Hướng dẫn code giao diện Flash Sale hiện đại

:root {
    --primary: #ff1744;
    --primary-dark: #d50032;
    --secondary: #ff6d00;
    --dark: #111318;
    --text: #24262d;
    --muted: #777b85;
    --border: #ececf1;
    --bg: #f7f7fa;
    --white: #ffffff;
    --radius: 20px;
    --shadow: 0 15px 45px rgba(20, 20, 30, .08);
}

* {
    box-sizing: border-box;
    margin: 0;
    padding: 0;
}

html {
    scroll-behavior: smooth;
}

body {
    font-family: "Be Vietnam Pro", sans-serif;
    background: var(--bg);
    color: var(--text);
    line-height: 1.6;
}

button,
a {
    font-family: inherit;
}

button {
    border: 0;
    cursor: pointer;
}

a {
    text-decoration: none;
    color: inherit;
}

.container {
    width: min(1200px, calc(100% - 40px));
    margin: auto;
}


/* =========================
   TOP BAR
========================= */

.top-bar {
    background: #0d0e12;
    color: #fff;
    font-size: 12px;
}

.top-bar-inner {
    min-height: 42px;
    display: flex;
    justify-content: space-between;
    align-items: center;
}

.top-left,
.top-right {
    display: flex;
    align-items: center;
    gap: 20px;
}

.live-dot {
    width: 8px;
    height: 8px;
    border-radius: 50%;
    background: #ff1744;
    box-shadow: 0 0 0 5px rgba(255, 23, 68, .15);
    animation: pulse 1.5s infinite;
}


/* =========================
   HERO
========================= */

.hero {
    position: relative;
    overflow: hidden;
    color: #fff;
    background:
        radial-gradient(circle at 80% 20%, rgba(255, 109, 0, .35), transparent 30%),
        linear-gradient(120deg, #9b002c, #f0003d 45%, #ff6d00);
}

.hero::after {
    content: "";
    position: absolute;
    left: 0;
    right: 0;
    bottom: -1px;
    height: 70px;
    background: var(--bg);
    clip-path: polygon(0 100%, 100% 100%, 100% 30%, 80% 70%, 60% 30%, 40% 70%, 20% 30%, 0 70%);
}

.hero-content {
    position: relative;
    z-index: 2;
    min-height: 500px;
    padding: 80px 0 100px;
    display: grid;
    grid-template-columns: 1.1fr .9fr;
    align-items: center;
    gap: 70px;
}

.hero-glow {
    position: absolute;
    border-radius: 50%;
    filter: blur(5px);
    opacity: .35;
}

.glow-1 {
    width: 400px;
    height: 400px;
    background: #ffb000;
    right: -120px;
    top: -150px;
}

.glow-2 {
    width: 300px;
    height: 300px;
    background: #7000ff;
    left: -120px;
    bottom: -180px;
}

.eyebrow {
    width: fit-content;
    padding: 7px 13px;
    margin-bottom: 18px;
    border: 1px solid rgba(255,255,255,.3);
    background: rgba(255,255,255,.1);
    border-radius: 999px;
    font-size: 12px;
    font-weight: 800;
    letter-spacing: .08em;
}

.eyebrow span {
    margin-right: 5px;
}

.hero h1 {
    font-size: clamp(58px, 8vw, 105px);
    line-height: .85;
    font-weight: 900;
    letter-spacing: -.06em;
}

.hero h1 strong {
    display: block;
    color: #ffd000;
    text-shadow: 4px 5px 0 rgba(100, 0, 0, .2);
}

.hero-copy > p {
    max-width: 580px;
    margin: 25px 0;
    color: rgba(255,255,255,.84);
    font-size: 16px;
}

.hero-actions {
    display: flex;
    gap: 12px;
    flex-wrap: wrap;
}

.btn {
    display: inline-flex;
    align-items: center;
    justify-content: center;
    gap: 12px;
    min-height: 50px;
    padding: 0 23px;
    border-radius: 12px;
    font-size: 13px;
    font-weight: 800;
    transition: .25s ease;
}

.btn-primary {
    background: #fff;
    color: var(--primary);
    box-shadow: 0 12px 30px rgba(0,0,0,.15);
}

.btn-primary:hover {
    transform: translateY(-3px);
}

.btn-outline {
    border: 1px solid rgba(255,255,255,.4);
    color: #fff;
    background: rgba(255,255,255,.08);
}

.btn-outline:hover {
    background: rgba(255,255,255,.16);
}


/* =========================
   COUNTDOWN
========================= */

.countdown-card {
    padding: 28px;
    border-radius: 25px;
    background: rgba(20, 10, 10, .25);
    border: 1px solid rgba(255,255,255,.18);
    backdrop-filter: blur(15px);
    box-shadow: 0 30px 70px rgba(70, 0, 0, .2);
}

.countdown-header {
    display: flex;
    align-items: center;
    justify-content: space-between;
    margin-bottom: 20px;
    font-size: 11px;
    font-weight: 800;
    letter-spacing: .08em;
}

.status {
    padding: 5px 9px;
    border-radius: 999px;
    background: rgba(255,255,255,.15);
}

.countdown {
    display: grid;
    grid-template-columns: 1fr auto 1fr auto 1fr auto 1fr;
    align-items: center;
    gap: 7px;
}

.time-box {
    padding: 15px 8px;
    text-align: center;
    border-radius: 15px;
    background: rgba(255,255,255,.12);
}

.time-box strong {
    display: block;
    font-size: 34px;
    line-height: 1;
    font-weight: 900;
}

.time-box small {
    display: block;
    margin-top: 8px;
    font-size: 9px;
    opacity: .7;
    text-transform: uppercase;
}

.separator {
    font-size: 25px;
    font-weight: 900;
    opacity: .6;
}

.countdown-note {
    margin-top: 20px;
    padding-top: 15px;
    border-top: 1px solid rgba(255,255,255,.12);
    text-align: center;
    font-size: 12px;
    opacity: .85;
}


/* =========================
   SALE INFO
========================= */

.sale-info {
    position: relative;
    z-index: 5;
    margin-top: -5px;
}

.sale-info-grid {
    display: grid;
    grid-template-columns: repeat(4, 1fr);
    background: #fff;
    border: 1px solid var(--border);
    border-radius: 18px;
    box-shadow: var(--shadow);
    overflow: hidden;
}

.info-item {
    display: flex;
    align-items: center;
    gap: 13px;
    padding: 22px;
    border-right: 1px solid var(--border);
}

.info-item:last-child {
    border-right: 0;
}

.info-icon {
    width: 42px;
    height: 42px;
    flex: 0 0 42px;
    display: grid;
    place-items: center;
    border-radius: 12px;
    background: #fff0f3;
    font-size: 18px;
}

.info-item strong,
.info-item span {
    display: block;
}

.info-item strong {
    font-size: 12px;
}

.info-item span {
    margin-top: 2px;
    color: var(--muted);
    font-size: 10px;
}


/* =========================
   PRODUCTS
========================= */

.products-section {
    padding: 85px 0;
}

.section-heading {
    display: flex;
    justify-content: space-between;
    align-items: end;
    gap: 30px;
    margin-bottom: 35px;
}

.section-label {
    margin-bottom: 7px;
    color: var(--primary);
    font-size: 11px;
    font-weight: 900;
    letter-spacing: .1em;
}

.section-heading h2 {
    font-size: clamp(30px, 4vw, 45px);
    line-height: 1.15;
    letter-spacing: -.04em;
}

.section-heading h2 span {
    color: var(--primary);
}

.section-heading p {
    margin-top: 8px;
    color: var(--muted);
    font-size: 13px;
}

.sale-progress {
    width: 230px;
}

.sale-progress > span,
.sale-progress strong {
    display: block;
    font-size: 11px;
}

.sale-progress strong {
    margin-top: 4px;
}

.total-progress {
    height: 7px;
    margin-top: 9px;
    overflow: hidden;
    border-radius: 999px;
    background: #e7e7eb;
}

.total-progress div {
    width: 64%;
    height: 100%;
    background: linear-gradient(90deg, #ff1744, #ff6d00);
    border-radius: inherit;
    transition: width .5s;
}

.products-grid {
    display: grid;
    grid-template-columns: repeat(4, 1fr);
    gap: 18px;
}

.product-card {
    position: relative;
    overflow: hidden;
    border: 1px solid var(--border);
    border-radius: var(--radius);
    background: #fff;
    box-shadow: 0 5px 20px rgba(20,20,30,.04);
    transition: .3s ease;
}

.product-card:hover {
    transform: translateY(-7px);
    box-shadow: 0 25px 55px rgba(20,20,30,.12);
}

.product-image {
    position: relative;
    height: 235px;
    display: grid;
    place-items: center;
    overflow: hidden;
    background: linear-gradient(145deg, #f5f5f7, #e8e8ed);
}

.product-placeholder {
    width: 145px;
    height: 145px;
    display: grid;
    place-items: center;
    border-radius: 35px;
    background: #fff;
    box-shadow: 0 25px 50px rgba(0,0,0,.12);
    font-size: 75px;
    transition: .4s ease;
}

.product-card:hover .product-placeholder {
    transform: scale(1.08) rotate(-3deg);
}

.discount-badge {
    position: absolute;
    z-index: 2;
    left: 13px;
    top: 13px;
    padding: 6px 9px;
    border-radius: 7px;
    background: var(--primary);
    color: #fff;
    font-size: 11px;
    font-weight: 900;
}

.hot-badge {
    position: absolute;
    z-index: 2;
    right: 13px;
    top: 13px;
    padding: 6px 9px;
    border-radius: 7px;
    background: #fff;
    color: var(--primary);
    font-size: 9px;
    font-weight: 900;
}

.wishlist {
    position: absolute;
    z-index: 3;
    right: 13px;
    bottom: 13px;
    width: 36px;
    height: 36px;
    border-radius: 50%;
    background: rgba(255,255,255,.95);
    font-size: 21px;
    color: #555;
    box-shadow: 0 5px 15px rgba(0,0,0,.08);
    transition: .2s;
}

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

.product-body {
    padding: 20px;
}

.product-category {
    margin-bottom: 5px;
    color: #9b9da4;
    font-size: 9px;
    font-weight: 800;
    letter-spacing: .1em;
}

.product-body h3 {
    min-height: 48px;
    font-size: 14px;
    line-height: 1.5;
}

.rating {
    display: flex;
    align-items: center;
    gap: 6px;
    margin: 7px 0;
}

.rating span {
    color: #ffb000;
    font-size: 11px;
    letter-spacing: -2px;
}

.rating small {
    color: #9b9da4;
    font-size: 9px;
}

.price {
    display: flex;
    align-items: baseline;
    gap: 8px;
    margin-top: 12px;
}

.price strong {
    color: var(--primary);
    font-size: 20px;
    font-weight: 900;
}

.price del {
    color: #a4a5aa;
    font-size: 10px;
}

.sold {
    margin-top: 14px;
}

.sold-text {
    display: flex;
    justify-content: space-between;
    margin-bottom: 5px;
    color: #777;
    font-size: 9px;
}

.sold-text strong {
    color: var(--primary);
}

.progress {
    height: 6px;
    overflow: hidden;
    border-radius: 999px;
    background: #eee;
}

.progress div {
    height: 100%;
    border-radius: inherit;
    background: linear-gradient(90deg, #ff1744, #ff6d00);
}

.buy-btn {
    width: 100%;
    height: 45px;
    margin-top: 16px;
    border-radius: 10px;
    background: #111318;
    color: #fff;
    font-size: 11px;
    font-weight: 900;
    transition: .25s;
}

.buy-btn span {
    margin-left: 8px;
}

.buy-btn:hover {
    background: var(--primary);
    transform: translateY(-2px);
}


/* =========================
   VIEW ALL
========================= */

.view-all {
    display: flex;
    justify-content: center;
    margin-top: 35px;
}

.view-all button {
    padding: 13px 24px;
    border: 1px solid #dddde3;
    border-radius: 10px;
    background: #fff;
    color: #333;
    font-size: 12px;
    font-weight: 800;
    transition: .2s;
}

.view-all button:hover {
    border-color: var(--primary);
    color: var(--primary);
}


/* =========================
   CTA
========================= */

.cta {
    padding: 65px 0;
    background:
        radial-gradient(circle at 80% 30%, rgba(255,109,0,.3), transparent 30%),
        linear-gradient(110deg, #a50032, #ef003c);
    color: #fff;
}

.cta-content {
    display: flex;
    justify-content: space-between;
    align-items: center;
    gap: 40px;
}

.cta-label {
    font-size: 10px;
    font-weight: 900;
    letter-spacing: .1em;
}

.cta h2 {
    max-width: 600px;
    margin-top: 7px;
    font-size: clamp(30px, 4vw, 45px);
    line-height: 1.15;
}

.cta h2 span {
    color: #ffd000;
}

.cta p {
    max-width: 600px;
    margin-top: 10px;
    color: rgba(255,255,255,.75);
    font-size: 13px;
}

.btn-white {
    flex-shrink: 0;
    background: #fff;
    color: var(--primary);
}


/* =========================
   FOOTER
========================= */

footer {
    background: #0c0d10;
    color: #fff;
}

.footer-inner {
    min-height: 110px;
    display: flex;
    justify-content: space-between;
    align-items: center;
}

.footer-inner strong {
    font-size: 20px;
    font-weight: 900;
}

.footer-inner strong span {
    color: var(--primary);
}

.footer-inner p {
    margin-top: 2px;
    color: #858791;
    font-size: 10px;
}

.footer-copy {
    color: #666872;
    font-size: 10px;
}


/* =========================
   TOAST
========================= */

.toast {
    position: fixed;
    z-index: 9999;
    right: 25px;
    bottom: 25px;
    display: flex;
    align-items: center;
    gap: 12px;
    min-width: 290px;
    padding: 15px 17px;
    border-radius: 13px;
    background: #111318;
    color: #fff;
    box-shadow: 0 20px 50px rgba(0,0,0,.25);
    transform: translateY(130px);
    opacity: 0;
    pointer-events: none;
    transition: .35s ease;
}

.toast.show {
    transform: translateY(0);
    opacity: 1;
}

.toast > span {
    width: 30px;
    height: 30px;
    display: grid;
    place-items: center;
    border-radius: 50%;
    background: #22c55e;
    font-weight: 900;
}

.toast strong,
.toast small {
    display: block;
}

.toast strong {
    font-size: 11px;
}

.toast small {
    margin-top: 2px;
    color: #999;
    font-size: 9px;
}


/* =========================
   ANIMATION
========================= */

@keyframes pulse {
    0%,100% {
        transform: scale(1);
        opacity: 1;
    }

    50% {
        transform: scale(.65);
        opacity: .5;
    }
}


/* =========================
   RESPONSIVE
========================= */

@media (max-width: 1000px) {

    .hero-content {
        grid-template-columns: 1fr;
        gap: 40px;
    }

    .countdown-card {
        max-width: 600px;
    }

    .sale-info-grid {
        grid-template-columns: repeat(2, 1fr);
    }

    .info-item:nth-child(2) {
        border-right: 0;
    }

    .info-item:nth-child(-n+2) {
        border-bottom: 1px solid var(--border);
    }

    .products-grid {
        grid-template-columns: repeat(2, 1fr);
    }
}


@media (max-width: 650px) {

    .container {
        width: min(100% - 28px, 1200px);
    }

    .top-right {
        display: none;
    }

    .hero-content {
        padding: 55px 0 80px;
    }

    .hero h1 {
        font-size: 70px;
    }

    .countdown-card {
        padding: 18px;
    }

    .time-box strong {
        font-size: 25px;
    }

    .sale-info-grid,
    .products-grid {
        grid-template-columns: 1fr;
    }

    .info-item {
        border-right: 0;
        border-bottom: 1px solid var(--border);
    }

    .info-item:last-child {
        border-bottom: 0;
    }

    .section-heading {
        display: block;
    }

    .sale-progress {
        width: 100%;
        margin-top: 25px;
    }

    .products-section {
        padding: 60px 0;
    }

    .product-image {
        height: 260px;
    }

    .cta-content {
        display: block;
    }

    .cta .btn {
        margin-top: 25px;
    }

    .footer-inner {
        display: block;
        padding: 30px 0;
    }

    .footer-copy {
        margin-top: 20px;
    }

    .toast {
        left: 14px;
        right: 14px;
        bottom: 14px;
        min-width: 0;
    }
}

document.addEventListener("DOMContentLoaded", () => {

    /* =========================
       COUNTDOWN
    ========================= */

    // Flash Sale kết thúc sau 24 giờ kể từ lúc mở trang
    const saleEnd = new Date();
    saleEnd.setHours(saleEnd.getHours() + 23);
    saleEnd.setMinutes(saleEnd.getMinutes() + 59);
    saleEnd.setSeconds(saleEnd.getSeconds() + 59);

    const daysEl = document.getElementById("days");
    const hoursEl = document.getElementById("hours");
    const minutesEl = document.getElementById("minutes");
    const secondsEl = document.getElementById("seconds");

    function updateCountdown() {

        const now = new Date();
        const distance = saleEnd - now;

        if (distance <= 0) {
            daysEl.textContent = "00";
            hoursEl.textContent = "00";
            minutesEl.textContent = "00";
            secondsEl.textContent = "00";
            return;
        }

        const days = Math.floor(distance / (1000 * 60 * 60 * 24));
        const hours = Math.floor(
            (distance / (1000 * 60 * 60)) % 24
        );
        const minutes = Math.floor(
            (distance / (1000 * 60)) % 60
        );
        const seconds = Math.floor(
            (distance / 1000) % 60
        );

        daysEl.textContent = String(days).padStart(2, "0");
        hoursEl.textContent = String(hours).padStart(2, "0");
        minutesEl.textContent = String(minutes).padStart(2, "0");
        secondsEl.textContent = String(seconds).padStart(2, "0");
    }

    updateCountdown();

    setInterval(updateCountdown, 1000);


    /* =========================
       WISHLIST
    ========================= */

    document.querySelectorAll(".wishlist").forEach(button => {

        button.addEventListener("click", () => {

            button.classList.toggle("active");

            if (button.classList.contains("active")) {
                button.innerHTML = "♥";
            } else {
                button.innerHTML = "♡";
            }

        });

    });


    /* =========================
       BUY BUTTON
    ========================= */

    const toast = document.getElementById("toast");
    let toastTimer;

    document.querySelectorAll(".buy-btn").forEach(button => {

        button.addEventListener("click", () => {

            button.classList.add("clicked");

            showToast();

            setTimeout(() => {
                button.classList.remove("clicked");
            }, 300);

        });

    });


    function showToast() {

        toast.classList.add("show");

        clearTimeout(toastTimer);

        toastTimer = setTimeout(() => {
            toast.classList.remove("show");
        }, 3000);

    }


    /* =========================
       VIEW ALL
    ========================= */

    const viewAllBtn = document.getElementById("viewAllBtn");

    viewAllBtn.addEventListener("click", () => {

        const cards = document.querySelectorAll(".product-card");

        cards.forEach((card, index) => {

            card.style.animation = "none";

            setTimeout(() => {
                card.style.transform = "translateY(-4px)";

                setTimeout(() => {
                    card.style.transform = "";
                }, 150);

            }, index * 70);

        });

        viewAllBtn.innerHTML = "✓ Đang hiển thị tất cả";

        setTimeout(() => {
            viewAllBtn.innerHTML = 'Xem tất cả sản phẩm <span>→</span>';
        }, 1800);

    });


    /* =========================
       RANDOM SOLD COUNTER
       TẠO CẢM GIÁC LIVE
    ========================= */

    let sold = 128;

    const soldTotal = document.getElementById("soldTotal");
    const totalProgress = document.getElementById("totalProgress");

    function increaseSold() {

        if (sold >= 200) return;

        const increase = Math.random() > .65 ? 2 : 1;

        sold = Math.min(200, sold + increase);

        soldTotal.textContent = sold;

        const percent = (sold / 200) * 100;

        totalProgress.style.width = percent + "%";
    }

    // Tăng số lượng đã bán ngẫu nhiên
    setInterval(increaseSold, 7000);


    /* =========================
       PRODUCT CARD REVEAL
    ========================= */

    const observer = new IntersectionObserver(
        entries => {

            entries.forEach(entry => {

                if (entry.isIntersecting) {

                    entry.target.style.opacity = "1";
                    entry.target.style.transform = "translateY(0)";

                    observer.unobserve(entry.target);

                }

            });

        },
        {
            threshold: .12
        }
    );


    document.querySelectorAll(".product-card").forEach(card => {

        card.style.opacity = "0";
        card.style.transform = "translateY(25px)";
        card.style.transition =
            "opacity .6s ease, transform .6s ease, box-shadow .3s ease";

        observer.observe(card);

    });


    /* =========================
       SMOOTH ANCHOR
    ========================= */

    document.querySelectorAll('a[href^="#"]').forEach(link => {

        link.addEventListener("click", event => {

            const targetId = link.getAttribute("href");

            if (targetId === "#") return;

            const target = document.querySelector(targetId);

            if (!target) return;

            event.preventDefault();

            target.scrollIntoView({
                behavior: "smooth",
                block: "start"
            });

        });

    });

});