style.css

@import url('https://fonts.googleapis.com/css?family=Roboto:400,700&display=swap');

body {
    font-family: 'Roboto', Arial, sans-serif;
    display: flex;
    justify-content: center;
    align-items: center;
    height: 100vh;
    margin: 0;
    background-color: #f5f5f5; /* Light theme background */
    color: #333; /* Light theme text */
    transition: background-color 0.3s, color 0.3s;
}

.container {
    display: flex;
    width: 85%;
    height: 85%;
    box-shadow: 0 4px 10px 0 rgba(0,0,0,0.1); /* subtle shadow for depth */
    border-radius: 8px; /* rounded corners */
    overflow: hidden; /* ensures child elements do not break border-radius */
}

.left-panel, .right-panel {
    flex: 1;
    padding: 20px;
    overflow-y: auto;
    height: 100%;
    transition: background-color 0.3s;
}

/* Scrollbar styles */
::-webkit-scrollbar {
    width: 8px;
}

::-webkit-scrollbar-track {
    background: #f1f1f1;
}

::-webkit-scrollbar-thumb {
    background: #888;
}

::-webkit-scrollbar-thumb:hover {
    background: #555;
}

.left-panel {
    display: flex;
    flex-direction: column;
}

.output {
    background-color: #fff;
    padding: 10px;
    height: calc(100% - 40px);
    overflow-y: auto;
    border: 1px solid #ddd; /* Light theme border */
    transition: background-color 0.3s;
}

/* Theme Switch */
#theme-switch-wrapper {
    position: fixed;
    top: 10px;
    right: 10px;
}

.theme-switch {
    display: inline-block;
    height: 34px;
    position: relative;
    width: 60px;
}

.theme-switch input {
    display:none;
}

.theme-switch input:not(:checked) + .slider {
    background-color: #000; /* Black background for the slider */
}

.theme-switch input:not(:checked) + .slider:before {
    background-color: #fff; /* Black circle for the light theme */
}

.slider {
    background-color: #ccc;
    bottom: 0;
    cursor: pointer;
    left: 0;
    position: absolute;
    right: 0;
    top: 0;
    transition: .4s;
}

.slider:before {
    background-color: #fff;
    bottom: 4px;
    content: "";
    height: 26px;
    left: 4px;
    position: absolute;
    transition: .4s;
    width: 26px;
}

input:checked + .slider {
    background-color: #fff;
}

input:checked + .slider:before {
    transform: translateX(26px);
    background-color: #333;
}

.slider.round {
    border-radius: 34px;
}

.slider.round:before {
    border-radius: 50%;
}

/* Item styles */
.item {
    margin-bottom: 15px;
    padding: 10px;
    border: 1px solid #ddd;
    border-radius: 5px;
    background-color: #e9e9e9;
    cursor: pointer;
    transition: background-color 0.3s, border 0.3s;
    flex: 1;
}

.item:hover {
    background-color: #d0d0d0;
}

/* When .dark-theme is applied, it will override the colors */
.dark-theme {
    background-color: #212121; /* Darker shade for the dark theme background */
    color: #e0e0e0; /* Softer text color for dark theme */
}

.dark-theme .left-panel,
.dark-theme .right-panel {
    background-color: #2a2a2a; /* Dark panel background */
}

.dark-theme .output {
    background-color: #333; /* Dark output background */
    border: 1px solid #444; /* Dark theme border */
}

/* Sub-item styles */
.sub-item {
    cursor: pointer;
    padding-left: 20px;
    border: 1px solid #ddd;
    margin: 5px 0;
    border-radius: 5px;
    background-color: #e0e0e0;
}

/* set font color */
.dark-theme .sub-item {
    color: #2a2a2a;
}

.sub-items {
    display: none;
}

.sub-items.show {
    display: block;
}

.sub-item:hover {
    background-color: #d0d0d0;
}

.item-header {
    font-weight: bold;
    color: blue;
    margin-bottom: 10px;
}

.sub-item:nth-child(odd) {
    background-color: lightblue;
}

.sub-item:nth-child(even) {
    background-color: lightgreen;
}

.item-header + .sub-items {
    margin-top: 10px;
}

pre {outline: 1px solid #ccc; padding: 5px; margin: 5px; white-space: pre-wrap;}
.string { color: green; }
.number { color: darkorange; }
.boolean { color: blue; }
.null { color: magenta; }
.key { color: red; }