/* ===== 全局重置与基础 ===== */
*, *::before, *::after {
    margin: 0;
    padding: 0;
    box-sizing: border-box;
}

:root {
    --color-bg: #0b1a2e;
    --color-bg-alt: #112240;
    --color-surface: #1a2d4a;
    --color-surface-glass: rgba(26, 45, 74, 0.6);
    --color-primary: #00b4d8;
    --color-primary-hover: #0096c7;
    --color-accent: #f77f00;
    --color-text: #e0e6ed;
    --color-text-secondary: #a0b0c0;
    --color-border: rgba(255,255,255,0.08);
    --color-gradient-start: #0b1a2e;
    --color-gradient-end: #1a3a5c;
    --shadow-card: 0 8px 32px rgba(0,0,0,0.3);
    --shadow-glass: 0 4px 20px rgba(0,0,0,0.25);
    --radius-card: 20px;
    --radius-button: 30px;
    --transition-base: 0.3s cubic-bezier(0.4, 0, 0.2, 1);
    --font-family: -apple-system, BlinkMacSystemFont, 'Segoe UI', Roboto, 'Noto Sans SC', 'PingFang SC', 'Microsoft YaHei', sans-serif;
}

html {
    scroll-behavior: smooth;
    font-size: 16px;
}

body {
    font-family: var(--font-family);
    background: linear-gradient(135deg, var(--color-gradient-start), var(--color-gradient-end));
    color: var(--color-text);
    line-height: 1.6;
    min-height: 100vh;
    overflow-x: hidden;
    transition: background 0.5s ease;
}

/* ===== 暗色模式（默认即为暗色，但保留切换能力） ===== */
body.light-mode {
    --color-bg: #f0f4f8;
    --color-bg-alt: #e2e8f0;
    --color-surface: #ffffff;
    --color-surface-glass: rgba(255,255,255,0.7);
    --color-primary: #0077b6;
    --color-primary-hover: #005f8a;
    --color-accent: #d97706;
    --color-text: #1e293b;
    --color-text-secondary: #475569;
    --color-border: rgba(0,0,0,0.08);
    --color-gradient-start: #e2e8f0;
    --color-gradient-end: #cbd5e1;
    --shadow-card: 0 8px 32px rgba(0,0,0,0.08);
    --shadow-glass: 0 4px 20px rgba(0,0,0,0.06);
}

/* ===== 滚动动画基础 ===== */
[data-animate] {
    opacity: 0;
    transform: translateY(30px);
    transition: opacity 0.6s ease, transform 0.6s ease;
}
[data-animate].visible {
    opacity: 1;
    transform: translateY(0);
}
[data-animate="fade-in"] {
    transform: translateY(0);
    opacity: 0;
}
[data-animate="fade-in"].visible {
    opacity: 1;
}
[data-animate="slide-up"] {
    transform: translateY(40px);
}
[data-animate="slide-up"].visible {
    transform: translateY(0);
}
[data-animate="scale-in"] {
    transform: scale(0.9);
}
[data-animate="scale-in"].visible {
    transform: scale(1);
}

/* ===== Header ===== */
header {
    position: fixed;
    top: 0;
    left: 0;
    width: 100%;
    z-index: 1000;
    backdrop-filter: blur(16px) saturate(180%);
    -webkit-backdrop-filter: blur(16px) saturate(180%);
    background: var(--color-surface-glass);
    border-bottom: 1px solid var(--color-border);
    transition: background var(--transition-base), border-color var(--transition-base);
}

nav {
    max-width: 1280px;
    margin: 0 auto;
    padding: 0.75rem 1.5rem;
    display: flex;
    align-items: center;
    justify-content: space-between;
    gap: 1rem;
}

nav a[aria-label="乐鱼LEYU 首页"] {
    display: flex;
    align-items: center;
    text-decoration: none;
    flex-shrink: 0;
}

nav ul {
    list-style: none;
    display: flex;
    gap: 0.5rem;
    margin: 0;
    padding: 0;
}

nav ul li a {
    color: var(--color-text-secondary);
    text-decoration: none;
    padding: 0.5rem 1rem;
    border-radius: var(--radius-button);
    font-size: 0.9rem;
    font-weight: 500;
    transition: color var(--transition-base), background var(--transition-base);
    position: relative;
}

nav ul li a::after {
    content: '';
    position: absolute;
    bottom: 4px;
    left: 50%;
    width: 0;
    height: 2px;
    background: var(--color-primary);
    transition: width 0.3s ease, left 0.3s ease;
    border-radius: 2px;
}

nav ul li a:hover,
nav ul li a:focus-visible {
    color: var(--color-primary);
    background: rgba(0, 180, 216, 0.08);
}

nav ul li a:hover::after,
nav ul li a:focus-visible::after {
    width: 60%;
    left: 20%;
}

nav button {
    background: none;
    border: none;
    cursor: pointer;
    font-size: 1.3rem;
    padding: 0.4rem 0.6rem;
    border-radius: 50%;
    transition: background var(--transition-base), transform var(--transition-base);
    color: var(--color-text);
    line-height: 1;
}

nav button:hover {
    background: rgba(255,255,255,0.1);
    transform: scale(1.1);
}

#mobileMenuBtn {
    display: none;
}

/* ===== Hero ===== */
#hero {
    min-height: 100vh;
    display: flex;
    flex-direction: column;
    align-items: center;
    justify-content: center;
    text-align: center;
    padding: 8rem 2rem 4rem;
    background: radial-gradient(ellipse at 30% 50%, rgba(0, 180, 216, 0.15) 0%, transparent 60%),
                radial-gradient(ellipse at 70% 30%, rgba(247, 127, 0, 0.1) 0%, transparent 50%),
                linear-gradient(135deg, var(--color-gradient-start), var(--color-gradient-end));
    position: relative;
    overflow: hidden;
}

#hero::before {
    content: '';
    position: absolute;
    top: -20%;
    left: -10%;
    width: 60%;
    height: 80%;
    background: radial-gradient(circle, rgba(0,180,216,0.08) 0%, transparent 70%);
    pointer-events: none;
    animation: heroGlow 12s ease-in-out infinite alternate;
}

@keyframes heroGlow {
    0% { transform: translate(0, 0) scale(1); }
    100% { transform: translate(10%, 5%) scale(1.2); }
}

#hero h1 {
    font-size: clamp(2.2rem, 6vw, 4.2rem);
    font-weight: 800;
    background: linear-gradient(135deg, var(--color-primary), var(--color-accent));
    -webkit-background-clip: text;
    -webkit-text-fill-color: transparent;
    background-clip: text;
    margin-bottom: 1rem;
    line-height: 1.2;
    position: relative;
    z-index: 1;
}

#hero p {
    font-size: clamp(1rem, 2vw, 1.3rem);
    color: var(--color-text-secondary);
    max-width: 600px;
    margin: 0 auto 2rem;
    position: relative;
    z-index: 1;
}

#hero a[role="button"] {
    display: inline-block;
    background: linear-gradient(135deg, var(--color-primary), var(--color-primary-hover));
    color: #fff;
    padding: 0.9rem 2.8rem;
    border-radius: var(--radius-button);
    font-size: 1.1rem;
    font-weight: 600;
    text-decoration: none;
    transition: transform var(--transition-base), box-shadow var(--transition-base);
    box-shadow: 0 4px 20px rgba(0, 180, 216, 0.3);
    position: relative;
    z-index: 1;
}

#hero a[role="button"]:hover {
    transform: translateY(-3px) scale(1.02);
    box-shadow: 0 8px 30px rgba(0, 180, 216, 0.4);
}

/* ===== 通用 Section 样式 ===== */
section {
    max-width: 1280px;
    margin: 0 auto;
    padding: 5rem 2rem;
}

section h2 {
    font-size: clamp(1.8rem, 4vw, 2.8rem);
    font-weight: 700;
    margin-bottom: 2rem;
    position: relative;
    display: inline-block;
    color: var(--color-text);
}

section h2::after {
    content: '';
    display: block;
    width: 60px;
    height: 4px;
    background: linear-gradient(90deg, var(--color-primary), var(--color-accent));
    border-radius: 4px;
    margin-top: 0.5rem;
}

/* ===== About ===== */
#about {
    background: var(--color-bg-alt);
    border-radius: var(--radius-card);
    margin: 2rem auto;
    padding: 3rem 2.5rem;
    box-shadow: var(--shadow-card);
    transition: background var(--transition-base);
}

#about p {
    color: var(--color-text-secondary);
    max-width: 800px;
    margin-bottom: 1rem;
    font-size: 1.05rem;
}

/* ===== Products ===== */
#products {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(280px, 1fr));
    gap: 2rem;
    padding: 5rem 2rem;
}

#products h2 {
    grid-column: 1 / -1;
}

#products article {
    background: var(--color-surface-glass);
    backdrop-filter: blur(12px);
    -webkit-backdrop-filter: blur(12px);
    border-radius: var(--radius-card);
    padding: 2.5rem 2rem;
    border: 1px solid var(--color-border);
    box-shadow: var(--shadow-glass);
    transition: transform var(--transition-base), box-shadow var(--transition-base), background var(--transition-base);
    cursor: default;
}

#products article:hover {
    transform: translateY(-8px);
    box-shadow: 0 12px 40px rgba(0,0,0,0.3);
    background: var(--color-surface-glass);
    border-color: var(--color-primary);
}

#products article h3 {
    font-size: 1.4rem;
    margin-bottom: 0.8rem;
    color: var(--color-primary);
}

#products article p {
    color: var(--color-text-secondary);
    font-size: 0.95rem;
}

/* ===== Services ===== */
#services {
    background: var(--color-bg-alt);
    border-radius: var(--radius-card);
    margin: 2rem auto;
    padding: 3rem 2.5rem;
    box-shadow: var(--shadow-card);
    transition: background var(--transition-base);
}

#services ul {
    list-style: none;
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(200px, 1fr));
    gap: 1.5rem;
    margin-top: 1.5rem;
}

#services ul li {
    background: var(--color-surface-glass);
    backdrop-filter: blur(8px);
    -webkit-backdrop-filter: blur(8px);
    padding: 1.5rem 1.2rem;
    border-radius: 14px;
    border: 1px solid var(--color-border);
    font-weight: 500;
    transition: transform var(--transition-base), border-color var(--transition-base);
    display: flex;
    align-items: center;
    gap: 0.6rem;
}

#services ul li::before {
    content: '⚡';
    font-size: 1.2rem;
}

#services ul li:hover {
    transform: translateY(-4px);
    border-color: var(--color-accent);
}

/* ===== Knowledge ===== */
#knowledge {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(300px, 1fr));
    gap: 2rem;
    padding: 5rem 2rem;
}

#knowledge h2 {
    grid-column: 1 / -1;
}

#knowledge article {
    background: var(--color-surface-glass);
    backdrop-filter: blur(12px);
    -webkit-backdrop-filter: blur(12px);
    border-radius: var(--radius-card);
    padding: 2rem 2rem 2.5rem;
    border: 1px solid var(--color-border);
    box-shadow: var(--shadow-glass);
    transition: transform var(--transition-base), border-color var(--transition-base);
}

#knowledge article:hover {
    transform: translateY(-4px);
    border-color: var(--color-primary);
}

#knowledge article h3 {
    font-size: 1.3rem;
    margin-bottom: 1rem;
    color: var(--color-primary);
}

#knowledge article ol,
#knowledge article ul {
    padding-left: 1.5rem;
    color: var(--color-text-secondary);
    line-height: 1.8;
}

#knowledge article ol li,
#knowledge article ul li {
    margin-bottom: 0.3rem;
}

#knowledge article dl {
    display: grid;
    gap: 1rem;
}

#knowledge article dt {
    font-weight: 600;
    color: var(--color-text);
    margin-top: 0.5rem;
}

#knowledge article dd {
    color: var(--color-text-secondary);
    padding-left: 0.5rem;
    border-left: 3px solid var(--color-primary);
    padding-left: 1rem;
}

#knowledge article ul li a {
    color: var(--color-primary);
    text-decoration: none;
    transition: color var(--transition-base);
}

#knowledge article ul li a:hover {
    color: var(--color-accent);
    text-decoration: underline;
}

/* ===== Contact ===== */
#contact {
    background: var(--color-bg-alt);
    border-radius: var(--radius-card);
    margin: 2rem auto;
    padding: 3rem 2.5rem;
    box-shadow: var(--shadow-card);
    text-align: center;
    transition: background var(--transition-base);
}

#contact p {
    color: var(--color-text-secondary);
    margin-bottom: 0.6rem;
    font-size: 1.05rem;
}

#contact p:first-of-type {
    font-size: 1.2rem;
    font-weight: 600;
    color: var(--color-primary);
}

/* ===== Footer ===== */
footer {
    text-align: center;
    padding: 2.5rem 2rem;
    border-top: 1px solid var(--color-border);
    color: var(--color-text-secondary);
    font-size: 0.9rem;
    backdrop-filter: blur(8px);
    -webkit-backdrop-filter: blur(8px);
    background: var(--color-surface-glass);
}

footer a {
    color: var(--color-primary);
    text-decoration: none;
    transition: color var(--transition-base);
}

footer a:hover {
    color: var(--color-accent);
    text-decoration: underline;
}

footer p {
    margin-bottom: 0.4rem;
}

/* ===== 响应式 ===== */
@media (max-width: 768px) {
    nav {
        padding: 0.6rem 1rem;
    }

    nav ul {
        display: none;
        flex-direction: column;
        position: absolute;
        top: 100%;
        left: 0;
        width: 100%;
        background: var(--color-surface-glass);
        backdrop-filter: blur(20px);
        -webkit-backdrop-filter: blur(20px);
        border-bottom: 1px solid var(--color-border);
        padding: 1rem 0;
        gap: 0;
    }

    nav ul.open {
        display: flex;
    }

    nav ul li a {
        padding: 0.8rem 2rem;
        border-radius: 0;
        width: 100%;
        text-align: center;
    }

    #mobileMenuBtn {
        display: inline-block;
    }

    section {
        padding: 3rem 1.2rem;
    }

    #hero {
        padding: 6rem 1.5rem 3rem;
    }

    #products {
        grid-template-columns: 1fr;
        padding: 3rem 1.2rem;
    }

    #knowledge {
        grid-template-columns: 1fr;
        padding: 3rem 1.2rem;
    }

    #services ul {
        grid-template-columns: 1fr;
    }

    #about,
    #services,
    #contact {
        padding: 2rem 1.5rem;
        margin: 1rem auto;
    }
}

@media (max-width: 480px) {
    html {
        font-size: 15px;
    }

    nav a[aria-label="乐鱼LEYU 首页"] svg {
        width: 100px;
        height: 34px;
    }

    #hero h1 {
        font-size: 2rem;
    }

    #products article {
        padding: 1.8rem 1.5rem;
    }
}

/* ===== 暗色切换按钮动画 ===== */
#darkModeToggle {
    transition: transform 0.4s ease;
}
#darkModeToggle:hover {
    transform: rotate(20deg) scale(1.15);
}

/* ===== 滚动条美化 ===== */
::-webkit-scrollbar {
    width: 8px;
}
::-webkit-scrollbar-track {
    background: var(--color-bg);
}
::-webkit-scrollbar-thumb {
    background: var(--color-primary);
    border-radius: 10px;
}
::-webkit-scrollbar-thumb:hover {
    background: var(--color-primary-hover);
}

/* ===== 选中文本 ===== */
::selection {
    background: var(--color-primary);
    color: #fff;
}