.lettera {
    margin: 0 10px 0 0;
    height: 57px;
    width: 57px;
    float: left;
    background: url('../images/lettera/a.png') center center no-repeat;
}
.lettera.la { background-image: url('../images/lettere/a.png'); }
.lettera.lb { background-image: url('../images/lettere/b.png'); }
.lettera.lc { background-image: url('../images/lettere/c.png'); }
.lettera.ld { background-image: url('../images/lettere/d.png'); }
.lettera.le { background-image: url('../images/lettere/e.png'); }
.lettera.lf { background-image: url('../images/lettere/f.png'); }
.lettera.lg { background-image: url('../images/lettere/g.png'); }
.lettera.lh { background-image: url('../images/lettere/h.png'); }
.lettera.li { background-image: url('../images/lettere/i.png'); }
.lettera.lj { background-image: url('../images/lettere/j.png'); }
.lettera.lk { background-image: url('../images/lettere/k.png'); }
.lettera.ll { background-image: url('../images/lettere/l.png'); }
.lettera.lm { background-image: url('../images/lettere/m.png'); }
.lettera.ln { background-image: url('../images/lettere/n.png'); }
.lettera.lo { background-image: url('../images/lettere/o.png'); }
.lettera.lp { background-image: url('../images/lettere/p.png'); }
.lettera.lq { background-image: url('../images/lettere/q.png'); }
.lettera.lr { background-image: url('../images/lettere/r.png'); }
.lettera.ls { background-image: url('../images/lettere/s.png'); }
.lettera.lt { background-image: url('../images/lettere/t.png'); }
.lettera.lu { background-image: url('../images/lettere/u.png'); }
.lettera.lv { background-image: url('../images/lettere/v.png'); }
.lettera.lw { background-image: url('../images/lettere/w.png'); }
.lettera.lx { background-image: url('../images/lettere/x.png'); }
.lettera.ly { background-image: url('../images/lettere/y.png'); }
.lettera.lz { background-image: url('../images/lettere/z.png'); }