document.getElementById("diagnosisBtn").addEventListener("click", function () {
  const f = document.getElementById("diagnosisForm");

  const q = n => f[n] ? f[n].value : null;

  const q1 = q("q1");
  const q2 = q("q2");
  const q3 = q("q3");
  const q4 = q("q4");
  const q5 = q("q5");
  const q6 = q("q6");
  const q7 = q("q7");

  if (!q1 || !q2 || !q3 || !q4 || !q5 || !q6 || !q7) {
    alert("すべての質問にお答えください。");
    return;
  }

  let target = "";

  // 前傾
  if (q1 === "A" && (q4 === "A" || q6 === "A")) {
    target = "/kotsuban-zengkei/";
  }
  // 後傾
  else if (q2 === "A" && q6 === "B") {
    target = "/kotsuban-koukei/";
  }
  // 左右差
  else if (q3 === "A" || q7 === "A") {
    target = "/kotsuban-sayusa/";
  }
  // ねじれ
  else {
    target = "/kotsuban-nejire/";
  }

  window.location.href = target;
});