/* ====================================================================
   导航栏（Sprint 4 重设计） — Metro UI
   结构：左 Logo + 主菜单（首页/全部分享）+ 右工具区（CTA / 图标 / 用户）
   ==================================================================== */

.navbar {
    position: sticky;
    top: 0;
    background: var(--card-bg);
    border-bottom: 2px solid var(--primary-color);
    z-index: 1000;
}

.nav-container {
    max-width: 1600px;
    margin: 0 auto;
    padding: 0 calc(var(--spacing-unit) * 3);
    height: 56px;
    display: flex;
    align-items: center;
    gap: calc(var(--spacing-unit) * 3);
}

/* ===== Logo ===== */
.nav-logo {
    display: flex;
    align-items: center;
    gap: calc(var(--spacing-unit) * 1.5);
    font-size: 18px;
    font-weight: 600;
    color: var(--text-primary);
    text-decoration: none;
    flex-shrink: 0;
    transition: color 0.15s;
}
.nav-logo:hover { color: var(--primary-color); }
.nav-logo svg { color: var(--primary-color); }

/* ===== 主菜单 ===== */
.nav-main {
    display: flex;
    align-items: center;
    gap: calc(var(--spacing-unit) * 1);
    margin-right: auto; /* 推动右侧工具区到最右 */
}

.nav-link {
    color: var(--text-secondary);
    text-decoration: none;
    font-weight: 400;
    font-size: 14px;
    padding: calc(var(--spacing-unit) * 1) calc(var(--spacing-unit) * 2);
    transition: color 0.15s;
    white-space: nowrap;
}
.nav-link:hover { color: var(--primary-color); }

.nav-link-compact {
    padding: 6px 12px;
    font-size: 13px;
}

.nav-link-outline {
    border: 1px solid var(--border-color);
    color: var(--text-primary);
}
.nav-link-outline:hover {
    border-color: var(--primary-color);
    color: var(--primary-color);
}

/* ===== 右侧工具区 ===== */
.nav-tools {
    display: flex;
    align-items: center;
    gap: calc(var(--spacing-unit) * 1.5);
    flex-shrink: 0;
}

/* ===== CTA：开始分享 ===== */
.nav-cta {
    display: inline-flex;
    align-items: center;
    gap: 6px;
    padding: 7px 14px;
    background: var(--primary-color);
    color: #fff;
    text-decoration: none;
    font-weight: 600;
    font-size: 13px;
    line-height: 1;
    white-space: nowrap;
    transition: background 0.15s;
}
.nav-cta:hover { background: var(--primary-hover); }
.nav-cta svg { flex-shrink: 0; }

/* ===== 图标按钮组 ===== */
.nav-icons {
    display: flex;
    align-items: center;
    gap: 2px;
}

.nav-icon-btn {
    background: transparent;
    border: none;
    cursor: pointer;
    width: 32px;
    height: 32px;
    display: inline-flex;
    align-items: center;
    justify-content: center;
    color: var(--text-secondary);
    padding: 0;
    transition: all 0.15s;
}
.nav-icon-btn:hover {
    color: var(--primary-color);
    background: var(--bg-color);
}

/* 主题图标显隐 */
.theme-icon { width: 18px; height: 18px; }
.sun-icon { display: none; }
.moon-icon { display: block; }
[data-theme="dark"] .sun-icon { display: block; }
[data-theme="dark"] .moon-icon { display: none; }
@media (prefers-color-scheme: dark) {
    .sun-icon { display: block; }
    .moon-icon { display: none; }
    [data-theme="light"] .sun-icon { display: none; }
    [data-theme="light"] .moon-icon { display: block; }
}

/* ===== 下拉菜单（语言 + 用户）===== */
.nav-dropdown {
    position: relative;
}

.nav-dropdown-menu {
    position: absolute;
    top: calc(100% + 4px);
    left: 0;
    min-width: 160px;
    background: var(--card-bg);
    border: 1px solid var(--border-color);
    box-shadow: 0 4px 12px rgba(0, 0, 0, 0.12);
    padding: 4px 0;
    z-index: 1100;
    opacity: 0;
    visibility: hidden;
    transform: translateY(-4px);
    transition: opacity 0.15s, transform 0.15s, visibility 0.15s;
}

.nav-dropdown-menu-right {
    left: auto;
    right: 0;
}

.nav-dropdown.is-open .nav-dropdown-menu {
    opacity: 1;
    visibility: visible;
    transform: translateY(0);
}

.nav-dropdown-item {
    display: flex;
    align-items: center;
    gap: 8px;
    padding: 8px 14px;
    color: var(--text-primary);
    text-decoration: none;
    font-size: 13px;
    background: transparent;
    border: none;
    width: 100%;
    text-align: left;
    cursor: pointer;
    font-family: inherit;
    transition: background 0.12s;
}
.nav-dropdown-item:hover {
    background: var(--bg-color);
    color: var(--primary-color);
}
.nav-dropdown-item.active {
    background: var(--bg-color);
    color: var(--primary-color);
    font-weight: 600;
}
.nav-dropdown-item svg { flex-shrink: 0; color: var(--text-secondary); }
.nav-dropdown-item:hover svg { color: var(--primary-color); }

.nav-dropdown-item-danger { color: var(--danger-color); }
.nav-dropdown-item-danger:hover { background: var(--bg-color); color: var(--danger-color); }
.nav-dropdown-item-danger svg { color: var(--danger-color); }

.nav-dropdown-sep {
    height: 1px;
    background: var(--border-color);
    margin: 4px 0;
}

.nav-dropdown-form { margin: 0; padding: 0; }

/* ===== 用户头像下拉 ===== */
.nav-avatar-btn {
    display: inline-flex;
    align-items: center;
    gap: 8px;
    padding: 4px 8px 4px 4px;
    background: transparent;
    border: 1px solid transparent;
    cursor: pointer;
    color: var(--text-primary);
    font-family: inherit;
    font-size: 13px;
    transition: all 0.15s;
}
.nav-avatar-btn:hover {
    border-color: var(--border-color);
    background: var(--bg-color);
}

.nav-avatar {
    width: 28px;
    height: 28px;
    background: var(--primary-color);
    color: #fff;
    display: inline-flex;
    align-items: center;
    justify-content: center;
    font-weight: 700;
    font-size: 13px;
    flex-shrink: 0;
    text-transform: uppercase;
}

.nav-avatar-name {
    max-width: 120px;
    overflow: hidden;
    text-overflow: ellipsis;
    white-space: nowrap;
}

.nav-user-dropdown .nav-dropdown-menu {
    min-width: 180px;
}

/* ===== 未登录按钮组 ===== */
.nav-auth-group {
    display: inline-flex;
    align-items: center;
    gap: 8px;
}

/* ===== 响应式 ===== */
@media (max-width: 900px) {
    .nav-avatar-name { display: none; }
    .nav-cta span { display: none; }
    .nav-cta { padding: 7px 10px; }
    .nav-brand-text { display: none; }
}

@media (max-width: 768px) {
    .nav-container {
        padding: 0 calc(var(--spacing-unit) * 2);
        gap: calc(var(--spacing-unit) * 1.5);
    }
    .nav-main { gap: 0; }
    .nav-main .nav-link {
        padding: 8px 10px;
        font-size: 13px;
    }
    .nav-tools {
        gap: calc(var(--spacing-unit) * 1);
    }
    .nav-icons {
        gap: 0;
    }
    .nav-icon-btn {
        width: 30px;
        height: 30px;
    }
}

@media (max-width: 480px) {
    /* 在极小屏隐藏不那么重要的图标，只留主题切换 */
    .nav-icons .nav-dropdown { display: none; }
    #historyBtn { display: none; }
}