[ticket/12126] Fixed position of alert box in IE

PHPBB3-12126
[ticket/12126] Changed .phpbb_alert "max-width: 640px" to "width: 620px"

PHPBB3-12126
[ticket/9255] Added max-height and overflow-x to cp-mini in cp.css

PHPBB3-9255
[ticket/9255] Changed overflow-x to overflow-y

PHPBB3-9255
[ticket/12126] left:0 and right: 0; admin.css --> width: auto

PHPBB3-12126
[ticket/12126] deleted left:0 and right:0 in responsive.css .phpbb_alert

PHPBB3-12126
Merge remote-tracking branch 'Crizz0/ticket/12126' into develop

* Crizz0/ticket/12126:
  [ticket/12126] deleted left:0 and right:0 in responsive.css .phpbb_alert
  [ticket/12126] left:0 and right: 0; admin.css --> width: auto
  [ticket/12126] Changed .phpbb_alert "max-width: 640px" to "width: 620px"
  [ticket/12126] Fixed position of alert box in IE
Merge remote-tracking branch 'Crizz0/ticket/9255' into develop

* Crizz0/ticket/9255:
  [ticket/9255] Changed overflow-x to overflow-y
  [ticket/9255] Added max-height and overflow-x to cp-mini in cp.css