Menu For Scheduler

HTML

<header>
    <img src="bla.png" />
    <nav>
        <ul class="top-level-menu">
            <li>Schedules

                <ul class="second-level-menu">
                    <li name="mniOpenExisting" id="mniOpenExisting">Open Existing</li>
                    <li>Create New...
                        <ul class="third-level-menu">
                            <li name="mniCreateNewScheduleBasedOnExisting" id="mniCreateNewScheduleBasedOnExisting">Based on Existing</li>
                            <li name="mniCreateNewScheduleFromScratch" id="mniCreateNewScheduleFromScratch">From Scratch</li>
                        </ul>
                    </li>
                    <li name="mniSaveCurrentSchedule" id="mniSaveCurrentSchedule">Save Current</li>
                    <li name="mniEmailCurrentSchedule" id="mniEmailCurrentSchedule">Email Current</li>
                    <li name="mniPrintCurrentSchedule" id="mniPrintCurrentSchedule">Print Current</li>
                </ul>
            </li>
            <li>Job/Locations

                <ul class="second-level-menu">
                    <li name="mniAddNewJobLoc" id="mniAddNewJobLoc">Add New</li>
                    <li name="mniViewOrEditJobLoc" id="mniViewOrEditJobLoc">View or Edit</li>
                </ul>
            </li>
            <li>Workers

                <ul class="second-level-menu">
                    <li name="mniAddNewWorker" id="mniAddNewWorker">Add New</li>
                    <li name="mniViewOrEditWorker" id="mniViewOrEditWorker">View or Edit</li>
                    <li name="mniWorkerPreferences" id="mniWorkerPreferences">Preferences</li>
                </ul>
            </li>
            <li>Rules

                <ul class="second-level-menu">
                    <li name="mniSetRules" id="mniSetRules">Establish/Maintain</li>
                </ul>
            </li>
            <li>Help

                <ul class="second-level-menu">
                    <li name="mniAbout"...

CSS

body {
    background-color: lightyellow;
}
nav {
    background-color: red;
}
.floatleft {
    float: left;
    display: block;
}
.third-level-menu {
    position: absolute;
    top: 0;
    right: -150px;
    width: 150px;
    list-style: none;
    padding: 0;
    margin: 0;
    display: none;
}
.third-level-menu > li {
    height: 30px;
    background: gray;
}
.third-level-menu > li:hover {
    background: white;
}
.second-level-menu {
    position: absolute;
    top: 30px;
    left: 0;
    width: 150px;
    list-style: none;
    padding: 0;
    margin: 0;
    display: none;
}
.second-level-menu > li {
    position: relative;
    height: 30px;
    background: orange;
    color: white;
}
.second-level-menu > li:hover {
    background: green;
}
.top-level-menu {
    list-style: none;
    padding: 0;
    margin-bottom: 12px;
    width: 100vw;
}
.top-level-menu > li {
    position: relative;
    float: left;
    height: 30px;
    width: 150px;
}
.top-level-menu > li:hover {
    background-color: forestgreen;
    color: white;
}
.top-level-menu> ul {
    /* On hover, display the next level's menu */
    display: inline;
    background-color: red;
}