jitsi_corner9/css/premeeting/_premeeting-screens.scss

 .premeeting-screen {
    background: #292929;
    bottom: 0;
    display: flex;
    font-size: 1.3em;
    left: 0;
    position: absolute;
    right: 0;
    top: 0;
    z-index: $toolbarZ + 2;

    .action-btn {
        border-radius: 6px;
        box-sizing: border-box;
        color: #fff;
        cursor: pointer;
        display: inline-block;
        font-size: 14px;
        font-weight: 600;
        line-height: 24px;
        margin-bottom: 16px;
        padding: 7px 16px;
        position: relative;
        text-align: center;
        width: 100%;

        &.primary {
            background: #0376DA;
            border: 1px solid #0376DA;
        }

        &.secondary {
            background: #3D3D3D;
            border: 1px solid transparent;
        }

        &.text {
            width: auto;
            font-size: 13px;
            margin: 0;
            padding: 0;
        }

        &.disabled {
            background: #5E6D7A;
            border: 1px solid #5E6D7A;
            color: #AFB6BC;
            cursor: initial;

            .icon {
                & > svg {
                    fill: #AFB6BC;
                }
            }
        }

        .options {
            border-radius: 3px;
            align-items: center;
            display: flex;
            height: 100%;
            justify-content: center;
            position: absolute;
            right: 0;
            top: 0;
            width: 36px;

            &:hover {
                background-color: #0262B6;
            }

            svg {
                pointer-events: none;
            }
        }
    }

    .content {
        align-items: center;
        box-sizing: border-box;
        display: flex;
        flex-direction: column;
        flex-shrink: 0;
        height: 100%;
        margin: 0 30px;
        padding: 24px 0 16px;
        position: relative;
        width: $prejoinDefaultContentWidth;
        z-index: $toolbarZ + 2;

        &-controls {
            align-items: center;
            display: flex;
            flex-direction: column;
            margin: auto;
            width: 100%;

            .title {
                color: #fff;
                font-size: 28px;
                font-weight: 600;
                letter-spacing: -0.015;
                line-height: 36px;
                margin-bottom: 32px;
                text-align: center;
            }

            input.field {
                background-color: white;
                border: none;
                outline: none;
                border-radius: 6px;
                font-size: 14px;
                line-height: 20px;
                margin-bottom: 16px;
                color: #1C2025;
                padding: 10px 16px;
                text-align: center;
                width: 100%;

                &.error {
                    border: 1px solid #E04757;
                }

                &.focused {
                    box-shadow: 0px 0px 1px 1.5px black, 0px 0px 1.3px 4px white;
                }
            }

            #new-toolbox {
                bottom: 0;
                position: relative;
                transition: none;

                .toolbox-content {
                    margin-bottom: 4px;
                }

                .toolbox-content-items {
                    @include ltr;
                    background: transparent;
                    box-shadow: none;
                    display: flex;
                    justify-content: space-evenly;
                    padding: 8px 0;
                }

                .toolbox-content,
                .toolbox-content-wrapper,
                .toolbox-content-items {
                    box-sizing: border-box;
                    width: 100%;
                }
            }
        }
    }

    @media (max-width: 720px) {
        flex-direction: column-reverse;

        .content {
            height: auto;
            margin: 0 auto;
        }
    }

    // mobile phone landscape
    @media (max-height: 420px) {
        div.content {
            padding: 16px 16px 0 16px;
        }
    }

    @media (max-width: 400px) {
        .content {
            padding: 16px;
            width: 100%;

            &-controls {
                input.field {
                    font-size: 16px;
                    padding: 14px 16px;
                }
            }

            .title {
                display: none;
            }
        }

        .device-status-error {
            border-radius: 0;
            margin: 0 -16px;
        }

        input.field {
            font-size: 16px;
            padding: 14px 16px;
        }

        .action-btn {
            font-size: 16px;
            margin-bottom: 8px;
            padding: 11px 16px;
        }
    }

    input::placeholder {
        color: #040404;
    }
}

#preview {
    background: #040404;
    display: flex;
    align-items: center;
    justify-content: center;
    height: 100%;
    width: 100%;

    .avatar {
        text {
            fill: white;
        }
    }

    video {
        height: 100%;
        object-fit: cover;
        width: 100%;
    }
}

@mixin flex-centered() {
    align-items: center;
    display: flex;
    justify-content: center;
}