Notes

The Box Model

• Box Model : A concept that basically boils down that every DOM element has a box around it.

Imagine a gift, inside is the gift, wrapped in foam all around (padding), and the giftbox outside of it (border) and then a wrapping paper on the giftbox (margin).

• For items that are using block as it’s display, the browser will follow these rules to layout the element:
  • The box fills 100% of the available container space.
  • Every new box takes on a new line/row.
  • Width and Height properties are respected.
  • Padding, Margin, and Border will push other elements away from the box.

• Certain elements have block as their default display, such as: divs, headers, and paragraphs.

• For items that are using inline as it’s display, the browser will follow these rules to layout the element:
  • Each box appears in a single line until it fills up the space.
  • Width and height are not respected.
  • Padding, Margin, and Border are applied but they do not push other elements away from the box.

• Certain elements have inline as their default display, such as: span tags, anchors, and images.

Standard Box Model vs Border-Box

• As per the standard Box Model, the width and height pertains to the content of the box and excludes any additional padding, borders, and margins.

• This bothered many programmers so they created the border box to include the calculation of the entire box’s height and width.

Inline-Block

• Inline-block uses the best features of both block and inline.
  • Elements still get laid out left to right.
  • Layout takes into account specified width and height.

Padding

• Padding applies padding to every side of a box. It is shorthand for four padding properties in this order: padding-top, padding-right, padding-bottom, padding-left (clockwise!)

Border

• Border applies a border on all sides of an element. It takes three values in this order: border-width, border-style, border-color.
• All three properties can be broken down in the four sides clockwise: top, right, bottom, left.

Margin

• Margin sets margins on every side of an element. It takes four values in this order: margin-top, margin-right, margin-bottom, margin-left.
• You can use margin: 0 auto to center an element.

Positioning

• The position property allows us to set the position of elements on a page and is an integral part of creatnig a Web page layout.
• It accepts five values: static, relative, absolute, fixed, sticky.
• Every property (minus static) is used with: top, right, bottom, and left to position an element on a page.

Static Positioning

• The default position value of page elements.
• Most likely will not use static that much.

Relative Positioning

• Remains in it’s original position in the page flow.
• It is positioned RELATIVE to the it’s ORIGINAL PLACE on the page flow.
• Creates a stacking context : overlapping elements whose order can be set by the z-index property.

#pink-box {
  background-color: #ff69b4;
  bottom: 0;
  left: -20px;
  position: relative;
  right: 0;
  top: 0;
}

Absolute Positioning

• Absolute elements are removed from the normal page flow and other elements around it act like it’s not there. (how we can easily achieve some layering)
• Here are some examples to illustration absolute positioning:

.container {
  background-color: #2b2d2f;
  position: relative;
}

#pink-box {
  position: absolute;
  top: 60px;
}

• Note that the container ele has a relative positioning - this is so that any changes made to the absolute positioned children will be positioned from it’s top-left corner.
• Note that because we removed the pink from the normal page flow, the container has now shifted the blue box to where the pink box should have been - which is why it is now layered beneath the pink.

.container {
  background-color: #2b2d2f;
  position: relative;
}

#pink-box {
  position: absolute;
  top: 60px;
}

#blue-box {
  position: absolute;
}

• As you can see here, since we have also taken the blue box out of the normal page flow by declaring it as absoutely positioned it now overlaps over the pink box.

.container {
  background-color: #2b2d2f;
  position: relative;
}

#pink-box {
  background-color: #ff69b4;
  bottom: 60px;
  position: absolute;
}

• Example where the absolute element has it’s bottom property modified.

.container {
  background-color: #2b2d2f;
}

#pink-box {
  background-color: #ff69b4;
  bottom: 60px;
  position: absolute;
}

• If we removed the container’s relative position. Our absolute unit would look for the nearest parent which would be the document itself.

Fixed Positioning

• Another positioning that removes it’s element from the page flow, and automatically positions it’s parent as the HTML doc itself.
• Fixed also uses top, right, bottom, and left.
• Useful for things like nav bars or other features we want to keep visible as the user scrolls.

Sticky Positioning

• Remains in it’s original position in the page flow, and it is positioned relative to it’s closest block-level ancestor and any scrolling ancestors.
• Behaves like a relatively positioned element until the point at which you would normally scroll past it’s viewport - then it sticks!
• It is positioned with top, right, bottom, and left.
• A good example are headers in a scrollable list.

Flexible Box Model

• Flexbox is a CSS module that provides a convenient way for us to display items inside a flexible container so that the layout is responsive.

• Float was used back in the day to display position of elements in a container.
  • A very inconvenient aspect of float is the need to clear the float.
  • To ‘clear’ a float we need to set up a ghost div to properly align - this is already sounds so inefficient.

Using Flexbox

• Flexbox automatically resizes a container element to fit the viewport size without needing to use breakpoints.

• Flexbox layout applies styles to the parent element, and it’s children.

.container {
  display: flex; /*sets display to use flex*/
  flex-wrap: wrap; /*bc flex tries to fit everything into one line, use wrap to have the elements wrap to the next line*/
  flex-direction: row; /*lets us create either rows or columns*/
}

• flex-flow can be used to combine wrap and direction.
• justify-content used to define the alignment of flex items along the main axis.
• align-items used to define the alignment on the Y-axis.

• align-content redistributes extra space on the cross axis.

• By default, flex items will appear in the order they are added to the DOM, but we can use the order property to change that.

• Some other properties we can use on flex items are:
  • flex-grow : dictates amount of avail. space the item should take up.
  • flex-shrink : defines the ability for a flex item to shrink.
  • flex-basis : Default size of an element before the remaining space is distributed.
  • flex : shorthand for grow, shrink and basis.
  • align-self : Overrides default alignment in the container.

Grid Layout

• CSS Grid is a 2d layout system that let’s use create a grid with columns and rows purely using Vanilla CSS. (flex is one dimensional)

Bootstrap vs CSS Grid

• Bootstrap was a front-end library commonly used to create grid layouts but now CSS grid provides greater flexibility and control.
• Grid applies style to a parent container and it’s child elements.

.grid-container {
  display: grid;
  grid-template-columns: repeat(3, 1fr);
  grid-template-rows: auto;
  grid-template-areas:
    "header header header"
    "main . sidebar"
    "footer footer footer";

  grid-column-gap: 20px;
  grid-row-gap: 30px;
  justify-items: stretch;
  align-items: stretch;
  justify-content: stretch;
  align-content: stretch;
}

.item-1 {
  grid-area: header;
}
.item-2 {
  grid-area: main;
}
.item-3 {
  grid-area: sidebar;
}
.item-4 {
  grid-area: footer;
}

• Columns and Rows can be defined with: pixels, percentages, auto, named grid lines, using repeat, fractions.
• Grid Template Areas gives us a handy way to map out and visualize areas of the grid layout.
• Combine areas with templates to define how much space an area should take up.

• Grid Gaps can be used to create ‘gutters’ between grid item.s

• The way we have defined our grid with grid-templates and areas are condidered explicit.

• We can also implicitly define grids.

.grid-container {
  display: grid;
  grid-template-columns: 100px 100px 100px 100px;
  grid-template-rows: 50px 50px 50px;
  grid-auto-columns: 100px;
  grid-auto-rows: 50px;
}

• Any grid items that aren’t explicity placed are automatically placed or re-flowed

Spanning Columns & Rows

• We can use the following properties to take up a specified num of cols and rows.

  • grid-column-start
  • grid-column-end
  • grid-row-start
  • grid-row-end

• All four properties can take any of the following values: the line number, span #, span name, auto.

.item-1 {
  grid-row-start: row2-start; /* Item starts at row line named "row2-start" */
  grid-row-end: 5; /* Item ends at row line 5 */
  grid-column-start: 1; /* Item starts at column line 1 */
  grid-column-end: three; /* Item ends at column line named "three" */
}

.item-2 {
  grid-row-start: 1; /* Item starts at row line 1 */
  grid-row-end: span 2; /* Item spans two rows and ends at row line 3 */
  grid-column-start: 3; /* Item starts at column line 3 */
  grid-column-end: span col5-start; /* Item spans and ends at line named "col5-start" */
}

Grid Areas

• We use the grid areas in conjunction with grid-container property to define sections of the layout.
• We can then assign named sections to individual element’s css rules.

Justify & Align Self

• Justify items and Align Items can be used to align all grid items at once.

• Justify Self is used to align self on the row.

  • It can take four values: start, end, center, stretch.
• Align Self is used to align self on the column.
  • It can take four values: start, end, center, stretch.