/* Layout Containers */
#app {
    display: flex;
    flex-direction: column;
    height: 100%;
    width: 100%;
    background-color: var(--bg-body);
    position: relative;
    /* iOS: 滿版顯示 - Capacitor 模式不限制寬度 */
    overflow: hidden;
}

/* 桌面瀏覽器預覽模式：限制最大寬度 */
@media (min-width: 769px) {
    #app {
        max-width: 600px;
        margin: 0 auto;
        box-shadow: 0 0 20px rgba(0,0,0,0.05);
    }
}

.page-container {
    flex: 1;
    padding: var(--spacing-md);
    /* iOS Safe Area: 頂部留白給動態島/瀏海 */
    padding-top: calc(var(--safe-area-inset-top) + var(--spacing-md));
    /* iOS Safe Area: 底部留白給 Home Indicator */
    padding-bottom: calc(var(--nav-height) + var(--safe-area-inset-bottom) + var(--spacing-md));
    overflow-y: auto;
    overflow-x: hidden;
    /* iOS: 內部滾動，防止整頁滑動 */
    -webkit-overflow-scrolling: touch;
    overscroll-behavior-y: contain;
}

@media (max-width: 480px) {
    .page-container {
        padding: var(--spacing-sm);
        padding-top: calc(var(--safe-area-inset-top) + var(--spacing-sm));
        padding-bottom: calc(var(--nav-height) + var(--safe-area-inset-bottom) + var(--spacing-md));
    }
}

/* Bottom Navigation */
.bottom-nav {
    position: fixed;
    bottom: 0;
    left: 0;
    right: 0;
    width: 100%;
    /* iOS Safe Area: 底部高度包含 Home Indicator */
    height: calc(var(--nav-height) + var(--safe-area-inset-bottom));
    padding-bottom: var(--safe-area-inset-bottom);
    background-color: var(--bg-surface);
    border-top: 1px solid var(--border-color);
    display: flex;
    justify-content: space-around;
    align-items: flex-start;
    padding-top: 8px;
    z-index: 1000;
}

/* 桌面瀏覽器預覽模式 */
@media (min-width: 769px) {
    .bottom-nav {
        left: 50%;
        right: auto;
        transform: translateX(-50%);
        max-width: 600px;
    }
}

.nav-item {
    display: flex;
    flex-direction: column;
    align-items: center;
    justify-content: center;
    color: var(--text-secondary);
    font-size: 0.75rem;
    padding: var(--spacing-xs);
    flex: 1;
    height: 100%;
}

.nav-item.active {
    color: var(--primary-color);
}

/* Center action button (浮動圓形按鈕 - FAB 設計) */
.nav-item-center {
    /* 浮動定位 */
    position: absolute;
    left: 50%;
    transform: translateX(-50%);
    bottom: calc(var(--nav-height) - 28px + var(--safe-area-inset-bottom));

    /* 圓形按鈕樣式 */
    width: 56px;
    height: 56px;
    border-radius: 50%;
    background: var(--primary-color);
    box-shadow: 0 4px 12px rgba(0, 0, 0, 0.15), 0 2px 4px rgba(0, 0, 0, 0.1);

    /* 內容置中 */
    display: flex;
    flex-direction: column;
    align-items: center;
    justify-content: center;

    /* 互動 */
    cursor: pointer;
    color: white;
    font-weight: 600;
    transition: transform 0.2s ease, box-shadow 0.2s ease;
    z-index: 1001;
}

.nav-item-center:active {
    transform: translateX(-50%) scale(0.95);
    box-shadow: 0 2px 8px rgba(0, 0, 0, 0.12);
}

.nav-item-center .center-icon {
    font-size: 1.5rem;
    line-height: 1;
}

.nav-item-center .center-label {
    font-size: 0.625rem;
    white-space: nowrap;
    margin-top: 2px;
    opacity: 0.9;
}

/* Hidden state for center button */
.nav-item-center-hidden {
    visibility: hidden;
    pointer-events: none;
}

/* Secondary style for utility actions (filter, settings, etc.) */
.nav-item-center-secondary {
    background: var(--bg-surface);
    color: var(--text-main);
    border: 2px solid var(--border-color);
    box-shadow: 0 2px 8px rgba(0, 0, 0, 0.08);
}

.nav-item-center-secondary:active {
    background: var(--bg-body);
}

/* 中間佔位區域（挖空效果） */
.nav-center-spacer {
    flex: 1;
    max-width: 72px;
    min-width: 56px;
}

.nav-icon {
    width: 24px;
    height: 24px;
    margin-bottom: 2px;
    display: flex;
    align-items: center;
    justify-content: center;
}

/* For SVG mask icons (when not using emoji) */
.nav-icon.use-mask {
    background-color: currentColor;
    mask-size: contain;
    -webkit-mask-size: contain;
    mask-repeat: no-repeat;
    -webkit-mask-repeat: no-repeat;
    mask-position: center;
    -webkit-mask-position: center;
}

/* Message Badge (Unread count) */
.message-badge {
    position: absolute;
    top: -4px;
    right: -8px;
    background-color: var(--color-error);
    color: var(--color-text-inverse);
    font-size: 10px;
    font-weight: 600;
    min-width: 16px;
    height: 16px;
    border-radius: 8px;
    display: flex;
    align-items: center;
    justify-content: center;
    padding: 0 4px;
    line-height: 1;
    box-shadow: var(--shadow-sm);
}

/* Utility to hide elements */
.hidden {
    display: none !important;
}

/* Page Headers */
.page-header {
    display: flex;
    align-items: center;
    justify-content: space-between;
    padding: var(--spacing-md) 0;
    margin-bottom: var(--spacing-md);
}

.page-title {
    font-size: var(--font-size-xl);
    font-weight: 700;
    color: var(--text-main);
}