I had the same problem and the workaround for me was not to have @imports nested. I use SimpLESS 1.4 and Bootstrap 2.1.0 on Win7, and it works if your style.less file looks like this:
// CSS Reset @import "reset.less"; // Core variables and mixins @import "variables.less"; // Modify this for custom colors, font-sizes, etc @import "mixins.less"; // Grid system and page structure @import "scaffolding.less"; @import "grid.less"; @import "layouts.less"; // Base CSS @import "type.less"; @import "code.less"; @import "forms.less"; @import "tables.less"; // Components: common @import "sprites.less"; @import "dropdowns.less"; @import "wells.less"; @import "component-animations.less"; @import "close.less"; // Components: Buttons & Alerts @import "buttons.less"; @import "button-groups.less"; @import "alerts.less"; // Note: alerts share common CSS with buttons and thus have styles in buttons.less // Components: Nav @import "navs.less"; @import "navbar.less"; @import "breadcrumbs.less"; @import "pagination.less"; @import "pager.less"; // Components: Popovers @import "modals.less"; @import "tooltip.less"; @import "popovers.less"; // Components: Misc @import "thumbnails.less"; @import "labels-badges.less"; @import "progress-bars.less"; @import "accordion.less"; @import "bootstrap/carousel.less"; @import "bootstrap/hero-unit.less"; // Utility classes @import "utilities.less"; // Has to be last to override when necessary //Needed if using fixed navbar body { padding-top: 60px; padding-bottom: 40px; } .sidebar-nav { padding: 9px 0; } // RESPONSIVE CLASSES // ------------------ @import "responsive-utilities.less"; // MEDIA QUERIES // ------------------ // Large desktops @import "responsive-1200px-min.less"; // Tablets to regular desktops @import "responsive-768px-979px.less"; // Phones to portrait tablets and narrow desktops @import "responsive-767px-max.less"; // RESPONSIVE NAVBAR // ------------------ // From 979px and below, show a button to toggle navbar contents @import "responsive-navbar.less";
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