:root {
    --fb-blue: #4267B2;
    --fb-bg: #f0f2f5;
    --fb-white: #ffffff;
    --fb-text-header: #ffffff;
    --fb-text-primary: #1c1e21;
    --fb-text-secondary: #65676b;
    --fb-gray-icon: #65676b;
    --header-height: 50px; /* Now used for tabs bar only */
}

body {
    background-color: var(--fb-bg);
    color: var(--fb-text-primary);
    font-family: -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, Helvetica, Arial, sans-serif;
    padding-top: var(--header-height);
    margin-bottom: 0;
    overscroll-behavior-y: none;
    -webkit-tap-highlight-color: transparent;
}

/* Ẩn scrollbar */
::-webkit-scrollbar {
    width: 0px;
    background: transparent; 
}

/* FB Mobile Tabs Bar (Single Header now) */
.fb-tabs-bar {
    background-color: var(--fb-blue); /* Changed to blue to match old FB mobile style */
    height: var(--header-height);
    position: fixed;
    top: 0;
    left: 0;
    right: 0;
    z-index: 1040;
    display: flex;
    box-shadow: 0 2px 4px rgba(0,0,0,0.1);
}

.fb-tab-item {
    flex: 1;
    display: flex;
    justify-content: center;
    align-items: center;
    color: rgba(255, 255, 255, 0.7); /* White with opacity */
    font-size: 22px;
    position: relative;
    cursor: pointer;
    text-decoration: none;
}

.fb-tab-item.active {
    color: var(--fb-white);
}

.fb-tab-item.active::after {
    content: '';
    position: absolute;
    bottom: 0;
    left: 0;
    right: 0;
    height: 4px;
    background-color: var(--fb-white);
}

/* Notification Box */
.fb-notif-box {
    position: fixed;
    top: var(--header-height);
    left: 0;
    right: 0;
    bottom: 0;
    background-color: var(--fb-bg);
    z-index: 1030;
    display: none;
    overflow-y: auto;
}

.fb-notif-box.show {
    display: block;
}

.notif-item {
    padding: 12px 16px;
    display: flex;
    align-items: center;
    background-color: var(--fb-white);
    cursor: pointer;
}

.notif-item.unread {
    background-color: #e7f3ff;
}

.notif-item i {
    width: 48px;
    height: 48px;
    border-radius: 50%;
    display: flex;
    justify-content: center;
    align-items: center;
    font-size: 20px;
    flex-shrink: 0;
}

.notif-item:active {
    background-color: #f2f2f2;
}

/* Side Menu */
.fb-menu-overlay {
    position: fixed;
    top: 0;
    bottom: 0;
    left: 0;
    right: 0;
    background-color: rgba(0, 0, 0, 0.5);
    z-index: 1050;
    display: none;
    opacity: 0;
}

.fb-side-menu {
    position: fixed;
    top: 0;
    bottom: 0;
    right: -280px;
    width: 280px;
    background-color: var(--fb-bg);
    z-index: 1060;
    transition: right 0.3s cubic-bezier(0.4, 0, 0.2, 1);
    box-shadow: -2px 0 5px rgba(0,0,0,0.1);
    display: flex;
    flex-direction: column;
    padding-top: 20px;
}

.fb-side-menu.show {
    right: 0;
}

.fb-menu-item {
    padding: 12px 20px;
    display: flex;
    align-items: center;
    text-decoration: none;
    color: var(--fb-text-primary);
    font-weight: 500;
}

.fb-menu-item i {
    width: 36px;
    height: 36px;
    background-color: #e4e6eb;
    border-radius: 50%;
    display: flex;
    justify-content: center;
    align-items: center;
    margin-right: 12px;
    font-size: 18px;
    color: var(--fb-text-primary);
}

.fb-menu-logout {
    margin-top: auto;
    border-top: 1px solid #ddd;
    color: #e41e3f;
    background-color: var(--fb-white);
}

.fb-menu-logout i {
    background-color: #fce8eb;
    color: #e41e3f;
}

/* Card Styling */
.fb-card {
    background-color: var(--fb-white);
    border-radius: 8px;
    box-shadow: 0 1px 2px rgba(0, 0, 0, 0.1);
    margin-bottom: 12px;
    padding: 12px;
}