The Steemit interface gives a vote slider for minnows only when they are over 500SP.
This is also valid for the downvotes.
There are many other interfaces that provide you this ability but if you are interested how to make one for yourself, this is the correct tutorial.
No requirement, just a text editor ( notepad is fine ) and any internet browser
Basic javascript knowledge and basic HTML knowledge would help.
We need four HTML elements for the vote slider
1- A slider that can take a value between -100 and +100
2- An input box where we will paste the URL of the post or comment that we will upvote or downvote
3- A button to complete the action
4- A message to inform us when the operation is performed
Complete code can be found at GitHub : https://github.com/firedreamgames/upvote_and_downvote_slider/blob/master/upvote_slider.html
An HTML element where we paste the URL we copied from SteemIt.
When the slider value is changed, we send this value to a function ShowValue to display the value selected.
The slider ranges between -100 to +100 allowing downvotes(flags) also.
The button, when presses calls the send_vote() function
Write your Steemit Name without @ and your posting key in the code.
@FireDream - Steemit
@firedream#3528 - Discord
GitHub for tutorial : https://github.com/firedreamgames/upvote_and_downvote_slider