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

body {
    font-family: Arial, Helvetica, sans-serif;
    background: #f4f4f4;
    color: #222;
}

header {
    background: #2c3e50;
    color: #fff;
    padding: 15px 20px;
}

header h1 {
    font-size: 22px;
}

.container {
    display: flex;
    height: calc(100vh - 60px);
}

#editor {
    width: 50%;
    height: 100%;
    padding: 20px;
    border: none;
    resize: none;
    font-family: monospace;
    font-size: 15px;
    outline: none;
}

#preview {
    width: 50%;
    height: 100%;
    padding: 20px;
    background: #fff;
    border-left: 1px solid #ddd;
    overflow-y: auto;
}

#preview h1,
#preview h2,
#preview h3 {
    margin-bottom: 10px;
}

#preview ul {
    margin: 10px 0 10px 25px;
}

#preview blockquote {
    border-left: 4px solid #2c3e50;
    padding-left: 12px;
    color: #555;
    margin: 10px 0;
}

#preview code {
    background: #eee;
    padding: 2px 5px;
    border-radius: 3px;
    font-size: 14px;
}

#preview a {
    color: #2980b9;
}

#preview img {
    max-width: 100%;
}