diff --git a/dynamic_form.js b/dynamic_form.js
index 46d4a1c..315f400 100644
--- a/dynamic_form.js
+++ b/dynamic_form.js
@@ -1,127 +1,128 @@
 /**
  * Copyright (C) 2019  The Software Heritage developers
  * See the AUTHORS file at the top-level directory of this distribution
  * License: GNU Affero General Public License version 3, or any later version
  * See top-level LICENSE file for more information
  */
 
 "use strict";
 
 function createPersonFieldset(personPrefix, legend) {
     // Creates a fieldset containing inputs for informations about a person
     var fieldset = document.createElement("fieldset")
     fieldset.classList.add("person");
+    fieldset.classList.add("leafFieldset");
     fieldset.id = personPrefix;
     
     fieldset.innerHTML = `
         <legend>${legend}</legend>
         <p>
             <label for="${personPrefix}_givenName">Given name</label>
             <input type="text" id="${personPrefix}_givenName" name="${personPrefix}_givenName"
                 placeholder="Jane" required="true" />
         </p>
         <p>
             <label for="${personPrefix}_familyName">Family name</label>
             <input type="text" id="${personPrefix}_familyName" name="${personPrefix}_familyName"
                 placeholder="Doe" />
         </p>
         <p>
             <label for="${personPrefix}_email">E-mail address</label>
             <input type="email" id="${personPrefix}_email" name="${personPrefix}_email"
                 placeholder="jane.doe@example.org" />
         </p>
         <p>
             <label for="${personPrefix}_id">URI</label>
             <input type="url" id="${personPrefix}_id" name="${personPrefix}_id"
                 placeholder="http://orcid.org/0000-0002-1825-0097" />
         </p>
         <p>
         <label for="${personPrefix}_affiliation">Affiliation</label>
             <input type="url" id="${personPrefix}_affiliation" name="${personPrefix}_affiliation"
                 placeholder="Department of Computer Science, University of Pisa" />
         </p>
     `;
 
     return fieldset;
 }
 
 function addPersonWithId(container, prefix, legend, id) {
     var fieldset = createPersonFieldset(`${prefix}_${id}`, `${legend} #${id}`);
 
     container.appendChild(fieldset);
 }
 
 function addPerson(prefix, legend) {
     var container = document.querySelector(`#${prefix}_container`);
     var personId = getNbPersons(prefix) + 1;
 
     addPersonWithId(container, prefix, legend, personId);
 
     setNbPersons(prefix, personId);
 
     return personId;
 }
 
 function removePerson(prefix) {
     var personId = getNbPersons(prefix);
 
     document.querySelector(`#${prefix}_${personId}`).remove();
 
     setNbPersons(prefix, personId-1);
 }
 
 // Initialize a group of persons (authors, contributors) on page load.
 // Useful if the page is reloaded.
 function initPersons(prefix, legend) {
     var nbPersons = getNbPersons(prefix);
     var personContainer = document.querySelector(`#${prefix}_container`)
 
     for (let personId = 1; personId <= nbPersons; personId++) {
         addPersonWithId(personContainer, prefix, legend, personId);
     }
 }
 
 function removePersons(prefix) {
     var nbPersons = getNbPersons(prefix);
     var personContainer = document.querySelector(`#${prefix}_container`)
 
     for (let personId = 1; personId <= nbPersons; personId++) {
         removePerson(prefix)
     }
 }
 
 function resetForm() {
     removePersons('author');
     removePersons('contributor');
 
     // Reset the form after deleting elements, so nbPersons doesn't get
     // reset before it's read.
     document.querySelector('#inputForm').reset();
 }
 
 function fieldToLower(event) {
     event.target.value = event.target.value.toLowerCase();
 }
 
 function initCallbacks() {
     document.querySelector('#license')
         .addEventListener('change', validateLicense);
 
     document.querySelector('#generateCodemeta')
         .addEventListener('click', generateCodemeta);
 
     document.querySelector('#resetForm')
         .addEventListener('click', resetForm);
 
     document.querySelector('#importCodemeta')
         .addEventListener('click', importCodemeta);
 
     document.querySelector('#inputForm')
         .addEventListener('change', generateCodemeta);
 
     document.querySelector('#developmentStatus')
         .addEventListener('change', fieldToLower);
 
     initPersons('author', 'Author');
     initPersons('contributor', 'Contributor');
 }
diff --git a/index.html b/index.html
index 5244816..0b33b2a 100644
--- a/index.html
+++ b/index.html
@@ -1,301 +1,301 @@
 <!doctype html>
 <!--
 Copyright (C) 2019  The Software Heritage developers
 See the AUTHORS file at the top-level directory of this distribution
 License: GNU Affero General Public License version 3, or any later version
 See top-level LICENSE file for more information
 -->
 <html lang="en">
 <head>
     <meta charset="utf-8">
     <title>CodeMeta generator</title>
     <script src="./utils.js"></script>
     <script src="./fields_data.js"></script>
     <script src="./dynamic_form.js"></script>
     <script src="./codemeta_generation.js"></script>
     <link rel="stylesheet" type="text/css" href="./style.css">
 </head>
 <body>
     <h1>CodeMeta generator</h1>
 
     <p>Most fields are optional. Mandatory fields will be highlighted when generating Codemeta.</p>
 
     <form id="inputForm">
-        <fieldset id="fieldsetSoftwareItself">
+        <fieldset id="fieldsetSoftwareItself" class="leafFieldset">
             <legend>The software itself</legend>
 
             <p title="The name of the software">
                 <label for="name">Name</label>
                 <input type="text" name="name" id="name" aria-describedby="name_descr"
                     placeholder="My Software" required="required" />
 
                 <br />
                 <span class="field-description" id="name_descr">the software title</span>
             </p>
 
             <p title="a brief description of the software">
                 <label for="description">Description</label>
                 <br />
                 <textarea rows="4" cols="50"
                     name="description" id="description"
                     placeholder="My Software computes ephemerides and orbit propagation. It has been developed from early ´80." ></textarea>
             </p>
 
 
             <p title="The date on which the software was created.">
                 <label for="dateCreated">Creation date</label>
                 <input type="text" name="dateCreated" id="dateCreated"
                     placeholder="YYYY-MM-DD" pattern="\d{4}-\d{2}-\d{2}" />
             </p>
 
             <p title="Date of first publication.">
                 <label for="datePublished">First release date</label>
                 <input type="text" name="datePublished" id="datePublished"
                     placeholder="YYYY-MM-DD" pattern="\d{4}-\d{2}-\d{2}" />
             </p>
 
             <p>
                 <label for="license">License</label>
                 <input list="licenses" name="license" id="license"
                     aria-describedby="licenses_descr"> <!-- TODO: insert placeholder -->
 
                 <datalist id="licenses">
                 </datalist>
                 <!-- This datalist is be filled automatically -->
 
                 <br />
                 <span class="field-description" id="licenses_descr">from <a href="https://spdx.org/license-list">SPDX licence list</a></span>
             </p>
         </fieldset>
 
-        <fieldset id="fieldsetDiscoverabilityAndCitation">
+        <fieldset id="fieldsetDiscoverabilityAndCitation" class="leafFieldset">
             <legend>Discoverability and citation</legend>
 
             <p title="Unique identifier">
                 <label for="identifier">Unique identifier</label>
                 <input type="text" name="identifier" id="identifier"
                     placeholder="10.151.xxxxx" aria-describedby="identifier_descr" />
 
                 <br />
                 <span class="field-description" id="identifier_descr">
                     such as ISBNs, GTIN codes, UUIDs etc..  <a href="http://schema.org/identifier">http://schema.org/identifier</a>
                 </span>
             </p>
             <!-- TODO:define better
 
             I looked at the schema.org definition of identifier (https://schema.org/identifier),
             it can be text, url or PropertyValue.
             Used as follows in data representation with microdata:
 
             <div property="identifier" typeof="PropertyValue">
             <span property="propertyID">DOI</span>:
             <span property="value">10.151.xxxxx</span>
             </div>
             we can use that with identifier-type and identifier-value to have a clearer idea
             of what needs to be in the input.
 
             -->
 
             <p title="Type of the software application">
                 <label for="applicationCategory">Application category</label>
                 <input type="text" name="applicationCategory" id="applicationCategory"
                     placeholder="Astronomy"  />
             </p>
 
             <p title="Comma-separated list of keywords">
                 <label for="keywords">Keywords</label>
                 <input type="text" name="keywords" id="keywords"
                     placeholder="ephemerides, orbit, astronomy"  />
             </p>
 
             <p title="Funding">
                 <label for="funding">Funding</label>
                 <input type="text" name="funding" id="funding" aria-describedby="funding_descr"
                     placeholder="Università di Pisa (PRA_2018_73)"/>
 
                 <br />
                 <span class="field-description" id="funding_descr">software funded by (e.g. specific grant)</span>
             </p>
 
             Authors and contributors can be added below
         </fieldset>
 
-        <fieldset id="fieldsetDevelopmentCommunity">
+        <fieldset id="fieldsetDevelopmentCommunity" class="leafFieldset">
             <legend>Development community / tools</legend>
 
             <p title="Link to the repository where the un-compiled, human readable code and related code is located (SVN, Git, GitHub, CodePlex, institutional GitLab instance, etc.).">
                 <label for="codeRepository">Code repository</label>
                 <input type="URL" name="codeRepository" id="codeRepository"
                     placeholder="git+https://github.com/You/RepoName.git" />
             </p>
 
             <p title="Link to continuous integration service (Travis-CI, Gitlab CI, etc.).">
                 <label for="contIntegration">Continuous integration</label>
                 <input type="URL" name="contIntegration" id="contIntegration"
                     placeholder="https://travis-ci.org/You/RepoName" />
             </p>
 
             <p title="Link to a place for users/developpers to report and manage bugs (JIRA, GitHub issues, etc.).">
                 <label for="issueTracker">Issue tracker</label>
                 <input type="URL" name="issueTracker" id="issueTracker"
                     placeholder="https://github.com/You/RepoName/issues" />
             </p>
 
             <p title="Related document, software, tools">
                 <label for="relatedLink">Related links</label>
                 <br />
                 <textarea rows="4" cols="50"
                     name="relatedLink" id="relatedLink"></textarea>
         </fieldset>
 
-        <fieldset id="fieldsetRuntime">
+        <fieldset id="fieldsetRuntime" class="leafFieldset">
             <legend>Run-time environment</legend>
 
             <p title="Programming Languages, separated by commas">
                 <label for="programmingLanguage">Programming Language</label>
                 <input type="text" name="programmingLanguage" id="programmingLanguage"
                     placeholder="C#, Java, Python 3"  />
             </p>
 
             <p title="Runtime Platforms, separated by commas">
                 <label for="runtimePlatform">Runtime Platform</label>
                 <input type="text" name="runtimePlatform" id="runtimePlatform"
                     placeholder=".NET, JVM" />
             </p>
 
             <p title="Operating Systems, separated by commas">
                 <label for="operatingSystem">Operating System</label>
                 <input type="text" name="operatingSystem" id="operatingSystem"
                     placeholder="Android 1.6, Linux, Windows, macOS" />
             </p>
 
             <p title="Required software to run/use this one.">
                 <label for="softwareRequirements">Other software requirements</label>
                 <br />
                 <textarea rows="4" cols="50"
                     name="softwareRequirements" id="softwareRequirements"
                     placeholder=
 "Python 3.4
 https://github.com/psf/requests"></textarea>
         </fieldset>
 
-        <fieldset id="fieldsetCurrentVersion">
+        <fieldset id="fieldsetCurrentVersion" class="leafFieldset">
             <legend>Current version of the software</legend>
 
             <p title="Version number of the software">
                 <label for="version">Version number</label>
                 <input type="text" name="version" id="version"
                     placeholder="1.0.0" />
             </p>
 
             <p title="The date on which the software was most recently modified.">
                 <label for="dateModified">Release date</label>
                 <input type="text" name="dateModified" id="dateModified"
                     placeholder="YYYY-MM-DD" pattern="\d{4}-\d{2}-\d{2}" />
             </p>
 
             <p title="Download link">
                 <label for="downloadUrl">Download URL</label>
                 <input type="URL" name="downloadUrl" id="downloadUrl"
                     placeholder="https://example.org/MySoftware.tar.gz" />
             </p>
 
             <p title="a brief description of the software">
                 <label for="releaseNotes">Release notes</label>
                 <br />
                 <textarea rows="4" cols="50"
                     name="releaseNotes" id="releaseNotes"
                     placeholder=
 "Change log: this and that;
 Bugfixes: that and this." ></textarea>
             </p>
 
 <!--TODO: referencePublication as ScholarlyArticle array -->
 
         </fieldset>
 
-        <fieldset id="fieldsetAdditionalInfo">
+        <fieldset id="fieldsetAdditionalInfo" class="leafFieldset">
             <legend>Additional Info</legend>
 
             <p title="Scholarly article describing this software">
                 <label for="referencePublication">Reference Publication</label>
                 <input type="URL" name="referencePublication" id="referencePublication"
                     placeholder="https://doi.org/10.1000/xyz123" />
             </p>
 
             <p title="Development Status">
             <label for="developmentStatus">Development Status</label>
                 <datalist id="developmentStatuses">
                         <option value="concept">
                         <option value="wip">
                         <option value="suspended">
                         <option value="abandoned">
                         <option value="active">
                         <option value="inactive">
                         <option value="unsupported">
                         <option value="moved">
                 </datalist>
                 <input list="developmentStatuses" id="developmentStatus" aria-describedby="developmentStatuses_descr"
                 pattern="concept|wip|suspended|abandoned|active|inactive|unsupported|moved">
 
                 <br />
                 <span class="field-description" id="developmentStatuses_descr">
                     see <a href="http://www.repostatus.org">www.repostatus.org</a> for details
                 </span>
             </p>
 
             <p title="Part of">
                 <label for="isPartOf">I part of </label>
                 <input type="URL" name="isPartOf" id="isPartOf"
                     placeholder="http://The.Bigger.Framework.org"  />
             </p>
         </fieldset>
 
         <div class="dynamicFields">
             <fieldset class="persons" id="author_container">
                 <legend>Authors</legend>
 
                 <p>Order of authors does not matter.</p>
 
                 <input type="hidden" id="author_nb" value="0" />
                 <div id="addRemoveAuthor">
                     <input type="button" id="author_add" value="Add one"
                         onclick="addPerson('author', 'Author');" />
                     <input type="button" id="author_remove" value="Remove last"
                         onclick="removePerson('author');" />
                 </div>
             </fieldset>
 
             <fieldset class="persons" id="contributor_container">
                 <legend>Contributors</legend>
 
                 <p>Order of contributors does not matter.</p>
 
                 <input type="hidden" id="contributor_nb" value="0" />
                 <div id="addRemoveContributor">
                     <input type="button" id="contributor_add" value="Add one"
                         onclick="addPerson('contributor', 'Contributor');" />
                     <input type="button" id="contributor_remove" value="Remove last"
                         onclick="removePerson('contributor');" />
                 </div>
             </fieldset>
         </div>
 
     </form>
     <form>
         <input type="button" id="generateCodemeta" value="Generate Codemeta" />
         <input type="button" id="resetForm" value="Reset form" />
         <input type="button" id="importCodemeta" value="Import Codemeta" />
     </form>
 
     <p id="errorMessage">
     </p>
     <pre contentEditable="true" id="codemetaText"></pre>
 
     <script>
         initFieldsData();
         initCallbacks();
         loadStateFromStorage();
     </script>
 </body>
 </html>
diff --git a/style.css b/style.css
index f5482cd..b54368e 100644
--- a/style.css
+++ b/style.css
@@ -1,60 +1,61 @@
 /**
  * Copyright (C) 2019  The Software Heritage developers
  * See the AUTHORS file at the top-level directory of this distribution
  * License: GNU Affero General Public License version 3, or any later version
  * See top-level LICENSE file for more information
  */
 
 
 .person {
     display: inline-block;
 }
 
 #inputForm {
     max-width: 100%;
 
     display: flex;
     flex-wrap: wrap;
 }
 
-#fieldsetSoftwareItself, #fieldsetDiscoverabilityAndCitation, #fieldsetDevelopmentCommunity, #fieldsetRuntime, #fieldsetCurrentVersion, #fieldsetAdditionalInfo {
+/* A fieldset that contains only label/input pairs */
+.leafFieldset {
     flex: auto;
 }
 
 .dynamicFields {
     width: 100%;
 }
 
 #license {
     /* License names are long */
     min-width: 20em;
 }
 
 #funding {
     /* Funding names are long */
     min-width: 20em;
 }
 
 input[type=URL] {
     /* URLs are longer than the other fields */
     min-width: 20em;
 }
 .field-description {
     color : rgb(100, 104, 103);
     font-size: small;
 }
 
 #codemetaText {
     width: 100%;
     min-height: 10em;
     border: 1px solid black;
 }
 
 #errorMessage {
     color: red;
 }
 
 input:invalid {
     color: red;
 }