style.css

@font-face {
    font-family: 'Holidays';
    src: url(fuentes/Holidays\ Homework.ttf);
    font-style: normal;
    font-weight: normal;
}
body{
    font-family: 'Holidays';
    margin: 0;
    padding: 0;
    background: url(imagenes/backgroundGreen.jpg) no-repeat center;
    min-height: 100vh;
    color: white;
    transition: all 0.4s;
}
header{
    color: white;
    padding: 3px;
    text-align: center;
}
.pizarra{
    width: 80px;
    height: 80px;
    background: url(imagenes/sol.png);
    border: none;
    position: absolute;
    top: 20px;
    right: 20px;
    cursor: pointer;
    transition: background 0.4s;
}
.pizarra:hover{
    background: url(imagenes/luna.png);
}

.active {
    background: url(imagenes/luna.png);
    transition: background 0.4s;
}
.active:hover {
    background: url(imagenes/sol.png);
}
#volver{
    background: url(imagenes/btns.png);
    position: absolute;
    top: 20px;
    left: 20px;
    width: 150px;
    height: 50px;
    color: white;
    font-size: 22px;
    font-family: 'Holidays';
    border: none;
    text-align: center;
    text-decoration: none;
}
main{
    width: 80%;
    margin: auto;
    padding: 20px;
}
#base{
    display: flex;
    flex-direction: column;
    align-items: center;
    width: 100%;
    
}
#baseAho{
    margin: auto;
    padding: 5px;
    height: 50vh;
}
#palabra-adivinar{
    height: 3em;
}
#palabra-adivinar span{
    vertical-align: bottom;
    margin: 0 3px;
    font-size: 1.5em;
    border-bottom: 2px solid white;
    align-items: center;
    min-width: 35px;
    text-align: center;
    display: inline-block;
}
#jugar{
    background: url(imagenes/btns.png);
    width: 150px;
    height: 50px;
    color: white;
    font-size: 22px;
    font-family: 'Holidays';
    border: none;
    text-align: center;
    cursor: pointer;
}
#letras{
    margin: 30px 21px 0 21px;
    display: flex;
    flex-wrap: wrap;
    justify-content: center;
    gap: 7px;
}
#letras button{
    background: url(imagenes/BtnLetras.png);
    width: 50px;
    padding: 7px 0 12px 0;
    text-align: center;
    font-family: 'Holidays';
    color: white;
    border: none;
    font-size: 20px;
    cursor: pointer;
}

body.darkMode{
    font-family: 'Holidays';
    margin: 0;
    padding: 0;
    background: url(imagenes/background.jpg) no-repeat center;
    min-height: 100vh;
    color: white;
}

/* hoja principal */

.contenedor{
    margin: auto;
    padding: 10% 4% 4% 4%;
    width: 80%;
    height: 60vh;
    position: relative;
    font-weight: 200;
}
.contenedorBtns{
    position: relative;
    display: flex;
    justify-content: center;
}
.contenedorLetras{

    padding: 10% 2% 2% 2%;
}
.btnsLinksMain{
    margin: auto;
    justify-content: center;
}
.imgBtns{
    width: 280px;
}
#btnIzq{
    position: absolute;
/*    height: 90px;
    width: 270px;*/
    top: 25%;
    left: 11%;
    text-decoration: none;
    color: white;
    font-size: 22px;
}
#btnDer{
    position: absolute;
   /* height: 90px;
    width: 270px;*/
    top: 25%;
    right: 10%;
    text-decoration: none;
    color: white;
    font-size: 22px;
}

.btnsLinks{
    margin: auto 40%;
    padding: 3% 0;
    background-position: center;
    width: 150px;
    color: white;
    font-size: 22px;
    border: none;
    text-align: center;
    text-decoration: none;
}
.btnsLinks a{
    text-decoration: none;
    color: white;
    font-size: 18px;
}

.text-info{
    text-align: center;
    font-size: 22px;
}
.caja-texto{
    border: none;
    width: 100%;
    height: 15%;
    text-align: center;
    font-family: 'Holidays';
    font-size: 22px;
    background: none;
    color: white;
    outline: none;
    margin: 5% 0;
    resize: none;
}
.caja-texto::placeholder{
    color: white;
}
.ingresarPalabra{
    justify-content: center;

}
#btnIniciar{
    position: relative;
}
#iniciar{
    position: absolute;
    top: 28%;
    right: 43%;
    text-decoration: none;
    color: white;
    font-size: 22px;
}