:root {
        --bg: #0c1a0c;
        --panel: #0f1e0d;
        --muted: rgba(230, 230, 230, 0.72);
        --accent: #e0b050;
        --olive: #7b9e6c;
        --glass: rgba(255, 255, 255, 0.03);
        --radius: 14px;
        --container: 1200px;
        font-family: "Inter", system-ui, -apple-system, "Segoe UI", Roboto, Arial;
    }

    * {
        box-sizing: border-box
    }

    html,
    body {
        height: 100%;
        margin: 0;
        background: linear-gradient(160deg, #091507 0%, #0f1e0d 80%);
        color: #fff;
        -webkit-font-smoothing: antialiased
    }

    a {
        color: inherit
    }

    .container {
        max-width: var(--container);
        margin: 0 auto;
        padding: 28px;
    }

    header {
        display: flex;
        align-items: center;
        justify-content: space-between;
        gap: 16px;
        padding-bottom: 12px
    }

    .brand {
        display: flex;
        align-items: center;
        gap: 12px;
        text-decoration: none
    }

    .brand img {
        width: 52px;
        height: 52px;
        object-fit: contain;
        border-radius: 8px;
        padding: 4px;
        background: rgba(255, 255, 255, 0.04)
    }

    nav a {
        color: var(--muted);
        margin-left: 18px;
        text-decoration: none;
        font-weight: 600
    }

    nav a.cta {
        background: linear-gradient(90deg, var(--olive), var(--accent));
        color: #07110a;
        padding: 10px 14px;
        border-radius: 12px
    }

    .course-shell {
        display: grid;
        grid-template-columns: 1fr;
        gap: 26px;
    }

    /* ====== HAMBURGER MENU ====== */

    /* Hide the checkbox itself */
    .menu-toggle {
        display: none;
    }

    /* Hamburger icon (three lines) */
    .menu-toggle-label {
        display: none;
        cursor: pointer;
        flex-direction: column;
        gap: 5px;
        z-index: 1001;
    }

    .menu-toggle-label span {
        width: 26px;
        height: 3px;
        background: #fff;
        border-radius: 3px;
        transition: 0.3s;
    }

    /* When checked (clicked), animate icon into "X" */
    .menu-toggle:checked+.menu-toggle-label span:nth-child(1) {
        transform: rotate(45deg) translateY(8px);
    }

    .menu-toggle:checked+.menu-toggle-label span:nth-child(2) {
        opacity: 0;
    }

    .menu-toggle:checked+.menu-toggle-label span:nth-child(3) {
        transform: rotate(-45deg) translateY(-8px);
    }


    .banner {
        background: linear-gradient(180deg, rgba(0, 0, 0, 0.12), transparent);
        border-radius: var(--radius);
        overflow: hidden;
        border: 1px solid rgba(255, 255, 255, 0.03);
        width: 100%;
        margin-bottom: 20px;
    }

    .banner img {
        width: 100%;
        height: auto;
        border-radius: 14px;
        object-fit: cover;
        object-position: top;
        display: block;
        background: #111;
        box-shadow: 0 8px 25px rgba(0, 0, 0, 0.4);
        transition: transform 0.4s ease, box-shadow 0.4s ease;
    }

    .banner img:hover {
        transform: scale(1.02);
        box-shadow: 0 10px 30px rgba(224, 176, 80, 0.3);
    }

    /* =====  Banner (inside course-shell) ===== */
    .course-shell>div .banner {
        width: 100%;
        margin-bottom: 24px;
    }

    .course-shell>div .banner img {
        display: block;
        width: 100%;
        height: auto;
        max-width: 100%;
        object-fit: cover;
        border-radius: 14px;
        box-shadow: 0 8px 25px rgba(0, 0, 0, 0.4);
        transition: transform 0.4s ease, box-shadow 0.4s ease;
    }

    /* hover effect for a polished look */
    .course-shell>div .banner img:hover {
        transform: scale(1.02);
        box-shadow: 0 12px 32px rgba(224, 176, 80, 0.35);
    }



    .main-card {
        padding: 22px;
        background: linear-gradient(180deg, rgba(255, 255, 255, 0.01), rgba(255, 255, 255, 0.00));
        border-radius: var(--radius);
        box-shadow: 0 10px 30px rgba(0, 0, 0, 0.5);
        border: 1px solid rgba(255, 255, 255, 0.02);
    }

    .title-row {
        display: flex;
        flex-direction: column;
        gap: 8px
    }

    .course-title {
        font-size: 28px;
        font-weight: 800;
        text-transform: uppercase;
        letter-spacing: 0.8px
    }

    .meta-small {
        color: var(--muted);
        font-size: 14px;
        margin-top: 4px
    }

    .tags {
        display: flex;
        gap: 10px;
        margin-top: 12px;
        flex-wrap: wrap
    }

    .pill {
        background: var(--glass);
        padding: 8px 10px;
        border-radius: 999px;
        color: var(--accent);
        font-weight: 700;
        font-size: 13px
    }

    .overview {
        margin-top: 16px;
        color: var(--muted);
        line-height: 1.6
    }

    .cta-actions {
        display: flex;
        gap: 12px;
        margin-top: 18px;
        flex-wrap: wrap
    }

    .btn {
        display: inline-flex;
        align-items: center;
        gap: 10px;
        padding: 12px 16px;
        border-radius: 10px;
        font-weight: 700;
        text-decoration: none;
        border: 0;
        cursor: pointer;
    }

    .btn-primary {
        background: linear-gradient(90deg, var(--olive), var(--accent));
        color: #07110a;
        box-shadow: 0 10px 30px rgba(224, 176, 80, 0.12)
    }

    .btn-ghost {
        background: transparent;
        border: 1px solid rgba(255, 255, 255, 0.06);
        color: var(--muted)
    }

    .sidebar {
        display: flex;
        flex-direction: column;
        gap: 18px;
    }

    .panel {
        background: linear-gradient(180deg, rgba(255, 255, 255, 0.01), rgba(255, 255, 255, 0.00));
        padding: 18px;
        border-radius: 12px;
        border: 1px solid rgba(255, 255, 255, 0.03);
    }

    .price-old {
        color: var(--muted);
        text-decoration: line-through;
        font-weight: 700
    }

    .price-now {
        font-size: 28px;
        font-weight: 800;
        color: var(--accent);
        margin-top: 6px
    }

    .save-note {
        color: var(--olive);
        font-weight: 700;
        margin-top: 6px
    }

    .learn-list {
        list-style: none;
        padding-left: 0;
        margin: 0;
        display: grid;
        gap: 10px
    }

    .learn-list li::before {
        content: "\25CF";
        color: var(--accent);
        display: inline-block;
        width: 18px;
        margin-left: -20px
    }

    .section {
        margin-top: 22px
    }

    .section h3 {
        margin: 0 0 10px 0;
        color: var(--accent);
        font-size: 18px
    }

    .topics-grid {
        display: grid;
        grid-template-columns: 1fr;
        gap: 12px
    }


    .topic {
        background: var(--glass);
        padding: 12px;
        border-radius: 10px;
        color: var(--muted);
        font-size: 14px
    }

    .lectures {
        margin-top: 12px;
        background: rgba(0, 0, 0, 0.02);
        padding: 12px;
        border-radius: 10px;
        border: 1px solid rgba(255, 255, 255, 0.02)
    }

    .lecture-item {
        display: flex;
        justify-content: space-between;
        padding: 8px 6px;
        border-bottom: 1px dashed rgba(255, 255, 255, 0.02);
        color: var(--muted)
    }

    .lecture-item:last-child {
        border-bottom: none
    }

    .muted {
        color: var(--muted)
    }

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

    a:focus,
    button:focus {
        outline: 3px solid rgba(224, 176, 80, 0.12);
        outline-offset: 3px;
        border-radius: 8px
    }

    /*============= Responsiveness ============*/

    @media(max-width:999px) {
        .banner img {
            height: 220px
        }

        .course-title {
            font-size: 22px
        }
    }

    @media (max-width: 900px) {
        nav {
            display: none;
            flex-direction: column;
            position: absolute;
            top: 70px;
            left: 0;
            width: 100%;
            background: rgba(12, 26, 12, 0.98);
            padding: 20px 0;
            text-align: center;
            z-index: 1000;
        }

        /* Show hamburger icon */
        .menu-toggle-label {
            display: flex;
        }

        /* Show menu when checkbox is checked */
        .menu-toggle:checked~nav {
            display: flex;
        }

        nav a {
            margin: 10px 0;
            color: #eee;
            font-size: 1.1rem;
        }
    }

    @media(min-width:700px) {
        .topics-grid {
            grid-template-columns: 1fr 1fr
        }
    }

    @media (max-width: 768px) {
        .banner img {
            border-radius: 10px;
        }

        .course-shell>div .banner img {
            border-radius: 10px;
        }
    }

    @media(min-width:1000px) {
        .course-shell {
            grid-template-columns: 2fr 420px;
            align-items: start
        }
    }