CSS inline layout practice summary_html/css_WEB-ITnose

Foreword

Normally, to arrange elements in a row, the usual way is to use float and then clear the float.
is as follows:

But if you want to center it vertically, you must manually adjust the position of the blue or green block, which is more cumbersome.

Or another method, use inline-block or inline (i.e. IFC), just encountered a pit here.

Related css

IFC (Inline formatting contexts) inline formatting context, I have no idea what it is.
Mainly affects the css of the layout within IFC

• font-size
• line-height
• height
• vertical-aligin

line-box

Line box model, which is a display area. According to the block container, multiple inline-level elements of each line will jointly generate a line. box model.

font-size

Common attributes used to specify the size of text type nodes. The values ​​of many attributes in IFC are based on this.

line-height & height

Line height is more clearly defined in w3c:

On a block container element whose content is composed of inline-level elements , 'line-height' specifies the minimal height of line boxes within the element.The minimum height consists of a minimum height above the baseline and a minimum depth below it.

Within a block container consisting of multiple inline elements, 'line-height' specifies a minimum height for the line box model of the inline elements.
This minimum height is composed of the minimum height above the baseline and the minimum depth below the baseline.

As shown in the stolen picture, the four lines from top to bottom are the top line, the middle line, the baseline, and the bottom line.
Then the line height refers to the vertical distance between the baselines of the current line of the context, that is, the vertical distance between the two red lines in the picture (actually, numerically, the line height is also equal to the distance between other same colors).

Another way of thinking is to understand the downward trend.
In fact, in many cases, there is only one row in a container, that is, only one baseline. How is the row height calculated to ensure this spacing?
As follows:

Blue is the scope of the container, and there is a line box between the boundary lines. Text within inline elements.

So,

When line-height > font-size

When a container with a set height is set to a line height, inline meta content The top and bottom will increase the height of 2 blank content. The height of the container will also be expanded so that the height of the container is equal to line-height.

a1 b1 c1 == line-height & a1 == c1

If the height of the container has been set, the part beyond the lower boundary line of the container will not be affected. layout.

When line-height < font-size,

When the height of the container is not specified, the upper and lower sides of the container collapse (similar to the case where margin is a negative value), but the above formula Still established.

a1 (negative value) b1 c1 (negative value) == line-height & a1 == c1

as follows:

The white is the collapsed part (i.e. a1 and c1), and the red is the line-height. If the container is set to overflow:hidden,
then only the red part can be seen.

If the container is specified with height,

height > line-height, then the yellow line will move down and the red part will show more,
height < line-height, then the yellow line will move up, and the red part will be covered more.

So what happens here is,

determines the priority of container height height > line-height > font-size

vertical-align

Vertical alignment line, default is baseline, from W3C definition:

This property affects the vertical positioning inside a line box of the boxes generated by an inline- level element.

This attribute affects the vertical positioning of an inline box model composed of box models generated by multiple inline elements

vertical has several specific value, or specify a value.

<br /><br /><p class="a1">  <span style="vertical-align:60px;">English中文  </span>  <span>中文English  </span></p>

For the first span, set a vertical offset of 60px, as shown below:

Among them, the yellow line is the baseline and the green line The distance from the yellow line is 60px.
Here you will find that the height of the container (blue) is increased.

The height of the container height = line-height vertical-align

Of course, the same is true. If the height of the container is specified, the height will not change, and the height will remain unchanged. Some parts do not affect the layout. If overflow:hidden is set, the excess part will not be visible.

The other special values ​​of vertical-align can be regarded as a relative value that changes according to the height of the container.

Conclusion

Proficiently use the attributes of inline-level elements and inline layout to achieve vertical and horizontal centering effects very quickly, and have good maintainability and scalability.

Reference

W3C IFC
W3C line-height and vertical-aligin
line-height detailed explanation