* {
    box-sizing: border-box;
}

html,
body {
    height: 100%;
    margin: 0;
}

body {
    font-family: -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, Helvetica, Arial, sans-serif;
    background-color: #1f1f1f;
    color: #f4f4f4;
}

.container {
    display: flex;
    width: 100%;
    height: 100vh;
}

.pane {
    flex: 1;
    min-width: 0;
    padding: 16px;
    display: flex;
    flex-direction: column;
    border-right: 1px solid #333;
}

.pane:last-child {
    border-right: none;
}

.pane-header {
    margin-bottom: 10px;
    font-weight: 600;
    color: #7fc5ff;
    text-transform: uppercase;
    letter-spacing: 0.5px;
    font-size: 0.85rem;
}

textarea {
    flex: 1;
    width: 100%;
    resize: none;
    border: 1px solid #3b3b3b;
    border-radius: 6px;
    background-color: #2a2a2a;
    color: #f4f4f4;
    padding: 14px;
    outline: none;
    font-family: "Consolas", "Monaco", monospace;
    font-size: 14px;
    line-height: 1.5;
}

textarea:focus {
    border-color: #7fc5ff;
}

#htmlPreview {
    flex: 1;
    width: 100%;
    border: 1px solid #3b3b3b;
    border-radius: 6px;
    background-color: #ffffff;
}

@media (max-width: 900px) {
    .container {
        flex-direction: column;
        height: auto;
        min-height: 100vh;
    }

    .pane {
        min-height: 50vh;
        border-right: none;
        border-bottom: 1px solid #333;
    }

    .pane:last-child {
        border-bottom: none;
    }
}