/* ========================================
   SUNPEEDE 速比特官网 - 主样式表
    ======================================== */

/* Noto Sans SC - Local Font */
@font-face {
    font-family: 'Noto Sans SC';
    src: url('../fonts/NotoSansSC-Variable.ttf') format('truetype');
    font-weight: 100 900;
    font-style: normal;
    font-display: swap;
}

/* CSS Variables */
:root {
    --color-primary: #000000;
    --color-secondary: #FFFFFF;
    --color-accent: #E63946;
    --color-neutral-light: #F5F5F5;
    --color-neutral-mid: #888888;
    --color-neutral-dark: #333333;
    --color-border: #E0E0E0;
    
    --font-family-base: 'Noto Sans SC', sans-serif;
    --font-family-numbers: 'Noto Sans SC', sans-serif;
    
    --spacing-unit: 8px;
    --container-max-width: 1440px;
    --header-height: 55px;
    --border-radius: 4px;
    
    --transition-fast: 0.2s ease;
    --transition-base: 0.3s ease;
    --transition-slow: 0.6s ease;
    
    --shadow-sm: 0 2px 8px rgba(0,0,0,0.08);
    --shadow-md: 0 4px 16px rgba(0,0,0,0.12);
    --shadow-lg: 0 8px 32px rgba(0,0,0,0.16);
}

/* Reset & Base */
*, *::before, *::after {
    margin: 0;
    padding: 0;
    box-sizing: border-box;
}

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

body {
    font-family: var(--font-family-base);
    color: var(--color-neutral-dark);
    background-color: var(--color-secondary);
    line-height: 1.6;
    -webkit-font-smoothing: antialiased;
    -moz-osx-font-smoothing: grayscale;
}

a {
    text-decoration: none;
    color: inherit;
    transition: color var(--transition-fast);
}

ul, ol {
    list-style: none;
}

img {
    max-width: 100%;
    height: auto;
    display: block;
}

/* Container */
.container {
    width: 100%;
    max-width: var(--container-max-width);
    margin: 0 auto;
    padding: 0 calc(var(--spacing-unit) * 3);
}

@media (max-width: 768px) {
    .container {
        padding: 0 calc(var(--spacing-unit) * 2);
    }
}

/* Section Titles */
.section-title {
    font-size: clamp(1.75rem, 3vw, 2.5rem);
    font-weight: 700;
    color: var(--color-primary);
    margin-bottom: calc(var(--spacing-unit) * 2);
    letter-spacing: -0.02em;
}

.section-title--center {
    text-align: center;
}

.section-title--light {
    color: var(--color-secondary);
}

.section-subtitle {
    text-align: center;
    color: var(--color-neutral-mid);
    font-size: 1.1rem;
    margin-bottom: calc(var(--spacing-unit) * 6);
}

/* Buttons */
.btn {
    display: inline-flex;
    align-items: center;
    justify-content: center;
    padding: 12px 28px;
    font-size: 1rem;
    font-weight: 500;
    border-radius: var(--border-radius);
    cursor: pointer;
    transition: all var(--transition-base);
    border: 2px solid transparent;
    text-align: center;
}

.btn:active {
    transform: scale(0.98);
}

.btn--primary {
    background-color: #ffffff;
    color: var(--color-primary);
    position: relative;
}

.btn--primary::after {
    content: '';
    position: absolute;
    bottom: 8px;
    left: 28px;
    right: 28px;
    width: 0;
    height: 2px;
    background-color: #000000;
    transition: width var(--transition-base);
}

.btn--primary:hover::after {
    width: calc(100% - 56px);
}

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

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

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

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

.btn--large {
    padding: 16px 40px;
    font-size: 1.1rem;
}

/* Image Placeholder */
.image-placeholder {
    background: linear-gradient(135deg, #e0e0e0 0%, #f5f5f5 100%);
    display: flex;
    align-items: center;
    justify-content: center;
    color: var(--color-neutral-mid);
    font-size: 0.9rem;
    border-radius: var(--border-radius);
    overflow: hidden;
}

.image-placeholder--large {
    width: 100%;
    height: 400px;
}

.image-placeholder--landscape {
    width: 100%;
    aspect-ratio: 3/2;
}

@media (max-width: 768px) {
    .image-placeholder--large {
        height: 250px;
    }
}

/* Fade-in Animation */
.fade-in-up {
    opacity: 0;
    transform: translateY(20px);
    transition: opacity var(--transition-slow), transform var(--transition-slow);
}

.fade-in-up.visible {
    opacity: 1;
    transform: translateY(0);
}

.delay-1 { transition-delay: 0.1s; }
.delay-2 { transition-delay: 0.2s; }
.delay-3 { transition-delay: 0.3s; }
.delay-4 { transition-delay: 0.4s; }

/* ========================================
   Header
   ======================================== */
.header {
    position: fixed;
    top: 0;
    left: 0;
    width: 100%;
    height: var(--header-height);
    background-color: var(--color-primary);
    z-index: 1000;
    transition: background-color var(--transition-base), box-shadow var(--transition-base);
}

.header.scrolled {
    box-shadow: var(--shadow-md);
}

.header__inner {
    display: grid;
    grid-template-columns: auto 1fr auto;
    align-items: center;
    width: 100%;
    max-width: var(--container-max-width);
    margin: 0 auto;
    height: 100%;
    padding: 0 calc(var(--spacing-unit) * 3);
}

.header__logo-img {
    height: auto;
    width: 208px;
    max-height: 100%;
    object-fit: contain;
    filter: brightness(0) invert(1);
}

.header__nav {
    justify-self: center;
    display: flex;
    align-items: center;
    gap: 100px;
}

.nav__list {
    display: flex;
    gap: 75px;
}

.nav__item {
    position: relative;
}

.nav__link {
    color: var(--color-secondary);
    font-size: 15px;
    font-weight: 500;
    padding: 8px 0;
    position: relative;
    transition: color var(--transition-fast);
    display: inline-flex;
    align-items: center;
    text-decoration: none;
    line-height: 1.2;
    letter-spacing: 0.5px;
}

.nav__link--button {
    border: 0;
    background: transparent;
    cursor: default;
    font-family: inherit;
}

.nav__link::after {
    content: '';
    position: absolute;
    bottom: 0;
    left: 0;
    width: 0;
    height: 2px;
    background-color: #000000;
    transition: width var(--transition-base);
}

.nav__link:hover::after,
.nav__link--active::after {
    width: 100%;
}

.nav__submenu {
    position: fixed;
    top: var(--header-height);
    left: 0;
    display: flex !important;
    flex-direction: row;
    justify-content: center;
    gap: 0;
    padding: 20px 0;
    width: 100%;
    background: #ffffff;
    box-shadow: 0 4px 20px rgba(0, 0, 0, 0.1);
    opacity: 0;
    visibility: hidden;
    transform: translateY(10px);
    transition: all var(--transition-fast);
    z-index: 999;
}

.nav__item--has-submenu:hover .nav__submenu,
.nav__item--has-submenu:focus-within .nav__submenu {
    opacity: 1;
    visibility: visible;
    transform: translateY(0);
}

.nav__submenu li {
    display: flex;
    align-items: flex-start;
    flex-direction: column;
    min-width: 160px;
}

.nav__submenu-link {
    padding: 6px 12px;
    color: #666666;
    font-size: 13px;
    transition: color var(--transition-fast);
    border-left: none;
    background: transparent;
    white-space: nowrap;
}

.nav__submenu-link:hover {
    color: #000000;
}

.nav__submenu-link--group-title {
    color: #666;
    font-weight: 400;
    font-size: 16px;
    cursor: pointer;
    padding: 0 12px 8px;
    border-bottom: 1px solid #eaeaea;
    margin-bottom: 4px;
}

.nav__submenu-link:hover {
    color: #000000;
    background-color: transparent;
}

.header__actions {
    justify-self: end;
    display: flex;
    align-items: center;
    gap: calc(var(--spacing-unit) * 2);
}

.lang-switch {
    background: transparent;
    border: 1px solid var(--color-secondary);
    color: var(--color-secondary);
    padding: 6px 12px;
    font-size: 0.85rem;
    border-radius: var(--border-radius);
    cursor: pointer;
    transition: all var(--transition-fast);
}

.lang-switch:hover {
    background-color: var(--color-secondary);
    color: var(--color-primary);
}

.mobile-menu-toggle {
    display: none;
    flex-direction: column;
    gap: 5px;
    background: transparent;
    border: none;
    cursor: pointer;
    padding: 8px;
}

.mobile-menu-toggle span {
    display: block;
    width: 24px;
    height: 2px;
    background-color: var(--color-secondary);
    transition: all var(--transition-fast);
}

@media (max-width: 1024px) {
    .header__nav {
        display: none;
    }
    
    .mobile-menu-toggle {
        display: flex;
    }
}

/* Mobile Menu */
.mobile-menu {
    position: fixed;
    top: 0;
    right: -100%;
    width: 80%;
    max-width: 320px;
    height: 100vh;
    background-color: var(--color-primary);
    z-index: 1100;
    padding: calc(var(--header-height) + 20px) 30px 30px;
    transition: right var(--transition-base);
}

.mobile-menu.open {
    right: 0;
}

.mobile-menu__close {
    position: absolute;
    top: 20px;
    right: 20px;
    background: transparent;
    border: none;
    color: var(--color-secondary);
    font-size: 2rem;
    cursor: pointer;
    line-height: 1;
}

.mobile-menu__list {
    display: flex;
    flex-direction: column;
    gap: calc(var(--spacing-unit) * 3);
}

.mobile-menu__link {
    color: var(--color-secondary);
    font-size: 1.2rem;
    font-weight: 500;
    padding: 12px 0;
    border-bottom: 1px solid rgba(255,255,255,0.1);
    display: block;
}

.mobile-menu__link--heading {
    cursor: default;
}

.mobile-menu__sublist {
    margin-top: -12px;
    padding-left: 18px;
}

.mobile-menu__sublink {
    color: rgba(255,255,255,0.78);
    font-size: 1rem;
    padding: 8px 0;
    display: block;
}

.mobile-menu-overlay {
    position: fixed;
    top: 0;
    left: 0;
    width: 100%;
    height: 100%;
    background-color: rgba(0,0,0,0.5);
    z-index: 1050;
    opacity: 0;
    visibility: hidden;
    transition: all var(--transition-base);
}

.mobile-menu-overlay.visible {
    opacity: 1;
    visibility: visible;
}

/* ========================================
   Hero Section
   ======================================== */
.hero {
    position: relative;
    height: 100vh;
    min-height: 600px;
    display: flex;
    align-items: center;
    justify-content: center;
    overflow: hidden;
}

.hero__bg {
    position: absolute;
    top: 0;
    left: 0;
    width: 100%;
    height: 100%;
    background: url('../assets/media/home1.jpg') center/cover no-repeat;
    z-index: 0;
}

.hero__bg::after {
    content: '';
    position: absolute;
    top: 0;
    left: 0;
    width: 100%;
    height: 100%;
    background: radial-gradient(circle at 70% 50%, rgba(230, 57, 70, 0.15) 0%, transparent 60%);
}

.hero__content {
    position: relative;
    z-index: 1;
    text-align: center;
    color: var(--color-secondary);
    max-width: 800px;
}

.hero__title {
    font-size: clamp(2.5rem, 6vw, 4.5rem);
    font-weight: 700;
    line-height: 1.2;
    margin-bottom: calc(var(--spacing-unit) * 3);
    letter-spacing: -0.03em;
}

.hero__subtitle {
    font-size: clamp(1rem, 2vw, 1.3rem);
    color: rgba(255,255,255,0.8);
    margin-bottom: calc(var(--spacing-unit) * 5);
}

.hero__cta {
    display: flex;
    gap: calc(var(--spacing-unit) * 2);
    justify-content: center;
    flex-wrap: wrap;
}

.hero__scroll-indicator {
    position: absolute;
    bottom: 40px;
    left: 50%;
    transform: translateX(-50%);
    z-index: 1;
    text-align: center;
    color: rgba(255,255,255,0.6);
    font-size: 0.8rem;
}

.scroll-line {
    width: 1px;
    height: 40px;
    background: linear-gradient(to bottom, rgba(255,255,255,0.6), transparent);
    margin: 10px auto 0;
    animation: scrollPulse 2s infinite;
}

@keyframes scrollPulse {
    0%, 100% { opacity: 0.6; transform: scaleY(1); }
    50% { opacity: 1; transform: scaleY(1.2); }
}

/* ========================================
   Hero Products Showcase
   ======================================== */
.hero-products {
    padding: 5px 0;
    background-color: var(--color-secondary);
    width: 100%;
}

.hero-products__grid {
    display: grid;
    grid-template-columns: repeat(3, 1fr);
    gap: 5px;
}

.hero-products__item {
    display: block;
    width: 100%;
    overflow: hidden;
    position: relative;
}

.hero-products__item::after {
    content: '';
    position: absolute;
    top: 0;
    left: 0;
    width: 100%;
    height: 100%;
    background: rgba(0,0,0,0);
    transition: background var(--transition-base);
}

.hero-products__item:hover::after {
    background: rgba(0,0,0,0.1);
}

.image-placeholder--9x16 {
    width: 100%;
    height: 650px;
    border-radius: 0;
}

.hero-card-1 {
    background: url('../assets/media/home2.jpg') center/cover no-repeat;
}

.hero-card-2 {
    background: url('../assets/media/home3.jpg') center/cover no-repeat;
}

.hero-card-3 {
    background: url('../assets/media/home4.jpg') center/cover no-repeat;
}

/* Ensure positioning context for badges inside image placeholders */
.image-placeholder {
    position: relative;
}

/* Badge Label */
.hero-products__badge {
    position: absolute;
    bottom: 20px;
    left: 20px;
    right: auto;
    width: 93px;
    height: 30px;
    display: flex;
    justify-content: center;
    align-items: center;
    background-color: rgba(255, 255, 255, 0.5);
    color: var(--color-primary, #111);
    padding: 0;
    font-size: 15px;
    font-weight: 400;
    line-height: 1;
    letter-spacing: 0.05em;
    z-index: 2;
    transition: background-color var(--transition-base);
}

.hero-products__item:hover .hero-products__badge {
    background-color: #ffffff;
}

@media (max-width: 768px) {
    .hero-products__grid {
        grid-template-columns: 1fr;
    }
}

/* ========================================
   Brand Philosophy
   ======================================== */
.brand-philosophy {
    position: relative;
    width: 100%;
    min-height: 800px;
    display: flex;
    align-items: center;
    overflow: hidden;
    margin-top: 5px;
}

.brand-philosophy__bg {
    position: absolute;
    top: 0;
    left: 0;
    width: 100%;
    height: 100%;
    background: url('../assets/media/home5.jpg') center/cover no-repeat;
    z-index: 0;
}

.brand-philosophy__bg::before {
    content: '品牌理念配图';
    position: absolute;
    top: 50%;
    left: 50%;
    transform: translate(-50%, -50%);
    color: rgba(255,255,255,0.1);
    font-size: 2rem;
    font-weight: 700;
    letter-spacing: 0.1em;
}

.brand-philosophy__overlay {
    position: absolute;
    top: 0;
    left: 0;
    width: 100%;
    height: 100%;
    background: rgba(0, 0, 0, 0.15);
    z-index: 1;
}

.brand-philosophy__content {
    position: relative;
    z-index: 2;
    padding: calc(var(--spacing-unit) * 10) 0 calc(var(--spacing-unit) * 10) 50px;
}

.brand-philosophy__content .section-title {
    margin-bottom: calc(var(--spacing-unit) * 3);
}

.brand-philosophy__desc {
    font-size: 1.05rem;
    line-height: 1.9;
    margin-bottom: calc(var(--spacing-unit) * 3);
    color: rgba(255, 255, 255, 0.9);
}

.brand-philosophy__quote {
    font-size: 1.4rem;
    font-weight: 600;
    color: var(--color-secondary);
    margin-bottom: calc(var(--spacing-unit) * 4);
    padding-left: calc(var(--spacing-unit) * 2);
    border-left: 3px solid var(--color-accent);
}

@media (max-width: 768px) {
    .brand-philosophy {
        min-height: 400px;
    }
    
    .brand-philosophy__content {
        padding: calc(var(--spacing-unit) * 8) 0;
    }
    
    .brand-philosophy__quote {
        font-size: 1.2rem;
    }
}

/* ========================================
   Product Categories
   ======================================== */
.product-categories {
    width: 100%;
    padding: 0;
    background-color: var(--color-secondary);
    margin-top: 5px;
}

.product-categories__grid {
    display: grid;
    grid-template-columns: repeat(4, 1fr);
    gap: 5px;
    width: 100%;
}

.product-categories__item {
    position: relative;
    display: block;
    overflow: hidden;
    aspect-ratio: 9/14;
    text-decoration: none;
}

.product-categories__bg {
    position: absolute;
    top: 0;
    left: 0;
    width: 100%;
    height: 100%;
    transition: transform var(--transition-slow);
}

.product-categories__item:hover .product-categories__bg {
    transform: scale(1.08);
}

.product-categories__bg .image-placeholder--full {
    width: 100%;
    height: 100%;
    border-radius: 0;
    background: linear-gradient(135deg, #2a2a2a 0%, #1a1a1a 100%);
}

.product-categories__overlay {
    position: absolute;
    top: 0;
    left: 0;
    width: 100%;
    height: 100%;
    background: linear-gradient(to top, rgba(0,0,0,0.75) 0%, rgba(0,0,0,0.2) 40%, rgba(0,0,0,0.05) 100%);
    transition: background var(--transition-base);
}

.product-categories__item:hover .product-categories__overlay {
    background: linear-gradient(to top, rgba(0,0,0,0.85) 0%, rgba(0,0,0,0.3) 40%, rgba(0,0,0,0.1) 100%);
}

.product-categories__text {
    position: absolute;
    bottom: 0;
    left: 0;
    width: 100%;
    padding: calc(var(--spacing-unit) * 4) calc(var(--spacing-unit) * 3);
    z-index: 2;
    color: var(--color-secondary);
    transform: translateY(0);
    transition: transform var(--transition-base);
}

.product-categories__item:hover .product-categories__text {
    transform: translateY(-8px);
}

.product-categories__title {
    font-size: clamp(1.1rem, 1.8vw, 1.5rem);
    font-weight: 700;
    margin-bottom: calc(var(--spacing-unit));
    color: var(--color-secondary);
    letter-spacing: 0.02em;
}

.product-categories__cta {
    font-size: 0.9rem;
    color: var(--color-accent);
    font-weight: 500;
    opacity: 0;
    transform: translateY(10px);
    transition: opacity var(--transition-base), transform var(--transition-base), color var(--transition-base);
    display: inline-block;
}

.product-categories__item:hover .product-categories__cta {
    opacity: 1;
    transform: translateY(0);
    color: #ffffff;
}

@media (max-width: 1024px) {
    .product-categories__grid {
        grid-template-columns: repeat(4, 1fr);
    }
}

@media (max-width: 768px) {
    .product-categories__grid {
        grid-template-columns: repeat(2, 1fr);
    }
    
    .product-categories__item:last-child {
        grid-column: span 2;
        aspect-ratio: 16/9;
    }
}

@media (max-width: 480px) {
    .product-categories__grid {
        grid-template-columns: 1fr;
    }
    
    .product-categories__item:last-child {
        grid-column: span 1;
        aspect-ratio: 9/14;
    }
}

/* ========================================
   Store Teaser
   ======================================== */
.store-teaser {
    padding: calc(var(--spacing-unit) * 10) 0;
    background: linear-gradient(135deg, #1a1a1a 0%, #333333 100%);
    color: var(--color-secondary);
    margin-top: 5px;
}

.store-teaser__inner {
    display: flex;
    align-items: center;
    justify-content: space-between;
    gap: calc(var(--spacing-unit) * 5);
    flex-wrap: wrap;
}

.store-teaser__text {
    flex: 1;
    min-width: 300px;
}

.store-teaser__desc {
    font-size: 1.1rem;
    color: rgba(255,255,255,0.8);
    line-height: 1.7;
}

@media (max-width: 768px) {
    .store-teaser__inner {
        flex-direction: column;
        text-align: center;
    }
}

/* ========================================
   Footer
   ======================================== */
.footer {
    background-color: var(--color-primary);
    color: var(--color-secondary);
    padding: calc(var(--spacing-unit) * 8) 0 calc(var(--spacing-unit) * 4);
}

.footer__grid {
    display: grid;
    grid-template-columns: 2fr 1fr 1fr 1.5fr;
    gap: calc(var(--spacing-unit) * 6);
    padding-bottom: calc(var(--spacing-unit) * 6);
    border-bottom: 1px solid rgba(255,255,255,0.1);
}

.footer__logo {
    height: 36px;
    width: auto;
    filter: brightness(0) invert(1);
    margin-bottom: calc(var(--spacing-unit) * 2);
}

.footer__tagline {
    font-size: 0.9rem;
    color: rgba(255,255,255,0.6);
    margin-bottom: calc(var(--spacing-unit) * 3);
    line-height: 1.6;
}

.footer__social {
    display: flex;
    gap: calc(var(--spacing-unit) * 2);
}

.social-icon {
    display: inline-flex;
    align-items: center;
    justify-content: center;
    width: 36px;
    height: 36px;
    border-radius: 50%;
    background-color: #444242;
    color: var(--color-secondary);
    transition: background-color var(--transition-fast);
}

.social-icon img {
    width: 20px;
    height: 20px;
    object-fit: contain;
}

.social-icon:hover {
    background-color: #444242;
}

/* Modal */
.modal-overlay {
    position: fixed;
    top: 0;
    left: 0;
    width: 100%;
    height: 100%;
    background: rgba(0,0,0,0.6);
    display: flex;
    align-items: center;
    justify-content: center;
    z-index: 9999;
    opacity: 0;
    visibility: hidden;
    transition: opacity var(--transition-base), visibility var(--transition-base);
}

.modal-overlay.is-active {
    opacity: 1;
    visibility: visible;
}

.modal-content {
    position: relative;
    background: #fff;
    padding: calc(var(--spacing-unit) * 3);
    border-radius: var(--border-radius);
    max-width: 320px;
    width: 90%;
    text-align: center;
}

.modal-content img {
    max-width: 100%;
    height: auto;
    display: block;
}

.modal-close {
    position: absolute;
    top: 8px;
    right: 12px;
    background: none;
    border: none;
    font-size: 24px;
    cursor: pointer;
    color: #333;
    line-height: 1;
}

.footer__heading {
    font-size: 1rem;
    font-weight: 600;
    margin-bottom: calc(var(--spacing-unit) * 3);
    color: var(--color-secondary);
}

.footer__links li {
    margin-bottom: calc(var(--spacing-unit) * 1.5);
}

.footer__links a {
    font-size: 0.9rem;
    color: rgba(255,255,255,0.6);
    transition: color var(--transition-fast);
}

.footer__links a:hover {
    color: var(--color-secondary);
}

.footer__address {
    font-style: normal;
    font-size: 0.9rem;
    color: rgba(255,255,255,0.6);
    line-height: 1.8;
}

.footer__address a {
    color: rgba(255,255,255,0.8);
}

.footer__address a:hover {
    color: var(--color-accent);
}

.footer__bottom {
    display: flex;
    align-items: center;
    justify-content: center;
    padding-top: calc(var(--spacing-unit) * 4);
    font-size: 0.85rem;
    color: rgba(255,255,255,0.4);
    flex-wrap: wrap;
    gap: calc(var(--spacing-unit) * 2);
    text-align: center;
}

.footer__legal {
    display: flex;
    gap: calc(var(--spacing-unit) * 3);
}

.footer__legal a {
    color: rgba(255,255,255,0.4);
    transition: color var(--transition-fast);
}

.footer__legal a:hover {
    color: var(--color-secondary);
}

@media (max-width: 1024px) {
    .footer__grid {
        grid-template-columns: 1fr 1fr;
        gap: calc(var(--spacing-unit) * 5);
    }
}

@media (max-width: 600px) {
    .footer__grid {
        grid-template-columns: 1fr;
    }
    
    .footer__bottom {
        flex-direction: column;
        text-align: center;
    }
}

.about-hero {
    position: relative;
    height: 400px;
    display: flex;
    align-items: center;
    justify-content: center;
    text-align: center;
    color: white;
    margin-top: var(--header-height);
    overflow: hidden;
}

.about-hero__bg {
    position: absolute;
    top: 0;
    left: 0;
    width: 100%;
    height: 100%;
    background-size: cover;
    background-position: center;
    background-repeat: no-repeat;
    z-index: 0;
}

.about-hero__bg::after {
    content: '';
    position: absolute;
    top: 0;
    left: 0;
    width: 100%;
    height: 100%;
    background: linear-gradient(135deg, rgba(0,0,0,0.6), rgba(0,0,0,0.3));
}

.about-hero__content {
    position: relative;
    z-index: 1;
}

.about-hero__content h1 {
    font-size: 3rem;
    margin-bottom: 16px;
    font-weight: 700;
}

.about-hero__content p {
    font-size: 1.2rem;
    color: rgba(255,255,255,0.9);
}

/* 返回顶部按钮 */
.back-to-top {
    position: fixed;
    bottom: 2rem;
    right: 2rem;
    z-index: 100;
    display: flex;
    align-items: center;
    justify-content: center;
    width: 48px;
    height: 48px;
    background: var(--color-secondary);
    color: var(--color-primary-inverse);
    border: none;
    border-radius: 50%;
    box-shadow: var(--shadow-lg);
    cursor: pointer;
    opacity: 0;
    visibility: hidden;
    transform: translateY(20px);
    transition: all var(--transition-base);
}

.back-to-top:hover {
    background: #000000;
    color: #ffffff;
    transform: translateY(-4px);
    box-shadow: var(--shadow-xl);
}

.back-to-top.visible {
    opacity: 1;
    visibility: visible;
    transform: translateY(0);
}

@media (max-width: 768px) {
    .back-to-top {
        bottom: 1.5rem;
        right: 1.5rem;
        width: 40px;
        height: 40px;
    }
}
a.nav__link { font-size: 14px; }