Web application development CSS and PHP note sharing involved in application development

Make some records about some problems encountered in the application and their solutions for future reference. I am a newbie, not yet technically proficient, and my note taking is relatively naive. Please laugh at the ridicule.
　1. Regarding the absolute positioning of layers.
There are two div layers, the main class div is the overall layer, and the cloud class div is the absolute positioning layer. The effect is to display a cloud gif image in the upper right corner of the screen. The div layout code is as follows:

Copy the code The code is as follows:

...

Once in the process The cloud layer is placed in the main layer, causing IE to be unable to display the cloud layer. Finally, the problem was solved by placing the cloud layer outside the main layer and changing the position of main to relative. The CSS code is as follows:

Copy code The code is as follows:

.main{
position:relative;
top:30px;
width:600px;
height:auto;
text-align:left;
background -color: #FFFFFF;
border:5px solid #FF0011;
}
.cloud {
background: url(../image/cloud.gif) no-repeat 100% 50%;
height: 171px;
position: absolute;
right: 0px;
top: 0px;
width: 345px;
z-index: 1000;
}

　　2. Implementation of drop-down box selection for year, month and day.
The drop-down box for year, month and day is very sluggish, and the date cannot change with the change of year and month. But this is a relatively basic solution, and I also refer to other people's methods on the Internet. We will look into newer methods later.

Copy the code The code is as follows:

$months = array (1 => 'January', 'February', 'March', 'April', '5 month', 'June', 'July', 'August', 'September', 'October', 'November', 'December');
$days = range(1,31);
$years = range(1930,2011);
echo '';
foreach ($years as $value) {
echo " $value year";
if ($value == 1987) {
echo '1987 year';
}
}
echo '< ;/select>';
echo '';
foreach ($months as $key => $value) {
echo " $value";
}
echo '';
echo '';
foreach ($days as $value) {
echo "< option value="$value"> $value day";
}
echo '';
?>

3. To be continued.

The above has introduced the sharing of CSS and PHP notes involved in web application development, including web application development. I hope it will be helpful to friends who are interested in PHP tutorials.