diff --git a/Cargo.lock b/Cargo.lock
index 10fae527f7..c1e3e0c283 100644
--- a/Cargo.lock
+++ b/Cargo.lock
@@ -68,9 +68,18 @@ dependencies = [
 
 [[package]]
 name = "autocfg"
-version = "1.0.1"
+version = "0.1.8"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "cdb031dd78e28731d87d56cc8ffef4a8f36ca26c38fe2de700543e627f8a464a"
+checksum = "0dde43e75fd43e8a1bf86103336bc699aa8d17ad1be60c76c0bdfd4828e19b78"
+dependencies = [
+ "autocfg 1.1.0",
+]
+
+[[package]]
+name = "autocfg"
+version = "1.1.0"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "d468802bab17cbc0cc575e9b053f41e72aa36bfa6b7f55e3529ffa43161b97fa"
 
 [[package]]
 name = "base64"
@@ -185,15 +194,15 @@ dependencies = [
 
 [[package]]
 name = "clap"
-version = "3.0.10"
+version = "3.1.15"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "7a30c3bf9ff12dfe5dae53f0a96e0febcd18420d1c0e7fad77796d9d5c4b5375"
+checksum = "85a35a599b11c089a7f49105658d089b8f2cf0882993c17daf6de15285c2c35d"
 dependencies = [
  "atty",
  "bitflags",
+ "clap_lex",
  "indexmap",
  "lazy_static",
- "os_str_bytes",
  "strsim",
  "termcolor",
  "textwrap",
@@ -208,6 +217,30 @@ dependencies = [
  "clap",
 ]
 
+[[package]]
+name = "clap_lex"
+version = "0.2.0"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "a37c35f1112dad5e6e0b1adaff798507497a18fceeb30cceb3bae7d1427b9213"
+dependencies = [
+ "os_str_bytes",
+]
+
+[[package]]
+name = "cloudabi"
+version = "0.0.3"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "ddfc5b9aa5d4507acaf872de71051dfd0e309860e88966e1051e462a077aac4f"
+dependencies = [
+ "bitflags",
+]
+
+[[package]]
+name = "convert_case"
+version = "0.4.0"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "6245d59a3e82a7fc217c5828a6692dbc6dfb63a0c8c90495621f7b9d79704a0e"
+
 [[package]]
 name = "cpufeatures"
 version = "0.1.5"
@@ -217,14 +250,54 @@ dependencies = [
  "libc",
 ]
 
+[[package]]
+name = "cssparser"
+version = "0.29.3"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "31542adad356e4fd6e9df55221485a22eb69c470141e110e7dbb4a8052e45fa6"
+dependencies = [
+ "cssparser-macros",
+ "dtoa-short",
+ "itoa",
+ "matches",
+ "phf 0.10.1",
+ "proc-macro2 1.0.28",
+ "quote 1.0.9",
+ "smallvec",
+ "syn 1.0.75",
+]
+
+[[package]]
+name = "cssparser-macros"
+version = "0.6.0"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "dfae75de57f2b2e85e8768c3ea840fd159c8f33e2b6522c7835b7abac81be16e"
+dependencies = [
+ "quote 1.0.9",
+ "syn 1.0.75",
+]
+
 [[package]]
 name = "ctor"
 version = "0.1.20"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "5e98e2ad1a782e33928b96fc3948e7c355e5af34ba4de7670fe8bac2a3b2006d"
 dependencies = [
- "quote",
- "syn",
+ "quote 1.0.9",
+ "syn 1.0.75",
+]
+
+[[package]]
+name = "derive_more"
+version = "0.99.17"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "4fb810d30a7c1953f91334de7244731fc3f3c10d7fe163338a35b9f640960321"
+dependencies = [
+ "convert_case",
+ "proc-macro2 1.0.28",
+ "quote 1.0.9",
+ "rustc_version",
+ "syn 1.0.75",
 ]
 
 [[package]]
@@ -263,6 +336,21 @@ version = "0.3.3"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "fea41bba32d969b513997752735605054bc0dfa92b4c56bf1189f2e174be7a10"
 
+[[package]]
+name = "dtoa"
+version = "0.4.8"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "56899898ce76aaf4a0f24d914c97ea6ed976d42fec6ad33fcbb0a1103e07b2b0"
+
+[[package]]
+name = "dtoa-short"
+version = "0.3.3"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "bde03329ae10e79ede66c9ce4dc930aa8599043b0743008548680f25b91502d6"
+dependencies = [
+ "dtoa",
+]
+
 [[package]]
 name = "either"
 version = "1.6.1"
@@ -356,6 +444,12 @@ dependencies = [
  "libc",
 ]
 
+[[package]]
+name = "fuchsia-cprng"
+version = "0.1.1"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "a06f77d526c1a601b7c4cdd98f54b5eaabffc14d5f2f0296febdc7f357c6d3ba"
+
 [[package]]
 name = "fuchsia-zircon"
 version = "0.3.3"
@@ -404,11 +498,11 @@ version = "0.3.16"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "c54913bae956fb8df7f4dc6fc90362aa72e69148e3f39041fbe8742d21e0ac57"
 dependencies = [
- "autocfg",
+ "autocfg 1.1.0",
  "proc-macro-hack",
- "proc-macro2",
- "quote",
- "syn",
+ "proc-macro2 1.0.28",
+ "quote 1.0.9",
+ "syn 1.0.75",
 ]
 
 [[package]]
@@ -429,7 +523,7 @@ version = "0.3.16"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "67eb846bfd58e44a8481a00049e82c43e0ccb5d61f8dc071057cb19249dd4d78"
 dependencies = [
- "autocfg",
+ "autocfg 1.1.0",
  "futures-core",
  "futures-macro",
  "futures-sink",
@@ -441,6 +535,15 @@ dependencies = [
  "slab",
 ]
 
+[[package]]
+name = "fxhash"
+version = "0.2.1"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "c31b6d751ae2c7f11320402d34e41349dd1016f8d5d45e48c4312bc8625af50c"
+dependencies = [
+ "byteorder",
+]
+
 [[package]]
 name = "generic-array"
 version = "0.12.4"
@@ -525,7 +628,7 @@ dependencies = [
  "log",
  "pest",
  "pest_derive",
- "quick-error",
+ "quick-error 2.0.1",
  "serde",
  "serde_json",
 ]
@@ -579,9 +682,9 @@ dependencies = [
  "log",
  "mac",
  "markup5ever",
- "proc-macro2",
- "quote",
- "syn",
+ "proc-macro2 1.0.28",
+ "quote 1.0.9",
+ "syn 1.0.75",
 ]
 
 [[package]]
@@ -665,7 +768,7 @@ version = "1.7.0"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "bc633605454125dec4b66843673f01c7df2b89479b32e0ed634e43a91cff62a5"
 dependencies = [
- "autocfg",
+ "autocfg 1.1.0",
  "hashbrown",
 ]
 
@@ -735,6 +838,44 @@ version = "1.3.0"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "830d08ce1d1d941e6b30645f1a0eb5643013d835ce3779a5fc208261dbe10f55"
 
+[[package]]
+name = "lewp-css"
+version = "0.2.0"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "39d5f56e217205b30a01e1ec42c608f8b14aade46c1355c7e031ac8c161dde14"
+dependencies = [
+ "bitflags",
+ "cssparser",
+ "either",
+ "lewp-selectors",
+ "ordermap",
+ "phf 0.7.24",
+ "phf_codegen 0.7.24",
+ "phf_macros 0.7.24",
+ "precomputed-hash",
+ "quick-error 1.2.3",
+ "servo_arc",
+ "smallvec",
+]
+
+[[package]]
+name = "lewp-selectors"
+version = "0.24.0"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "08b1dc58ea0886a660510a1be6a62677aee0f6e9892932e43d3257e2b1a58886"
+dependencies = [
+ "bitflags",
+ "cssparser",
+ "derive_more",
+ "fxhash",
+ "log",
+ "phf 0.8.0",
+ "phf_codegen 0.8.0",
+ "precomputed-hash",
+ "servo_arc",
+ "smallvec",
+]
+
 [[package]]
 name = "libc"
 version = "0.2.100"
@@ -769,8 +910,8 @@ source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "a24f40fb03852d1cdd84330cddcaf98e9ec08a7b7768e952fad3b4cf048ec8fd"
 dependencies = [
  "log",
- "phf",
- "phf_codegen",
+ "phf 0.8.0",
+ "phf_codegen 0.8.0",
  "string_cache",
  "string_cache_codegen",
  "tendril",
@@ -810,6 +951,7 @@ dependencies = [
  "gitignore",
  "handlebars",
  "lazy_static",
+ "lewp-css",
  "log",
  "memchr",
  "notify",
@@ -935,6 +1077,12 @@ version = "1.0.4"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "e4a24736216ec316047a1fc4252e27dabb04218aa4a3f37c6e7ddbf1f9782b54"
 
+[[package]]
+name = "nodrop"
+version = "0.1.14"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "72ef4a56884ca558e5ddb05a1d1e7e1bfd9a68d9ed024c21704cc98872dae1bb"
+
 [[package]]
 name = "normalize-line-endings"
 version = "0.3.0"
@@ -974,7 +1122,7 @@ version = "0.1.44"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "d2cc698a63b549a70bc047073d2949cce27cd1c7b0a4a862d08a8031bc2801db"
 dependencies = [
- "autocfg",
+ "autocfg 1.1.0",
  "num-traits",
 ]
 
@@ -984,7 +1132,7 @@ version = "0.2.14"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "9a64b1ec5cda2586e284722486d802acf1f7dbdc623e2bfc57e65ca1cd099290"
 dependencies = [
- "autocfg",
+ "autocfg 1.1.0",
 ]
 
 [[package]]
@@ -1019,14 +1167,17 @@ dependencies = [
  "winapi 0.3.9",
 ]
 
+[[package]]
+name = "ordermap"
+version = "0.2.13"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "b81cf3b8cb96aa0e73bbedfcdc9708d09fec2854ba8d474be4e6f666d7379e8b"
+
 [[package]]
 name = "os_str_bytes"
 version = "6.0.0"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "8e22443d1643a904602595ba1cd8f7d896afe56d26712531c5ff73a15b2fbf64"
-dependencies = [
- "memchr",
-]
 
 [[package]]
 name = "output_vt100"
@@ -1070,9 +1221,9 @@ checksum = "99b8db626e31e5b81787b9783425769681b347011cc59471e33ea46d2ea0cf55"
 dependencies = [
  "pest",
  "pest_meta",
- "proc-macro2",
- "quote",
- "syn",
+ "proc-macro2 1.0.28",
+ "quote 1.0.9",
+ "syn 1.0.75",
 ]
 
 [[package]]
@@ -1086,13 +1237,43 @@ dependencies = [
  "sha-1 0.8.2",
 ]
 
+[[package]]
+name = "phf"
+version = "0.7.24"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "b3da44b85f8e8dfaec21adae67f95d93244b2ecf6ad2a692320598dcc8e6dd18"
+dependencies = [
+ "phf_shared 0.7.24",
+]
+
 [[package]]
 name = "phf"
 version = "0.8.0"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "3dfb61232e34fcb633f43d12c58f83c1df82962dcdfa565a4e866ffc17dafe12"
 dependencies = [
- "phf_shared",
+ "phf_shared 0.8.0",
+]
+
+[[package]]
+name = "phf"
+version = "0.10.1"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "fabbf1ead8a5bcbc20f5f8b939ee3f5b0f6f281b6ad3468b84656b658b455259"
+dependencies = [
+ "phf_macros 0.10.0",
+ "phf_shared 0.10.0",
+ "proc-macro-hack",
+]
+
+[[package]]
+name = "phf_codegen"
+version = "0.7.24"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "b03e85129e324ad4166b06b2c7491ae27fe3ec353af72e72cd1654c7225d517e"
+dependencies = [
+ "phf_generator 0.7.24",
+ "phf_shared 0.7.24",
 ]
 
 [[package]]
@@ -1101,8 +1282,18 @@ version = "0.8.0"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "cbffee61585b0411840d3ece935cce9cb6321f01c45477d30066498cd5e1a815"
 dependencies = [
- "phf_generator",
- "phf_shared",
+ "phf_generator 0.8.0",
+ "phf_shared 0.8.0",
+]
+
+[[package]]
+name = "phf_generator"
+version = "0.7.24"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "09364cc93c159b8b06b1f4dd8a4398984503483891b0c26b867cf431fb132662"
+dependencies = [
+ "phf_shared 0.7.24",
+ "rand 0.6.5",
 ]
 
 [[package]]
@@ -1111,17 +1302,72 @@ version = "0.8.0"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "17367f0cc86f2d25802b2c26ee58a7b23faeccf78a396094c13dced0d0182526"
 dependencies = [
- "phf_shared",
+ "phf_shared 0.8.0",
  "rand 0.7.3",
 ]
 
+[[package]]
+name = "phf_generator"
+version = "0.10.0"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "5d5285893bb5eb82e6aaf5d59ee909a06a16737a8970984dd7746ba9283498d6"
+dependencies = [
+ "phf_shared 0.10.0",
+ "rand 0.8.4",
+]
+
+[[package]]
+name = "phf_macros"
+version = "0.7.24"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "bdb45e833315153371697760dad1831da99ce41884162320305e4f123ca3fe37"
+dependencies = [
+ "phf_generator 0.7.24",
+ "phf_shared 0.7.24",
+ "proc-macro2 0.4.30",
+ "quote 0.6.13",
+ "syn 0.15.44",
+]
+
+[[package]]
+name = "phf_macros"
+version = "0.10.0"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "58fdf3184dd560f160dd73922bea2d5cd6e8f064bf4b13110abd81b03697b4e0"
+dependencies = [
+ "phf_generator 0.10.0",
+ "phf_shared 0.10.0",
+ "proc-macro-hack",
+ "proc-macro2 1.0.28",
+ "quote 1.0.9",
+ "syn 1.0.75",
+]
+
+[[package]]
+name = "phf_shared"
+version = "0.7.24"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "234f71a15de2288bcb7e3b6515828d22af7ec8598ee6d24c3b526fa0a80b67a0"
+dependencies = [
+ "siphasher 0.2.3",
+]
+
 [[package]]
 name = "phf_shared"
 version = "0.8.0"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "c00cf8b9eafe68dde5e9eaa2cef8ee84a9336a47d566ec55ca16589633b65af7"
 dependencies = [
- "siphasher",
+ "siphasher 0.3.6",
+]
+
+[[package]]
+name = "phf_shared"
+version = "0.10.0"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "b6796ad771acdc0123d2a88dc428b5e38ef24456743ddb1744ed628f9815c096"
+dependencies = [
+ "siphasher 0.3.6",
 ]
 
 [[package]]
@@ -1139,9 +1385,9 @@ version = "1.0.8"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "6e8fe8163d14ce7f0cdac2e040116f22eac817edabff0be91e8aff7e9accf389"
 dependencies = [
- "proc-macro2",
- "quote",
- "syn",
+ "proc-macro2 1.0.28",
+ "quote 1.0.9",
+ "syn 1.0.75",
 ]
 
 [[package]]
@@ -1222,13 +1468,22 @@ version = "0.1.7"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "bc881b2c22681370c6a780e47af9840ef841837bc98118431d4e1868bd0c1086"
 
+[[package]]
+name = "proc-macro2"
+version = "0.4.30"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "cf3d2011ab5c909338f7887f4fc896d35932e29146c12c8d01da6b22a80ba759"
+dependencies = [
+ "unicode-xid 0.1.0",
+]
+
 [[package]]
 name = "proc-macro2"
 version = "1.0.28"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "5c7ed8b8c7b886ea3ed7dde405212185f423ab44682667c8c6dd14aa1d9f6612"
 dependencies = [
- "unicode-xid",
+ "unicode-xid 0.2.2",
 ]
 
 [[package]]
@@ -1242,19 +1497,53 @@ dependencies = [
  "unicase",
 ]
 
+[[package]]
+name = "quick-error"
+version = "1.2.3"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "a1d01941d82fa2ab50be1e79e6714289dd7cde78eba4c074bc5a4374f650dfe0"
+
 [[package]]
 name = "quick-error"
 version = "2.0.1"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "a993555f31e5a609f617c12db6250dedcac1b0a85076912c436e6fc9b2c8e6a3"
 
+[[package]]
+name = "quote"
+version = "0.6.13"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "6ce23b6b870e8f94f81fb0a363d65d86675884b34a09043c81e5562f11c1f8e1"
+dependencies = [
+ "proc-macro2 0.4.30",
+]
+
 [[package]]
 name = "quote"
 version = "1.0.9"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "c3d0b9745dc2debf507c8422de05d7226cc1f0644216dfdfead988f9b1ab32a7"
 dependencies = [
- "proc-macro2",
+ "proc-macro2 1.0.28",
+]
+
+[[package]]
+name = "rand"
+version = "0.6.5"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "6d71dacdc3c88c1fde3885a3be3fbab9f35724e6ce99467f7d9c5026132184ca"
+dependencies = [
+ "autocfg 0.1.8",
+ "libc",
+ "rand_chacha 0.1.1",
+ "rand_core 0.4.2",
+ "rand_hc 0.1.0",
+ "rand_isaac",
+ "rand_jitter",
+ "rand_os",
+ "rand_pcg 0.1.2",
+ "rand_xorshift",
+ "winapi 0.3.9",
 ]
 
 [[package]]
@@ -1268,7 +1557,7 @@ dependencies = [
  "rand_chacha 0.2.2",
  "rand_core 0.5.1",
  "rand_hc 0.2.0",
- "rand_pcg",
+ "rand_pcg 0.2.1",
 ]
 
 [[package]]
@@ -1283,6 +1572,16 @@ dependencies = [
  "rand_hc 0.3.1",
 ]
 
+[[package]]
+name = "rand_chacha"
+version = "0.1.1"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "556d3a1ca6600bfcbab7c7c91ccb085ac7fbbcd70e008a98742e7847f4f7bcef"
+dependencies = [
+ "autocfg 0.1.8",
+ "rand_core 0.3.1",
+]
+
 [[package]]
 name = "rand_chacha"
 version = "0.2.2"
@@ -1303,6 +1602,21 @@ dependencies = [
  "rand_core 0.6.3",
 ]
 
+[[package]]
+name = "rand_core"
+version = "0.3.1"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "7a6fdeb83b075e8266dcc8762c22776f6877a63111121f5f8c7411e5be7eed4b"
+dependencies = [
+ "rand_core 0.4.2",
+]
+
+[[package]]
+name = "rand_core"
+version = "0.4.2"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "9c33a3c44ca05fa6f1807d8e6743f3824e8509beca625669633be0acbdf509dc"
+
 [[package]]
 name = "rand_core"
 version = "0.5.1"
@@ -1321,6 +1635,15 @@ dependencies = [
  "getrandom 0.2.3",
 ]
 
+[[package]]
+name = "rand_hc"
+version = "0.1.0"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "7b40677c7be09ae76218dc623efbf7b18e34bced3f38883af07bb75630a21bc4"
+dependencies = [
+ "rand_core 0.3.1",
+]
+
 [[package]]
 name = "rand_hc"
 version = "0.2.0"
@@ -1339,6 +1662,50 @@ dependencies = [
  "rand_core 0.6.3",
 ]
 
+[[package]]
+name = "rand_isaac"
+version = "0.1.1"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "ded997c9d5f13925be2a6fd7e66bf1872597f759fd9dd93513dd7e92e5a5ee08"
+dependencies = [
+ "rand_core 0.3.1",
+]
+
+[[package]]
+name = "rand_jitter"
+version = "0.1.4"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "1166d5c91dc97b88d1decc3285bb0a99ed84b05cfd0bc2341bdf2d43fc41e39b"
+dependencies = [
+ "libc",
+ "rand_core 0.4.2",
+ "winapi 0.3.9",
+]
+
+[[package]]
+name = "rand_os"
+version = "0.1.3"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "7b75f676a1e053fc562eafbb47838d67c84801e38fc1ba459e8f180deabd5071"
+dependencies = [
+ "cloudabi",
+ "fuchsia-cprng",
+ "libc",
+ "rand_core 0.4.2",
+ "rdrand",
+ "winapi 0.3.9",
+]
+
+[[package]]
+name = "rand_pcg"
+version = "0.1.2"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "abf9b09b01790cfe0364f52bf32995ea3c39f4d2dd011eac241d2914146d0b44"
+dependencies = [
+ "autocfg 0.1.8",
+ "rand_core 0.4.2",
+]
+
 [[package]]
 name = "rand_pcg"
 version = "0.2.1"
@@ -1348,6 +1715,24 @@ dependencies = [
  "rand_core 0.5.1",
 ]
 
+[[package]]
+name = "rand_xorshift"
+version = "0.1.1"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "cbf7e9e623549b0e21f6e97cf8ecf247c1a8fd2e8a992ae265314300b2455d5c"
+dependencies = [
+ "rand_core 0.3.1",
+]
+
+[[package]]
+name = "rdrand"
+version = "0.4.0"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "678054eb77286b51581ba43620cc911abf02758c91f93f479767aed0f90458b2"
+dependencies = [
+ "rand_core 0.3.1",
+]
+
 [[package]]
 name = "redox_syscall"
 version = "0.2.10"
@@ -1389,6 +1774,15 @@ dependencies = [
  "winapi 0.3.9",
 ]
 
+[[package]]
+name = "rustc_version"
+version = "0.4.0"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "bfa0f585226d2e68097d4f95d113b15b83a82e819ab25717ec0590d9584ef366"
+dependencies = [
+ "semver",
+]
+
 [[package]]
 name = "ryu"
 version = "1.0.5"
@@ -1442,9 +1836,9 @@ version = "1.0.129"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "e57ae87ad533d9a56427558b516d0adac283614e347abf85b0dc0cbbf0a249f3"
 dependencies = [
- "proc-macro2",
- "quote",
- "syn",
+ "proc-macro2 1.0.28",
+ "quote 1.0.9",
+ "syn 1.0.75",
 ]
 
 [[package]]
@@ -1470,6 +1864,16 @@ dependencies = [
  "serde",
 ]
 
+[[package]]
+name = "servo_arc"
+version = "0.1.1"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "d98238b800e0d1576d8b6e3de32827c2d74bee68bb97748dcf5071fb53965432"
+dependencies = [
+ "nodrop",
+ "stable_deref_trait",
+]
+
 [[package]]
 name = "sha-1"
 version = "0.8.2"
@@ -1501,6 +1905,12 @@ version = "1.0.0"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "42a568c8f2cd051a4d283bd6eb0343ac214c1b0f1ac19f93e1175b2dee38c73d"
 
+[[package]]
+name = "siphasher"
+version = "0.2.3"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "0b8de496cf83d4ed58b6be86c3a275b8602f6ffe98d3024a869e124147a9a3ac"
+
 [[package]]
 name = "siphasher"
 version = "0.3.6"
@@ -1513,6 +1923,12 @@ version = "0.4.4"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "c307a32c1c5c437f38c7fd45d753050587732ba8628319fbdf12a7e289ccc590"
 
+[[package]]
+name = "smallvec"
+version = "1.8.0"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "f2dd574626839106c320a323308629dcb1acfc96e32a8cba364ddc61ac23ee83"
+
 [[package]]
 name = "socket2"
 version = "0.4.1"
@@ -1523,6 +1939,12 @@ dependencies = [
  "winapi 0.3.9",
 ]
 
+[[package]]
+name = "stable_deref_trait"
+version = "1.2.0"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "a8f112729512f8e442d81f95a8a7ddf2b7c6b8a1a6f509a95864142b30cab2d3"
+
 [[package]]
 name = "string_cache"
 version = "0.8.1"
@@ -1531,7 +1953,7 @@ checksum = "8ddb1139b5353f96e429e1a5e19fbaf663bddedaa06d1dbd49f82e352601209a"
 dependencies = [
  "lazy_static",
  "new_debug_unreachable",
- "phf_shared",
+ "phf_shared 0.8.0",
  "precomputed-hash",
  "serde",
 ]
@@ -1542,10 +1964,10 @@ version = "0.5.1"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "f24c8e5e19d22a726626f1a5e16fe15b132dcf21d10177fa5a45ce7962996b97"
 dependencies = [
- "phf_generator",
- "phf_shared",
- "proc-macro2",
- "quote",
+ "phf_generator 0.8.0",
+ "phf_shared 0.8.0",
+ "proc-macro2 1.0.28",
+ "quote 1.0.9",
 ]
 
 [[package]]
@@ -1554,15 +1976,26 @@ version = "0.10.0"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "73473c0e59e6d5812c5dfe2a064a6444949f089e20eec9a2e5506596494e4623"
 
+[[package]]
+name = "syn"
+version = "0.15.44"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "9ca4b3b69a77cbe1ffc9e198781b7acb0c7365a883670e8f1c1bc66fba79a5c5"
+dependencies = [
+ "proc-macro2 0.4.30",
+ "quote 0.6.13",
+ "unicode-xid 0.1.0",
+]
+
 [[package]]
 name = "syn"
 version = "1.0.75"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "b7f58f7e8eaa0009c5fec437aabf511bd9933e4b2d7407bd05273c01a8906ea7"
 dependencies = [
- "proc-macro2",
- "quote",
- "unicode-xid",
+ "proc-macro2 1.0.28",
+ "quote 1.0.9",
+ "unicode-xid 0.2.2",
 ]
 
 [[package]]
@@ -1601,9 +2034,9 @@ dependencies = [
 
 [[package]]
 name = "textwrap"
-version = "0.14.2"
+version = "0.15.0"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "0066c8d12af8b5acd21e00547c3797fde4e8677254a7ee429176ccebbe93dd80"
+checksum = "b1141d4d61095b28419e22cb0bbf02755f5e54e0526f97f1e3d1d160e60885fb"
 
 [[package]]
 name = "thiserror"
@@ -1620,9 +2053,9 @@ version = "1.0.31"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "0396bc89e626244658bef819e22d0cc459e795a5ebe878e6ec336d1674a8d79a"
 dependencies = [
- "proc-macro2",
- "quote",
- "syn",
+ "proc-macro2 1.0.28",
+ "quote 1.0.9",
+ "syn 1.0.75",
 ]
 
 [[package]]
@@ -1672,9 +2105,9 @@ version = "1.8.0"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "9724f9a975fb987ef7a3cd9be0350edcbe130698af5b8f7a631e23d42d052484"
 dependencies = [
- "proc-macro2",
- "quote",
- "syn",
+ "proc-macro2 1.0.28",
+ "quote 1.0.9",
+ "syn 1.0.75",
 ]
 
 [[package]]
@@ -1824,6 +2257,12 @@ dependencies = [
  "tinyvec",
 ]
 
+[[package]]
+name = "unicode-xid"
+version = "0.1.0"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "fc72304796d0818e357ead4e000d19c9c174ab23dc11093ac919054d20a6a7fc"
+
 [[package]]
 name = "unicode-xid"
 version = "0.2.2"
diff --git a/Cargo.toml b/Cargo.toml
index b1c095d3c5..cc780054ce 100644
--- a/Cargo.toml
+++ b/Cargo.toml
@@ -18,7 +18,7 @@ description = "Creates a book from markdown files"
 [dependencies]
 anyhow = "1.0.28"
 chrono = "0.4"
-clap = { version = "3.0", features = ["cargo"] }
+clap = { version = "3.1.15", features = ["cargo"] }
 clap_complete = "3.0"
 env_logger = "0.9.0"
 handlebars = "4.0"
@@ -34,6 +34,7 @@ shlex = "1"
 tempfile = "3.0"
 toml = "0.5.1"
 topological-sort = "0.1.0"
+lewp-css = "0.2"
 
 # Watch feature
 notify = { version = "4.0", optional = true }
diff --git a/guide/src/SUMMARY.md b/guide/src/SUMMARY.md
index 974d65fae7..73133affb1 100644
--- a/guide/src/SUMMARY.md
+++ b/guide/src/SUMMARY.md
@@ -30,6 +30,7 @@
         - [index.hbs](format/theme/index-hbs.md)
         - [Syntax highlighting](format/theme/syntax-highlighting.md)
         - [Editor](format/theme/editor.md)
+    - [Custom fonts](format/custom-fonts.md)
     - [MathJax Support](format/mathjax.md)
     - [mdBook-specific features](format/mdbook.md)
     - [Markdown](format/markdown.md)
diff --git a/guide/src/format/custom-fonts.md b/guide/src/format/custom-fonts.md
new file mode 100644
index 0000000000..281606c30d
--- /dev/null
+++ b/guide/src/format/custom-fonts.md
@@ -0,0 +1,59 @@
+# Custom fonts
+
+It is possible to use custom fonts by using a combination of the parameters
+`copy-fonts` and `copy-custom-fonts`. `copy-fonts` is enabled by default.
+
+The fonts are specified by the `fonts/fonts.css` file, relative to the root directory
+of your book project.
+
+## The copy-fonts option
+
+If `copy-fonts` is enabled, the build in `fonts/fonts.css` file is being copied
+to the output directory. In addition to that, the default fonts are copied to
+the output directory.
+
+## The copy-custom-fonts option
+
+If `copy-custom-fonts` is enabled, the `fonts/fonts.css` file that you have created
+is copied to the output directory. Also, the file gets parsed and searched for
+`@font-face` rules having a `src: url(CUSTOM-FONT)` definition. These `CUSTOM-FONT`
+files are copied to the output directory.
+
+## Enabling both options
+
+It is also possible to use both options in parallel. Then, the build in fonts
+are copied, as well as the custom font files that have been found. The build in
+and the custom definition of `fonts/fonts.css` are combined and copied to the
+output directory as well.
+
+## Example with both options enabled
+
+Create a `fonts/` folder in your book root. Then copy the fonts you want to use
+into this folder (in this example we are assuming `Lato-Regular.ttf`)
+
+Create a custom fonts file `fonts/fonts.css`
+
+```css
+@font-face {
+     font-family: "Lato";
+     font-style: normal;
+     font-weight: normal;
+     src: url('Lato-Regular.ttf');
+}
+```
+
+Setup your `book.toml` that it contains the following parameters:
+
+```toml
+[output.html]
+copy-fonts = true
+copy-custom-fonts = true
+```
+
+Adjust your `theme/css/general.css` file according to your needs, for example:
+
+```css
+html {
+    font-family: "Lato", sans-serif;
+}
+```
diff --git a/src/cmd/build.rs b/src/cmd/build.rs
index 5fe73236ca..bf8e431d90 100644
--- a/src/cmd/build.rs
+++ b/src/cmd/build.rs
@@ -1,11 +1,11 @@
 use crate::{get_book_dir, open};
-use clap::{arg, App, Arg, ArgMatches};
+use clap::{arg, Arg, ArgMatches, Command};
 use mdbook::errors::Result;
 use mdbook::MDBook;
 
 // Create clap subcommand arguments
-pub fn make_subcommand<'help>() -> App<'help> {
-    App::new("build")
+pub fn make_subcommand<'help>() -> Command<'help> {
+    Command::new("build")
         .about("Builds a book from its markdown files")
         .arg(
             Arg::new("dest-dir")
diff --git a/src/cmd/clean.rs b/src/cmd/clean.rs
index 0569726e1b..51dce46a06 100644
--- a/src/cmd/clean.rs
+++ b/src/cmd/clean.rs
@@ -1,12 +1,12 @@
 use crate::get_book_dir;
 use anyhow::Context;
-use clap::{arg, App, Arg, ArgMatches};
+use clap::{arg, Arg, ArgMatches, Command};
 use mdbook::MDBook;
 use std::fs;
 
 // Create clap subcommand arguments
-pub fn make_subcommand<'help>() -> App<'help> {
-    App::new("clean")
+pub fn make_subcommand<'help>() -> Command<'help> {
+    Command::new("clean")
         .about("Deletes a built book")
         .arg(
             Arg::new("dest-dir")
diff --git a/src/cmd/init.rs b/src/cmd/init.rs
index c964dcc137..80513255f3 100644
--- a/src/cmd/init.rs
+++ b/src/cmd/init.rs
@@ -1,5 +1,5 @@
 use crate::get_book_dir;
-use clap::{arg, App, Arg, ArgMatches};
+use clap::{arg, Arg, ArgMatches, Command as ClapCommand};
 use mdbook::config;
 use mdbook::errors::Result;
 use mdbook::MDBook;
@@ -8,8 +8,8 @@ use std::io::Write;
 use std::process::Command;
 
 // Create clap subcommand arguments
-pub fn make_subcommand<'help>() -> App<'help> {
-    App::new("init")
+pub fn make_subcommand<'help>() -> ClapCommand<'help> {
+    ClapCommand::new("init")
         .about("Creates the boilerplate structure and files for a new book")
         // the {n} denotes a newline which will properly aligned in all help messages
         .arg(arg!([dir]
diff --git a/src/cmd/serve.rs b/src/cmd/serve.rs
index 00eaa46b4d..e207ac3622 100644
--- a/src/cmd/serve.rs
+++ b/src/cmd/serve.rs
@@ -1,7 +1,7 @@
 #[cfg(feature = "watch")]
 use super::watch;
 use crate::{get_book_dir, open};
-use clap::{arg, App, Arg, ArgMatches};
+use clap::{arg, Arg, ArgMatches, Command};
 use futures_util::sink::SinkExt;
 use futures_util::StreamExt;
 use mdbook::errors::*;
@@ -18,8 +18,8 @@ use warp::Filter;
 const LIVE_RELOAD_ENDPOINT: &str = "__livereload";
 
 // Create clap subcommand arguments
-pub fn make_subcommand<'help>() -> App<'help> {
-    App::new("serve")
+pub fn make_subcommand<'help>() -> Command<'help> {
+    Command::new("serve")
         .about("Serves a book at http://localhost:3000, and rebuilds it on changes")
         .arg(
             Arg::new("dest-dir")
diff --git a/src/cmd/test.rs b/src/cmd/test.rs
index f5ca3ee419..12e0e8eba1 100644
--- a/src/cmd/test.rs
+++ b/src/cmd/test.rs
@@ -1,11 +1,11 @@
 use crate::get_book_dir;
-use clap::{arg, App, Arg, ArgMatches};
+use clap::{arg, Arg, ArgMatches, Command};
 use mdbook::errors::Result;
 use mdbook::MDBook;
 
 // Create clap subcommand arguments
-pub fn make_subcommand<'help>() -> App<'help> {
-    App::new("test")
+pub fn make_subcommand<'help>() -> Command<'help> {
+    Command::new("test")
         .about("Tests that a book's Rust code samples compile")
         .arg(
             Arg::new("dest-dir")
@@ -37,8 +37,8 @@ pub fn make_subcommand<'help>() -> App<'help> {
             .long("library-path")
             .value_name("dir")
             .takes_value(true)
-            .use_delimiter(true)
-            .require_delimiter(true)
+            .use_value_delimiter(true)
+            .require_value_delimiter(true)
             .multiple_values(true)
             .multiple_occurrences(true)
             .forbid_empty_values(true)
diff --git a/src/cmd/watch.rs b/src/cmd/watch.rs
index 9336af779a..b3debc3471 100644
--- a/src/cmd/watch.rs
+++ b/src/cmd/watch.rs
@@ -1,5 +1,5 @@
 use crate::{get_book_dir, open};
-use clap::{arg, App, Arg, ArgMatches};
+use clap::{arg, Arg, ArgMatches, Command};
 use mdbook::errors::Result;
 use mdbook::utils;
 use mdbook::MDBook;
@@ -10,8 +10,8 @@ use std::thread::sleep;
 use std::time::Duration;
 
 // Create clap subcommand arguments
-pub fn make_subcommand<'help>() -> App<'help> {
-    App::new("watch")
+pub fn make_subcommand<'help>() -> Command<'help> {
+    Command::new("watch")
         .about("Watches a book's files and rebuilds it on changes")
         .arg(
             Arg::new("dest-dir")
diff --git a/src/config.rs b/src/config.rs
index 6b8f141461..a31220196e 100644
--- a/src/config.rs
+++ b/src/config.rs
@@ -489,6 +489,9 @@ pub struct HtmlConfig {
     pub mathjax_support: bool,
     /// Whether to fonts.css and respective font files to the output directory.
     pub copy_fonts: bool,
+    /// If true, find custom font files by parsing the fonts/fonts.css and copy
+    /// them to the output directory.
+    pub copy_custom_fonts: bool,
     /// An optional google analytics code.
     pub google_analytics: Option<String>,
     /// Additional CSS stylesheets to include in the rendered page's `<head>`.
@@ -549,6 +552,7 @@ impl Default for HtmlConfig {
             curly_quotes: false,
             mathjax_support: false,
             copy_fonts: true,
+            copy_custom_fonts: false,
             google_analytics: None,
             additional_css: Vec::new(),
             additional_js: Vec::new(),
diff --git a/src/main.rs b/src/main.rs
index 35562e64bb..82c5739729 100644
--- a/src/main.rs
+++ b/src/main.rs
@@ -5,7 +5,7 @@ extern crate log;
 
 use anyhow::anyhow;
 use chrono::Local;
-use clap::{App, AppSettings, Arg, ArgMatches};
+use clap::{Arg, ArgMatches, Command};
 use clap_complete::Shell;
 use env_logger::Builder;
 use log::LevelFilter;
@@ -61,13 +61,13 @@ fn main() {
 }
 
 /// Create a list of valid arguments and sub-commands
-fn create_clap_app() -> App<'static> {
-    let app = App::new(crate_name!())
+fn create_clap_app() -> Command<'static> {
+    let app = Command::new(crate_name!())
         .about(crate_description!())
         .author("Mathieu David <mathieudavid@mathieudavid.org>")
         .version(VERSION)
-        .setting(AppSettings::PropagateVersion)
-        .setting(AppSettings::ArgRequiredElseHelp)
+        .propagate_version(true)
+        .arg_required_else_help(true)
         .after_help(
             "For more information about a specific command, try `mdbook <command> --help`\n\
              The source code for mdBook is available at: https://github.com/rust-lang/mdBook",
@@ -77,7 +77,7 @@ fn create_clap_app() -> App<'static> {
         .subcommand(cmd::test::make_subcommand())
         .subcommand(cmd::clean::make_subcommand())
         .subcommand(
-            App::new("completions")
+            Command::new("completions")
                 .about("Generate shell completions for your shell to stdout")
                 .arg(
                     Arg::new("shell")
diff --git a/src/renderer/html_handlebars/hbs_renderer.rs b/src/renderer/html_handlebars/hbs_renderer.rs
index 9c126feb89..ad65258fd3 100644
--- a/src/renderer/html_handlebars/hbs_renderer.rs
+++ b/src/renderer/html_handlebars/hbs_renderer.rs
@@ -289,6 +289,24 @@ impl HtmlHandlebars {
                 theme::fonts::SOURCE_CODE_PRO.1,
             )?;
         }
+        if html_config.copy_custom_fonts {
+            let mut custom_fonts_css = std::fs::read(&Path::new("fonts/fonts.css"))?;
+            if html_config.copy_fonts {
+                // we need to extend the custom fonts file by the build in one
+                // to have the build in ones still available
+                custom_fonts_css.extend(theme::fonts::CSS);
+            }
+            write_file(destination, "fonts/fonts.css", &custom_fonts_css)?;
+            let custom_font_file_names =
+                helpers::custom_fonts::find_custom_font_files(Path::new("fonts/fonts.css"))?;
+            for font_file in custom_font_file_names {
+                write_file(
+                    &Path::new(destination).join("fonts"),
+                    &font_file,
+                    &std::fs::read(&Path::new("fonts").join(&font_file))?,
+                )?;
+            }
+        }
 
         let playground_config = &html_config.playground;
 
@@ -658,6 +676,10 @@ fn make_data(
         data.insert("copy_fonts".to_owned(), json!(true));
     }
 
+    if html_config.copy_custom_fonts {
+        data.insert("copy_custom_fonts".to_owned(), json!(true));
+    }
+
     // Add check to see if there is an additional style
     if !html_config.additional_css.is_empty() {
         let mut css = Vec::new();
diff --git a/src/renderer/html_handlebars/helpers/custom_fonts.rs b/src/renderer/html_handlebars/helpers/custom_fonts.rs
new file mode 100644
index 0000000000..ed47f94010
--- /dev/null
+++ b/src/renderer/html_handlebars/helpers/custom_fonts.rs
@@ -0,0 +1,42 @@
+use crate::errors::Result;
+use lewp_css::{
+    domain::{
+        at_rules::font_face::{FontFaceAtRule, FontUrlSource, Source},
+        CssRule,
+    },
+    Stylesheet,
+};
+use std::path::{Path, PathBuf};
+
+/// Parses the given file_name and extracts the given font file names.
+pub fn find_custom_font_files(css_file_name: &Path) -> Result<Vec<PathBuf>> {
+    let stylesheet = std::fs::read_to_string(css_file_name)?;
+    let stylesheet = Stylesheet::parse(&stylesheet).unwrap_or_else(|_| {
+        panic!(
+            "Stylesheet: \"{}\" could not be parsed!",
+            css_file_name.display()
+        )
+    });
+    let css_rules = stylesheet.rules.0;
+    let mut file_names = vec![];
+    for rule in css_rules {
+        match rule {
+            CssRule::FontFace(font) => {
+                if let Some(f) = extract_font_file_name(font) {
+                    file_names.push(f);
+                }
+            }
+            _ => continue,
+        }
+    }
+    Ok(file_names)
+}
+
+/// Extracts the first file name given in an URL statement from the rule.
+pub fn extract_font_file_name(at_rule: FontFaceAtRule) -> Option<PathBuf> {
+    at_rule.sources.as_ref()?;
+    match at_rule.sources.unwrap().get(0) {
+        Some(Source::Url(FontUrlSource { url, .. })) => Some(PathBuf::from(url.0.clone())),
+        _ => None,
+    }
+}
diff --git a/src/renderer/html_handlebars/helpers/mod.rs b/src/renderer/html_handlebars/helpers/mod.rs
index 52be6d204b..d8d1c62c67 100644
--- a/src/renderer/html_handlebars/helpers/mod.rs
+++ b/src/renderer/html_handlebars/helpers/mod.rs
@@ -1,3 +1,4 @@
+pub mod custom_fonts;
 pub mod navigation;
 pub mod theme;
 pub mod toc;
diff --git a/src/theme/index.hbs b/src/theme/index.hbs
index 0321e1413f..598664ff6b 100644
--- a/src/theme/index.hbs
+++ b/src/theme/index.hbs
@@ -35,7 +35,7 @@
 
         <!-- Fonts -->
         <link rel="stylesheet" href="{{ path_to_root }}FontAwesome/css/font-awesome.css">
-        {{#if copy_fonts}}
+        {{#if (or copy_fonts copy_custom_fonts)}}
         <link rel="stylesheet" href="{{ path_to_root }}fonts/fonts.css">
         {{/if}}