:root {
    --color-primary: #3B82F6;
    --color-secondary: #8B5CF6;
    --color-accent: #F59E0B;
    --color-dark: #1F2937;
    --color-light: #F9FAFB;
}
/* Tailwind CSS 自定义配置样式 */
@layer utilities {
    .text-shadow {
        text-shadow: 0 2px 4px rgba(0, 0, 0, 0.1);
    }
    .text-shadow-lg {
        text-shadow: 0 4px 8px rgba(0, 0, 0, 0.12), 0 2px 4px rgba(0, 0, 0, 0.08);
    }
    .transition-all-300 {
        transition: all 0.3s cubic-bezier(0.4, 0, 0.2, 1);
    }
    .transition-all-500 {
        transition: all 0.5s cubic-bezier(0.4, 0, 0.2, 1);
    }
    .bg-gradient-primary {
        background: linear-gradient(135deg, #1e40af 0%, #8b5cf6 50%, #3b82f6 100%);
    }
    .bg-gradient-secondary {
        background: linear-gradient(135deg, #8b5cf6 0%, #ec4899 100%);
    }
    .bg-gradient-accent {
        background: linear-gradient(135deg, #f59e0b 0%, #ef4444 100%);
    }
    .card-hover:hover {
        transform: translateY(-8px) scale(1.02);
    }
    .glass-effect {
        backdrop-filter: blur(16px) saturate(180%);
        background-color: rgba(255, 255, 255, 0.75);
        border: 1px solid rgba(209, 213, 219, 0.3);
    }
    .gradient-text {
        background: linear-gradient(135deg, #1e40af, #8b5cf6);
        -webkit-background-clip: text;
        -webkit-text-fill-color: transparent;
        background-clip: text;
    }
}

/* 自定义动画 */
@keyframes float {
    0%, 100% { transform: translateY(0px); }
    50% { transform: translateY(-20px); }
}

.animate-float {
    animation: float 6s ease-in-out infinite;
}

/* 额外的动画延迟类 */
.animation-delay-2000 {
    animation-delay: 2s;
}

.animation-delay-4000 {
    animation-delay: 4s;
}

/* Blob 动画 */
@keyframes blob {
    0% {
        transform: translate(0px, 0px) scale(1);
    }
    33% {
        transform: translate(30px, -50px) scale(1.1);
    }
    66% {
        transform: translate(-20px, 20px) scale(0.9);
    }
    100% {
        transform: translate(0px, 0px) scale(1);
    }
}

.animate-blob {
    animation: blob 7s infinite;
}

/* 背景渐变 */
.bg-gradient-hero {
    background: linear-gradient(135deg, #f8fafc 0%, #e2e8f0 50%, #f1f5f9 100%);
}

/* 统一图标容器为正方形并居中 */
.icon-square {
    width: 80px; /* 5rem 对应 w-20 */
    height: 80px; /* 5rem 对应 h-20 */
    display: flex;
    align-items: center;
    justify-content: center;
    line-height: 1; /* 避免字号影响容器高度 */
}
.icon-square i { line-height: 1; }

/* 小型正方形图标容器（用于卡片内的小图标） */
.icon-square-sm {
    width: 40px; /* 2.5rem 对应 w-10 */
    height: 40px; /* 2.5rem 对应 h-10 */
    display: flex;
    align-items: center;
    justify-content: center;
    line-height: 1;
    border-radius: 0.5rem; /* 近似 rounded-lg 兜底 */
}
.icon-square-sm i { line-height: 1; }

/* 教程标签按钮样式修复（防止白字白底不可见） */
.tutorial-tab {
    background-color: #e5e7eb; /* gray-200 */
    color: #374151; /* gray-700 */
}
.tutorial-tab.active {
    background-color: #3B82F6; /* primary */
    color: #ffffff;
}

/* 渐变色块中的图标强制居中（在无 Tailwind 构建时兜底） */
.bg-gradient-primary.w-20.h-20,
.bg-gradient-secondary.w-20.h-20,
.bg-gradient-accent.w-20.h-20 {
    display: flex;
    align-items: center;
    justify-content: center;
}

/* 深色页脚兜底样式（Tailwind 未生效时） */
.bg-dark { background-color: #0f172a; }
.text-white { color: #ffffff; }
.text-gray-400 { color: #9ca3af; }
.border-gray-800 { border-color: #1f2937; }

.btn {
    display: inline-flex;
    align-items: center;
    justify-content: center;
    gap: 0.5rem;
    font-weight: 600;
    border-radius: 9999px;
    padding: 0.75rem 1.5rem;
    transition: transform 0.2s ease, box-shadow 0.2s ease, background-color 0.2s ease, color 0.2s ease;
    line-height: 1;
    min-height: 44px;
}
.btn i { line-height: 1; }
.btn:focus-visible { outline: none; box-shadow: 0 0 0 3px rgba(59, 130, 246, 0.35); }
.btn[disabled] { opacity: 0.6; pointer-events: none; }
.btn-primary { background: linear-gradient(135deg, var(--color-primary), var(--color-secondary)); color: #fff; }
.btn-primary:hover { transform: translateY(-1px); }
.btn-secondary { background: linear-gradient(135deg, var(--color-secondary), var(--color-accent)); color: #fff; }
.btn-outline { background: #ffffff; color: var(--color-primary); border: 2px solid var(--color-primary); }
.btn-outline:hover { background: var(--color-primary); color: #ffffff; }

.shadow-soft { box-shadow: 0 10px 30px rgba(17, 24, 39, 0.08), 0 4px 12px rgba(17, 24, 39, 0.06); }
.shadow-glow { box-shadow: 0 8px 24px rgba(59, 130, 246, 0.25), 0 0 1px rgba(17, 24, 39, 0.05); }

header.is-scrolled { backdrop-filter: blur(10px) saturate(160%); background-color: rgba(255, 255, 255, 0.85); box-shadow: 0 8px 20px rgba(17, 24, 39, 0.08); }
header.is-scrolled nav { padding-top: 0.75rem; padding-bottom: 0.75rem; }

#mobile-menu { transition: opacity 0.2s ease, transform 0.2s ease; opacity: 0; transform: translateY(-6px); }
#mobile-menu.open { opacity: 1; transform: translateY(0); }

.faq-question:focus-visible, .tutorial-tab:focus-visible, a:focus-visible, button:focus-visible { outline: none; box-shadow: 0 0 0 3px rgba(59, 130, 246, 0.35); }