style.css

* {
    margin: 0;
    padding: 0;
    box-sizing: border-box;
}

body {
    font-family: 'Arial', sans-serif;
    background-color: #121212; /* Dark background color */
    color: #f0f0f0; /* Lighter text color for readability */
    display: flex;
    justify-content: center;
    padding: 20px;
}

.container {
    display: flex;
    flex-direction: row;
    width: 100%;
    max-width: 1200px;
    margin-top: 20px;
}

.sidebar {
    width: 15%;
    padding: 20px;
    background-color: #1e1e1e; /* Darker background for sidebar */
    border-radius: 12px; /* Rounded corners */
    box-shadow: 0 4px 12px rgba(0, 0, 0, 0.4);
    margin-right: 20px;
    height: 100%;
}

.sidebar h1 {
    text-align: center;
    color: #ffcc00; /* Bright yellow text for heading */
    margin-bottom: 30px;
}

.sidebar h2 {
    margin-top: 20px;
    font-size: 18px;
    color: #dcdcdc; /* Soft light gray */
}

.sidebar input,
.sidebar button {
    width: 100%;
    padding: 12px;
    margin: 12px 0;
    border-radius: 6px; /* Softer rounded corners */
    font-size: 14px;
    background-color: #333333; /* Dark background for inputs */
    color: #f0f0f0; /* Light text inside inputs */
    border: 1px solid #444444; /* Slightly lighter border */
}

.sidebar button {
    background-color: #3498db; /* Bright blue button */
    color: white;
    cursor: pointer;
    transition: background-color 0.3s ease;
}

.sidebar button:hover {
    background-color: #2980b9; /* Darker blue on hover */
}

.contacts-section {
    flex-grow: 1;
    padding: 20px;
    background-color: #222222; /* Darker background for contact section */
    border-radius: 12px;
    box-shadow: 0 4px 12px rgba(0, 0, 0, 0.4);
    overflow-y: auto;  /* Enable vertical scrolling */
    max-height: 600px; /* Set maximum height for scrolling */
}

.contacts-section h2 {
    color: #ffffff; /* White text for section titles */
}

.contacts-section ul {
    list-style-type: none;
    padding: 0;
}

.contacts-section li {
    padding: 12px;
    margin-bottom: 12px;
    background-color: #333333; /* Dark background for contact items */
    border-radius: 6px;
    box-shadow: 0 2px 6px rgba(0, 0, 0, 0.2);
}

.contacts-section button {
    background-color: #e74c3c; /* Red for delete buttons */
    color: white;
    border: none;
    cursor: pointer;
    padding: 6px 12px;
    margin: 5px;
    border-radius: 6px;
    transition: background-color 0.3s ease;
}

.contacts-section button:hover {
    background-color: #c0392b; /* Darker red on hover */
}

.tree-section {
    width: 100%;
    padding: 20px;
    background-color: #222222; /* Dark background for tree visualization */
    border-radius: 12px;
    box-shadow: 0 4px 12px rgba(0, 0, 0, 0.4);
    margin-top: 20px;
    display: flex;
    justify-content: center;
    align-items: center;
    flex-direction: column;
}

#bstCanvas {
    border: 2px solid #444444; /* Subtle border for the canvas */
    background-color: #181818; /* Darker canvas background */
    margin-top: 20px;
    border-radius: 8px; /* Rounded canvas border */
}