html - limit min width of div -

i have div ff css properties:

.header {  width: 100%;  background-color: #1cb14d;  position: fixed; top: 0; left:0; border-bottom: none; z-index: 999;  font-family:'segoe ui light'; color: #ffffff; } 

html:

<div class="header">          <div class="section_container">             <div class="col span_1_of_12">                 //something here             </div>             <div class="col span_1_of_12">                 //something here             </div>             <div class="col span_7_of_12">                 //something here             </div>             <div class="col span_3_of_12">                 //something here             </div>         </div>      </div> 

i want limit min-width of doesn't seem work. need set min-width prevent div covering other contents when browser size adjusted. there way it? thanks

if .header needs have min-width, can add it:

.header { width: 100%; min-width: 200px; }

otherwise, if want section_container have min-width:

.section_container { min-width: 200px; }

this override/add frameworks default min-width if exists