Doesn’t actually requires adjusting. You can however change default storage size at which Opera will propose increasing limit. It is defined by Domain Quota For localStorage option. It’s value is in kilobytes.
Firefox：
Go to about:config and search for “dom.storage.default_quota” option. It’s value is in kilobytes.
在這個網頁上可以測試各種瀏覽器的最大限制，其中還給出了Firefox最大空間限制設定的方法,如下：
Adjusting quotas
Opera：
Doesn’t actually requires adjusting. You can however change default storage size at which Opera will propose increasing limit. It is defined by Domain Quota For localStorage option. It’s value is in kilobytes.
Firefox：
Go to about:config and search for “dom.storage.default_quota” option. It’s value is in kilobytes.