Lighthouse Report

Performance

First Contentful Paint

1.3 s

First Contentful Paint marks the time at which the first text or image is painted. Learn more.

Speed Index

1.3 s

Speed Index shows how quickly the contents of a page are visibly populated. Learn more.

Largest Contentful Paint

1.7 s

Largest Contentful Paint marks the time at which the largest text or image is painted. Learn More

Time to Interactive

1.6 s

Time to interactive is the amount of time it takes for the page to become fully interactive. Learn more.

Total Blocking Time

220 ms

Sum of all time periods between FCP and Time to Interactive, when task length exceeded 50ms, expressed in milliseconds. Learn more.

Cumulative Layout Shift

Cumulative Layout Shift measures the movement of visible elements within the viewport. Learn more.

Values are estimated and may vary. The performance score is calculated directly from these metrics.See calculator.

Eliminate render-blocking resources

0.63 s

Resources are blocking the first paint of your page. Consider delivering critical JS/CSS inline and deferring all non-critical JS/styles. Learn more.

URL	Transfer Size	Potential Savings
/main.css (127.0.0.1)	1.1 KB	720 ms

Does not use HTTP/2 for all of its resources 3 requests not served via HTTP/2

HTTP/2 offers many benefits over HTTP/1.1, including binary headers, multiplexing, and server push. Learn more.

URL	Protocol
/index.html (127.0.0.1)	http/1.1
/main.js (127.0.0.1)	http/1.1
/main.css (127.0.0.1)	http/1.1

Serve static assets with an efficient cache policy 2 resources found

A long cache lifetime can speed up repeat visits to your page. Learn more.

URL	Cache TTL	Transfer Size
/main.js (127.0.0.1)	None	38 KB
/main.css (127.0.0.1)	None	1 KB

Avoid chaining critical requests 1 chain found

The Critical Request Chains below show you what resources are loaded with a high priority. Consider reducing the length of chains, reducing the download size of resources, or deferring the download of unnecessary resources to improve page load. Learn more.

Maximum critical path latency: 1,170 ms

Initial Navigation

/index.html

(127.0.0.1)

/main.css

(127.0.0.1)

- 580 ms, 1.08 KB

Keep request counts low and transfer sizes small 3 requests • 41 KB

To set budgets for the quantity and size of page resources, add a budget.json file. Learn more.

Resource Type	Requests	Transfer Size
Total	3	41 KB
Script	1	37.6 KB
Document	1	2.4 KB
Stylesheet	1	1.1 KB
Image	0	0 KB
Media	0	0 KB
Font	0	0 KB
Other	0	0 KB
Third-party	0	0 KB

Largest Contentful Paint element 1 element found

This is the element that was identified as the Largest Contentful Paint. Learn More

Element
Uup <div class="symbol">

Avoid large layout shifts No elements found

These DOM elements contribute most to the CLS of the page.

Properly size images

Serve images that are appropriately-sized to save cellular data and improve load time. Learn more.

Defer offscreen images

Consider lazy-loading offscreen and hidden images after all critical resources have finished loading to lower time to interactive. Learn more.

Minify CSS

Minifying CSS files can reduce network payload sizes. Learn more.

Minify JavaScript

Minifying JavaScript files can reduce payload sizes and script parse time. Learn more.

Remove unused CSS

Remove dead rules from stylesheets and defer the loading of CSS not used for above-the-fold content to reduce unnecessary bytes consumed by network activity. Learn more.

Remove unused JavaScript Potential savings of 16 KB

Remove unused JavaScript to reduce bytes consumed by network activity. Learn more.

URL	Transfer Size	Potential Savings
/main.js (127.0.0.1)	37.6 KB	15.5 KB

Efficiently encode images

Optimized images load faster and consume less cellular data. Learn more.

Serve images in next-gen formats

Image formats like JPEG 2000, JPEG XR, and WebP often provide better compression than PNG or JPEG, which means faster downloads and less data consumption. Learn more.

Enable text compression

Text-based resources should be served with compression (gzip, deflate or brotli) to minimize total network bytes. Learn more.

Preconnect to required origins

Consider adding `preconnect` or `dns-prefetch` resource hints to establish early connections to important third-party origins. Learn more.

Initial server response time was short Root document took 570 ms

Keep the server response time for the main document short because all other requests depend on it. Learn more.

Avoid multiple page redirects

Redirects introduce additional delays before the page can be loaded. Learn more.

Preload key requests

Consider using `<link rel=preload>` to prioritize fetching resources that are currently requested later in page load. Learn more.

Use video formats for animated content

Large GIFs are inefficient for delivering animated content. Consider using MPEG4/WebM videos for animations and PNG/WebP for static images instead of GIF to save network bytes. Learn more

Avoids enormous network payloads Total size was 41 KB

Large network payloads cost users real money and are highly correlated with long load times. Learn more.

URL	Transfer Size
/main.js (127.0.0.1)	37.6 KB
/index.html (127.0.0.1)	2.4 KB
/main.css (127.0.0.1)	1.1 KB

Avoids an excessive DOM size 763 elements

A large DOM will increase memory usage, cause longer style calculations, and produce costly layout reflows. Learn more.

Statistic	Element	Value
Total DOM Elements		763
Maximum DOM Depth	<br>	7
Maximum Child Elements	<div class="periodic-row">	18

User Timing marks and measures

Consider instrumenting your app with the User Timing API to measure your app's real-world performance during key user experiences. Learn more.

JavaScript execution time 0.2 s

Consider reducing the time spent parsing, compiling, and executing JS. You may find delivering smaller JS payloads helps with this. Learn more.

URL	Total CPU Time	Script Evaluation	Script Parse
/main.js (127.0.0.1)	214 ms	210 ms	1 ms
/index.html (127.0.0.1)	198 ms	2 ms	0 ms

Minimizes main-thread work 0.4 s

Consider reducing the time spent parsing, compiling and executing JS. You may find delivering smaller JS payloads helps with this. Learn more

Category	Time Spent
Script Evaluation	214 ms
Style & Layout	112 ms
Rendering	67 ms
Other	31 ms
Parse HTML & CSS	4 ms
Script Parsing & Compilation	3 ms

All text remains visible during webfont loads

Leverage the font-display CSS feature to ensure text is user-visible while webfonts are loading. Learn more.

Minimize third-party usage

Third-party code can significantly impact load performance. Limit the number of redundant third-party providers and try to load third-party code after your page has primarily finished loading. Learn more.

Uses passive listeners to improve scrolling performance

Consider marking your touch and wheel event listeners as `passive` to improve your page's scroll performance. Learn more.

Avoids document.write()

For users on slow connections, external scripts dynamically injected via `document.write()` can delay page load by tens of seconds. Learn more.

Accessibility

These checks highlight opportunities to improve the accessibility of your web app. Only a subset of accessibility issues can be automatically detected so manual testing is also encouraged.

Background and foreground colors do not have a sufficient contrast ratio.

Low-contrast text is difficult or impossible for many users to read. Learn more.

Failing Elements
hydrogen hydrogen <div class="at_details"> hydrogen <br> hydrogen </div>
He <div class="symbol">He</div>
helium helium <div class="at_details"> helium <br> helium </div>
Li <div class="symbol">Li</div>
lithium lithium <div class="at_details"> lithium <br> lithium </div>
Be <div class="symbol">Be</div>
beryllium beryllium <div class="at_details"> beryllium <br> beryllium </div>
boron boron <div class="at_details"> boron <br> boron </div>
carbon carbon <div class="at_details"> carbon <br> carbon </div>
nidivogen nidivogen <div class="at_details"> nidivogen <br> nidivogen </div>
oxygen oxygen <div class="at_details"> oxygen <br> oxygen </div>
fluorine fluorine <div class="at_details"> fluorine <br> fluorine </div>
10 <div class="at_num">10</div>
Ne <div class="symbol">Ne</div>
neon neon <div class="at_details"> neon <br> neon </div>
11 <div class="at_num">11</div>
Na <div class="symbol">Na</div>
sodium sodium <div class="at_details"> sodium <br> sodium </div>
12 <div class="at_num">12</div>
Mg <div class="symbol">Mg</div>
magnesium magnesium <div class="at_details"> magnesium <br> magnesium </div>
13 <div class="at_num">13</div>
Al <div class="symbol">Al</div>
aluminum aluminum <div class="at_details"> aluminum <br> aluminum </div>
14 <div class="at_num">14</div>
Si <div class="symbol">Si</div>
silicon silicon <div class="at_details"> silicon <br> silicon </div>
15 <div class="at_num">15</div>
phosphorus phosphorus <div class="at_details"> phosphorus <br> phosphorus </div>
16 <div class="at_num">16</div>
sulfur sulfur <div class="at_details"> sulfur <br> sulfur </div>
17 <div class="at_num">17</div>
Cl <div class="symbol">Cl</div>
chlorine chlorine <div class="at_details"> chlorine <br> chlorine </div>
18 <div class="at_num">18</div>
Ar <div class="symbol">Ar</div>
argon argon <div class="at_details"> argon <br> argon </div>
19 <div class="at_num">19</div>
potassium potassium <div class="at_details"> potassium <br> potassium </div>
20 <div class="at_num">20</div>
Ca <div class="symbol">Ca</div>
calcium calcium <div class="at_details"> calcium <br> calcium </div>
21 <div class="at_num">21</div>
Sc <div class="symbol">Sc</div>
scandium scandium <div class="at_details"> scandium <br> scandium </div>
22 <div class="at_num">22</div>
Ti <div class="symbol">Ti</div>
titanium titanium <div class="at_details"> titanium <br> titanium </div>
23 <div class="at_num">23</div>
vanadium vanadium <div class="at_details"> vanadium <br> vanadium </div>
24 <div class="at_num">24</div>
Cr <div class="symbol">Cr</div>
chromium chromium <div class="at_details"> chromium <br> chromium </div>
25 <div class="at_num">25</div>
Mn <div class="symbol">Mn</div>
manganese manganese <div class="at_details"> manganese <br> manganese </div>
26 <div class="at_num">26</div>
Fe <div class="symbol">Fe</div>
iron iron <div class="at_details"> iron <br> iron </div>
27 <div class="at_num">27</div>
Co <div class="symbol">Co</div>
cobalt cobalt <div class="at_details"> cobalt <br> cobalt </div>
28 <div class="at_num">28</div>
Ni <div class="symbol">Ni</div>
nickel nickel <div class="at_details"> nickel <br> nickel </div>
29 <div class="at_num">29</div>
Cu <div class="symbol">Cu</div>
copper copper <div class="at_details"> copper <br> copper </div>
30 <div class="at_num">30</div>
Zn <div class="symbol">Zn</div>
zinc zinc <div class="at_details"> zinc <br> zinc </div>
31 <div class="at_num">31</div>
Ga <div class="symbol">Ga</div>
gallium gallium <div class="at_details"> gallium <br> gallium </div>
32 <div class="at_num">32</div>
Ge <div class="symbol">Ge</div>
germanium germanium <div class="at_details"> germanium <br> germanium </div>
33 <div class="at_num">33</div>
As <div class="symbol">As</div>
arsenic arsenic <div class="at_details"> arsenic <br> arsenic </div>
34 <div class="at_num">34</div>
Se <div class="symbol">Se</div>
selenium selenium <div class="at_details"> selenium <br> selenium </div>
35 <div class="at_num">35</div>
Br <div class="symbol">Br</div>
bromine bromine <div class="at_details"> bromine <br> bromine </div>
36 <div class="at_num">36</div>
Kr <div class="symbol">Kr</div>
krypton krypton <div class="at_details"> krypton <br> krypton </div>
37 <div class="at_num">37</div>
Rb <div class="symbol">Rb</div>
rubidium rubidium <div class="at_details"> rubidium <br> rubidium </div>
38 <div class="at_num">38</div>
Sr <div class="symbol">Sr</div>
sdivontium sdivontium <div class="at_details"> sdivontium <br> sdivontium </div>
39 <div class="at_num">39</div>
ytdivium ytdivium <div class="at_details"> ytdivium <br> ytdivium </div>
40 <div class="at_num">40</div>
Zr <div class="symbol">Zr</div>
zirconium zirconium <div class="at_details"> zirconium <br> zirconium </div>
41 <div class="at_num">41</div>
Nb <div class="symbol">Nb</div>
niobium niobium <div class="at_details"> niobium <br> niobium </div>
42 <div class="at_num">42</div>
Mo <div class="symbol">Mo</div>
molybdenum molybdenum <div class="at_details"> molybdenum <br> molybdenum </div>
43 <div class="at_num">43</div>
Tc <div class="symbol">Tc</div>
technetium technetium <div class="at_details"> technetium <br> technetium </div>
44 <div class="at_num">44</div>
Ru <div class="symbol">Ru</div>
ruthenium ruthenium <div class="at_details"> ruthenium <br> ruthenium </div>
45 <div class="at_num">45</div>
Rh <div class="symbol">Rh</div>
rhodium rhodium <div class="at_details"> rhodium <br> rhodium </div>
46 <div class="at_num">46</div>
Pd <div class="symbol">Pd</div>
palladium palladium <div class="at_details"> palladium <br> palladium </div>
47 <div class="at_num">47</div>
Ag <div class="symbol">Ag</div>
silver silver <div class="at_details"> silver <br> silver </div>
48 <div class="at_num">48</div>
Cd <div class="symbol">Cd</div>
cadmium cadmium <div class="at_details"> cadmium <br> cadmium </div>
49 <div class="at_num">49</div>
In <div class="symbol">In</div>
indium indium <div class="at_details"> indium <br> indium </div>
50 <div class="at_num">50</div>
Sn <div class="symbol">Sn</div>
tin tin <div class="at_details"> tin <br> tin </div>
51 <div class="at_num">51</div>
Sb <div class="symbol">Sb</div>
antimony antimony <div class="at_details"> antimony <br> antimony </div>
52 <div class="at_num">52</div>
Te <div class="symbol">Te</div>
tellurium tellurium <div class="at_details"> tellurium <br> tellurium </div>
53 <div class="at_num">53</div>
iodine iodine <div class="at_details"> iodine <br> iodine </div>
54 <div class="at_num">54</div>
Xe <div class="symbol">Xe</div>
xenon xenon <div class="at_details"> xenon <br> xenon </div>
55 <div class="at_num">55</div>
Cs <div class="symbol">Cs</div>
cesium cesium <div class="at_details"> cesium <br> cesium </div>
56 <div class="at_num">56</div>
Ba <div class="symbol">Ba</div>
barium barium <div class="at_details"> barium <br> barium </div>
72 <div class="at_num">72</div>
Hf <div class="symbol">Hf</div>
hafnium hafnium <div class="at_details"> hafnium <br> hafnium </div>
73 <div class="at_num">73</div>
Ta <div class="symbol">Ta</div>
tantalum tantalum <div class="at_details"> tantalum <br> tantalum </div>
74 <div class="at_num">74</div>
tungsten tungsten <div class="at_details"> tungsten <br> tungsten </div>
75 <div class="at_num">75</div>
Re <div class="symbol">Re</div>
rhenium rhenium <div class="at_details"> rhenium <br> rhenium </div>
76 <div class="at_num">76</div>
Os <div class="symbol">Os</div>
osmium osmium <div class="at_details"> osmium <br> osmium </div>
77 <div class="at_num">77</div>
Ir <div class="symbol">Ir</div>
iridium iridium <div class="at_details"> iridium <br> iridium </div>
78 <div class="at_num">78</div>
Pt <div class="symbol">Pt</div>
platinum platinum <div class="at_details"> platinum <br> platinum </div>
79 <div class="at_num">79</div>
Au <div class="symbol">Au</div>
gold gold <div class="at_details"> gold <br> gold </div>
80 <div class="at_num">80</div>
Hg <div class="symbol">Hg</div>
mercury mercury <div class="at_details"> mercury <br> mercury </div>
81 <div class="at_num">81</div>
Tl <div class="symbol">Tl</div>
thallium thallium <div class="at_details"> thallium <br> thallium </div>
82 <div class="at_num">82</div>
Pb <div class="symbol">Pb</div>
lead lead <div class="at_details"> lead <br> lead </div>
83 <div class="at_num">83</div>
Bi <div class="symbol">Bi</div>
bismuth bismuth <div class="at_details"> bismuth <br> bismuth </div>
84 <div class="at_num">84</div>
Po <div class="symbol">Po</div>
polonium polonium <div class="at_details"> polonium <br> polonium </div>
85 <div class="at_num">85</div>
At <div class="symbol">At</div>
astatine astatine <div class="at_details"> astatine <br> astatine </div>
86 <div class="at_num">86</div>
Rn <div class="symbol">Rn</div>
radon radon <div class="at_details"> radon <br> radon </div>
87 <div class="at_num">87</div>
Fr <div class="symbol">Fr</div>
francium francium <div class="at_details"> francium <br> francium </div>
88 <div class="at_num">88</div>
Ra <div class="symbol">Ra</div>
radium radium <div class="at_details"> radium <br> radium </div>
104 <div class="at_num">104</div>
Rf <div class="symbol">Rf</div>
rutherfordium rutherfordium <div class="at_details"> rutherfordium <br> rutherfordium </div>
105 <div class="at_num">105</div>
Db <div class="symbol">Db</div>
dubnium dubnium <div class="at_details"> dubnium <br> dubnium </div>
106 <div class="at_num">106</div>
Sg <div class="symbol">Sg</div>
seaborgium seaborgium <div class="at_details"> seaborgium <br> seaborgium </div>
107 <div class="at_num">107</div>
Bh <div class="symbol">Bh</div>
bohrium bohrium <div class="at_details"> bohrium <br> bohrium </div>
108 <div class="at_num">108</div>
Hs <div class="symbol">Hs</div>
hassium hassium <div class="at_details"> hassium <br> hassium </div>
109 <div class="at_num">109</div>
Mt <div class="symbol">Mt</div>
meitnerium meitnerium <div class="at_details"> meitnerium <br> meitnerium </div>
110 <div class="at_num">110</div>
Ds <div class="symbol">Ds</div>
darmstadtium darmstadtium <div class="at_details"> darmstadtium <br> darmstadtium </div>
111 <div class="at_num">111</div>
Rg <div class="symbol">Rg</div>
roentgenium roentgenium <div class="at_details"> roentgenium <br> roentgenium </div>
112 <div class="at_num">112</div>
Cn <div class="symbol">Cn</div>
copernicium copernicium <div class="at_details"> copernicium <br> copernicium </div>
113 <div class="at_num">113</div>
Uut <div class="symbol">Uut</div>
unundivium unundivium <div class="at_details"> unundivium <br> unundivium </div>
114 <div class="at_num">114</div>
Fl <div class="symbol">Fl</div>
flerovium flerovium <div class="at_details"> flerovium <br> flerovium </div>
115 <div class="at_num">115</div>
Uup <div class="symbol">Uup</div>
ununpentium ununpentium <div class="at_details"> ununpentium <br> ununpentium </div>
116 <div class="at_num">116</div>
Lv <div class="symbol">Lv</div>
livermorium livermorium <div class="at_details"> livermorium <br> livermorium </div>
117 <div class="at_num">117</div>
Uus <div class="symbol">Uus</div>
ununseptium ununseptium <div class="at_details"> ununseptium <br> ununseptium </div>
118 <div class="at_num">118</div>
Uuo <div class="symbol">Uuo</div>
ununoctium ununoctium <div class="at_details"> ununoctium <br> ununoctium </div>
57 <div class="at_num">57</div>
La <div class="symbol">La</div>
lanthanum lanthanum <div class="at_details"> lanthanum <br> lanthanum </div>
58 <div class="at_num">58</div>
Ce <div class="symbol">Ce</div>
cerium cerium <div class="at_details"> cerium <br> cerium </div>
59 <div class="at_num">59</div>
Pr <div class="symbol">Pr</div>
praseodymium praseodymium <div class="at_details"> praseodymium <br> praseodymium </div>
60 <div class="at_num">60</div>
Nd <div class="symbol">Nd</div>
neodymium neodymium <div class="at_details"> neodymium <br> neodymium </div>
61 <div class="at_num">61</div>
Pm <div class="symbol">Pm</div>
promethium promethium <div class="at_details"> promethium <br> promethium </div>
62 <div class="at_num">62</div>
Sm <div class="symbol">Sm</div>
samarium samarium <div class="at_details"> samarium <br> samarium </div>
63 <div class="at_num">63</div>
Eu <div class="symbol">Eu</div>
europium europium <div class="at_details"> europium <br> europium </div>
64 <div class="at_num">64</div>
Gd <div class="symbol">Gd</div>
gadolinium gadolinium <div class="at_details"> gadolinium <br> gadolinium </div>
65 <div class="at_num">65</div>
Tb <div class="symbol">Tb</div>
terbium terbium <div class="at_details"> terbium <br> terbium </div>
66 <div class="at_num">66</div>
Dy <div class="symbol">Dy</div>
dysprosium dysprosium <div class="at_details"> dysprosium <br> dysprosium </div>
67 <div class="at_num">67</div>
Ho <div class="symbol">Ho</div>
holmium holmium <div class="at_details"> holmium <br> holmium </div>
68 <div class="at_num">68</div>
Er <div class="symbol">Er</div>
erbium erbium <div class="at_details"> erbium <br> erbium </div>
69 <div class="at_num">69</div>
Tm <div class="symbol">Tm</div>
thulium thulium <div class="at_details"> thulium <br> thulium </div>
70 <div class="at_num">70</div>
Yb <div class="symbol">Yb</div>
ytterbium ytterbium <div class="at_details"> ytterbium <br> ytterbium </div>
71 <div class="at_num">71</div>
Lu <div class="symbol">Lu</div>
lutetium lutetium <div class="at_details"> lutetium <br> lutetium </div>
89 <div class="at_num">89</div>
Ac <div class="symbol">Ac</div>
actinium actinium <div class="at_details"> actinium <br> actinium </div>
90 <div class="at_num">90</div>
Th <div class="symbol">Th</div>
thorium thorium <div class="at_details"> thorium <br> thorium </div>
91 <div class="at_num">91</div>
Pa <div class="symbol">Pa</div>
protactinium protactinium <div class="at_details"> protactinium <br> protactinium </div>
92 <div class="at_num">92</div>
uranium uranium <div class="at_details"> uranium <br> uranium </div>
93 <div class="at_num">93</div>
Np <div class="symbol">Np</div>
neptunium neptunium <div class="at_details"> neptunium <br> neptunium </div>
94 <div class="at_num">94</div>
Pu <div class="symbol">Pu</div>
plutonium plutonium <div class="at_details"> plutonium <br> plutonium </div>
95 <div class="at_num">95</div>
Am <div class="symbol">Am</div>
americium americium <div class="at_details"> americium <br> americium </div>
96 <div class="at_num">96</div>
Cm <div class="symbol">Cm</div>
curium curium <div class="at_details"> curium <br> curium </div>
97 <div class="at_num">97</div>
Bk <div class="symbol">Bk</div>
berkelium berkelium <div class="at_details"> berkelium <br> berkelium </div>
98 <div class="at_num">98</div>
Cf <div class="symbol">Cf</div>
californium californium <div class="at_details"> californium <br> californium </div>
99 <div class="at_num">99</div>
Es <div class="symbol">Es</div>
einsteinium einsteinium <div class="at_details"> einsteinium <br> einsteinium </div>
100 <div class="at_num">100</div>
Fm <div class="symbol">Fm</div>
fermium fermium <div class="at_details"> fermium <br> fermium </div>
101 <div class="at_num">101</div>
Md <div class="symbol">Md</div>
mendelevium mendelevium <div class="at_details"> mendelevium <br> mendelevium </div>
102 <div class="at_num">102</div>
No <div class="symbol">No</div>
nobelium nobelium <div class="at_details"> nobelium <br> nobelium </div>
103 <div class="at_num">103</div>
Lr <div class="symbol">Lr</div>
lawrencium lawrencium <div class="at_details"> lawrencium <br> lawrencium </div>

The page has a logical tab order

Tabbing through the page follows the visual layout. Users cannot focus elements that are offscreen. Learn more.

Interactive controls are keyboard focusable

Custom interactive controls are keyboard focusable and display a focus indicator. Learn more.

Interactive elements indicate their purpose and state

Interactive elements, such as links and buttons, should indicate their state and be distinguishable from non-interactive elements. Learn more.

The user's focus is directed to new content added to the page

If new content, such as a dialog, is added to the page, the user's focus is directed to it. Learn more.

User focus is not accidentally trapped in a region

A user can tab into and out of any control or region without accidentally trapping their focus. Learn more.

Custom controls have associated labels

Custom interactive controls have associated labels, provided by aria-label or aria-labelledby. Learn more.

Custom controls have ARIA roles

Custom interactive controls have appropriate ARIA roles. Learn more.

Visual order on the page follows DOM order

DOM order matches the visual order, improving navigation for assistive technology. Learn more.

Offscreen content is hidden from assistive technology

Offscreen content is hidden with display: none or aria-hidden=true. Learn more.

HTML5 landmark elements are used to improve navigation

Landmark elements (<main>, <nav>, etc.) are used to improve the keyboard navigation of the page for assistive technology. Learn more.

[aria-hidden="true"] is not present on the document <body>

Assistive technologies, like screen readers, work inconsistently when `aria-hidden="true"` is set on the document `<body>`. Learn more.

Document has a <title> element

The title gives screen reader users an overview of the page, and search engine users rely on it heavily to determine if a page is relevant to their search. Learn more.

<html> element has a [lang] attribute

If a page doesn't specify a lang attribute, a screen reader assumes that the page is in the default language that the user chose when setting up the screen reader. If the page isn't actually in the default language, then the screen reader might not announce the page's text correctly. Learn more.

<html> element has a valid value for its [lang] attribute

Specifying a valid BCP 47 language helps screen readers announce text properly. Learn more.

[accesskey] values are unique

Access keys let users quickly focus a part of the page. For proper navigation, each access key must be unique. Learn more.

[aria-*] attributes match their roles

Each ARIA `role` supports a specific subset of `aria-*` attributes. Mismatching these invalidates the `aria-*` attributes. Learn more.

[aria-hidden="true"] elements do not contain focusable descendents

Focusable descendents within an `[aria-hidden="true"]` element prevent those interactive elements from being available to users of assistive technologies like screen readers. Learn more.

ARIA input fields have accessible names

When an input field doesn't have an accessible name, screen readers announce it with a generic name, making it unusable for users who rely on screen readers. Learn more.

[role]s have all required [aria-*] attributes

Some ARIA roles have required attributes that describe the state of the element to screen readers. Learn more.

Elements with an ARIA [role] that require children to contain a specific [role] have all required children.

Some ARIA parent roles must contain specific child roles to perform their intended accessibility functions. Learn more.

[role]s are contained by their required parent element

Some ARIA child roles must be contained by specific parent roles to properly perform their intended accessibility functions. Learn more.

[role] values are valid

ARIA roles must have valid values in order to perform their intended accessibility functions. Learn more.

ARIA toggle fields have accessible names

When a toggle field doesn't have an accessible name, screen readers announce it with a generic name, making it unusable for users who rely on screen readers. Learn more.

[aria-*] attributes have valid values

Assistive technologies, like screen readers, can't interpret ARIA attributes with invalid values. Learn more.

[aria-*] attributes are valid and not misspelled

Assistive technologies, like screen readers, can't interpret ARIA attributes with invalid names. Learn more.

Buttons have an accessible name

When a button doesn't have an accessible name, screen readers announce it as "button", making it unusable for users who rely on screen readers. Learn more.

The page contains a heading, skip link, or landmark region

Adding ways to bypass repetitive content lets keyboard users navigate the page more efficiently. Learn more.

<dl>'s contain only properly-ordered <dt> and <dd> groups, <script>, <template> or <div> elements.

When definition lists are not properly marked up, screen readers may produce confusing or inaccurate output. Learn more.

Definition list items are wrapped in <dl> elements

Definition list items (`<dt>` and `<dd>`) must be wrapped in a parent `<dl>` element to ensure that screen readers can properly announce them. Learn more.

[id] attributes on active, focusable elements are unique

All focusable elements must have a unique `id` to ensure that they're visible to assistive technologies. Learn more.

ARIA IDs are unique

The value of an ARIA ID must be unique to prevent other instances from being overlooked by assistive technologies. Learn more.

No form fields have multiple labels

Form fields with multiple labels can be confusingly announced by assistive technologies like screen readers which use either the first, the last, or all of the labels. Learn more.

<frame> or <iframe> elements have a title

Screen reader users rely on frame titles to describe the contents of frames. Learn more.

Heading elements appear in a sequentially-descending order

Properly ordered headings that do not skip levels convey the semantic structure of the page, making it easier to navigate and understand when using assistive technologies. Learn more.

Image elements have [alt] attributes

Informative elements should aim for short, descriptive alternate text. Decorative elements can be ignored with an empty alt attribute. Learn more.

<input type="image"> elements have [alt] text

When an image is being used as an `<input>` button, providing alternative text can help screen reader users understand the purpose of the button. Learn more.

Form elements have associated labels

Labels ensure that form controls are announced properly by assistive technologies, like screen readers. Learn more.

Presentational <table> elements avoid using <th>, <caption> or the [summary] attribute.

A table being used for layout purposes should not include data elements, such as the th or caption elements or the summary attribute, because this can create a confusing experience for screen reader users. Learn more.

Links have a discernible name

Link text (and alternate text for images, when used as links) that is discernible, unique, and focusable improves the navigation experience for screen reader users. Learn more.

Lists contain only <li> elements and script supporting elements (<script> and <template>).

Screen readers have a specific way of announcing lists. Ensuring proper list structure aids screen reader output. Learn more.

List items (<li>) are contained within <ul> or <ol> parent elements

Screen readers require list items (`<li>`) to be contained within a parent `<ul>` or `<ol>` to be announced properly. Learn more.

The document does not use <meta http-equiv="refresh">

Users do not expect a page to refresh automatically, and doing so will move focus back to the top of the page. This may create a frustrating or confusing experience. Learn more.

[user-scalable="no"] is not used in the <meta name="viewport"> element and the [maximum-scale] attribute is not less than 5.

Disabling zooming is problematic for users with low vision who rely on screen magnification to properly see the contents of a web page. Learn more.

<object> elements have [alt] text

Screen readers cannot translate non-text content. Adding alt text to `<object>` elements helps screen readers convey meaning to users. Learn more.

No element has a [tabindex] value greater than 0

A value greater than 0 implies an explicit navigation ordering. Although technically valid, this often creates frustrating experiences for users who rely on assistive technologies. Learn more.

Cells in a <table> element that use the [headers] attribute refer to table cells within the same table.

Screen readers have features to make navigating tables easier. Ensuring `<td>` cells using the `[headers]` attribute only refer to other cells in the same table may improve the experience for screen reader users. Learn more.

<th> elements and elements with [role="columnheader"/"rowheader"] have data cells they describe.

Screen readers have features to make navigating tables easier. Ensuring table headers always refer to some set of cells may improve the experience for screen reader users. Learn more.

[lang] attributes have a valid value

Specifying a valid BCP 47 language on elements helps ensure that text is pronounced correctly by a screen reader. Learn more.

<video> elements contain a <track> element with [kind="captions"]

When a video provides a caption it is easier for deaf and hearing impaired users to access its information. Learn more.

<video> elements contain a <track> element with [kind="description"]

Audio descriptions provide relevant information for videos that dialogue cannot, such as facial expressions and scenes. Learn more.

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Best Practices

Uses HTTPS

All sites should be protected with HTTPS, even ones that don't handle sensitive data. This includes avoiding mixed content, where some resources are loaded over HTTP despite the initial request being servedover HTTPS. HTTPS prevents intruders from tampering with or passively listening in on the communications between your app and your users, and is a prerequisite for HTTP/2 and many new web platform APIs. Learn more.

Links to cross-origin destinations are safe

Add `rel="noopener"` or `rel="noreferrer"` to any external links to improve performance and prevent security vulnerabilities. Learn more.

Avoids requesting the geolocation permission on page load

Users are mistrustful of or confused by sites that request their location without context. Consider tying the request to a user action instead. Learn more.

Avoids requesting the notification permission on page load

Users are mistrustful of or confused by sites that request to send notifications without context. Consider tying the request to user gestures instead. Learn more.

Avoids front-end JavaScript libraries with known security vulnerabilities

Some third-party scripts may contain known security vulnerabilities that are easily identified and exploited by attackers. Learn more.

Allows users to paste into password fields

Preventing password pasting undermines good security policy. Learn more.

Displays images with correct aspect ratio

Image display dimensions should match natural aspect ratio. Learn more.

Displays images with appropriate size

Image natural dimensions should be proportional to the display size and the pixel ratio to maximize image clarity. Learn more.

Page has the HTML doctype

Specifying a doctype prevents the browser from switching to quirks-mode. Learn more.

Properly defines charset

A character encoding declaration is required. It can be done with a <meta> tag in the first 1024 bytes of the HTML or in the Content-Type HTTP response header. Learn more.

Avoids Application Cache

Application Cache is deprecated. Learn more.

Detected JavaScript libraries

All front-end JavaScript libraries detected on the page. Learn more.

Name	Version
Vue

Avoids deprecated APIs

Deprecated APIs will eventually be removed from the browser. Learn more.

No browser errors logged to the console

Errors logged to the console indicate unresolved problems. They can come from network request failures and other browser concerns. Learn more

SEO

These checks ensure that your page is optimized for search engine results ranking. There are additional factors Lighthouse does not check that may affect your search ranking. Learn more.

Does not have a <meta name="viewport"> tag with width or initial-scale

No `<meta name="viewport">` tag found

Add a `<meta name="viewport">` tag to optimize your app for mobile screens. Learn more.

Document doesn't use legible font sizes

Text is illegible because there's no viewport meta tag optimized for mobile screens.

Font sizes less than 12px are too small to be legible and require mobile visitors to “pinch to zoom” in order to read. Strive to have >60% of page text ≥12px. Learn more.

Tap targets are not sized appropriately

Tap targets are too small because there's no viewport meta tag optimized for mobile screens

Interactive elements like buttons and links should be large enough (48x48px), and have enough space around them, to be easy enough to tap without overlapping onto other elements. Learn more.

Structured data is valid

Run the Structured Data Testing Tool and the Structured Data Linter to validate structured data. Learn more.

Document has a <title> element

The title gives screen reader users an overview of the page, and search engine users rely on it heavily to determine if a page is relevant to their search. Learn more.

Page has successful HTTP status code

Pages with unsuccessful HTTP status codes may not be indexed properly. Learn more.

Links have descriptive text

Descriptive link text helps search engines understand your content. Learn more.

Page isn’t blocked from indexing

Search engines are unable to include your pages in search results if they don't have permission to crawl them. Learn more.

Document has a valid hreflang

hreflang links tell search engines what version of a page they should list in search results for a given language or region. Learn more.

Document avoids plugins

Search engines can't index plugin content, and many devices restrict plugins or don't support them. Learn more.

robots.txt is valid

If your robots.txt file is malformed, crawlers may not be able to understand how you want your website to be crawled or indexed. Learn more.

Image elements have [alt] attributes

Informative elements should aim for short, descriptive alternate text. Decorative elements can be ignored with an empty alt attribute. Learn more.

Document has a valid rel=canonical

Canonical links suggest which URL to show in search results. Learn more.

Progressive Web App

These checks validate the aspects of a Progressive Web App. Learn more.

Page load is fast enough on mobile networks

A fast page load over a cellular network ensures a good mobile user experience. Learn more.

Current page does not respond with a 200 when offline

If you're building a Progressive Web App, consider using a service worker so that your app can work offline. Learn more.

start_url does not respond with a 200 when offline

No usable web app manifest found on page.

A service worker enables your web app to be reliable in unpredictable network conditions. Learn more.

Uses HTTPS

Does not register a service worker that controls page and start_url

The service worker is the technology that enables your app to use many Progressive Web App features, such as offline, add to homescreen, and push notifications. Learn more.

Web app manifest does not meet the installability requirements

Failures: No manifest was fetched.

Browsers can proactively prompt users to add your app to their homescreen, which can lead to higher engagement. Learn more.

Does not redirect HTTP traffic to HTTPS

If you've already set up HTTPS, make sure that you redirect all HTTP traffic to HTTPS in order to enable secure web features for all your users. Learn more.

Is not configured for a custom splash screen

Failures: No manifest was fetched.

A themed splash screen ensures a high-quality experience when users launch your app from their homescreens. Learn more.

Does not set a theme color for the address bar.

Failures: No manifest was fetched, No `<meta name="theme-color">` tag found.

The browser address bar can be themed to match your site. Learn more.

Content is not sized correctly for the viewport

The viewport size of 980px does not match the window size of 360px.

If the width of your app's content doesn't match the width of the viewport, your app might not be optimized for mobile screens. Learn more.

Does not have a <meta name="viewport"> tag with width or initial-scale

No `<meta name="viewport">` tag found

Add a `<meta name="viewport">` tag to optimize your app for mobile screens. Learn more.

Contains some content when JavaScript is not available

Your app should display some content when JavaScript is disabled, even if it's just a warning to the user that JavaScript is required to use the app. Learn more.

Does not provide a valid apple-touch-icon

For ideal appearance on iOS when users add a progressive web app to the home screen, define an `apple-touch-icon`. It must point to a non-transparent 192px (or 180px) square PNG. Learn More.

Manifest doesn't have a maskable icon

No manifest was fetched

A maskable icon ensures that the image fills the entire shape without being letterboxed when installing the app on a device. Learn more.

Site works cross-browser

To reach the most number of users, sites should work across every major browser. Learn more.

Page transitions don't feel like they block on the network

Transitions should feel snappy as you tap around, even on a slow network. This experience is key to a user's perception of performance. Learn more.

Each page has a URL

Ensure individual pages are deep linkable via URL and that URLs are unique for the purpose of shareability on social media. Learn more.