style.css

body {
    padding: 0;
    margin: 0;
    background: rgba(0, 0, 0, 0.7);
    overflow: hidden;
    width: Calc(100vw - 1em);
    height: 100vh;
    display: grid;
    grid-gap: 0.5em;
    grid-template-columns: 100vw;
    grid-template-rows: 4em 3.5fr auto 1.5em;
    grid-template-areas: 'banner'
                         'canvas'
                         'editor'
                         'footer';
}

#banner {
    grid-area: banner;
    background: #F5F5F5;
    height: 20px;
    padding: 10px 20px 35px 20px;
    font-weight: 800;
    display: grid;
    grid-template-columns: 1.5fr 18fr 3.5fr 1fr 1.4fr;
    font-size: 20px;
    font-family: 'Montserrat', 'Open Sans';
}

#LOGO {
    padding-top: 10px;
    padding-left: 10px;
}

#banner select {
    margin-right: 10px;
}

span[tooltip]::before {
    content: '';
    opacity: 0;
}

span[tooltip]:hover::before {
    content: attr(tooltip);
    opacity: 1;
    position: absolute;
    top: 60px;
    right: 2%;
    background: rgba(0, 0, 0, .7);
    color: #ffffff;
    font-size: 15px;
    padding: 5px 10px;
    border-radius: 10px;

    transition: opacity 1ms ease-in-out;
}

.ico_btn_dark img {
    border-radius: 100px;
    transition: all .2s ease-in;
}

.ico_btn_dark img:hover {
    background: #00000013;
}

.ico_btn_dark img:active {
    background: #00000038;
}

select {
    border: 2px solid #ad9bf8;
    border-radius: 10px;
    outline: none;
}

a {
    color: #ad9bf8;
    text-decoration: none;
}

.editor-container {
    grid-area: editor;
    position: relative;
    overflow: hidden;
    margin: 0 10px 0 9px;
    width: 99%;
    width: Calc(100% - 18px);
    min-height: 6em;
    outline: none;
    border-radius: 10px;
    box-shadow: 0px 5px 8px 1px rgba(0, 0, 0, .3);
    background-color:#1f2223;
}

.textarea-container {
    position: absolute;
    top: 0;
    left: 0;
    right: 0;
    bottom: 0;
    overflow: hidden;
}

#code {
    width: Calc(100% - 34px);
    height: Calc(100% - 11px);
    font-size: 20px;
    font-family: 'Courier New', Courier, monospace;
    padding: 5px 18px 0 10px;
    outline: none;
    border-radius: 10px;
    border: 3px solid rgba(83, 81, 81, 0.6);
    white-space: pre-wrap;
	word-wrap: break-word;
    color: #ffffff;
    background: transparent;

    transition: border 250ms ease-in;
}

#code_bg {
    position: absolute;
    top: 3px;
    left: 3px;
    right: 3px;
    bottom: 0;
    overflow: hidden;
    font-family: 'Courier New', Courier, monospace;
    resize: none;
    white-space: pre-wrap;
    word-wrap: break-word;
    font-size: 20px;
    padding: 5px 18px 0 10px;
    color: transparent;
    background-color:#1f2223;
}

mark {
    color: #ffffff;
    background-color: rgba(255, 0, 0, .6);
    border-radius: 5px;
}

textarea#code {
    resize: none;
    color: transparent;
    caret-color: #528bff;       /* Browser Compatibility Warning */
}

#code:focus {
    border: 3px solid rgba(11, 44, 230, 0.5);
}

#logo-canvas {
    grid-area: canvas;
    margin: 0 0.5em;
    cursor: grab;
    overflow: hidden;
    border-radius: 10px;
    box-shadow: 0px 5px 8px 1px rgba(0, 0, 0, .3);
}

#logo-canvas:active {
    cursor: grabbing;
}

.copyright-footer {
    grid-area: footer;
    color: white;
    font-family: 'Montserrat';
    padding: 0 0.5em;
}

.resize-handle {
    position: fixed;
    left: 0;
    right: 0;
    width: 300px;
    height: 16px;
    margin: 0 auto;
    padding: 0;
    background-color: transparent;
    cursor: row-resize;
    z-index: 2;
}

.resize-handle div {
    position: relative;
    top: 50%;
    width: 90%;
    margin: 0 auto;
    height: 0;
    background-color: rgb(55, 55, 55);
    background-color: #f5f5f5;
    box-shadow: 0px 2px 16px rgba(0, 0, 0, .3);
    transition: all 150ms ease-in-out;
}

.resize-handle:hover div {
    top: 0;
    height: 16px;
}