グラデーション＋シャドウボタン

<div class="push-button_box">
  <a href="#" class="push-button gradient-modern">今すぐ始める</a>
</div>

.push-button_box{
  width:30%;
  margin:50px auto;
}

.push-button.gradient-modern {
  display: inline-block;
  width: 100%;
  max-width: 280px;
  padding: 14px 0;
  background: linear-gradient(135deg, #43cea2 0%, #185a9d 100%);
  color: white;
  font-weight: 600;
  font-size: 16px;
  text-align: center;
  text-decoration: none;
  border-radius: 8px;
  box-shadow: 0 6px 20px rgba(102, 126, 234, 0.3);
  transition: transform 0.2s ease, box-shadow 0.2s ease;
}

.push-button.gradient-modern:hover {
  transform: translateY(-3px);
  box-shadow: 0 8px 24px rgba(102, 126, 234, 0.4);
}