SingleFile/extension/ui/pages/options.css

body {
    background-color: transparent;
    font-family: sans-serif;
    max-width: 800px;
}

button {
    background-color: transparent;
    border-color: rgb(191, 191, 191);
    border-style: solid;
    border-radius: 2px;
    padding-top: 5px;
    padding-bottom: 5px;
    padding-left: 15px;
    padding-right: 15px;
    border-width: 1px;
}

button:active {
    border-color: rgb(237, 237, 237);
}

input {
    margin-left: 5px;
}

label,
input {
    align-self: center;
}

input[type="text"] {
    min-width: 70%;
}

input[type="number"] {
    max-width: 40px;
}

h3 {
    padding-left: 8px;
    margin-bottom: 10px;
    margin-top: 10px;
}

details {
    margin-left: 12px;
    margin-right: 12px;
    border-top: gray 1px dashed;
}

details:last-of-type {
    border-bottom: gray 1px dashed;
}

details>summary {
    margin-bottom: 10px;
    margin-top: 10px;
    cursor: pointer;
}

details>summary:focus {
    outline-width: 0px;
}

a {
    display: inline-block;
    padding-top: 5px;
}

.option.second-level {
    margin-left: 10px;
}

.option {
    display: flex;
    justify-content: space-between;
    margin-top: 5px;
    padding-left: 12px;
    min-height: 24px;
}

.option.vertical {
    flex-direction: column;
}

.option.vertical label {
    align-self: flex-start;
}

.option.vertical input {
    margin-top: 3px;
    align-self: flex-end;
    width: calc(100% - 3px);
}

.option:last-of-type {
    padding-bottom: 12px;
}

.option:first-of-type {
    padding-top: 6px;
}

.option.bottom {
    padding-top: 24px;
    padding-right: 12px;
}

#expandAllButton {
    opacity: .3;
    transition: opacity 250ms;
    cursor: pointer;
    font-size: .9em;
    margin-right: 1px;
}

#expandAllButton::after {
    content: '▷';
}

#expandAllButton.opened::after {
    content: '▽';
    position: relative;
    top: 1px;
}

#expandAllButton:hover {
    opacity: 1;
}

@media (max-width:400px) {
    body {
        font-size: 11px;
    }
    body,
    input {
        font-size: 12px;
    }
}