body {
  margin: 0;
  background: #0a0a0a;
  color: white;
  font-family: system-ui;
}

/* 顶部Banner */
.top-banner {
  position: fixed;
  width: 100%;
  top: 0;
  background: linear-gradient(90deg,#ff3d3d,#ff8c00);
  text-align: center;
  font-size: 18px;
  font-weight: bold;
  padding: 12px;
  z-index: 1000;
}

/* 主体 */
.app {
  padding-top: 80px;
  display: flex;
  flex-direction: column;
  height: 100vh;
}

/* viewer */
.viewer {
  flex: 1;
  display: flex;
  align-items: center;
  justify-content: center;
  position: relative;
}

#main-photo {
  max-width: 92vw;
  max-height: 80vh;
  border-radius: 12px;
}

/* 底部按钮 */
.controls {
  display: flex;
  justify-content: center;
  gap: 20px;
  padding: 15px;
}

button {
  background: #222;
  border: 1px solid #444;
  color: white;
  padding: 10px 20px;
  border-radius: 8px;
  cursor: pointer;
}

button:hover {
  background: #444;
}

/* loader */
.loader {
  position: absolute;
  display: none;
  align-items: center;
  justify-content: center;
}

.spinner {
  width: 40px;
  height: 40px;
  border: 4px solid #333;
  border-top: 4px solid #fff;
  border-radius: 50%;
  animation: spin 1s linear infinite;
}

@keyframes spin {
  to { transform: rotate(360deg); }
}

/* 动画 */
.fade-in {
  animation: fade 0.3s;
}

@keyframes fade {
  from { opacity: 0 }
  to { opacity: 1 }
}

/* 移动端 */
@media (max-width:768px) {
  .top-banner {
    font-size: 16px;
  }

  button {
    flex: 1;
  }
}