<style>
    div.test {
        inline-size: 50px;
        block-size: 100px;
        background-color: red;
    }

    div.float {
        float: left;
        block-size: 50px;
        inline-size: 50px;
        background-color: blue;
    }

    div.clear {
        clear: left;
    }

    div.green {
        background-color: green;
        block-size: 25px;
    }

    div.lr {
        -webkit-writing-mode: vertical-lr;
    }

    div.rl {
        -webkit-writing-mode: vertical-rl;
    }
</style>
<div class="test lr">
    <div class="float"></div>
    <div class="clear"></div>
    <div class="green"></div>
    <div class="green"></div>
</div>

<div class="test lr">
    <div class="float"></div>
    <div class="clear green"></div>
    <div class="green"></div>
</div>

<div class="test rl">
    <div class="float"></div>
    <div class="clear"></div>
    <div class="green"></div>
    <div class="green"></div>
</div>

<div class="test rl">
    <div class="float"></div>
    <div class="clear green"></div>
    <div class="green"></div>
</div>