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Is it possible to change only the alpha of a rgba background colour on hover?

... { display: block; position: relative; } div { position: absolute; bottom: 0; background-color: rgba(var(--rgb), 0.8); } a:hover div { background-color: rgba(var(--rgb), 1); } To understand how this works, see How do I apply opacity to a CSS color variable? If custom properties are not an option,...
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Regex how to match an optional character

...e letter optional. {1} is redundant. (Of course you could also write [A-Z]{0,1} which would mean the same, but that's what the ? is there for.) You could improve your regex to ^([0-9]{5})+\s+([A-Z]?)\s+([A-Z])([0-9]{3})([0-9]{3})([A-Z]{3})([A-Z]{3})\s+([A-Z])[0-9]{3}([0-9]{4})([0-9]{2})([0-9]{2}) ...
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HTML5 Pre-resize images before uploading

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Relative frequencies / proportions with dplyr

...n = n()) %>% mutate(freq = n / sum(n)) # am gear n freq # 1 0 3 15 0.7894737 # 2 0 4 4 0.2105263 # 3 1 4 8 0.6153846 # 4 1 5 5 0.3846154 From the dplyr vignette: When you group by multiple variables, each summary peels off one level of the grouping. That makes ...
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Providing white space in a Swing GUI

... +200 Using various LayoutManagers one can provide spacing between various components. 1.) BorderLayout : Overloaded Constructor : Bor...
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How to determine if a point is in a 2D triangle? [closed]

... d2 = sign(pt, v2, v3); d3 = sign(pt, v3, v1); has_neg = (d1 < 0) || (d2 < 0) || (d3 < 0); has_pos = (d1 > 0) || (d2 > 0) || (d3 > 0); return !(has_neg && has_pos); } share ...
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Disable/turn off inherited CSS3 transitions

..." class="transition">Content</a> ...and CSS: a { color: #f90; -webkit-transition:color 0.8s ease-in, background-color 0.1s ease-in ; -moz-transition:color 0.8s ease-in, background-color 0.1s ease-in; -o-transition:color 0.8s ease-in, background-color 0.1s ease-in; ...
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What is a regular expression for a MAC Address?

... The standard (IEEE 802) format for printing MAC-48 addresses in human-friendly form is six groups of two hexadecimal digits, separated by hyphens - or colons :. So: ^([0-9A-Fa-f]{2}[:-]){5}([0-9A-Fa-f]{2})$ ...
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Best way to make Java's modulus behave like it should with negative numbers?

...the negative values of a, since (a % b) is a negative value between -b and 0, (a % b + b) is necessarily lower than b and positive. The last modulo is there in case a was positive to begin with, since if a is positive (a % b + b) would become larger than b. Therefore, (a % b + b) % b turns it into s...
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How do I generate random numbers in Dart?

...h: import 'dart:math'; main() { var rng = new Random(); for (var i = 0; i < 10; i++) { print(rng.nextInt(100)); } } This code was tested with the Dart VM and dart2js, as of the time of this writing. share ...