changing the background color ia easy:
set(gca, 'Color', [0.1, 0.1, 0.1])
I cant find a line width property for the gridlines, you can change their line style or color. And if you absolutely must have thick gridlines, you can simply plot them yourself.
plot(1:10);
x = xticks(gca);
y = yticks(gca);
xMinMax = xlim(gca);
yMinMax = ylim(gca);
hold on;
plot([x(:)'; x(:)'], repmat(yMinMax(:), 1, numel(x)), 'k-', 'LineWidth', 1);
plot(repmat(xMinMax(:), 1, numel(y)), [y(:)'; y(:)'], 'k-', 'LineWidth', 1);
Off point, i wouldn't want tomake thick gridlines, because that would make it harder to read your plot,unless you are
