el .c no lo copies, el IDE de Arduino podría intentar compilarlo y causar error porque es para windows, es solo para que puedas ver el código, solo copia el exe y el bat y eso pasa los comandos para que se regenere el archivo .h
así como lo abriste esta bien, intentaba reorganizar el código del html, prueba con este
	
	
	
		
traté de separar las funciones del script para que sea más entendible, pero es mi amiga la que sabe de esta modalidad, a mí me confunde esta forma de script. También realicé algunas correcciones al HTML porque está con el formato del 5 pero usaba sintaxis del 4.
				
			así como lo abriste esta bien, intentaba reorganizar el código del html, prueba con este
		HTML:
	
	<!doctype html>
<html>
<head>
    <meta charset="utf-8">
    <meta name="viewport" content="width=device-width,initial-scale=1">
    <title>GALLINER LOS QUINTOS</title>
    <style>
        body {
            font-family: Arial, Helvetica, sans-serif;
            background: #181818;
            color: #EFEFEF;
            font-size: 16px
        }
        h2 {
            font-size: 18px
        }
        section.main {
            display: flex
        }
        #menu,
        section.main {
            flex-direction: column
        }
        #menu {
            display: none;
            flex-wrap: nowrap;
            min-width: 340px;
            background: #363636;
            padding: 8px;
            border-radius: 4px;
            margin-top: -10px;
            margin-right: 10px
        }
        #content {
            display: flex;
            flex-wrap: wrap;
            align-items: stretch
        }
        figure {
            padding: 0;
            margin: 0;
            -webkit-margin-before: 0;
            margin-block-start: 0;
            -webkit-margin-after: 0;
            margin-block-end: 0;
            -webkit-margin-start: 0;
            margin-inline-start: 0;
            -webkit-margin-end: 0;
            margin-inline-end: 0
        }
        figure img {
            display: block;
            width: 100%;
            height: auto;
            border-radius: 4px;
            margin-top: 8px
        }
        @media (min-width: 800px) and (orientation:landscape) {
            #content {
                display: flex;
                flex-wrap: nowrap;
                align-items: stretch
            }
            figure img {
                display: block;
                max-width: 100%;
                max-height: calc(100vh - 40px);
                width: auto;
                height: auto
            }
            figure {
                padding: 0;
                margin: 0;
                -webkit-margin-before: 0;
                margin-block-start: 0;
                -webkit-margin-after: 0;
                margin-block-end: 0;
                -webkit-margin-start: 0;
                margin-inline-start: 0;
                -webkit-margin-end: 0;
                margin-inline-end: 0
            }
        }
        section#buttons {
            display: flex;
            flex-wrap: nowrap;
            justify-content: space-between
        }
        #nav-toggle {
            cursor: pointer;
            display: block
        }
        #nav-toggle-cb {
            outline: 0;
            opacity: 0;
            width: 0;
            height: 0
        }
        #nav-toggle-cb:checked+#menu {
            display: flex
        }
        .input-group {
            display: flex;
            flex-wrap: nowrap;
            line-height: 22px;
            margin: 5px 0
        }
        .input-group>label {
            display: inline-block;
            padding-right: 10px;
            min-width: 47%
        }
        .input-group input,
        .input-group select {
            flex-grow: 1
        }
        .range-max,
        .range-min {
            display: inline-block;
            padding: 0 5px
        }
        button {
            display: block;
            margin: 5px;
            padding: 0 12px;
            border: 0;
            line-height: 28px;
            cursor: pointer;
            color: #fff;
            background: #ff3034;
            border-radius: 5px;
            font-size: 16px;
            outline: 0
        }
        button:hover {
            background: #ff494d
        }
        button:active {
            background: #f21c21
        }
        button.disabled {
            cursor: default;
            background: #a0a0a0
        }
        input[type=range] {
            -webkit-appearance: none;
            width: 100%;
            height: 22px;
            background: #363636;
            cursor: pointer;
            margin: 0
        }
        input[type=range]:focus {
            outline: 0
        }
        input[type=range]::-webkit-slider-runnable-track {
            width: 100%;
            height: 2px;
            cursor: pointer;
            background: #EFEFEF;
            border-radius: 0;
            border: 0 solid #EFEFEF
        }
        input[type=range]::-webkit-slider-thumb {
            border: 1px solid rgba(0, 0, 30, 0);
            height: 22px;
            width: 22px;
            border-radius: 50px;
            background: #ff3034;
            cursor: pointer;
            -webkit-appearance: none;
            margin-top: -11.5px
        }
        input[type=range]:focus::-webkit-slider-runnable-track {
            background: #EFEFEF
        }
        input[type=range]::-moz-range-track {
            width: 100%;
            height: 2px;
            cursor: pointer;
            background: #EFEFEF;
            border-radius: 0;
            border: 0 solid #EFEFEF
        }
        input[type=range]::-moz-range-thumb {
            border: 1px solid rgba(0, 0, 30, 0);
            height: 22px;
            width: 22px;
            border-radius: 50px;
            background: #ff3034;
            cursor: pointer
        }
        input[type=range]::-ms-track {
            width: 100%;
            height: 2px;
            cursor: pointer;
            background: 0 0;
            border-color: transparent;
            color: transparent
        }
        input[type=range]::-ms-fill-lower {
            background: #EFEFEF;
            border: 0 solid #EFEFEF;
            border-radius: 0
        }
        input[type=range]::-ms-fill-upper {
            background: #EFEFEF;
            border: 0 solid #EFEFEF;
            border-radius: 0
        }
        input[type=range]::-ms-thumb {
            border: 1px solid rgba(0, 0, 30, 0);
            height: 22px;
            width: 22px;
            border-radius: 50px;
            background: #ff3034;
            cursor: pointer;
            height: 2px
        }
        input[type=range]:focus::-ms-fill-lower {
            background: #EFEFEF
        }
        input[type=range]:focus::-ms-fill-upper {
            background: #363636
        }
        .switch {
            display: block;
            position: relative;
            line-height: 22px;
            font-size: 16px;
            height: 22px
        }
        .switch input {
            outline: 0;
            opacity: 0;
            width: 0;
            height: 0
        }
        .slider {
            width: 50px;
            height: 22px;
            border-radius: 22px;
            cursor: pointer;
            background-color: grey
        }
        .slider,
        .slider:before {
            display: inline-block;
            transition: .4s
        }
        .slider:before {
            position: relative;
            content: "";
            border-radius: 50%;
            height: 16px;
            width: 16px;
            left: 4px;
            top: 3px;
            background-color: #fff
        }
        input:checked+.slider {
            background-color: #ff3034
        }
        input:checked+.slider:before {
            -webkit-transform: translateX(26px);
            transform: translateX(26px)
        }
        select {
            border: 1px solid #363636;
            font-size: 14px;
            height: 22px;
            outline: 0;
            border-radius: 5px
        }
        .image-container {
            position: relative;
            min-width: 160px
        }
        .close {
            position: absolute;
            right: 5px;
            top: 5px;
            background: #ff3034;
            width: 16px;
            height: 16px;
            border-radius: 100px;
            color: #fff;
            text-align: center;
            line-height: 18px;
            cursor: pointer
        }
        .hidden {
            display: none
        }
    </style>
</head>
<body>
    <figure>
        <div id="stream-container" class="image-container hidden">
            <div class="close" id="close-stream">×</div>
            <img id="stream" src="">
        </div>
    </figure>
    <h1 style="color:green; font-size:5;">...GALLINERO LOS QUINTOS...</h1>
    <section class="main">
        <section id="buttons">
            <table>
                <tr>
                    <td><button id="get-still" style="text-align:center">IMAGEN</button></td>
                    <td></td>
                    <td><button id="toggle-stream" style="text-align:center">CAMARA</button></td>
                </tr>
                <tr>
                    <td></td>
                </tr>
                <tr>
                    <td></td>
                </tr>
                <tr>
                    <td></td>
                </tr>
                <tr>
                    <td></td>
                </tr>
                <tr>
                    <td></td>
                </tr>
                <tr>
                    <td></td>
                </tr>
                <tr>
                    <td></td>
                </tr>
                <tr>
                    <td></td>
                </tr>
                <tr>
                    <td></td>
                </tr>
                <tr>
                    <td></td>
                    <td style="text-align:center"><button id="forward"
                            onclick="fetch(document.location.origin+'/control?var=car&val=1');">ABRE</button></td>
                    <td></td>
                </tr>
                <tr>
                    <td></td>
                </tr>
                <tr>
                    <td></td>
                </tr>
                <tr>
                    <td></td>
                </tr>
                <tr>
                    <td></td>
                </tr>
                <tr>
                    <td></td>
                </tr>
                <tr>
                    <td></td>
                </tr>
                <tr>
                    <td></td>
                </tr>
                <tr>
                    <td></td>
                </tr>
                <tr>
                    <td></td>
                    <td style="text-align:center"><button id="backward"
                            onclick="fetch(document.location.origin+'/control?var=car&val=5');">CIERRA</button></td>
                <tr>
                    </td>
                </tr>
                </td>
                <tr></tr>
                </td>
                <tr></tr>
                </td>
                <tr></tr>
                </td>
                <tr>
                    </td>
                </tr>
                </td>
                <tr></tr>
                </td>
                <tr></tr>
                </td>
                <tr></tr>
                <tr>
                    <td></td>
                </tr>
                <tr>
                    <td></td>
                </tr>
                <tr>
                    <td></td>
                </tr>
                <tr>
                    <td></td>
                </tr>
                <tr>
                    <td></td>
                </tr>
                <tr>
                    <td></td>
                </tr>
                <tr>
                    <td></td>
                </tr>
                <tr>
                    <td></td>
                </tr>
                <tr>
                    <td>LUZ</td>
                    <td style="text-align:center" colspan="2"><input type="range" id="flash" min="0" max="255" value="0"
                            onchange="try{fetch(document.location.origin+'/control?var=flash&val='+this.value);}catch(e){}">
                    </td>
                </tr>
                <tr>
                    </td>
                </tr>
                </td>
                <tr></tr>
                </td>
                <tr></tr>
                </td>
                <tr></tr>
                </td>
                <tr>
                    </td>
                </tr>
                </td>
                <tr></tr>
                </td>
                <tr></tr>
                </td>
                <tr></tr>
                <tr>
                    <td></td>
                </tr>
                <tr>
                    <td>CALIDAD</td>
                    <td style="text-align:center" colspan="2"><input type="range" id="quality" min="10" max="63"
                            value="10"
                            onchange="try{fetch(document.location.origin+'/control?var=quality&val='+this.value);}catch(e){}">
                    </td>
                </tr>
                <tr>
                    <td></td>
                </tr>
                <tr>
                    <td></td>
                </tr>
                <tr>
                    <td></td>
                </tr>
                <tr>
                    <td></td>
                </tr>
                <tr>
                    <td></td>
                </tr>
                <tr>
                    <td></td>
                </tr>
                <tr>
                    <td></td>
                </tr>
            </table>
        </section>
    </section>
    <p style="color:#FFFFFF; font-size:2">Exclusivo Para Ignacio Carrasco, by A.Del Río</p>
    <script>
        document.addEventListener('DOMContentLoaded', function () {
            function b(B) {
                let C;
                switch (B.type) {
                    case 'checkbox': C = B.checked ? 1 : 0;
                        break;
                    case 'range':
                    case 'select-one': C = B.value;
                        break;
                    case 'button':
                    case 'submit': C = '1';
                        break;
                    default: return;
                }
                const D = `${c}/control?var=${B.id}&val=${C}`;
                fetch(D).then(E => { console.log(`request to ${D} finished, status: ${E.status}`); })
            }
            var c = document.location.origin;
            const e = B => { B.classList.add('hidden') },
                f = B => { B.classList.remove('hidden') },
                g = B => {
                    B.classList.add('disabled'),
                        B.disabled = !0
                },
                h = B => { B.classList.remove('disabled'), B.disabled = !1 },
                i = (B, C, D) => {
                    D = !(null != D) || D;
                    let E;
                    'checkbox' === B.type ? (E = B.checked, C = !!C, B.checked = C) : (E = B.value, B.value = C),
                        D && E !== C ? b(B) : !D && ('aec' === B.id ? C ? e(v) : f(v) : 'agc' === B.id ? C ? (f(t), e(s)) : (e(t), f(s)) : 'awb_gain' === B.id ? C ? f(x) : e(x) : 'face_recognize' === B.id && (C ? h(n) : g(n)))
                };
            document.querySelectorAll('.close').forEach(B => { B.onclick = () => { e(B.parentNode) } }),
                fetch(`${c}/status`).then(function (B) { return B.json() }).then(function (B) { document.querySelectorAll('.default-action').forEach(C => { i(C, B[C.id], !1) }) });
            const j = document.getElementById('stream'),
                k = document.getElementById('stream-container'),
                l = document.getElementById('get-still'),
                m = document.getElementById('toggle-stream'),
                n = document.getElementById('face_enroll'),
                o = document.getElementById('close-stream'),
                p = () => {
                    window.stop(),
                        m.innerHTML = 'CAMARA'
                },
                q = () => {
                    j.src = `${c + ':8555'}/stream`,
                        f(k), m.innerHTML = 'DIRECTO'
                };
            l.onclick = () => {
                p(), j.src = `${c}/capture?_cb=${Date.now()}`,
                    f(k)
            },
                o.onclick = () => {
                    p(),
                        e(k)
                },
                m.onclick = () => {
                    const B = 'Stop Stream' === m.innerHTML;
                    B ? p() : q()
                },
                n.onclick = () => { b(n) },
                document.querySelectorAll('.default-action').forEach(B => { B.onchange = () => b(B) });
            const r = document.getElementById('agc'),
                s = document.getElementById('agc_gain-group'),
                t = document.getElementById('gainceiling-group');
            r.onchange = () => {
                b(r),
                    r.checked ? (f(t), e(s)) : (e(t), f(s))
            };
            const u = document.getElementById('aec'),
                v = document.getElementById('aec_value-group');
            u.onchange = () => {
                b(u),
                    u.checked ? e(v) : f(v)
            };
            const w = document.getElementById('awb_gain'),
                x = document.getElementById('wb_mode-group');
            w.onchange = () => {
                b(w),
                    w.checked ? f(x) : e(x)
            };
            const y = document.getElementById('face_detect'),
                z = document.getElementById('face_recognize'),
                A = document.getElementById('framesize');
            A.onchange = () => {
                b(A),
                    5 < A.value && (i(y, !1), i(z, !1))
            },
                y.onchange = () => {
                    return 5 < A.value ? (alert('Please select CIF or lower resolution before enabling this feature!'),
                        void i(y, !1)) : void (b(y), !y.checked && (g(n), i(z, !1)))
                },
                z.onchange = () => {
                    return 5 < A.value ? (alert('Please select CIF or lower resolution before enabling this feature!'),
                        void i(z, !1)) : void (b(z),
                            z.checked ? (h(n), i(y, !0)) : g(n))
                }
        });
    </script>
</body>
</html> 
   
				 
						 
 
		


 
 
		 
 
		
 
 
		 
 
		 
 
		 
 
		