/* 按钮基础样式 */
.btn {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  padding: 8px 20px;
  font-size: 0.875rem;
  font-weight: 500;
  border-radius: 8px;
  cursor: pointer;
  gap: 0.625rem;
  position: relative;
  overflow: hidden;
  transform: translateZ(0);
  transition: all var(--duration-normal) var(--ease-out);
  text-decoration: none;
  -webkit-tap-highlight-color: transparent;
  user-select: none;
  background: var(--button-bg);
  color: var(--fg);
  border: 1px solid var(--border-subtle);
  min-height: 38px;
  min-width: 80px;
  white-space: nowrap;
  backdrop-filter: blur(8px);
}

.btn::before {
  content: '';
  position: absolute;
  inset: 0;
  background: currentColor;
  opacity: 0;
  transition: all var(--duration-normal) var(--ease-out);
  transform: scale(0.8);
  border-radius: inherit;
}

.btn:hover {
  transform: translateY(calc(var(--slide-small) * -1));
  box-shadow: 0 var(--slide-small) var(--slide-normal) rgba(0, 0, 0, 0.2);
}

.btn:hover::before {
  opacity: 0.1;
  transform: scale(1);
}

.btn:active {
  transform: translateY(0);
  transition-duration: var(--duration-fast);
  box-shadow: none;
}

.btn:active::before {
  opacity: 0.15;
  transform: scale(0.95);
}

.btn svg {
  transition: all var(--duration-normal) var(--ease-bounce);
  transform-origin: center;
}

.btn:hover svg {
  transform: scale(1.15) rotate(5deg);
  filter: drop-shadow(0 2px 4px rgba(0, 0, 0, 0.2));
}

.btn:active svg {
  transform: scale(0.95) rotate(0deg);
  transition-duration: var(--duration-fast);
}

/* 主要按钮 - 强调样式 */
.btn.primary {
  background: linear-gradient(135deg, var(--btn-primary-bg) 0%, var(--btn-primary-active) 100%);
  color: var(--btn-primary-fg);
  border: none;
  padding: 10px 24px;
  font-weight: 600;
  letter-spacing: 0.01em;
  box-shadow: 
    0 2px 8px rgba(0, 0, 0, 0.15),
    0 0 0 1px rgba(255, 255, 255, 0.1) inset;
  text-shadow: 0 1px 1px rgba(0, 0, 0, 0.1);
}

.btn.primary:hover {
  background: linear-gradient(135deg, var(--btn-primary-hover) 0%, var(--btn-primary-bg) 100%);
  box-shadow: 
    0 4px 12px rgba(0, 0, 0, 0.2),
    0 0 0 1px rgba(255, 255, 255, 0.15) inset;
  transform: translateY(-3px);
}

.btn.primary:active {
  background: var(--btn-primary-active);
  box-shadow: 
    0 2px 4px rgba(0, 0, 0, 0.1),
    0 0 0 1px rgba(255, 255, 255, 0.05) inset;
  transform: translateY(-1px);
}

/* 次要按钮 */
.btn.secondary {
  background: var(--btn-secondary-bg);
  color: var(--btn-secondary-fg);
  border: 1px solid var(--border-subtle);
  backdrop-filter: blur(8px);
}

.btn.secondary:hover {
  background: var(--btn-secondary-hover);
  border-color: var(--border-hover);
}

.btn.secondary:active {
  background: var(--btn-secondary-active);
  border-color: var(--border-active);
}

/* 轮廓按钮 */
.btn.outline {
  background: var(--btn-outline-bg);
  color: var(--btn-outline-fg);
  border: 1.5px solid var(--btn-outline-border);
  font-weight: 500;
}

.btn.outline:hover {
  background: var(--btn-outline-hover);
  border-color: var(--btn-primary-bg);
  color: var(--btn-primary-bg);
}

.btn.outline:active {
  background: var(--btn-outline-active);
  border-color: var(--btn-primary-active);
  color: var(--btn-primary-active);
}

/* 危险按钮 */
.btn.danger {
  background: var(--btn-danger-bg);
  color: var(--btn-danger-fg);
  border: none;
  font-weight: 500;
}

.btn.danger:hover {
  background: var(--btn-danger-hover);
  box-shadow: 0 4px 12px rgba(220, 38, 38, 0.2);
}

.btn.danger:active {
  background: var(--btn-danger-active);
  box-shadow: 0 2px 4px rgba(220, 38, 38, 0.1);
}

/* 禁用状态 */
.btn:disabled,
.btn.disabled {
  opacity: 0.5;
  cursor: not-allowed;
  pointer-events: none;
  box-shadow: none !important;
  transform: none !important;
}

.btn:disabled::before,
.btn.disabled::before {
  display: none;
}

/* 加载状态 */
.btn.loading {
  cursor: wait;
  pointer-events: none;
}

.btn.loading::after {
  content: '';
  width: 16px;
  height: 16px;
  border: 2px solid currentColor;
  border-right-color: transparent;
  border-radius: 50%;
  animation: btn-spin 0.75s linear infinite;
  margin-left: 8px;
}

.btn.loading.icon::after {
  position: absolute;
  margin: 0;
}

@keyframes btn-spin {
  from {
    transform: rotate(0deg);
  }
  to {
    transform: rotate(360deg);
  }
}

/* 图标按钮 */
.btn.icon {
  padding: 8px;
  min-width: 38px;
  width: 38px;
  height: 38px;
  border-radius: 8px;
  display: inline-flex;
  align-items: center;
  justify-content: center;
}

.btn.icon svg {
  width: 20px;
  height: 20px;
}

/* 按钮大小变体 */
.btn.sm {
  padding: 6px 16px;
  min-height: 32px;
  min-width: 64px;
  font-size: 0.75rem;
  border-radius: 6px;
  gap: 0.5rem;
}

.btn.sm.icon {
  padding: 6px;
  min-width: 32px;
  width: 32px;
  height: 32px;
}

.btn.sm.icon svg {
  width: 16px;
  height: 16px;
}

.btn.lg {
  padding: 12px 28px;
  min-height: 44px;
  min-width: 96px;
  font-size: 1rem;
  border-radius: 10px;
  gap: 0.75rem;
}

.btn.lg.icon {
  padding: 10px;
  min-width: 44px;
  width: 44px;
  height: 44px;
}

.btn.lg.icon svg {
  width: 24px;
  height: 24px;
}