I am trying to modify the font attributes (weight, color, etc) of a jupyter label widget in python 2.7. As an example, I have tried the following:
import ipywidgets as widgets myLabel= widgets.Label(value = 'Some Label',color = '#ff0000') #change font color to red myLabel When I run this bit of code, I get no errors, however the label color remains the default black.
There are 2 methods that I know of.
text = 'Some text' htmlWidget = widgets.HTML(value = f"<b><font color='red'>{text}</b>") labelWidget = widgets.Label(value = r'\(\color{red} {' + text + '}\)') 
Update: and now with Ipyvuetify....
import ipyvuetify as v text = 'Some text' v.Html(tag="div", children=[text], style_ = "color: red; font-weight: bold") 
htmlWidget = widgets.HTML(value = f"<b><font color='red'><font size=10>{text}</b>"). This appears to be measured in pixels. Note that increasing this font size will probably saturate a global layout bound. E.g. you might ask for font size=100 but it still looks like font size=10.
HTML(value= r'<p style="font-size:24px"><b>My Title</b></p>)This is a late reply, but for everyone who's still having this issue, you can add styling to the widget labels and description by using latex formatting. Here's an example to color the label text in red:
myLabel= widgets.Label(value = r'\(\color{red} {highlighted}\)') There are limitations with both the HTML widget (can't be aggregated in a collection, e.g. VBox, Hbox, Tab), and the use of LaTeX formating inside a label (will format as an equation - which is typically not what is wanted).
A way to overcome both these limitations, is to use the add_class method of the widget, to allow you to create any CSS styling:
from ipywidgets import Label from IPython.display import display, HTML display(HTML("<style>.red_label { color:red }</style>")) l = Label(value="My Label") l.add_class("red_label") display(l) 
widgets.HTML class can be aggregated in a collection. I found this out struggling with a similar issue.one of the developers of the widgets says here that all the layout options shall be done in the layout attribute.
Currently i am exploring the capabilities of this attribute, but there seems to be no way to change font, font color or font size.
It may be that you have to write your own css file.
If the label was using a specific element of HTML, which it doesn't, you could use
import IPython import ipywidgets as widgets IPython.display.HTML('<style> widget-label { color: red; } </style>') myLabel= widgets.Label(value = 'Some Label') ; myLabel However widget-label is not an element but a CSS class in this case, therefore the above code doesn't work. Hence, the option given by @AlanDyke is the next best one, either using the class it already has.
import IPython import ipywidgets as widgets IPython.display.HTML('<style> .widget-label { color: red; } </style>') myLabel= widgets.Label(value = 'Some Label') myLabel Note: In google-colab you must replace IPython.display.HTML ... with display(HTML('<style> .widget-label { color: red; } </style>')).
Alternatively, creating a new one and attaching it.
import IPython import ipywidgets as widgets #IPython.display.HTML('<style> .widget-label, .redlabel { color: red; } </style>') IPython.display.HTML('<style> .redlabel { color: red; } </style>') myLabel= widgets.Label(value = 'Some Label') ; myLabel.add_class('redlabel'); myLabel 
For similar question see https://stackoverflow.com/a/70228454/4752223
I'm not sure if this will work for the original question in Python 2.7, but since this is one of the first search results for styling ipywidgets:
In recent versions of ipywidgets, some style properties can be set with the style attribute. For example, for Labels: ipywidgets.widgets.widget_string.LabelStyle
