function calcBK(){var t50=parseFloat(document.getElementById("t50").value)||40;var glide=parseFloat(document.getElementById("glide").value)||4;var kick_time=t50-(glide+5);var kick_pct=Math.round((kick_time/t50)*100);var rating=kick_pct>55?"Efficient kick":kick_pct>45?"Average — room for improvement":"Below average";var glide_rating=glide<3?"Too short":glide>6?"Good long glide":"Optimal";document.getElementById("r1").textContent=kick_pct+"% kick";document.getElementById("r2").textContent=glide_rating;document.getElementById("desc").innerHTML="50m breaststroke: "+t50+"s
Kick accounts for "+kick_pct+"% of total time
"+rating+"
Key tips: Ankles flexed outward, heels together at finish, streamline immediately after.";document.getElementById("results").style.display="block";}