/* ===========================
   FIX OVERFLOW TOÀN TRANG
=========================== */
html, body {
    overflow-x: hidden;
    width: 100%;
    max-width: 100%;
}

.Overview,
.research,
.design-system,
.wireframe,
.mockup-phone-1,
.mockup-layout,
.video-prototype,
.design-process,
.design-system-title,
.main-footer {
    overflow-x: hidden;
    max-width: 100%;
    box-sizing: border-box;
}

img, video {
    max-width: 100%;
    height: auto;
}

/* ============================================================
   MOBILE BREAKPOINT (< 480px)
   ============================================================ */
@media (max-width: 480px) {
    .header {
        padding: 14px 20px;
    }

    .logo-img {
        height: 40px;
    }

    .main-menu {
        font-size: 13px;
    }

    .main-menu li {
        margin-right: 10px;
    }

    .nav-actions {
        gap: 10px;
    }

    .theme-toggle {
        width: 18px;
        height: 18px;
    }

    .hamburger-menu {
        width: 20px;
        height: 16px;
    }

    .hamburger-menu.active .bar:nth-child(1) {
        transform: rotate(-45deg) translate(-4px, 6px);
    }

    .hamburger-menu.active .bar:nth-child(3) {
        transform: rotate(45deg) translate(-4px, -6px);
    }

    .dropdown-menu {
        top: 55px;
        min-width: 120px;
        padding: 6px 8px;
    }

    .dropdown-menu li {
        padding: 6px 16px;
    }

    .sub-item {
        font-size: 13px;
    }

    /* --- ALERNA SPECIFIC --- */
    .Little-detail-overview { font-size: 11px; margin: 5px 16px; }
    .Title { font-size: clamp(32px, 14vw, 120px); }
    .hand-img { margin: 36px auto 0; padding: 0 12px; width: calc(100% - 24px); }
    .black-img { height: 240px; border-radius: 10px 10px 0 0; justify-content: center; }
    .black-img img { width: 100%; height: 100%; object-fit: cover; }
    .overview-text { font-size: 15px; padding: 16px 20px; }
    .phone-black-img { height: 240px; border-radius: 10px 10px 0 0; }
    .phone-black-img img { width: 100%; height: 100%; object-fit: cover; }
    .design-process { padding: 36px 20px; }
    .design-process .title { font-size: 28px; margin-bottom: 24px; }
    .design-thinking { flex-direction: column; gap: 10px; }
    .step { padding: 12px 36px 12px 16px; font-size: 14px; width: 100%; text-align: left; box-sizing: border-box; }
    .step::after { right: 12px; font-size: 14px; }
    .research { padding: 24px 16px; }
    .research::before { top: 12px; left: 12px; right: 12px; bottom: 12px; border-radius: 8px; }
    .research > div { margin-top: 24px; }
    .research h1 { font-size: 18px; }
    .research-img { width: 100%; }
    .persona { margin: 20px 0; }
    .persona-title { padding: 10px 14px; font-size: 14px; border-radius: 20px; margin: 12px auto; }
    .persona p { font-size: 13px; }
    .research-findings { margin-top: 20px; }
    .research-note { font-size: 12px; }
    .findings-columns { grid-template-columns: 1fr; gap: 16px; }
    .findings-col { font-size: 13px; }
    .findings-col strong { font-size: 15px; }
    .design-system-title { padding: 36px 20px; margin-top: -10px; }
    .design-system-title h1 { font-size: 28px; }
    .design-system { padding: 24px 16px; gap: 14px; }
    .design-system::before { top: 12px; left: 12px; right: 12px; bottom: 12px; }
    .design-system h1 { font-size: 18px; }
    .design-img { width: 100%; margin: 12px auto; }
    .wireframe { padding: 24px 20px; }
    .wireframe h1 { font-size: 18px; margin: 0 0 20px; }
    .mockup-phone-1 { padding: 24px 20px; }
    .mockup-phone-1 h1 { font-size: 18px; margin: 0 0 20px; }
    .video-prototype { padding: 12px 0; margin-top: 20px; }
    .mockup-layout { gap: 20px; padding: 20px 20px 60px; margin-bottom: -40px; margin-top: 0; }
    .title-mockup { font-size: 18px; }

    /* Footer */
    .main-footer {
        min-height: auto;
        margin-top: 50px;
        padding-bottom: 20px;
    }

    .logo-footer {
        padding: 20px 16px 10px;
    }

    .logo-footer .logo-img {
        height: 34px;
    }

    .back-to-top {
        position: static;
        display: block;
        text-align: right;
        padding: 0 16px 10px;
        font-size: 13px;
    }

    .footer {
        flex-direction: column;
        align-items: flex-start;
        padding: 8px 16px 16px;
        gap: 5px;
        font-size: 11px;
    }
}

/* ============================================================
   MOBILE BREAKPOINT (481px – 767px)
   ============================================================ */
@media (min-width: 481px) and (max-width: 767px) {
    .header {
        padding: 16px 28px;
    }

    .logo-img {
        height: 46px;
    }

    .main-menu {
        font-size: 15px;
    }

    .main-menu li {
        margin-right: 16px;
    }

    .nav-actions {
        gap: 12px;
    }

    .theme-toggle {
        width: 20px;
        height: 20px;
    }

    .dropdown-menu {
        top: 58px;
        padding: 8px 10px;
    }

    .dropdown-menu li {
        padding: 6px 24px;
    }

    .sub-item {
        font-size: 14px;
    }

    /* --- ALERNA SPECIFIC --- */
    .Little-detail-overview { font-size: 12px; margin: 5px 28px; }
    .Title { font-size: clamp(36px, 15vw, 160px); }
    .hand-img { margin: 44px auto 0; padding: 0 18px; }
    .black-img { height: 320px; border-radius: 12px 12px 0 0; justify-content: center; }
    .black-img img { width: 100%; height: 100%; object-fit: cover; }
    .overview-text { font-size: 15px; padding: 18px 28px; }
    .phone-black-img { height: 320px; border-radius: 12px 12px 0 0; }
    .design-process { padding: 44px 28px; }
    .design-process .title { font-size: 36px; margin-bottom: 30px; }
    .design-thinking { flex-direction: column; gap: 10px; }
    .step { width: 100%; padding: 14px 40px 14px 22px; font-size: 15px; text-align: left; box-sizing: border-box; }
    .research { padding: 32px 28px; }
    .research::before { top: 18px; left: 18px; right: 18px; bottom: 18px; }
    .research h1 { font-size: 20px; }
    .research-img { width: 96%; }
    .persona-title { font-size: 16px; padding: 12px 18px; }
    .persona p { font-size: 14px; }
    .findings-columns { grid-template-columns: 1fr; gap: 20px; }
    .findings-col { font-size: 14px; }
    .design-system-title { padding: 44px 28px; }
    .design-system-title h1 { font-size: 36px; }
    .design-system { padding: 32px 28px; }
    .design-system::before { top: 18px; left: 18px; right: 18px; bottom: 18px; }
    .design-system h1 { font-size: 20px; }
    .design-img { width: 96%; }
    .wireframe { padding: 28px; }
    .wireframe h1 { font-size: 20px; }
    .mockup-phone-1 { padding: 36px 28px; }
    .mockup-phone-1 h1 { font-size: 20px; }
    .video-prototype { margin-top: 26px; }
    .mockup-layout { gap: 26px; padding: 26px 28px 80px; margin-bottom: -50px; }
    .title-mockup { font-size: 20px; }

    /* Footer */
    .main-footer {
        margin-top: 60px;
        padding-bottom: 20px;
    }

    .logo-footer {
        padding: 24px 28px 10px;
    }

    .back-to-top {
        position: static;
        display: block;
        text-align: right;
        padding: 0 28px 10px;
        font-size: 14px;
    }

    .footer {
        flex-direction: column;
        align-items: flex-start;
        padding: 8px 28px 16px;
        gap: 5px;
        font-size: 12px;
    }
}


/* ============================================================
   TABLET BREAKPOINT (768px – 1023px)
   ============================================================ */
@media (min-width: 768px) and (max-width: 1023px) {
    .header {
        padding: 20px 40px;
    }

    .logo-img {
        height: 55px;
    }

    .main-menu {
        font-size: 18px;
    }

    .main-menu li {
        margin-right: 25px;
    }

    .nav-actions {
        gap: 18px;
    }

    .hamburger-menu {
        width: 22px;
        height: 19px;
    }

    .hamburger-menu.active .bar:nth-child(1) {
        transform: rotate(-45deg) translate(-4.5px, 7.5px);
    }

    .hamburger-menu.active .bar:nth-child(3) {
        transform: rotate(45deg) translate(-4.5px, -7.5px);
    }

    .dropdown-menu {
        top: 65px;
        min-width: 140px;
    }

    .dropdown-menu li {
        padding: 8px 60px;
    }

    .sub-item {
        font-size: 15px;
    }
    /* --- ALERNA SPECIFIC --- */
    .Little-detail-overview { font-size: 13px; margin: 5px 40px; }
    .hand-img { margin: 50px auto 0; padding: 0 30px; }
    .black-img { height: 550px; border-radius: 18px 18px 0 0; }
    .overview-text { font-size: 17px; padding: 20px 40px; }
    .phone-black-img { height: 520px; border-radius: 18px 18px 0 0; }
    .design-process { padding: 60px 40px; }
    .design-process .title { font-size: 48px; margin-bottom: 45px; }
    .step { padding: 16px 40px 16px 30px; font-size: 16px; }
    .research { padding: 45px 40px; }
    .research::before { top: 22px; left: 22px; right: 22px; bottom: 22px; }
    .research h1 { font-size: 26px; }
    .research-img { width: 90%; }
    .persona-title { padding: 16px 22px; font-size: 19px; }
    .persona p { font-size: 17px; }
    .findings-columns { gap: 35px; }
    .findings-col { font-size: 16px; }
    .findings-col strong { font-size: 18px; }
    .design-system-title { padding: 60px 40px; }
    .design-system-title h1 { font-size: 48px; }
    .design-system { padding: 45px 40px; }
    .design-system::before { top: 22px; left: 22px; right: 22px; bottom: 22px; }
    .design-system h1 { font-size: 26px; }
    .design-img { width: 90%; }
    .wireframe { padding: 35px 40px; }
    .wireframe h1 { font-size: 26px; }
    .mockup-phone-1 { padding: 45px 40px; }
    .mockup-phone-1 h1 { font-size: 26px; }
    .video-prototype { padding: 18px 0; margin-top: 35px; }
    .mockup-layout { gap: 35px; padding: 35px 40px 100px; margin-bottom: -70px; }
    .title-mockup { font-size: 26px; }

    /* Footer */
    .main-footer {
        height: 220px;
        margin-top: 80px;
    }

    .logo-footer {
        padding: 35px 40px;
    }

    .footer {
        padding: 50px 40px 0px;
    }

    .back-to-top {
        top: 35px;
        right: 40px;
        font-size: 17px;
    }
}

/* ============================================================
   DESKTOP BREAKPOINT (1024px and up)
   ============================================================ */
@media (min-width: 1024px) {
    .header {
        padding: 20px 60px;
    }

    .logo-img {
        height: 65px;
    }

    .main-menu {
        font-size: 20px;
    }

    .main-menu li {
        margin-right: 30px;
    }

    .nav-actions {
        gap: 20px;
    }

    .hamburger-menu {
        width: 24px;
        height: 20px;
    }

    .hamburger-menu.active .bar:nth-child(1) {
        transform: rotate(-45deg) translate(-5px, 8px);
    }

    .hamburger-menu.active .bar:nth-child(3) {
        transform: rotate(45deg) translate(-5px, -8px);
    }

    .dropdown-menu {
        top: 70px;
        min-width: 150px;
    }

    .dropdown-menu li {
        padding: 8px 85px;
    }

    .sub-item {
        font-size: 16px;
    }

    .main-footer {
        height: 250px;
        margin-top: 100px;
    }

    .logo-footer {
        padding: 40px 60px;
    }

    .footer {
        padding: 60px 60px 0px;
    }

    .back-to-top {
        top: 40px;
        right: 60px;
        font-size: 18px;
    }
}

/* ============================================================
   LARGE DESKTOP (1440px and up)
   ============================================================ */
@media (min-width: 1440px) {

    .header {
        padding: 20px 60px;
    }

    .logo-img {
        height: 65px;
    }

    .main-footer {
        height: 250px;
        margin-top: 100px;
    }

    .logo-footer {
        padding: 40px 60px;
    }

    .footer {
        padding: 60px 60px 0px;
    }

    .back-to-top {
        top: 40px;
        right: 60px;
        font-size: 18px;
    }

}

/* ============================================================
   PRINT
   ============================================================ */
@media print {
    .header,
    .hamburger-menu,
    .dropdown-menu,
    .back-to-top {
        display: none;
    }

    body {
        background: white;
        color: black;
    }

    .main-footer {
        background: #eee;
    }
}

/* ===========================
   MOBILE dropdown right fix
=========================== */
@media (max-width: 767px) {
    .dropdown-menu { right: 20px; }
}