* {
    margin: 0;
    padding: 0;
    box-sizing: border-box;
}

body {
    font-family: -apple-system, BlinkMacSystemFont, "Segoe UI", "Roboto", "Helvetica Neue", Arial, sans-serif;
    transition: background-color 0.3s ease;
}

/* 主题基色（具体渐变由 Tailwind 类控制） */
body.light-mode {
    color: #1a1a1a;
}

body.dark-mode {
    color: #f5f3f0;
}

.fade-in {
    animation: fadeIn 0.3s ease;
}

@keyframes fadeIn {
    from {
        opacity: 0;
    }
    to {
        opacity: 1;
    }
}

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

.tutorial-annotation {
    position: relative;
    min-height: 0;
}

.annotation-zone {
    position: relative;
}