA;
    display: flex;
    flex-direction: column;
    justify-content: center;
    align-items: center;
    margin: 0px;
    font-family: monospace;
}

.app {
    width: 420px;
    height: 295px;
    background: #282B33;
    display: flex;
    color: var(--color);
    overflow: hidden;
    border-radius: 0px;
    user-select: none;
}

.app .time {
    flex: 0 0 auto;
    width: 119px;
    display: flex;
    flex-direction: column;
    justify-content: center;
    align-items: center;
}

.app .time span {
    font-size: 40px;
    width: 48px;
    text-align: center;
    border-bottom: 1px solid var(--border);
    user-select: none;
    line-height: 66px;
}

.app .time span:last-child {
    border: none;
}

.app .calendar {
    padding: 0px 10px;
    flex: 1 1 auto;
    display: flex;
    flex-direction: column;
    border-right: 1px solid var(--border);
}

.app .calendar .header {
    margin-top: 5px;
    flex: 0 0 auto;
    height: 40px;
    display: flex;
    justify-content: space-between;
    align-items: center;
}

.app .calendar .header svg {
    padding: 8px;
    cursor: pointer;
}

.app .calendar .grid {
    display: flex;
    flex-wrap: wrap;
}

.app .calendar .grid span {
    width: 32px;
    height: 32px;
    margin: 4px;
    background-color: #2E343D;
    border-radius: 0px;
    display: flex;
    justify-content: center;
    align-items: center;
    user-select: none;
}

.app .calendar .grid span.today {
    background-color: var(--hl);
    box-shadow: 0px 0px 15px 1px var(--hl);
}

.app .calendar .grid span:empty {
    background-color: #2E343D50;
}