/* _nav.css - Modern Navigation Design */

/* ==========================================================================
   Site Header
   ========================================================================== */
.site-header__inner {
    display: flex;
    align-items: center;
    justify-content: space-between;
    height: 100%;
    margin-top: 0;
}

.header-left {
    display: flex;
    align-items: center;
    flex: 0 0 auto;
    z-index: 110;
}

.header-center {
    display: flex;
    align-items: center;
    justify-content: center;
    flex: 1 1 auto;
}

.header-right {
    display: flex;
    align-items: center;
    justify-content: flex-end;
    gap: 20px;
    flex: 0 0 auto;
    z-index: 110;
}

/* Logo Text - Sharp & Bold */
.site-logo__text {
    font-family: 'Segoe UI', sans-serif;
    font-weight: 700;
    letter-spacing: -0.5px;
    margin-left: 8px;
}

/* ---------------------------------------------------------
   Desktop Navigation (Center) - Minimal Style
   --------------------------------------------------------- */
.nav-menu {
    display: flex;
    list-style: none;
    margin: 0;
    padding: 0;
    gap: 32px; /* Open spacing */
}

.nav-menu__item {
    position: relative;
    height: 100%;
    display: flex;
    align-items: center;
}

.nav-menu__link {
    display: flex;
    align-items: center;
    gap: 6px;
    color: var(--color-text-secondary);
    font-weight: 500;
    font-size: 0.95rem;
    padding: 4px 0;
    position: relative;
    transition: color 0.2s ease;
}

/* Hard/Sharp Active State: Underline */
.nav-menu__link::after {
    content: '';
    position: absolute;
    bottom: -4px;
    left: 0;
    width: 100%;
    height: 2px;
    background-color: var(--color-primary);
    transform: scaleX(0);
    transform-origin: right;
    transition: transform 0.2s ease;
}

.nav-menu__link:hover {
    color: var(--color-text-main);
}

.nav-menu__link:hover::after {
    transform: scaleX(1);
    transform-origin: left;
}

/* Active State */
.nav-menu__item--active .nav-menu__link {
    color: var(--color-primary);
    font-weight: 600;
}

.nav-menu__item--active .nav-menu__link::after {
    transform: scaleX(1);
    background-color: var(--color-primary);
}

.nav-menu__arrow {
    font-size: 0.75em;
    margin-left: 4px;
    transition: transform 0.2s;
}

.nav-menu__item--has-sub:hover .nav-menu__arrow {
    transform: rotate(180deg);
}

/* Desktop Dropdown - Boxy & Sharp */
.nav-dropdown {
    position: absolute;
    top: 100%;
    left: 50%;
    transform: translateX(-50%) translateY(10px);
    background-color: var(--color-bg-surface);
    border: 1px solid var(--color-border);
    /* No border radius or very small */
    border-radius: 2px;
    box-shadow: 0 4px 12px rgba(0, 0, 0, 0.08);
    min-width: 160px;
    padding: 8px 0;
    opacity: 0;
    visibility: hidden;
    transition: all 0.15s cubic-bezier(0.4, 0, 0.2, 1);
    z-index: 100;
    margin-top: 12px;
}

/* Bridge to prevent closing when moving mouse to dropdown */
.nav-dropdown::before {
    content: '';
    position: absolute;
    top: -12px;
    left: 0;
    width: 100%;
    height: 12px;
}

.nav-menu__item--has-sub:hover .nav-dropdown {
    opacity: 1;
    visibility: visible;
    transform: translateX(-50%) translateY(0);
}

.nav-dropdown__item {
    display: flex;
    align-items: center;
    gap: 10px;
    padding: 10px 16px;
    color: var(--color-text-secondary);
    font-size: 0.9rem;
    transition: background-color 0.1s, color 0.1s;
}

.nav-dropdown__item:hover,
.nav-dropdown__item.active { /* Added active state */
    background-color: var(--color-bg-surface-alt);
    color: var(--color-primary);
}

.nav-dropdown__item i {
    width: 16px;
    text-align: center;
    font-size: 0.9em;
}

/* ---------------------------------------------------------
   User & Actions (Right)
   --------------------------------------------------------- */
.nav-user {
    display: flex;
    align-items: center;
}

.nav-user__avatar {
    width: 32px;
    height: 32px;
    border-radius: 50%; /* Circle */
    border: 1px solid var(--color-border);
    cursor: pointer;
    object-fit: cover;
    transition: border-color 0.2s;
}

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

.nav-user__login-btn {
    background: transparent;
    color: var(--color-text-main);
    border: 1px solid transparent;
    padding: 4px;
    border-radius: 50%;
    cursor: pointer;
    transition: all 0.2s;
    display: flex;
    align-items: center;
    justify-content: center;
}

.nav-user__login-btn:hover {
    color: var(--color-primary);
    background-color: var(--color-bg-surface-alt);
}


/* ---------------------------------------------------------
   Mobile Toggle (Hamburger)
   --------------------------------------------------------- */
.nav-toggle {
    display: none;
    background: none;
    border: none;
    cursor: pointer;
    padding: 4px;
    z-index: 120;
}

.nav-toggle__icon {
    display: block;
    width: 24px;
    height: 2px;
    background-color: var(--color-text-main);
    position: relative;
    transition: background-color 0.3s;
}

.nav-toggle__icon::before,
.nav-toggle__icon::after {
    content: '';
    position: absolute;
    width: 100%;
    height: 100%;
    background-color: var(--color-text-main);
    transition: transform 0.3s;
}

.nav-toggle__icon::before { transform: translateY(-7px); }
.nav-toggle__icon::after { transform: translateY(7px); }

.nav-toggle--active .nav-toggle__icon { background-color: transparent; }
.nav-toggle--active .nav-toggle__icon::before { transform: translateY(0) rotate(45deg); }
.nav-toggle--active .nav-toggle__icon::after { transform: translateY(0) rotate(-45deg); }


/* ---------------------------------------------------------
   Mobile Styles (Responsive)
   --------------------------------------------------------- */
@media (max-width: 900px) {
    .header-center {
        position: fixed;
        top: 0;
        right: 0;
        width: 0; /* 修改: 默认宽度为0，防止撑开页面 */
        max-width: 320px; /* Limit width on larger mobile screens */
        height: 100vh;
        /* Modern Glassmorphism Background */
        background-color: rgba(var(--color-bg-surface-rgb), 0.9);
        backdrop-filter: blur(10px);
        -webkit-backdrop-filter: blur(10px);

        padding: calc(var(--header-height) + 2rem) 0 2rem;
        box-shadow: -10px 0 30px var(--color-shadow);
        transform: translateX(100%);
        visibility: hidden; /* 双重保险 */
        /* 关键: 关闭时，width 和 visibility 延迟 0.4s 变化（等待 transform 动画结束） */
        transition: transform 0.4s cubic-bezier(0.16, 1, 0.3, 1), width 0s 0.4s, visibility 0s 0.4s;
        z-index: 100;
        display: block;
        overflow-y: auto;
    }

    .nav-toggle {
        display: block;
    }

    .nav-menu {
        flex-direction: column;
        gap: 0;
        width: 100%;
        padding: 0 16px; /* Add side padding */
    }

    .nav-menu__item {
        width: 100%;
        display: block;
        height: auto;
        border-bottom: 1px solid rgba(var(--color-border-rgb), 0.6);
        opacity: 0; /* For animation */
        transform: translateX(20px);
        transition: opacity 0.3s ease, transform 0.3s ease;
    }

    /* Staggered Animation for Items when Open */
    .header-center.is-open .nav-menu__item {
        opacity: 1;
        transform: translateX(0);
    }

    .header-center.is-open .nav-menu__item:nth-child(1) { transition-delay: 0.1s; }
    .header-center.is-open .nav-menu__item:nth-child(2) { transition-delay: 0.15s; }
    .header-center.is-open .nav-menu__item:nth-child(3) { transition-delay: 0.2s; }
    .header-center.is-open .nav-menu__item:nth-child(4) { transition-delay: 0.25s; }
    .header-center.is-open .nav-menu__item:nth-child(5) { transition-delay: 0.3s; }
    .header-center.is-open .nav-menu__item:nth-child(6) { transition-delay: 0.35s; }


    .nav-menu__link {
        width: 100%;
        padding: 18px 12px; /* Larger touch target */
        font-size: 1.1rem; /* Bigger font */
        justify-content: space-between;
        color: var(--color-text-main);
        border-radius: 8px; /* Rounded corners */
    }

    .nav-menu__link::after { display: none; }

    .nav-menu__link:hover {
        background-color: rgba(var(--color-text-main-rgb), 0.03);
    }

    .nav-menu__item--active .nav-menu__link {
        color: var(--color-primary);
        background-color: rgba(var(--color-primary-rgb), 0.05);
        font-weight: 600;
    }

    /* Mobile Dropdown Logic */
    .nav-dropdown {
        position: static;
        transform: none;
        opacity: 1;
        visibility: visible;
        box-shadow: none;
        border: none;
        margin: 0;
        padding: 0;
        border-radius: 0;
        background-color: transparent;
        display: none;
        padding-left: 12px; /* Indent content */
    }

    .nav-menu__item--expanded .nav-dropdown {
        display: block;
        animation: slideDown 0.3s ease;
    }

    .nav-menu__item--has-sub:hover .nav-dropdown {
        transform: none;
    }

    .nav-menu__item--expanded .nav-menu__arrow {
        transform: rotate(180deg);
    }

    .nav-dropdown__item {
        padding: 14px 16px;
        border-left: 2px solid rgba(var(--color-text-main-rgb), 0.08); /* Guide line */
        font-size: 1rem;
        margin: 4px 0;
        border-radius: 0 8px 8px 0;
    }

    .nav-dropdown__item.active {
        border-left-color: var(--color-primary);
        background-color: rgba(var(--color-text-main-rgb), 0.03);
        color: var(--color-primary);
        font-weight: 600;
    }

    /* Mobile Menu Open State */
    .header-center.is-open {
        transform: translateX(0);
        width: 100%; /* 打开时恢复宽度 */
        visibility: visible;
        /* 打开时: width 和 visibility 立即变化，不延迟 */
        transition: transform 0.4s cubic-bezier(0.16, 1, 0.3, 1), width 0s, visibility 0s;
    }

    .mobile-menu-overlay {
        position: fixed;
        inset: 0;
        background-color: var(--color-overlay); /* Lighter overlay */
        backdrop-filter: blur(2px); /* Blur background content */
        z-index: 99;
        opacity: 0;
        visibility: hidden;
        transition: opacity 0.3s;
    }

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

@keyframes slideDown {
    from { opacity: 0; transform: translateY(-10px); }
    to { opacity: 1; transform: translateY(0); }
}

.site-header {
    height: var(--header-height);
    background-color: rgba(255, 255, 255, 0.8);
    border-bottom: 1px solid var(--color-border);
    position: sticky;
    top: 0;
    z-index: 100;
    backdrop-filter: blur(10px);
}

@media (prefers-color-scheme: dark) {
    .site-header {
        background-color: rgba(30, 41, 59, 0.8);
    }
}

.site-header__inner {
    height: 100%;
    display: flex;
    align-items: center;
    justify-content: space-between;
}

.site-logo {
    display: flex;
    align-items: center;
    gap: var(--spacing-sm);
    font-weight: 700;
    font-size: 1.25rem;
    color: var(--color-text-main);
}

.site-logo__img {
    height: 32px;
    width: 32px;
    border-radius: var(--radius-sm);
}