.main-card {
            max-width: 800px;
            margin: 20px auto 50px;
            background: #fff;
            border-radius: 18px;
            padding: 25px;
            box-shadow: 0 8px 35px rgba(0, 0, 0, 0.08);
        }

        /* ===============================
           SCREEN
        =============================== */

        .screen-container {
            position: relative;
            width: 100%;
            height: 560px;
            overflow: hidden;
            background: #000;
            border: 1px solid #222;
            border-radius: 14px;
        }

        .screen-container.fullscreen {
            position: fixed;
            inset: 0;
            width: 100vw;
            height: 100vh;
            border: 0;
            border-radius: 0;
            z-index: 9999;
        }

        #testScreen {
            width: 100%;
            height: 100%;
            position: relative;
            display: flex;
            align-items: center;
            justify-content: center;
            overflow: hidden;
            user-select: none;
        }

        .screen-label {
            position: absolute;
            top: 18px;
            left: 18px;
            z-index: 100;
            padding: 7px 12px;
            border-radius: 7px;
            background: rgba(0, 0, 0, 0.65);
            color: #fff;
            font-size: 13px;
            pointer-events: none;
        }

        .fullscreen .screen-label {
            display: none;
        }

        /* ===============================
           WELCOME
        =============================== */

        .welcome {
            text-align: center;
            color: #777;
            padding: 20px;
        }

        .welcome h2 {
            font-size: 28px;
            font-weight: 700;
        }

        /* ===============================
           COLOR
        =============================== */

        .full-pattern {
            position: absolute;
            inset: 0;
        }

        /* ===============================
           GRAYSCALE
        =============================== */

        .grayscale {
            position: absolute;
            inset: 0;
            display: flex;
        }

        .gray-block {
            flex: 1;
            height: 100%;
        }

        /* ===============================
           GRADIENT
        =============================== */

        .gradient-horizontal {
            position: absolute;
            inset: 0;
            background: linear-gradient(
                to right,
                #000 0%,
                #fff 100%
            );
        }

        .gradient-vertical {
            position: absolute;
            inset: 0;
            background: linear-gradient(
                to bottom,
                #000 0%,
                #fff 100%
            );
        }

        /* ===============================
           CONTRAST
        =============================== */

        .contrast {
            position: absolute;
            inset: 0;

            background:
                repeating-linear-gradient(
                    90deg,
                    #000 0,
                    #000 10px,
                    #fff 10px,
                    #fff 20px
                );
        }

        /* ===============================
           SHARPNESS
        =============================== */

        .grid-pattern {
            position: absolute;
            inset: 0;

            background-color: #fff;

            background-image:
                linear-gradient(
                    #000 1px,
                    transparent 1px
                ),
                linear-gradient(
                    90deg,
                    #000 1px,
                    transparent 1px
                );

            background-size: 20px 20px;
        }

        .fine-grid {
            position: absolute;
            inset: 0;

            background-color: #fff;

            background-image:
                linear-gradient(
                    #000 1px,
                    transparent 1px
                ),
                linear-gradient(
                    90deg,
                    #000 1px,
                    transparent 1px
                );

            background-size: 5px 5px;
        }

        .one-pixel-grid {
            position: absolute;
            inset: 0;

            background-color: #fff;

            background-image:
                linear-gradient(
                    #000 1px,
                    transparent 1px
                ),
                linear-gradient(
                    90deg,
                    #000 1px,
                    transparent 1px
                );

            background-size: 1px 1px;
        }

        /* ===============================
           PIXEL PATTERNS
        =============================== */

        .pixel-pattern {
            position: absolute;
            inset: 0;

            background-color: #000;

            display: flex;
            align-items: center;
            justify-content: center;
        }

        .pixel-square {
            background: #fff;
        }

        .pixel-1 {
            width: 1px;
            height: 1px;
        }

        .pixel-2 {
            width: 2px;
            height: 2px;
        }

        .pixel-5 {
            width: 5px;
            height: 5px;
        }

        .pixel-10 {
            width: 10px;
            height: 10px;
        }

        /* ===============================
           COLOR BARS
        =============================== */

        .color-bars {
            position: absolute;
            inset: 0;
            display: flex;
        }

        .color-bars div {
            flex: 1;
        }

        /* ===============================
           VIEWING ANGLE
        =============================== */

        .angle-test {
            position: absolute;
            inset: 0;

            display: flex;
            align-items: center;
            justify-content: center;

            background: #808080;
        }

        .angle-inner {
            width: 75%;
            height: 75%;

            border: 4px solid #fff;

            display: flex;
            align-items: center;
            justify-content: center;

            color: #fff;

            text-align: center;

            font-size: 24px;
            font-weight: 700;
        }

        /* ===============================
           BURN-IN TEST
        =============================== */

        .burnin-test {
            position: absolute;
            inset: 0;

            display: flex;
            align-items: center;
            justify-content: center;

            background: #fff;
        }

        .burnin-box {
            width: 70%;
            height: 65%;

            border: 12px solid #000;

            display: flex;
            align-items: center;
            justify-content: center;

            color: #000;

            font-size: clamp(25px, 5vw, 70px);
            font-weight: 800;
        }

        /* ===============================
           MOTION TEST
        =============================== */

        .motion-test {
            position: absolute;
            inset: 0;

            background: #000;
            overflow: hidden;
        }

        .motion-ball {
            position: absolute;

            width: 70px;
            height: 70px;

            border-radius: 50%;

            background: #fff;

            top: 50%;

            transform: translateY(-50%);

            animation:
                moveBall 2s linear infinite alternate;
        }

        @keyframes moveBall {

            from {
                left: 0;
            }

            to {
                left: calc(100% - 70px);
            }

        }

        /* ===============================
           RESOLUTION INFO
        =============================== */

        .resolution-test {
            position: absolute;
            inset: 0;

            display: flex;
            align-items: center;
            justify-content: center;

            background: #111;
            color: #fff;

            text-align: center;
        }

        .resolution-test h2 {
            font-size: clamp(24px, 4vw, 45px);
        }

        .resolution-test p {
            margin-bottom: 6px;
        }

        /* ===============================
           CONTROLS
        =============================== */

        .controls {
            margin-top: 20px;
        }

        .control-btn {
            min-width: 125px;
        }

        /* ===============================
           TEST SELECTOR
        =============================== */

        .test-selector {
            display: flex;
            flex-wrap: wrap;
            gap: 8px;
            margin-top: 20px;
        }

        .test-selector button {
            border: 1px solid #dee2e6;
            background: #fff;
            color: #212529;

            border-radius: 8px;

            padding: 8px 12px;

            font-size: 14px;

            cursor: pointer;

            transition: 0.2s;
        }

        .test-selector button:hover {
            background: #f1f3f5;
        }

        .test-selector button.active {
            background: #212529;
            color: #fff;
            border-color: #212529;
        }

        /* ===============================
           PROGRESS
        =============================== */

        .progress {
            height: 8px;
            border-radius: 20px;
        }

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

        .info-box {
            margin-top: 25px;

            padding: 20px;

            background: #f8f9fa;

            border: 1px solid #e9ecef;

            border-radius: 12px;
        }

        .info-box h3 {
            font-size: 1.15rem;
            font-weight: 600;
        }

        .info-box p {
            color: #6c757d;
            line-height: 1.7;
            margin-bottom: 0;
        }

        /* ===============================
           FEATURE CARDS
        =============================== */

        .feature-card {
            height: 100%;

            background: #fff;

            border: 1px solid #e9ecef;

            border-radius: 14px;

            padding: 22px;

            transition: 0.2s;
        }

        .feature-card:hover {
            transform: translateY(-3px);

            box-shadow:
                0 8px 25px rgba(0, 0, 0, 0.07);
        }

        .feature-card h4 {
            font-size: 1.05rem;
            font-weight: 600;
            margin-bottom: 10px;
        }

        .feature-card p {
            color: #6c757d;
            line-height: 1.6;
            margin: 0;
        }

        /* ===============================
           FULLSCREEN BUTTON
        =============================== */

        .fullscreen-exit {
            position: fixed;

            top: 20px;
            right: 20px;

            z-index: 10001;

            display: none;
        }

        .fullscreen-exit.show {
            display: block;
        }

        /* ===============================
           MOBILE
        =============================== */

        @media (max-width: 768px) {

            .hero {
                padding-top: 35px;
            }

            .main-card {
                margin: 15px 10px 35px;
                padding: 15px;
            }

            .screen-container {
                height: 400px;
            }

            .control-btn {
                width: 100%;
                margin-bottom: 8px;
            }

            .test-selector button {
                flex: 1 1 auto;
            }

            .angle-inner {
                font-size: 18px;
            }
        }

        @media (max-width: 480px) {

            .screen-container {
                height: 320px;
            }

            .hero h1 {
                font-size: 2rem;
            }
        }