/* =========================
   RESET
========================= */
* {
    box-sizing: border-box;
}

body {
    margin: 0;
    padding-top: 90px;
    font-family: system-ui, -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto;
}

/* =========================
   HEADER
========================= */
.main_header {
    position: fixed;
    top: 0;
    left: 0;
    width: 100%;
    background: #fff;
    z-index: 2000;
    box-shadow: 0 2px 10px rgba(0,0,0,.06);
}

.header_container {
    max-width: 1200px;
    margin: 0 auto;
    height: 90px;
    display: flex;
    align-items: center;
    justify-content: space-between;
    padding: 0 20px;
}

/* =========================
   LOGO
========================= */
.logo img {
    max-height: 88px;
    display: block;
}

/* =========================
   MENU DESKTOP
========================= */
.main_menu {
    display: flex;
    align-items: center;
}

.main_menu nav > ul {
    display: flex;
    gap: 32px;
    list-style: none;
    margin: 0;
    padding: 0;
}

.main_menu nav > ul > li {
    position: relative;
}

.main_menu nav > ul > li > a {
    font-size: 15px;
    font-weight: 500;
    color: #1f2937;
    text-decoration: none;
    padding: 30px 0;
    position: relative;
    white-space: nowrap;
}

/* underline hover */
.main_menu nav > ul > li > a::after {
    content: "";
    position: absolute;
    left: 0;
    bottom: 18px;
    width: 0;
    height: 2px;
    background: #16b3a3;
    transition: width .3s ease;
}

.main_menu nav > ul > li:hover > a::after {
    width: 100%;
}

/* =========================
   SUBMENU DESKTOP
========================= */
.main_menu .sub_menu {
    position: absolute;
    top: calc(100% + 10px);
    left: 0;
    min-width: 220px;
    background: #fff;
    border-radius: 6px;
    box-shadow: 0 10px 30px rgba(0,0,0,.08);
    opacity: 0;
    visibility: hidden;
    transform: translateY(10px);
    transition: .25s ease;
    z-index: 2100;
}

.main_menu li:hover > .sub_menu {
    opacity: 1;
    visibility: visible;
    transform: translateY(0);
}

.main_menu .sub_menu li a {
    display: block;
    padding: 12px 18px;
    font-size: 14px;
    color: #111;
    text-decoration: none;
}

.main_menu .sub_menu li a:hover {
    background: #f4f6f8;
    color: #16b3a3;
}

/* ❌ KHÔNG HIỂN THỊ MŨI TÊN DESKTOP */
.submenu-toggle {
    display: none;
}

/* =========================
   MOBILE BUTTON
========================= */
.btn-toggle-offcanvas {
    display: none;
    font-size: 26px;
    background: none;
    border: none;
    cursor: pointer;
}

/* =========================
   OVERLAY
========================= */
.menu-overlay {
    position: fixed;
    inset: 0;
    background: rgba(0,0,0,.55);
    opacity: 0;
    visibility: hidden;
    transition: .3s;
    z-index: 2500;
}

.menu-overlay.active {
    opacity: 1;
    visibility: visible;
}

/* =========================
   MOBILE & TABLET
========================= */
@media (max-width: 990px) {

    .btn-toggle-offcanvas {
        display: block;
    }

    .main_menu nav {
        position: fixed;
        inset: 0;
        background: #0b132b;
        padding-top: 80px;
        transform: translateX(-100%);
        transition: transform .35s ease;
        z-index: 3000;
        overflow-y: auto;
    }

    .main_menu nav.active {
        transform: translateX(0);
    }

    .main_menu nav > ul {
        flex-direction: column;
        gap: 0;
    }

    .main_menu nav > ul > li {
        position: relative; /* BẮT BUỘC */
    }

    .main_menu nav > ul > li > a {
        width: 100%;
        padding: 16px 52px 16px 22px;
        font-size: 20px;
        color: #fff;
        border-bottom: 1px solid #1e293b;
    }

    /* ===== MŨI TÊN ===== */
    .submenu-toggle {
        display: flex;
        align-items: center;
        justify-content: center;

        position: absolute;
        right: 12px;
        top: 50%;

        width: 36px;
        height: 36px;

        color: #fff;
        cursor: pointer;
        z-index: 2;

        transform: translateY(-50%) rotate(0deg);
        transition: transform .25s ease;
        transform-origin: center;
    }

    /* QUAY ĐÚNG */
    .main_menu li.open > .submenu-toggle {
        transform: translateY(-50%) rotate(180deg);
    }

    /* i KHÔNG XOAY */
    .submenu-toggle i {
        pointer-events: none;
    }

    /* ===== SUBMENU ===== */
    .main_menu .sub_menu {
        position: static;
        display: none;
        background: #020617;
        box-shadow: none;
    }

    .main_menu li.open > .sub_menu {
        display: block;
    }

    .main_menu .sub_menu li a {
        padding: 12px 40px;
        font-size: 15px;
        color: #cbd5f5;
    }
}