en primer lugar, bienvenida a FDW @lidianavarro
Lo que te está haciendo el efecto es el css
no el javascript, que utiliza jquery, y la librería jquery no se carga en ninguna parte, tenés que definirte como lo vas a hacer, con el css el fade no lo vas a conseguir.
Cargar jquery tan solo para eso es algo exagerado.
Por otra parte tu html tiene muchos errores que deben ser solucionados (algunos graves)
Result: 30 errors / 0 warnings
line 6 column 172 - Error: end tag for "meta" omitted, but OMITTAG NO was specified
line 6 - Info: start tag was here
line 7 column 104 - Error: end tag for "meta" omitted, but OMITTAG NO was specified
line 7 - Info: start tag was here
line 8 column 44 - Error: end tag for "meta" omitted, but OMITTAG NO was specified
line 8 - Info: start tag was here
line 49 column 59 - Error: end tag for "img" omitted, but OMITTAG NO was specified
line 49 column 4 - Info: start tag was here
line 52 column 12 - Error: ID "londres" already defined
line 47 column 12 - Info: ID "londres" first defined here
line 53 column 11 - Error: ID "titular" already defined
line 48 column 11 - Info: ID "titular" first defined here
line 54 column 59 - Error: end tag for "img" omitted, but OMITTAG NO was specified
line 54 column 4 - Info: start tag was here
line 63 column 11 - Error: ID "titular" already defined
line 48 column 11 - Info: ID "titular" first defined here
line 64 column 61 - Error: end tag for "img" omitted, but OMITTAG NO was specified
line 64 column 4 - Info: start tag was here
line 66 column 12 - Error: ID "retirada" already defined
line 62 column 12 - Info: ID "retirada" first defined here
line 67 column 11 - Error: ID "titular" already defined
line 48 column 11 - Info: ID "titular" first defined here
line 68 column 61 - Error: end tag for "img" omitted, but OMITTAG NO was specified
line 68 column 4 - Info: start tag was here
line 101 column 11 - Error: ID "titular" already defined
line 48 column 11 - Info: ID "titular" first defined here
line 124 column 8 - Error: end tag for element "ul" which is not open
line 125 column 16 - Error: there is no attribute "tableid"
line 128 column 8 - Error: end tag for "ul" which is not finished
line 137 column 119 - Error: required attribute "alt" not specified
line 137 column 123 - Error: end tag for "img" omitted, but OMITTAG NO was specified
line 137 column 91 - Info: start tag was here
line 140 column 123 - Error: required attribute "alt" not specified
line 140 column 127 - Error: end tag for "img" omitted, but OMITTAG NO was specified
line 140 column 94 - Info: start tag was here
line 163 column 9 - Error: ID "creditos" already defined
line 162 column 9 - Info: ID "creditos" first defined here
line 163 column 18 - Error: document type does not allow element "li" here; missing one of "ul", "ol", "menu", "dir" start-tag
line 163 column 122 - Error: required attribute "alt" not specified
line 163 column 123 - Error: end tag for "img" omitted, but OMITTAG NO was specified
line 163 column 36 - Info: start tag was here
line 164 column 85 - Error: required attribute "alt" not specified
line 164 column 86 - Error: end tag for "img" omitted, but OMITTAG NO was specified
line 164 - Info: start tag was here
line 164 column 206 - Error: required attribute "alt" not specified
line 164 column 238 - Error: ":" is not a member of a group specified for any attribute
line 164 column 250 - Error: "lidianavarro" is not a member of a group specified for any attribute
line 164 column 294 - Error: "lidianavarro" is not a member of a group specified for any attribute
Saludos