@font-face {
    font-family: 'Fira Sans';
    src: url('fonts/FiraSans-Regular.ttf') format('truetype');
    font-weight: 400; /* Regular */
    font-style: normal;
    font-display: swap;
}

@font-face {
    font-family: 'Fira Sans';
    src: url('fonts/FiraSans-Italic.ttf') format('truetype');
    font-weight: 400; /* Regular Italic */
    font-style: italic;
    font-display: swap;
}

@font-face {
    font-family: 'Fira Sans';
    src: url('fonts/FiraSans-Bold.ttf') format('truetype');
    font-weight: 700; /* Bold */
    font-style: normal;
    font-display: swap;
}

@font-face {
    font-family: 'Fira Sans';
    src: url('fonts/FiraSans-BoldItalic.ttf') format('truetype');
    font-weight: 700; /* Bold Italic */
    font-style: italic;
    font-display: swap;
}

/* Использование */
body {
    font-family: 'Fira Sans', 'Trebuchet MS', Tahoma, Verdana, sans-serif;
    font-weight: 400; /* Regular по умолчанию */
}