iron-flex-layout demo

#### Horizontal and vertical layout

#### Flexible children

#### Flexible children in vertical layouts

#### Flex ratios

#### Cross-axis stretch alignment (default)

#### Cross-axis center alignment

#### Cross-axis start alignment

#### Cross-axis end alignment

#### Justification, start justified

#### Justification, end justified

#### Justification, equal space between elements

#### Justification, equal space around each element

#### Self alignment

#### Wrapping

#### Reversed layouts

#### General purpose ruls