1. A computer-implemented method comprising: analyzing, using multiple block function criteria, content of a document; assigning, based on the analyzing, a respective block function of multiple block functions to semantic blocks of the content; and generating one or more customized documents for browsing by a user, each customized document having a respective layout based on block function(s) assigned to respective ones of the semantic blocks, wherein the analyzing comprises: partitioning the document into multiple semantic blocks; for each semantic block of the semantic blocks, extracting spatial features and content features; for each semantic block of the semantic blocks, generating a respective feature vector from respective spatial and content features; creating a semantic tree of the document from respective feature vectors generated from the semantic blocks, the semantic tree grouping related content in respective blocks of the multiple semantic blocks; and assigning a respective degree of coherence to node(s) of the semantic tree.