.sub-header {
      background: url("../images/club.JPG") center/cover no-repeat;
      /* ↑ 適宜、コース写真に差し替えてください */
      padding: 80px 16px 60px;
      text-align: center;
      color: #fff;
      position: relative;
      margin-top: 75px;
    }

    .sub-header::before {
      content: "";
      position: absolute;
      inset: 0;
      background: rgba(0, 0, 0, 0.35);
    }

    .sub-header .inner {
      position: relative;
      max-width: 960px;
      margin: 0 auto;
    }

    .sub-header h1 {
      font-size:clamp(1.75rem,5vw,2rem);
      line-height:1.3;
      font-weight:600;
      letter-spacing:.05em;
      text-shadow:0 2px 4px rgba(0,0,0,.4);
    }

    .sub-header p {
      margin-top: 1rem;
      font-size: 1rem;
    }
    @media (max-width: 640px) {
      .sub-header {
        padding: 64px 12px 48px;
      }

      .sub-header h1 {
        font-size: 20px;
      }
    }