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

        body {
            font-family: system-ui, 'Segoe UI', 'Roboto', 'Helvetica Neue', sans-serif;
            background-color: #16263F;
            min-height: 100vh;
            display: flex;
            flex-direction: column;
        }

        header {
            background: #FFC107;
            backdrop-filter: blur(8px);
            padding: 0.7rem 2rem;
            display: flex;
            justify-content: space-between;
            align-items: center;
            flex-wrap: wrap;
            gap: 1rem;
            box-shadow: 0 8px 20px rgba(0, 0, 0, 0.15);
            border-bottom: 1px solid rgba(255, 255, 255, 0.2);
            position: sticky;
            top: 0;
            z-index: 100;
        }

        .brand-box {
            display: flex;
            justify-content: center;
            align-items: center;
            gap: 1rem;
        }

        .brand-img {
            width: 50px;
        }

        .brand {
            font-size: 1.8rem;
            font-weight: 700;
            letter-spacing: -0.5px;
            color: #1E2F4D;
        }

        nav ul {
            display: flex;
            gap: 1rem;
            list-style: none;
        }

        nav ul li a {
            color: #1E2F4D;
            text-decoration: none;
            font-weight: 600;
            padding: 0.5rem 0.8rem;
            border-radius: 40px;
            transition: all 0.25s ease;
            font-size: 1rem;
        }

        nav ul li a:hover {
            background: rgba(255, 255, 255, 0.2);
            color: blue;
            transform: translateY(-2px);
        }

        main {
            flex: 1;
            max-width: 1400px;
            margin: 0 auto;
            padding: 2rem 1.5rem;
            width: 100%;
        }

        .head {
            text-align: center;
            margin: 0.5rem 0 2rem;
            font-size: 2.4rem;
            font-weight: 800;
            background: linear-gradient(135deg, #1e2a5e, #3852B4);
            background-clip: text;
            -webkit-background-clip: text;
            color: #FFFFFF;
            position: relative;
            display: inline-block;
            width: 100%;
        }

        .head::after {
            content: '';
            display: block;
            width: 80px;
            height: 4px;
            background: #3852B4;
            margin: 0.5rem auto 0;
            border-radius: 4px;
        }

        .section-1 {
            display: flex;
            justify-content: center;
            flex-wrap: wrap;
            gap: 2rem;
            margin: 0.5rem 0 2.5rem;
        }

        .textbooks {
            width: 260px;
            height: 300px;
            border-radius: 28px;
            display: flex;
            text-align: center;
            flex-direction: column;
            justify-content: center;
            align-items: center;
            font-weight: 800;
            font-size: 1.8rem;
            color: white;
            transition: all 0.35s cubic-bezier(0.2, 0.9, 0.4, 1.1);
            box-shadow: 0 15px 30px rgba(0, 0, 0, 0.2);
            cursor: pointer;
            position: relative;
            overflow: hidden;
            backdrop-filter: blur(2px);
            line-height: 1.3;
            border-left: 10px solid black;
        }

        .section-1 a {
            border-radius: 27px;
            text-decoration: none;
            display: block;
        }

        .section-1 a:hover .textbooks {
            transform: translateY(-10px) scale(1.02);
            box-shadow: 0 25px 40px rgba(0, 0, 0, 0.3);
        }

        .textbooks[data-sem="1"] { background: linear-gradient(135deg, #ff3730, #ff0800); }
        .textbooks[data-sem="2"] { background: linear-gradient(135deg, #36abd1, #00aeff); }
        .textbooks[data-sem="3"] { background: linear-gradient(135deg, #F58529, #e07a1f); }
        .textbooks[data-sem="4"] { background: linear-gradient(135deg, #474A8A, #35386e); }
        .textbooks[data-sem="5"] { background: linear-gradient(135deg, #669933, #4d7a26); }
        .textbooks[data-sem="6"] { background: linear-gradient(135deg, #9C3433, #7a2827); }

        .ripple-effect {
            position: absolute;
            border-radius: 50%;
            background-color: rgba(255, 255, 255, 0.4);
            transform: scale(0);
            animation: rippleAnim 0.5s linear;
            pointer-events: none;
        }

        @keyframes rippleAnim {
            to {
                transform: scale(10);
                opacity: 0;
            }
        }

        /* Modal Styles */
        .modal {
            display: none;
            position: fixed;
            top: 0;
            left: 0;
            width: 100%;
            height: 100%;
            background: rgba(0, 0, 0, 0.8);
            z-index: 1000;
            justify-content: center;
            align-items: center;
        }

        .modal-content {
            background: white;
            width: 90%;
            max-width: 500px;
            border-radius: 28px;
            overflow: hidden;
            animation: modalSlideIn 0.3s ease;
        }

        @keyframes modalSlideIn {
            from {
                transform: translateY(-50px);
                opacity: 0;
            }
            to {
                transform: translateY(0);
                opacity: 1;
            }
        }

        .modal-header {
            background: #FFC107;
            padding: 1.2rem;
            display: flex;
            justify-content: space-between;
            align-items: center;
            position: sticky;
            top: 0;
            z-index: 10;
        }

        .modal-header h2 {
            color: #1E2F4D;
            font-size: 1.3rem;
            margin: 0;
        }

        .close-modal {
            background: none;
            border: none;
            font-size: 1.8rem;
            cursor: pointer;
            color: #1E2F4D;
            transition: all 0.2s;
        }

        .close-modal:hover {
            transform: scale(1.1);
        }

        /* Modal Body with Scrollbar INSIDE */
        .modal-body {
            max-height: 65vh;
            overflow-y: auto;
            padding: 0.5rem;
        }

        /* Custom Scrollbar inside modal body */
        .modal-body::-webkit-scrollbar {
            width: 8px;
        }

        .modal-body::-webkit-scrollbar-track {
            background: #f1f1f1;
            border-radius: 10px;
        }

        .modal-body::-webkit-scrollbar-thumb {
            background: #3852B4;
            border-radius: 10px;
        }

        .modal-body::-webkit-scrollbar-thumb:hover {
            background: #2a3f94;
        }

        .modal-body {
            scrollbar-width: thin;
            scrollbar-color: #3852B4 #f1f1f1;
        }

        .subject-item {
            display: flex;
            justify-content: space-between;
            align-items: center;
            padding: 0.8rem 1rem;
            border-bottom: 1px solid #eee;
            transition: all 0.2s ease;
            gap: 1rem;
            flex-wrap: nowrap;
        }

        .subject-item:hover {
            background: #f5f5f5;
        }

        .subject-name {
            font-size: 1rem;
            color: #1e2a5e;
            font-weight: 500;
            flex: 1;
            min-width: 0;
            word-break: break-word;
            text-transform: uppercase;
        }

        .download-subject {
            background: #3852B4;
            color: white;
            border: none;
            padding: 0.4rem 1rem;
            border-radius: 20px;
            cursor: pointer;
            font-size: 0.75rem;
            font-weight: 500;
            transition: all 0.2s;
            text-decoration: none;
            display: inline-block;
            white-space: nowrap;
            min-width: 100px;
            text-align: center;
            flex-shrink: 0;
        }

        .download-subject:hover {
            background: #2a3f94;
            transform: scale(1.02);
        }

        @media (max-width: 768px) {
            .subject-item {
                flex-wrap: nowrap;
                gap: 0.8rem;
            }
            .download-subject {
                min-width: 90px;
                padding: 0.35rem 0.8rem;
                font-size: 0.7rem;
            }
        }

        @media (max-width: 550px) {
            .subject-item {
                flex-wrap: wrap;
                gap: 0.5rem;
            }
            .download-subject {
                align-self: flex-start;
                min-width: 100px;
            }
        }

        .why-textbooks {
            text-align: center;
            padding: 2rem;
            background: linear-gradient(120deg, #e9efff, #ffffff);
            border-radius: 48px;
            margin: 2rem 0 1rem;
            box-shadow: 0 8px 20px rgba(56, 82, 180, 0.1);
            border: 1px solid rgba(56, 82, 180, 0.15);
        }

        .why-textbooks h2 {
            font-size: 1.9rem;
            color: #1e2a5e;
            margin-bottom: 1rem;
            font-weight: 700;
        }

        .why-textbooks ul {
            list-style: none;
            display: flex;
            justify-content: center;
            flex-wrap: wrap;
            gap: 2rem;
            margin-top: 1rem;
        }

        .why-textbooks li {
            font-size: 1.1rem;
            background: #3852B4;
            color: white;
            padding: 0.6rem 1.4rem;
            border-radius: 60px;
            font-weight: 500;
            transition: all 0.2s ease;
        }

        .why-textbooks li:hover {
            transform: translateY(-3px);
            background: #2a3f94;
            box-shadow: 0 6px 12px rgba(56, 82, 180, 0.3);
        }

        footer {
            background: #FFC107;
            text-align: center;
            padding: 0.5rem;
            color: #1E2F4D;
            font-weight: 500;
            border-top: 1px solid rgba(255, 255, 255, 0.1);
        }

        .social {
            display: flex;
            justify-content: center;
            align-items: center;
            gap: 1rem;
        }

        .social a {
            color: #1E2F4D;
            font-size: 1.5rem;
        }

        hr {
            margin-top: 0.5rem;
            border: 1px solid white;
            margin-bottom: 0.5rem;
        }

        @media (max-width: 768px) {
            header {
                padding: 0.8rem 1.2rem;
            }
            .brand {
                font-size: 1.4rem;
            }
            nav ul {
                gap: 1rem;
            }
            .head {
                font-size: 1.9rem;
            }
            .textbooks {
                width: 220px;
                height: 260px;
                font-size: 1.5rem;
            }
            .why-textbooks ul {
                flex-direction: column;
                align-items: center;
            }
            .why-textbooks li {
                width: 80%;
            }
        }

        @media (max-width: 480px) {
            header {
                display: flex;
                justify-content: center;
                align-items: center;
            }
            .head {
                font-size: 1.8rem;
            }
            main {
                padding: 1rem;
            }
            .section-1 {
                gap: 1.2rem;
            }
            .textbooks {
                width: 160px;
                height: 200px;
                font-size: 1.2rem;
            }

            .subject-name{
                font-size: 0.75rem;
            }
            
            .why-textbooks {
                padding: 1.5rem;
            }
            .why-textbooks h2 {
                font-size: 1.2rem;
            }
            .why-textbooks li {
                width: 90%;
                font-size: 0.9rem;
            }
            footer {
                font-size: 0.9rem;
            }
        }

        .textbooks::after {
            content: "📚 Click to view";
            position: absolute;
            bottom: 20px;
            left: 0;
            right: 0;
            font-size: 0.75rem;
            font-weight: normal;
            opacity: 0;
            transition: opacity 0.2s ease;
            background: rgba(0, 0, 0, 0.5);
            width: fit-content;
            margin: 0 auto;
            padding: 4px 10px;
            border-radius: 30px;
            color: white;
        }

        .textbooks:hover::after {
            opacity: 1;
        }