style.css

body {
    background-color: #869EF4;
    user-select: none;
}

#title {
    width: 600px;
    height: 130px;
    margin-left: 120px;

    font-family: 'Indie Flower';
    font-size: 90px;
    font-weight: 900;
    color: #FFFFFF;
    
    display: flex;
    justify-content: center;
    align-items: center;

    /* StackOverflow */
    text-shadow: 2px 2px 25px #6A5EFF, 2px 2px 25px #6A5EFF, 2px 2px 25px #6A5EFF, 2px 2px 25px #6A5EFF;
    -webkit-text-stroke-width: 4px;
    -webkit-text-stroke-color: #6A5EFF;
}

.main-container {
    display: flex;
    flex-direction: column;
    justify-content: center;
    align-items: center;
}

.middle-container {
    display: flex;
    justify-content: center;
    align-items: center;
}
.grid-container {
    width: 450px;
    height: 450px;
    border: 3px solid black;
    box-shadow: 10px 10px 5px hsla(0, 0%, 0%, 25%);
}

.grid-square {
    width: 45px;
    height: 45px;
}
  
.row {
    display: flex;
}

.toolbar {
    display: flex;
    flex-direction: column;
    gap: 25px;
    margin-right: 53px;
}

#color-picker,
.option {
    width: 67px;
    height: 67px;
    border-radius: 67px;
    background-color: #4F54D3; /* doesn't affect color-picker */

    /* center the images */
    display: flex;
    justify-content: center;
    align-items: center;
}

.option:hover {
    background-color: #4842a0;
    transition: 500ms;
}

.tooltip {
    position: relative;
}

.tooltip .tooltiptext {
    width: 55px;
    height: 40px;
    visibility: hidden;

    background-color: #E7E7E7;
    color: #6A5EFF;
    font-family: "Indie Flower";
    font-weight: 900;
    border-radius: 10px;

    /* position */
    position: absolute;
    z-index: 1;
    right: 100%;
    margin-right: 5px;

    display: flex;
    justify-content: center;
    align-items: center;

    /* transition effect */
    opacity: 0;
    transition: opacity 800ms;
}

.tooltip:hover .tooltiptext {
    visibility: visible;

    /* transition */
    opacity: 1;
}