left boxes style width has no parameter if BOX_WIDTH_LEFT not set

If in Admin->Layout Settings->Column Width - Left Boxes (BOX_WIDTH_LEFT) has no value, neither does $column_width and so tp_box_default_left.php

<div class="leftBoxContainer" id="<?php echo str_replace('_', '-', $box_id ); ?>" style="width: <?php echo $column_width; ?>">

produces

"style=width:"

I have no value at the moment while playing with a responsive layout.

I assume this is the same for the right.

I did this

( $column_width == '' ) ? $style_width = '' : $style_width = ' style="width:' . $column_width . '"'; 

<div class="leftBoxContainer" id="<?php echo str_replace('_', '-', $box_id ); ?>"<?php echo $style_width; ?>>

Perhaps set to 100%.

In my responsive template, I set negative margins (which does the reverse of positive margins) as a percentage for each of the side columns.

Actually, in my responsive template, I removed the section of code for style="width..." in two php files, but cannot recall exactly what I did as I am not at my developer computer atm.

The following applies to 3-column site, left col width = right col width. Centre column has no prescribed width as it flexes.
The footer always sits at bottom of screen unless pushed down further by content (see margin-left and margin-right css settings)
As left and right column workings are same, for brevity only left column workings are shown.

A. admin > configuration > layout settings

Column Width - Left 	26%
Column Width - Right 	26%

Note 1: both settings are superfluous (could be blank) as now controlled by css

B. includes\templates\MY_TEMPLATE\common\tpl_box_default_left.php

<!--// bof: <?php echo $box_id; ?> //-->
<div class="leftBoxContainer" id="<?php echo str_replace('_', '-', $box_id ); ?>" style="width: <?php echo $column_width; ?>">

replaced by responsive code

<!--// bof: <?php echo $box_id; ?> //-->
<?php if (COLUMN_WIDTH == '0'){ ?>
<div class="leftBoxContainer" id="<?php echo str_replace('_', '-', $box_id ); ?>" style="width: <?php echo $column_width; ?>">
<?php } else { ?>
<div class="leftBoxContainer <?php echo $minWidthHide; ?>" id="<?php echo str_replace('_', '-', $box_id ); ?>">
<?php } ?>

C. includes\templates\MY_TEMPLATE\common\tpl_main_page.php

if (!isset($flag_disable_left) || !$flag_disable_left) {
?>
  <td id="navColumnOne" class="columnLeft" style="width: <?php echo COLUMN_WIDTH_LEFT; ?>">
<?php
 /**
  * prepares and displays left column sideboxes
  *
  */
?>
<div id="navColumnOneWrapper" style="width: <?php echo BOX_WIDTH_LEFT; ?>"><?php require(DIR_WS_MODULES . zen_get_module_directory('column_left.php')); ?></div></td>
<?php
}
?>

replaced by

if (!isset($flag_disable_left) || !$flag_disable_left) {
?>
  <div id="navColumnOne" class="columnLeft"> <!-- removed style="width: <?php echo COLUMN_WIDTH_LEFT; ?>"-->
    <div id="navColumnOneWrapper" style="width: <?php echo BOX_WIDTH_LEFT; ?>"><?php require(DIR_WS_MODULES . zen_get_module_directory('column_left.php')); ?></div>
  </div>
<?php } ?>
```Note 2: COLUMN_WIDTH_LEFT width setting now in stylesheet.css and responsive.css as width: under id=navColumnOne 

D. includes\templates\MY_TEMPLATE\css\stylesheet.css

#navColumnOne {
position:relative; /* ie needs this to show float /
width:26%; / this is the COLUMN_WIDTH_LEFT setting /
float:left;
margin-left:-26%; / must be same as width /
margin-right:1px; / makes element 1px smaller than width otherwise won't push footer down */
padding-top:1.5em;
padding-bottom:1em;
z-index:1;
}

.columnLeft {/* width:26%; / / see #navColumnOne /} / this is superfluous, should be deleted */

Note 3: class="columnLeft" in stylesheet.css is superfluous, should be deleted

E. includes\templates\MY_TEMPLATE\css\responsive.css

#navColumnOne {
float:left; /* only for smallest screen size, otherwise delete this /
width:10%;%; / this is the COLUMN_WIDTH_LEFT setting /
margin-left:-10%; / must be same as width */
}

Note 4: /* settings vary depending on screen size*/

.columnLeft { display:none; } /* only used to turn off sideboxes on small screens */

Note 5: class="columnLeft" in responsive.css only ever contains display:none for small screen sizes

Many thanks for taking the time to detail this....I will attempt to find a quiet/kid-free darkened room over the weekend where I can assimilate this!