Try <input type="number" step="any" />
It won’t have validation problems and the arrows will have step of “1”
Constraint validation: When the element has an allowed value step, and
the result of applying the algorithm to convert a string to a number
to the string given by the element’s value is a number, and that
number subtracted from the step base is not an integral multiple of
the allowed value step, the element is suffering from a step mismatch.The following range control only accepts values in the range 0..1, and
allows 256 steps in that range:
<input name=opacity type=range min=0 max=1 step=0.00392156863>The
following control allows any time in the day to be selected, with any
accuracy (e.g. thousandth-of-a-second accuracy or more):
<input name=favtime type=time step=any>Normally, time controls are
limited to an accuracy of one minute.
http://www.w3.org/TR/2012/WD-html5-20121025/common-input-element-attributes.html#attr-input-step