Build a CSS fractural grid.

fractural-grid.php

<?php


/**
 * Build a CSS fractural grid.
 *
 * @var (int) $columns, Amount of columns, 10 columns means 10 columns of 10% width
 * @var (string) $prefix, Classname prefix
 */

function grid($columns = 12, $prefix = ".col-", $suffix = "") {

    $decimals = 3; // Amount of decimals
    $out = '';
    $array = array();

    // Group by value
    foreach (range(1, $columns) as $range) {
        foreach (range(1, $range) as $not_used => $step) {
            $width = (string) floorDec( 100 / $range * $step, $decimals);
            $classname = $prefix . $step . "-" . $range . $suffix;
            $array[$width][] = $classname;
        }
    }
    ksort($array, SORT_NUMERIC);

    foreach ($array as $width => $classname) {
        $out .= implode(", ", $classname) . '';
        $out .= " { width: " . $width . "%; }\n";
    }

    return $out;
}


/**
 * Floor with decimals by using the round() and substract an half.
 * - Substract (0.05) for 1 decimal
 * - Substract (0.0005) for 3 decimals etc.
 */

function floorDec($input, $decimals) {
    return round($input - (5 / pow(10, $decimals + 1)), $decimals);
}