 | split:'x' -%}
                {%- assign w = dims[0] | strip -%}
                {%- assign h = dims[1] | default: '' | strip -%}
            {%- elsif dim_spec contains '=' -%}
                {%- assign kvs = dim_spec | split:',' -%}
                {%- for kv in kvs -%}
                    {%- assign pair = kv | split:'=' -%}
                    {%- assign k = pair[0] | strip | downcase -%}
                    {%- assign v = pair[1] | default: '' | strip -%}
                    {%- if k == 'w' -%}
   