<div class="container">
    <div class="sidebar"></div>
    <div class="content"></div>
</div>
.container {
    display: flex;
    height: 100vh;
}

.sidebar {
    width: 260px;
    background: #565656;
}

.content {
    background: #f1f1f1;
    width: calc(100% - 260px);
}

External CSS

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External JavaScript

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