/** Horizontal shell geometry shared by every classic surface. */
export declare function horizontalPadding(columns: number): number;
/** Width available between the shell's left and right terminal margins. */
export declare function innerShellWidth(columns: number): number;
/** Columns reserved at the right screen edge for the scrollbar gutter. */
export declare const SCROLLBAR_GUTTER_COLS = 1;
/**
 * Content width with the scrollbar gutter parked in the right shell margin:
 * the gutter takes one column of the right padding (or one content column on
 * narrow screens), leaving a gap between the content and the track.
 */
export declare function gutterShellWidth(columns: number): number;