The following Sassy CSS block is filled weirdly by SCSS mode when pressing `M-q' at the beginning of the block: @media #{$medium} { background: #f0f0f0; } Is filled to: @media #{ $medium } { background: #f0f0f0; } As a more complicated example, the following: @mixin firefox-message($selector) { body.firefox #{$selector}:before { content: "Hi, Firefox users!"; } } Is filled to: @mixin firefox-message($selector) { body.firefox #{ $selector }:before { content: "Hi, Firefox users!"; } } There seems to be an error with how SCSS mode does filling when interpolated variables are involved, misinterpreting it as an ordinary block. In GNU Emacs 25.0.50.9 (x86_64-unknown-linux-gnu, GTK+ Version 3.14.5) of 2015-02-02 on x240 Repository revision: c10828bd8520db83cc06a2ad5de6f8a1ad74b83c Windowing system distributor `The X.Org Foundation', version 11.0.11602901 System Description: Debian GNU/Linux 8.0 (jessie) Configured using: `configure --without-makeinfo' Configured features: XPM JPEG TIFF GIF PNG SOUND DBUS GSETTINGS NOTIFY LIBXML2 FREETYPE XFT ZLIB Important settings: value of $LANG: en_US.UTF-8 locale-coding-system: utf-8-unix Major mode: Lisp Interaction Minor modes in effect: tooltip-mode: t global-eldoc-mode: t electric-indent-mode: t mouse-wheel-mode: t tool-bar-mode: t menu-bar-mode: t file-name-shadow-mode: t global-font-lock-mode: t font-lock-mode: t blink-cursor-mode: t auto-composition-mode: t auto-encryption-mode: t auto-compression-mode: t line-number-mode: t Recent messages: For information about GNU Emacs and the GNU system, type C-h C-a. Load-path shadows: None found. Features: (shadow sort gnus-util mail-extr emacsbug message dired format-spec rfc822 mml easymenu mml-sec mm-decode mm-bodies mm-encode mail-parse rfc2231 mailabbrev gmm-utils mailheader sendmail rfc2047 rfc2045 ietf-drums mm-util help-fns mail-prsvr mail-utils time-date tooltip eldoc electric uniquify ediff-hook vc-hooks lisp-float-type mwheel x-win x-dnd tool-bar dnd fontset image regexp-opt fringe tabulated-list newcomment elisp-mode lisp-mode prog-mode register page menu-bar rfn-eshadow timer select scroll-bar mouse jit-lock font-lock syntax facemenu font-core frame cham georgian utf-8-lang misc-lang vietnamese tibetan thai tai-viet lao korean japanese hebrew greek romanian slovak czech european ethiopic indian cyrillic chinese case-table epa-hook jka-cmpr-hook help simple abbrev minibuffer cl-preloaded nadvice loaddefs button faces cus-face macroexp files text-properties overlay sha1 md5 base64 format env code-pages mule custom widget hashtable-print-readable backquote make-network-process dbusbind gfilenotify dynamic-setting system-font-setting font-render-setting move-toolbar gtk x-toolkit x multi-tty emacs) Memory information: ((conses 16 75204 8420) (symbols 48 17974 0) (miscs 40 50 149) (strings 32 10960 3858) (string-bytes 1 296445) (vectors 16 9363) (vector-slots 8 386521 15780) (floats 8 70 103) (intervals 56 176 1) (buffers 976 11) (heap 1024 32725 968))