ui.css

@media screen and (min-width: 320px) and (max-width: 480px) {
    .container {
        display: grid;
        grid-template-columns: 8px repeat(4, 1fr) 8px;
        gap: 4px;
    }

    header {
        grid-column-start: 2;
        grid-column-end: 6;
        grid-row-start: 1;
        background: url(images/header_800.png) no-repeat center;
        height: 24vh;
        border: 4px solid #467ba6;
    }

    nav {
        grid-column-start: 2;
        grid-column-end: 6;
        grid-row-start: 2;
        border: 4px solid #467ba6;
        padding: 0 0.5em;
    }
    
    main {
        display: grid;
        grid-column: 2 / 6;
        grid-row-start: 3;
        border: 4px solid #467ba6;
        padding: 0 0.5em;
        grid-template-columns: subgrid;
    }

    .section-head {
        grid-column: 1 / 5;
    }
    
    [role="tabpanel"] {
        display: grid;
        grid-column: 1 / 5;
        grid-template-columns: subgrid;
    }
    
    .sub-item {
        border: 2px solid #344162;
        border-radius: 8px;
        box-shadow: 2px 2px 2px #344162;
        margin-bottom: 8px;
        padding: 4px;
        height: 8em;
        text-align: center;
    }
}

@media screen and (min-width: 480px) and (max-width: 1000px) {    
    .container {
        display: grid;
        grid-template-columns: 8vw repeat(3, 1fr) 8vw;
        gap: 4px;
    }

    header {
        grid-column-start: 2;
        grid-column-end: 5;
        background: url(images/header_1000.png) no-repeat center;
        height: 24vh;
        border: 4px solid #467ba6;
    }

    nav {
        grid-column-start: 2;
        grid-column-end: 3;
        grid-row-start: 2;
        border: 4px solid #467ba6;
        padding: 0 0.5em;
    }

    main {
        display: grid;
        grid-column: 3 / 5;
        grid-row-start: 2;
        border: 4px solid #467ba6;
        padding: 0 0.5em;
        grid-template-columns: subgrid;
    }

    .section-head {
        grid-column: 1 / 3;
    }
    
    [role="tabpanel"] {
        display: grid;
        grid-column: 1 / 3;
        grid-template-columns: subgrid;
    }
    
    .sub-item {
        border: 2px solid #344162;
        border-radius: 8px;
        box-shadow: 2px 2px 2px #344162;
        margin-bottom: 0.5em;
        padding: 0.25em;
        height: 8em;
        text-align: center;
    }
}

@media screen and (min-width: 1000px) {
    .container {
        display: grid;
        grid-template-columns: 12vw repeat(4, 1fr) 12vw;
        gap: 8px;
    }

    header {
        grid-column-start: 2;
        grid-column-end: 6;
        background: url(images/header_1200.png) no-repeat center;
        height: 24vh;
        border: 4px solid #467ba6;
    }

    nav {
        grid-column-start: 2;
        grid-column-end: 3;
        grid-row-start: 2;
        border: 4px solid #467ba6;
        padding: 0 0.5em;
    }

    main {
        display: grid;
        grid-column: 3 / 6;
        grid-row-start: 2;
        border: 4px solid #467ba6;
        padding: 0 0.5em;
        grid-template-columns: subgrid;
    }

    .section-head {
        grid-column: 1 / 4;
    }
    
    [role="tabpanel"] {
        display: grid;
        grid-column: 1 / 4;
        grid-template-columns: subgrid;
    }
    
    .sub-item {
        border: 2px solid #344162;
        border-radius: 8px;
        box-shadow: inset -2px -2px 2px #344162;
        margin-bottom: 8px;
        padding: 0 0.25em;
        height: 8em;
        text-align: center;
    }
} 

html {
    font-size: 16px;
    background-color: #d2d6e2;
    font-family: "Nunito", sans-serif;
    font-weight: 300;
    font-style: normal;
}

h1 {
    font-family: "Sour Gummy", sans-serif;
    font-weight: 300;
    font-style: normal;
    font-size: 2em;
    margin: 0;
  }

h2 {
    font-family: "Sour Gummy", sans-serif;
    font-weight: 300;
    font-style: normal;
    font-size: 1.5em;
    margin: 0;
}

h3 {
    font-family: "Sour Gummy", sans-serif;
    font-weight: 200;
    font-style: normal;
    font-size: 1.2em;
    margin: 0;
}

p {
    font-family: "Nunito", sans-serif;
}

[role="tablist"] {
    min-width: 100%;
}

button {
    font-family: "Sour Gummy", sans-serif;
    padding: 0.5em;
    font-size: 1.2em;
    margin: 0.25em 0;
    width: 100%;
    border: 4px groove #467ba6;
    border-radius: 8px;
    box-shadow: inset -2px -2px 2px #467ba6;
}

button:focus, button:hover {
    border: 4px double #467ba6;
}

button[aria-selected="true"] {
    border: 4px double #f8fdf3;
    background-color: #467ba6;
    color: #f8fdf3;
    box-shadow: inset -2px -2px 2px #344162;
}

button[aria-selected="false"] {
    border: 4px groove #467ba6;
    background-color: #d2d6e2;
}

[role="tab"] span.focus {
    display: inline-block;
}

[role="tab"]:hover,
[role="tab"]:focus,
[role="tab"]:focus-visible,
[role="tab"]:active {
  border: 4px double #467ba6;
  box-shadow: inset 2px 2px 2px #344162;
}

[role="tabpanel"].is-hidden {
    display: none;
}

.surprise {
    visibility: hidden;
}

.sub-item:hover, 
.sub-item:focus {
    border: 4px double #344162;
    background-color: #d2d6e2;
    box-shadow: inset 2px 2px 2px #344162;
}

.sub-item:hover > .surprise, 
.sub-item:focus > .surprise {
    visibility: visible;
}

.sub-item:hover > h3, 
.sub-item:focus > h3 {
    visibility: hidden;
}