.btn{display:block;width:100%;padding:12px;background-color:#3f51b5;color:#fff;border:none;border-radius:4px;font-size:16px;font-weight:500;cursor:pointer;transition:background-color 0.2s ease;text-align:center;}.btn:hover{background-color:#303f9f;}.btn:active{background-color:#1a237e;}.btn:disabled{background-color:#bdbdbd;cursor:not-allowed;}.btn-outline{background-color:transparent;border:1px solid #3f51b5;color:#3f51b5;}.btn-outline:hover{background-color:rgba(63,81,181,0.08);}.btn.loading{position:relative;color:transparent;}.btn.loading::after{content:"";position:absolute;width:20px;height:20px;top:calc(50% - 10px);left:calc(50% - 10px);border:2px solid #fff;border-radius:50%;border-top-color:transparent;animation:btn-loading 0.8s linear infinite;}@keyframes btn-loading{to{transform:rotate(360deg);}}.social-login{display:flex;justify-content:center;gap:16px;margin-top:16px;}.social-login-btn{width:40px;height:40px;border-radius:50%;border:1px solid #e0e0e0;background-color:#fff;color:#555;font-size:18px;display:flex;align-items:center;justify-content:center;cursor:pointer;transition:all 0.2s ease;}.social-login-btn:hover{transform:translateY(-2px);box-shadow:0 2px 8px rgba(0,0,0,0.1);}.social-login-btn.wechat{color:#07C160;}.social-login-btn.qq{color:#12B7F5;}.social-login-btn.weibo{color:#E6162D;}@media screen and (max-width:768px){.btn{padding:10px;}}@media screen and (max-width:480px){.btn{font-size:14px;}}