/* === 1. Block: Header === */
.header {
    position: fixed;
    top: 0;
    left: 0;
    right: 0;
    height: var(--header-height);
    display: flex;
    align-items: center;
    justify-content: space-between;
    padding: 0 var(--container-padding);
    z-index: var(--z-sticky);
    background-color: var(--color-bg);
    transition:
        background-color var(--transition-base),
        box-shadow var(--transition-base);
}

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

.header--transparent {
    background-color: transparent;
}

.header__logo {
    display: flex;
    align-items: center;
    gap: var(--space-xs);
    text-decoration: none;
    flex-shrink: 0;
}

.header__logo-icon {
    height: 40px;
    width: 110px;
}

.header__logo-text {
    display: flex;
    flex-direction: column;
    align-items: flex-start;
    line-height: 1;
}

.header__logo-name {
    font-family: var(--font-family-en);
    font-size: 35px;
    font-weight: var(--font-weight-black);
    letter-spacing: 3px;
    color: var(--color-text);
}

.header__logo-sub {
    font-family: var(--font-family-en);
    font-weight: 900;
    font-size: 12px;
    text-transform: uppercase;
    color: var(--color-text);
    margin-top: 2px;
}

.header__menu-btn {
    display: flex;
    flex-direction: column;
    justify-content: center;
    align-items: center;
    width: 40px;
    height: 40px;
    gap: 7px;
    cursor: pointer;
    padding: 4px;
    transition: opacity var(--transition-fast);
}

.header__menu-btn-icon {
    width: var(--font-size-2xl);
    height: var(--font-size-2xl);
}

.header__menu-btn:hover {
    opacity: 0.6;
}

.header--nav-open .header__menu-btn {
    opacity: 0;
    visibility: hidden;
    pointer-events: none;
}

.header__menu-line {
    display: block;
    width: 28px;
    height: 3px;
    background-color: var(--color-text);
    transition:
        transform var(--transition-base),
        opacity var(--transition-base);
}

/* === 2. Block: Navigation Overlay === */
.nav-overlay {
    position: fixed;
    top: 0;
    left: 0;
    width: 100%;
    height: 80%;
    background-color: rgba(255, 255, 255, 0.8);
    z-index: var(--z-overlay);
    display: flex;
    flex-direction: column;
    align-items: center;
    justify-content: center;
    opacity: 0;
    visibility: hidden;
    transition:
        opacity var(--transition-nav),
        visibility var(--transition-nav);
    -webkit-backdrop-filter: blur(20px);
    pointer-events: none;
}

.nav-overlay--active {
    opacity: 1;
    visibility: visible;
    pointer-events: auto;
}

.nav-overlay__close {
    position: absolute;
    top: 10px;
    right: var(--container-padding);
    width: 40px;
    height: 40px;
    display: flex;
    align-items: center;
    justify-content: center;
    cursor: pointer;
    transition: opacity var(--transition-fast);
}

.nav-overlay__close:hover {
    opacity: 0.6;
}

.nav-overlay__close-icon {
    width: var(--font-size-2xl);
    height: var(--font-size-2xl);
}

.nav-overlay__list {
    display: flex;
    flex-direction: column;
    align-items: center;
    gap: 0;
    width: 100%;
    max-width: 400px;
    position: relative;
    pointer-events: auto;
}

.nav-overlay__arrow {
    width: 20px;
    height: 15px;
    position: absolute;
    right: 110px;
    opacity: 0;
    visibility: hidden;
    transition: all var(--transition-base);
    pointer-events: none;
    line-height: 1;
    transform: translateY(-50%);
}

.nav-overlay__item {
    width: 100%;
    text-align: center;
    position: relative;
}
.nav-overlay__link {
    display: flex;
    align-items: center;
    justify-content: center;
    gap: var(--space-2xs);
    padding: var(--space-md) var(--space-lg);
    font-family: var(--font-family);
    font-size: var(--font-size-lg);
    font-weight: var(--font-weight-bold);
    color: var(--color-text);
    transition: color var(--transition-fast);
    border-bottom: 1px solid rgb(202, 204, 208);
    text-decoration: none;
    position: relative;
}

.nav-overlay__link:hover {
    color: var(--color-primary);
}

.nav-overlay__item:first-child .nav-overlay__link {
    font-weight: var(--font-weight-bold);
}

.nav-overlay__link-arrow {
    font-size: 18px;
    transition: transform var(--transition-fast);
    opacity: 0;
    line-height: 1;
    vertical-align: middle;
}

.nav-overlay__link:hover .nav-overlay__link-arrow {
    transform: translateX(4px);
    opacity: 1;
}

.nav-overlay__lang-link {
    font-family: var(--font-family-en);
    font-size: var(--font-size-lg);
    font-weight: var(--font-weight-bold);
    color: var(--color-text);
    padding: var(--space-sm) var(--space-lg);
}

/* === 3. Block: Footer === */
.footer {
    background-color: var(--color-bg);
    border-top: 1px solid var(--color-border);
    padding: var(--space-lg) 0;
}

.footer__inner {
    display: flex;
    align-items: center;
    justify-content: center;
    gap: var(--space-lg);
    flex-wrap: wrap;
    font-size: var(--font-size-xs);
    color: rgb(153, 153, 153);
}

.footer__link {
    color: rgb(153, 153, 153);
    transition: color var(--transition-fast);
}

.footer__link:hover {
    color: var(--color-text);
}

.footer__divider {
    width: 1px;
    height: 12px;
    background-color: var(--color-border);
}

@media (max-width: 768px){
    .footer {
        background-color: var(--color-bg-gray);
        border-top: 1px solid var(--color-border);
        padding: var(--space-sm) 0;
    }

    .footer__inner {
        display: flex;
        align-items: center;
        justify-content: center;
        gap: var(--space-2xs);
        flex-wrap: wrap;
        font-size: var(--font-size-xs);
        color: rgb(153, 153, 153);
    }
}

/* ==========================================
   Sticky Footer: 内容不足时 footer 固定在底部
   ========================================== */
html, body {
    height: 100%;
}

body {
    display: flex;
    flex-direction: column;
    min-height: 100vh;
}

main {
    flex: 1 0 auto;
}

.footer {
    flex-shrink: 0;
}