diff --git a/templates/contribute.html b/templates/contribute.html
index c7f796f64d5761ff5aab3aa96ff7b8c00bd76054_dGVtcGxhdGVzL2NvbnRyaWJ1dGUuaHRtbA==..6b53e0a06b873497f6d8d87c86d55ab474fdcf74_dGVtcGxhdGVzL2NvbnRyaWJ1dGUuaHRtbA== 100644
--- a/templates/contribute.html
+++ b/templates/contribute.html
@@ -77,6 +77,7 @@
             <h2 class="card-title" id="spread">Spread the Word</h2>
             <p class="card-text">
             Help us increase the popularity of Tryton:
+            </p>
             <ul>
                 <li>Share your experiences on social networks and follow Tryton on
                     <a href="https://twitter.com/TrytonSoftware">Twitter</a>,
@@ -89,7 +90,6 @@
                     etc.</li>
                 <li><a href="https://discuss.tryton.org/c/communication/news-proposal">Propose news</a></li>
             </ul>
-            </p>
         </div>
     </div>
 </div>
diff --git a/templates/donate.html b/templates/donate.html
index c7f796f64d5761ff5aab3aa96ff7b8c00bd76054_dGVtcGxhdGVzL2RvbmF0ZS5odG1s..6b53e0a06b873497f6d8d87c86d55ab474fdcf74_dGVtcGxhdGVzL2RvbmF0ZS5odG1s 100644
--- a/templates/donate.html
+++ b/templates/donate.html
@@ -71,14 +71,15 @@
 <div class="card mb-5 w-100">
     <h2 class="h4 card-header" id="wire-transfer">Wire Transfer</h2>
     <div class="card-body">
-        <p class="card-text">You can make a wire transfer to our bank account:
-        <address>
-            <abbr title="International Bank Account Number">IBAN:</abbr>BE82 0688 9627 4468<br/>
-            <abbr title="Bank Identifier Codes">BIC:</abbr>GKCCBEBB<br/>
-        </address>
-        </p>
+        <div class="card-text">
+            <p>You can make a wire transfer to our bank account:</p>
+            <address>
+                <abbr title="International Bank Account Number">IBAN:</abbr>BE82 0688 9627 4468<br/>
+                <abbr title="Bank Identifier Codes">BIC:</abbr>GKCCBEBB<br/>
+            </address>
+        </div>
     </div>
 </div>
 <div class="card mb-5 w-100">
     <h2 class="h4 card-header" id="paypal">PayPal</h2>
     <div class="card-body">
@@ -80,18 +81,24 @@
     </div>
 </div>
 <div class="card mb-5 w-100">
     <h2 class="h4 card-header" id="paypal">PayPal</h2>
     <div class="card-body">
-        <p class="card-text">You can easily make a one-time contribution using PayPal:
-        <form action="https://www.paypal.com/cgi-bin/webscr" method="post">
-            <input type="hidden" name="cmd" value="_donations">
-            <input type="hidden" name="business" value="paypal@tryton.org">
-            <input type="hidden" name="item_name" value="Tryton Donation">
-            <input type="hidden" name="item_number" value="Donation">
-            <input type="hidden" name="currency_code" value="EUR">
-            <input type="hidden" name="return" value="{{ url_for('donate_thanks') }}">
-            <input type="hidden" name="cancel" value="{{ url_for('donate_cancel') }}">
-            <div class="input-group mb-3">
-                <div class="input-group-prepend">
-                    <span class="input-group-text">€</span>
+        <div class="card-text">
+            <p>You can easily make a one-time contribution using PayPal:</p>
+            <form action="https://www.paypal.com/cgi-bin/webscr" method="post">
+                <input type="hidden" name="cmd" value="_donations">
+                <input type="hidden" name="business" value="paypal@tryton.org">
+                <input type="hidden" name="item_name" value="Tryton Donation">
+                <input type="hidden" name="item_number" value="Donation">
+                <input type="hidden" name="currency_code" value="EUR">
+                <input type="hidden" name="return" value="{{ url_for('donate_thanks') }}">
+                <input type="hidden" name="cancel" value="{{ url_for('donate_cancel') }}">
+                <div class="input-group mb-3">
+                    <div class="input-group-prepend">
+                        <span class="input-group-text">€</span>
+                    </div>
+                    <input name="amount" class="form-control" title="Amount" placeholder="Enter amount" value="10.00" min="5.00" step="0.01" required type="number">
+                    <div class="input-group-append">
+                        <button class="btn btn-outline-primary" type="submit">{{ heart | safe }}Donate</button>
+                    </div>
                 </div>
@@ -97,17 +104,12 @@
                 </div>
-                <input name="amount" class="form-control" title="Amount" placeholder="Enter amount" value="10.00" min="5.00" step="0.01" required type="number">
-                <div class="input-group-append">
-                    <button class="btn btn-outline-primary" type="submit">{{ heart | safe }}Donate</button>
-                </div>
-            </div>
-        </form>
-        <small>
-            You can use this form even if you don't have or want to create a PayPal account.
-            Instead you can pay with your credit card.
-        </small>
-        </p>
+            </form>
+            <small>
+                You can use this form even if you don't have or want to create a PayPal account.
+                Instead you can pay with your credit card.
+            </small>
+        </div>
     </div>
 </div>
 <div class="card mb-5 w-100">
     <h2 class="h4 card-header" id="paypal-recurring">Recurring PayPal</h2>
     <div class="card-body">
@@ -109,23 +111,25 @@
     </div>
 </div>
 <div class="card mb-5 w-100">
     <h2 class="h4 card-header" id="paypal-recurring">Recurring PayPal</h2>
     <div class="card-body">
-        <p class="card-text">You can easily make a monthly contribution using PayPal:
-        <form action="https://www.paypal.com/cgi-bin/webscr" method="post">
-            <input type="hidden" name="cmd" value="_s-xclick">
-            <input type="hidden" name="hosted_button_id" value="SUPKSJEB34BME">
-            <input type="hidden" name="on0" value="">
-            <div class="input-group mb-3">
-                <select name="os0" title="Amount by Frequency" class="custom-select" style="-moz-appearance: none; -webkit-appearance: none;">
-                    <option value="Donation">Donation : €10,00 EUR - monthly</option>
-                    <option value="Donation">Donation : €20,00 EUR - monthly</option>
-                    <option value="Donation">Donation : €50,00 EUR - monthly</option>
-                    <option value="Donation">Donation : €100,00 EUR - monthly</option>
-                    <option value="Donation">Donation : €200,00 EUR - monthly</option>
-                    <option value="Donation">Donation : €500,00 EUR - monthly</option>
-                </select>
-                <input type="hidden" name="currency_code" value="EUR">
-                <div class="input-group-append">
-                    <button class="btn btn-outline-primary" type="submit">{{ heart | safe }}Subscribe</button>
+        <div class="card-text">
+            <p>You can easily make a monthly contribution using PayPal:</p>
+            <form action="https://www.paypal.com/cgi-bin/webscr" method="post">
+                <input type="hidden" name="cmd" value="_s-xclick">
+                <input type="hidden" name="hosted_button_id" value="SUPKSJEB34BME">
+                <input type="hidden" name="on0" value="">
+                <div class="input-group mb-3">
+                    <select name="os0" title="Amount by Frequency" class="custom-select" style="-moz-appearance: none; -webkit-appearance: none;">
+                        <option value="Donation">Donation : €10,00 EUR - monthly</option>
+                        <option value="Donation">Donation : €20,00 EUR - monthly</option>
+                        <option value="Donation">Donation : €50,00 EUR - monthly</option>
+                        <option value="Donation">Donation : €100,00 EUR - monthly</option>
+                        <option value="Donation">Donation : €200,00 EUR - monthly</option>
+                        <option value="Donation">Donation : €500,00 EUR - monthly</option>
+                    </select>
+                    <input type="hidden" name="currency_code" value="EUR">
+                    <div class="input-group-append">
+                        <button class="btn btn-outline-primary" type="submit">{{ heart | safe }}Subscribe</button>
+                    </div>
                 </div>
@@ -131,12 +135,11 @@
                 </div>
-            </div>
-        </form>
-        <small>
-            PayPal does not require you to create an account for recurring donations.
-        </small>
-        </p>
+            </form>
+            <small>
+                PayPal does not require you to create an account for recurring donations.
+            </small>
+        </div>
     </div>
 </div>
 <div class="card mb-5 w-100">
     <h2 class="h4 card-header" id="bitcoin">Bitcoin</h2>
     <div class="card-body">
@@ -138,54 +141,12 @@
     </div>
 </div>
 <div class="card mb-5 w-100">
     <h2 class="h4 card-header" id="bitcoin">Bitcoin</h2>
     <div class="card-body">
-        <p class="card-text">You can easily donate in bitcoin:
-        <form action="https://bitpay.com/checkout" method="post">
-            <input name="action" type="hidden" value="checkout">
-            <div class="input-group mb-3">
-                <input name="orderID" type="email" class="form-control" title="Email Address" placeholder="Email address (optional)" maxlength="50" autocapitalize="off" autocorrect="off">
-            </div>
-            <div class="input-group mb-3">
-                <input name="price" type="number" value="10.00" title="Amount" placeholder="Amount" maxlength="10" min="0.01" step="0.01" class="form-control" required>
-                <select name="currency" title="Currency" class="custom-select" style="-moz-appearance: none; -webkit-appearance: none;">
-                    <option value="USD">USD</option>
-                    <option value="BTC">BTC</option>
-                    <option value="EUR" selected>EUR</option>
-                    <option value="GBP">GBP</option>
-                    <option value="AUD">AUD</option>
-                    <option value="BGN">BGN</option>
-                    <option value="BRL">BRL</option>
-                    <option value="CAD">CAD</option>
-                    <option value="CHF">CHF</option>
-                    <option value="CNY">CNY</option>
-                    <option value="CZK">CZK</option>
-                    <option value="DKK">DKK</option>
-                    <option value="HKD">HKD</option>
-                    <option value="HRK">HRK</option>
-                    <option value="HUF">HUF</option>
-                    <option value="IDR">IDR</option>
-                    <option value="ILS">ILS</option>
-                    <option value="INR">INR</option>
-                    <option value="JPY">JPY</option>
-                    <option value="KRW">KRW</option>
-                    <option value="LTL">LTL</option>
-                    <option value="LVL">LVL</option>
-                    <option value="MXN">MXN</option>
-                    <option value="MYR">MYR</option>
-                    <option value="NOK">NOK</option>
-                    <option value="NZD">NZD</option>
-                    <option value="PHP">PHP</option>
-                    <option value="PLN">PLN</option>
-                    <option value="RON">RON</option>
-                    <option value="RUB">RUB</option>
-                    <option value="SEK">SEK</option>
-                    <option value="SGD">SGD</option>
-                    <option value="THB">THB</option>
-                    <option value="TRY">TRY</option>
-                    <option value="ZAR">ZAR</option>
-                </select>
-                <input type="hidden" name="data" value="DTV4JaKv709xq02lnDoV6YQzckpuFjSKkWgOIEaHst13ciMsAsGhH+lsBgTnSgZUhdcrDUWYx6UE4QolrN26/QN7O/4kpMfJkjkImN+nLRGmR05AM/UJhWVXsidBuo4N1u8LGqe1e5ohy+w7uRNew7y57qR8N6dngxEPcRHlPK9UuJu6OS3/aRho33vG0D0oVDUL4bwPTn5ITu1Eal1vM15fb/wWtoPX5+JwZgaYj2DdZJMEEV5T1K06zBhcAGWg">
-                <div class="input-group-append">
-                    <button class="btn btn-outline-primary" type="submit">{{ heart | safe }}Donate</button>
+        <div class="card-text">
+            <p>You can easily donate in bitcoin:</p>
+            <form action="https://bitpay.com/checkout" method="post">
+                <input name="action" type="hidden" value="checkout">
+                <div class="input-group mb-3">
+                    <input name="orderID" type="email" class="form-control" title="Email Address" placeholder="Email address (optional)" maxlength="50" autocapitalize="off">
                 </div>
@@ -191,7 +152,50 @@
                 </div>
-            </div>
-        </form>
-        </p>
+                <div class="input-group mb-3">
+                    <input name="price" type="number" value="10.00" title="Amount" placeholder="Amount" min="0.01" step="0.01" class="form-control" required>
+                    <select name="currency" title="Currency" class="custom-select" style="-moz-appearance: none; -webkit-appearance: none;">
+                        <option value="USD">USD</option>
+                        <option value="BTC">BTC</option>
+                        <option value="EUR" selected>EUR</option>
+                        <option value="GBP">GBP</option>
+                        <option value="AUD">AUD</option>
+                        <option value="BGN">BGN</option>
+                        <option value="BRL">BRL</option>
+                        <option value="CAD">CAD</option>
+                        <option value="CHF">CHF</option>
+                        <option value="CNY">CNY</option>
+                        <option value="CZK">CZK</option>
+                        <option value="DKK">DKK</option>
+                        <option value="HKD">HKD</option>
+                        <option value="HRK">HRK</option>
+                        <option value="HUF">HUF</option>
+                        <option value="IDR">IDR</option>
+                        <option value="ILS">ILS</option>
+                        <option value="INR">INR</option>
+                        <option value="JPY">JPY</option>
+                        <option value="KRW">KRW</option>
+                        <option value="LTL">LTL</option>
+                        <option value="LVL">LVL</option>
+                        <option value="MXN">MXN</option>
+                        <option value="MYR">MYR</option>
+                        <option value="NOK">NOK</option>
+                        <option value="NZD">NZD</option>
+                        <option value="PHP">PHP</option>
+                        <option value="PLN">PLN</option>
+                        <option value="RON">RON</option>
+                        <option value="RUB">RUB</option>
+                        <option value="SEK">SEK</option>
+                        <option value="SGD">SGD</option>
+                        <option value="THB">THB</option>
+                        <option value="TRY">TRY</option>
+                        <option value="ZAR">ZAR</option>
+                    </select>
+                    <input type="hidden" name="data" value="DTV4JaKv709xq02lnDoV6YQzckpuFjSKkWgOIEaHst13ciMsAsGhH+lsBgTnSgZUhdcrDUWYx6UE4QolrN26/QN7O/4kpMfJkjkImN+nLRGmR05AM/UJhWVXsidBuo4N1u8LGqe1e5ohy+w7uRNew7y57qR8N6dngxEPcRHlPK9UuJu6OS3/aRho33vG0D0oVDUL4bwPTn5ITu1Eal1vM15fb/wWtoPX5+JwZgaYj2DdZJMEEV5T1K06zBhcAGWg">
+                    <div class="input-group-append">
+                        <button class="btn btn-outline-primary" type="submit">{{ heart | safe }}Donate</button>
+                    </div>
+                </div>
+            </form>
+        </div>
     </div>
 </div>
 <div class="card mb-5 w-100">
diff --git a/templates/donate_cancel.html b/templates/donate_cancel.html
index c7f796f64d5761ff5aab3aa96ff7b8c00bd76054_dGVtcGxhdGVzL2RvbmF0ZV9jYW5jZWwuaHRtbA==..6b53e0a06b873497f6d8d87c86d55ab474fdcf74_dGVtcGxhdGVzL2RvbmF0ZV9jYW5jZWwuaHRtbA== 100644
--- a/templates/donate_cancel.html
+++ b/templates/donate_cancel.html
@@ -2,9 +2,9 @@
 {% extends "layout.html" %}
 {% block content %}
 {{ super() }}
-<section class="section bg-light">
+<div class="section bg-light">
     <div class="container">
         <section class="section-header text-center bg-light mb1">
             <h1 class="pl-3 pr-3">Donation Cancelled</h1>
         </section>
     </div>
@@ -6,7 +6,7 @@
     <div class="container">
         <section class="section-header text-center bg-light mb1">
             <h1 class="pl-3 pr-3">Donation Cancelled</h1>
         </section>
     </div>
-</section>
+</div>
 
@@ -12,5 +12,5 @@
 
-<section class="section">
+<div class="section">
     <div class="container">
         <div class="row">
             <div class="col-md">
@@ -26,5 +26,5 @@
             </div>
         </div>
     </div>
-</section>
+</div>
 {% endblock content %}
diff --git a/templates/donate_thanks.html b/templates/donate_thanks.html
index c7f796f64d5761ff5aab3aa96ff7b8c00bd76054_dGVtcGxhdGVzL2RvbmF0ZV90aGFua3MuaHRtbA==..6b53e0a06b873497f6d8d87c86d55ab474fdcf74_dGVtcGxhdGVzL2RvbmF0ZV90aGFua3MuaHRtbA== 100644
--- a/templates/donate_thanks.html
+++ b/templates/donate_thanks.html
@@ -2,9 +2,9 @@
 {% extends "layout.html" %}
 {% block content %}
 {{ super() }}
-<section class="section bg-light">
+<div class="section bg-light">
     <div class="container">
         <section class="section-header text-center bg-light mb1 wow fadeInDown">
             <h1 class="pl-3 pr-3">{{ heart | safe }}Thanks You!</h1>
         </section>
     </div>
@@ -6,7 +6,7 @@
     <div class="container">
         <section class="section-header text-center bg-light mb1 wow fadeInDown">
             <h1 class="pl-3 pr-3">{{ heart | safe }}Thanks You!</h1>
         </section>
     </div>
-</section>
+</div>
 
@@ -12,5 +12,5 @@
 
-<section class="section">
+<div class="section">
     <div class="container">
         <div class="row">
             <div class="col-md">
@@ -26,5 +26,5 @@
             </div>
         </div>
     </div>
-</section>
+</div>
 {% endblock content %}
diff --git a/templates/download.html b/templates/download.html
index c7f796f64d5761ff5aab3aa96ff7b8c00bd76054_dGVtcGxhdGVzL2Rvd25sb2FkLmh0bWw=..6b53e0a06b873497f6d8d87c86d55ab474fdcf74_dGVtcGxhdGVzL2Rvd25sb2FkLmh0bWw= 100644
--- a/templates/download.html
+++ b/templates/download.html
@@ -17,7 +17,7 @@
 {{ background('banner-download') }}
 {% endblock %}
 {% block content %}
-<section class="section section-banner background-banner-download filter filter-primary text-center">
+<div class="section section-banner background-banner-download filter filter-primary text-center">
     <div class="container">
         <h1 class="mb-0 text-white position-relative z-1">{{ title }}</h1>
     </div>
@@ -21,7 +21,7 @@
     <div class="container">
         <h1 class="mb-0 text-white position-relative z-1">{{ title }}</h1>
     </div>
-</section>
+</div>
 {{ super() }}
 {% endblock content %}
 
diff --git a/templates/events/layout.html b/templates/events/layout.html
index c7f796f64d5761ff5aab3aa96ff7b8c00bd76054_dGVtcGxhdGVzL2V2ZW50cy9sYXlvdXQuaHRtbA==..6b53e0a06b873497f6d8d87c86d55ab474fdcf74_dGVtcGxhdGVzL2V2ZW50cy9sYXlvdXQuaHRtbA== 100644
--- a/templates/events/layout.html
+++ b/templates/events/layout.html
@@ -12,7 +12,7 @@
 <link rel="profile" href="http://microformats.org/profile/hcalendar">
 {% endblock style %}
 {% block content %}
-<section class="section section-banner filter filter-primary text-center" style="background-image:url({{ url_for('static', filename='images/events/%s' % banner) }};">
+<div class="section section-banner filter filter-primary text-center" style="background-image:url({{ url_for('static', filename='images/events/%s' % banner) }});">
     <div class="container">
         <h1 class="mb-0 text-white position-relative z-1">{% block title %}{{ title }}{% endblock %}</h1>
     </div>
@@ -16,8 +16,8 @@
     <div class="container">
         <h1 class="mb-0 text-white position-relative z-1">{% block title %}{{ title }}{% endblock %}</h1>
     </div>
-</section>
+</div>
 {{ super() }}
 {% endblock content %}
 {% block main %}
 {{ super() }}
@@ -20,10 +20,10 @@
 {{ super() }}
 {% endblock content %}
 {% block main %}
 {{ super() }}
-<section class="section bg-light">
+<div class="section bg-light">
     <div class="container text-center">
         {% block lead %}
         <a href="#register" class="btn btn-primary btn-lg">Register</a>
         {% endblock lead %}
     </div>
@@ -25,8 +25,8 @@
     <div class="container text-center">
         {% block lead %}
         <a href="#register" class="btn btn-primary btn-lg">Register</a>
         {% endblock lead %}
     </div>
-</section>
+</div>
 <section class="section" id="schedule">
     <div class="container">
@@ -31,4 +31,4 @@
 <section class="section" id="schedule">
     <div class="container">
-        <section class="section-header bg-white text-primary text-center wow fadeInDown">
+        <div class="section-header bg-white text-primary text-center wow fadeInDown">
             <h2 class="pl-3 pr-3 text-uppercase"><span class="material-icons">timer</span> Schedule</h2>
@@ -34,5 +34,5 @@
             <h2 class="pl-3 pr-3 text-uppercase"><span class="material-icons">timer</span> Schedule</h2>
-        </section>
+        </div>
         {% block schedule %}
         <div class="mx-auto" style="max-width: 600px;">
             {% for day in events %}
@@ -36,7 +36,7 @@
         {% block schedule %}
         <div class="mx-auto" style="max-width: 600px;">
             {% for day in events %}
-            <section class="subsection" id="schedule-2019-06-04">
+            <section class="subsection" id="schedule-{{ day.date.strftime('%Y-%m-%d') }}">
                 <h3 class="d-flex justify-content-between align-items-baseline flex-wrap">{{ day.date.strftime('%A, %d %B') }} {% if day.events %}<small>from {{ day.start.strftime('%H:%M') }} to {{ day.end.strftime('%H:%M') }}</small>{% endif %}</h3>
                 {% if day.events %}
                 <ol class="list-group mx-auto">
@@ -57,7 +57,7 @@
                             {% for profile in event.profiles %}
                             <div class="vcard d-flex flex-wrap justify-content-start align-items-start">
                                 <a class="url" href="//www.gravatar.com/{{ profile.gravatar }}">
-                                    <img class="img-thumbnail photo" src="//www.gravatar.com/avatar/{{ profile.gravatar }}?=48"/>
+                                    <img class="img-thumbnail photo" src="//www.gravatar.com/avatar/{{ profile.gravatar }}?=48" alt="Avatar of {{ profile.name }}"/>
                                 </a>
                                 <span class="fn m-1">{{ profile.name }}{% if profile.company %},<br/><a class="org" href="{{ profile.url }}">{{ profile.company }}</a>{% endif %}</span>
                             </div>
@@ -80,5 +80,5 @@
 </section>
 <section class="section bg-light" id="register">
     <div class="container">
-        <section class="section-header bg-light">
+        <div class="section-header bg-light">
             <h2 class="pl-3 pr-3 text-uppercase">Register</h2>
@@ -84,8 +84,8 @@
             <h2 class="pl-3 pr-3 text-uppercase">Register</h2>
-        </section>
+        </div>
         {% block register %}
         {% endblock register %}
     </div>
 </section>
 <section class="section" id="venue">
     <div class="container">
@@ -86,8 +86,8 @@
         {% block register %}
         {% endblock register %}
     </div>
 </section>
 <section class="section" id="venue">
     <div class="container">
-        <section class="section-header bg-white">
+        <div class="section-header bg-white">
             <h2 class="pl-3 pr-3 text-uppercase">Venue <span class="material-icons">place</span></h2>
@@ -93,8 +93,8 @@
             <h2 class="pl-3 pr-3 text-uppercase">Venue <span class="material-icons">place</span></h2>
-        </section>
+        </div>
         {% block venue %}
         {% endblock venue %}
     </div>
 </section>
 <section class="section bg-light" id="accommodations">
     <div class="container">
@@ -95,8 +95,8 @@
         {% block venue %}
         {% endblock venue %}
     </div>
 </section>
 <section class="section bg-light" id="accommodations">
     <div class="container">
-        <section class="section-header bg-light">
+        <div class="section-header bg-light">
             <h2 class="pl-3 pr-3 text-uppercase">Accommodations <span class="material-icons">hotel</span></h2>
@@ -102,5 +102,5 @@
             <h2 class="pl-3 pr-3 text-uppercase">Accommodations <span class="material-icons">hotel</span></h2>
-        </section>
+        </div>
         {% block accommodations %}
         {% endblock accommodations %}
     </div>
diff --git a/templates/events/tum2019.html b/templates/events/tum2019.html
index c7f796f64d5761ff5aab3aa96ff7b8c00bd76054_dGVtcGxhdGVzL2V2ZW50cy90dW0yMDE5Lmh0bWw=..6b53e0a06b873497f6d8d87c86d55ab474fdcf74_dGVtcGxhdGVzL2V2ZW50cy90dW0yMDE5Lmh0bWw= 100644
--- a/templates/events/tum2019.html
+++ b/templates/events/tum2019.html
@@ -80,6 +80,6 @@
         <span class="locality">Marseille</span><br/>
 </address>
 </div>
-<iframe width="100%" height="500" frameborder="0" scrolling="no" marginheight="0" marginwidth="0" src="https://www.openstreetmap.org/export/embed.html?bbox=5.37457823753357%2C43.302074626344606%2C5.378113389015199%2C43.303889933242516&amp;layer=mapnik&amp;marker=43.30298228656913%2C5.3763458132743835" style="border: 1px solid black"></iframe><br/><small><a href="https://www.openstreetmap.org/?mlat=43.30298&amp;mlon=5.37635#map=19/43.30298/5.37635">View Larger Map</a></small>
+<iframe height="500" src="https://www.openstreetmap.org/export/embed.html?bbox=5.37457823753357%2C43.302074626344606%2C5.378113389015199%2C43.303889933242516&amp;layer=mapnik&amp;marker=43.30298228656913%2C5.3763458132743835" style="width: 100%; border: 1px solid black; overflow: hidden; margin: 0"></iframe><br/><small><a href="https://www.openstreetmap.org/?mlat=43.30298&amp;mlon=5.37635#map=19/43.30298/5.37635">View Larger Map</a></small>
 <h3>Transportations</h3>
 <ul>
@@ -84,14 +84,16 @@
 <h3>Transportations</h3>
 <ul>
-    <li>By Train</li>
-    <ul>
-        <li>The <a href="https://en.wikipedia.org/wiki/TGV">TGV</a> <a href="https://www.gares-sncf.com/fr/gare/frmsc/marseille-saint-charles">station St Charles</a> in the center of Marseille is preferred.</li>
-        <li>The other TGV <a href="https://www.gares-sncf.com/fr/gare/frqxb/aix-provence">station Aix en Provence</a> is also an option but requires a 25km of bus shuttle.</li>
-    </ul>
-    <li>By Plane</li>
-    <ul>
-        <li>The <a href="https://www.marseille-airport.com/">Marseille Provence Airport</a> has <a href="https://www.marseille-airport.com/access-car-parks/access/bus/marseille-gare-saint-charles">bus shuttle to Marseille</a> every 15 minutes.</li>
-    </ul>
+    <li>By Train
+        <ul>
+            <li>The <a href="https://en.wikipedia.org/wiki/TGV">TGV</a> <a href="https://www.gares-sncf.com/fr/gare/frmsc/marseille-saint-charles">station St Charles</a> in the center of Marseille is preferred.</li>
+            <li>The other TGV <a href="https://www.gares-sncf.com/fr/gare/frqxb/aix-provence">station Aix en Provence</a> is also an option but requires a 25km of bus shuttle.</li>
+        </ul>
+    </li>
+    <li>By Plane
+        <ul>
+            <li>The <a href="https://www.marseille-airport.com/">Marseille Provence Airport</a> has <a href="https://www.marseille-airport.com/access-car-parks/access/bus/marseille-gare-saint-charles">bus shuttle to Marseille</a> every 15 minutes.</li>
+        </ul>
+    </li>
 </ul>
 <p>Inside Marseille, we recommend to use the <a href="http://www.rtm.fr/">public transport</a> which has 2 metro lines and many bus lines.</p>
 {% endblock %}
@@ -111,5 +113,5 @@
 {{ super() }}
 <section class="section" id="sponsors">
     <div class="container">
-        <section class="section-header">
+        <div class="section-header">
             <h2 class="bg-white">Sponsors</h2>
@@ -115,5 +117,5 @@
             <h2 class="bg-white">Sponsors</h2>
-        </section>
+        </div>
         <p>With the support of:</p>
         <a href="http://www.emd-management.fr/">
             <img class="img-thumbnail" src="{{ url_for('static', filename='images/events/tum2019-emd.jpg') }}" alt="École de Commerce et de Management"/>
diff --git a/templates/forum.html b/templates/forum.html
index c7f796f64d5761ff5aab3aa96ff7b8c00bd76054_dGVtcGxhdGVzL2ZvcnVtLmh0bWw=..6b53e0a06b873497f6d8d87c86d55ab474fdcf74_dGVtcGxhdGVzL2ZvcnVtLmh0bWw= 100644
--- a/templates/forum.html
+++ b/templates/forum.html
@@ -87,7 +87,8 @@
                 <h3>Announces</h3>
                 <p>
                 You receive notifications about Tryton releases and news by subscribing to announces mailing list.
+                </p>
                 <ul>
                     <li>To subscribe, send an email to <a href="mailto:announces+subscribe@tryton.org">announces+subscribe@tryton.org</a></li>
                     <li>To unsubscribe, send an email to <a href="mailto:announces+unsubscribe@tryton.org">announces+unsubscribe@tryton.org</a></li>
                 </ul>
@@ -90,11 +91,10 @@
                 <ul>
                     <li>To subscribe, send an email to <a href="mailto:announces+subscribe@tryton.org">announces+subscribe@tryton.org</a></li>
                     <li>To unsubscribe, send an email to <a href="mailto:announces+unsubscribe@tryton.org">announces+unsubscribe@tryton.org</a></li>
                 </ul>
-                </p>
                 <a href="https://www.mail-archive.com/announces@tryton.org/" class="card-link">Archive</a>
             </li>
             <li class="list-group-item">
                 <h3>Commits</h3>
                 <p>
                 You receive notifications about all Tryton commits by subscribing to commits mailing list.
@@ -95,10 +95,11 @@
                 <a href="https://www.mail-archive.com/announces@tryton.org/" class="card-link">Archive</a>
             </li>
             <li class="list-group-item">
                 <h3>Commits</h3>
                 <p>
                 You receive notifications about all Tryton commits by subscribing to commits mailing list.
+                </p>
                 <ul>
                     <li>To subscribe, send an email to <a href="mailto:commits+subscribe@tryton.org">commits+subscribe@tryton.org</a></li>
                     <li>To unsubscribe, send an email to <a href="mailto:commits+unsubscribe@tryton.org">commits+unsubscribe@tryton.org</a></li>
                 </ul>
@@ -101,8 +102,7 @@
                 <ul>
                     <li>To subscribe, send an email to <a href="mailto:commits+subscribe@tryton.org">commits+subscribe@tryton.org</a></li>
                     <li>To unsubscribe, send an email to <a href="mailto:commits+unsubscribe@tryton.org">commits+unsubscribe@tryton.org</a></li>
                 </ul>
-                </p>
                 <a href="https://www.mail-archive.com/commits@tryton.org/" class="card-link">Archive</a>
             </li>
         </ul>
diff --git a/templates/foundation.html b/templates/foundation.html
index c7f796f64d5761ff5aab3aa96ff7b8c00bd76054_dGVtcGxhdGVzL2ZvdW5kYXRpb24uaHRtbA==..6b53e0a06b873497f6d8d87c86d55ab474fdcf74_dGVtcGxhdGVzL2ZvdW5kYXRpb24uaHRtbA== 100644
--- a/templates/foundation.html
+++ b/templates/foundation.html
@@ -54,10 +54,10 @@
         <div class="row">
             <div class="col-md mb-gutter text-justify">
                 <h3>What does the Tryton Foundation do?</h3>
-                <p>The Tryton Foundation:
+                <p>The Tryton Foundation:</p>
                 <ul>
                     <li>aims to develop and support conferences, meetings and community activities,</li>
                     <li>holds and administers the tryton.org infrastructure</li>
                     <li>organizes the community of supporters,</li>
                     <li>manages and promotes the Tryton trademark.</li>
                 </ul>
@@ -58,10 +58,9 @@
                 <ul>
                     <li>aims to develop and support conferences, meetings and community activities,</li>
                     <li>holds and administers the tryton.org infrastructure</li>
                     <li>organizes the community of supporters,</li>
                     <li>manages and promotes the Tryton trademark.</li>
                 </ul>
-                </p>
             </div>
             <div class="col-md mb-gutter text-justify">
                 <h3>How is the foundation organized?</h3>
@@ -69,7 +68,7 @@
                 So a specific status is available for people or companies active in the community:
                 the <a href="{{ url_for('supporters') }}">supporter</a> status.
                 This body of people represents the Tryton community and will have some power over the board of directors.</p>
-                <p>In order to manage the day to day duties of the foundation and the nomination of new members a board of directors has been appointed. They are currently:
+                <p>In order to manage the day to day duties of the foundation and the nomination of new members a board of directors has been appointed. They are currently:</p>
                 <ul>
                     <li>Axel Braun from Germany,</li>
                     <li>Jonathan Levy from United States of America,</li>
@@ -79,7 +78,6 @@
                     <li>Sebastián Marró from Argentina,</li>
                     <li>Sergi Almacellas Abellana from Spain.</li>
                 </ul>
-                </p>
                 <p>Nicolas Évrard is the current president of the board.</p>
                 <p>The statutes of the foundation foresee the role of managing directors and Administration Delegates,
                 depending whether they are members of the board or not.
@@ -83,8 +81,8 @@
                 <p>Nicolas Évrard is the current president of the board.</p>
                 <p>The statutes of the foundation foresee the role of managing directors and Administration Delegates,
                 depending whether they are members of the board or not.
-                The current directors are:
+                The current directors are:</p>
                 <ul>
                     <li>Cédric Krier from Belgium as Administration Delegate,</li>
                     <li>Nicolas Évrard from Belgium as Managing Director.</li>
                 </ul>
@@ -87,8 +85,7 @@
                 <ul>
                     <li>Cédric Krier from Belgium as Administration Delegate,</li>
                     <li>Nicolas Évrard from Belgium as Managing Director.</li>
                 </ul>
-                </p>
                 <p>The <a href="http://www.ejustice.just.fgov.be/tsv_pdf/2012/11/29/12193839.pdf">complete statutes of the Tryton Foundation</a> are available electronically.</p>
             </div>
         </div>
diff --git a/templates/index.html b/templates/index.html
index c7f796f64d5761ff5aab3aa96ff7b8c00bd76054_dGVtcGxhdGVzL2luZGV4Lmh0bWw=..6b53e0a06b873497f6d8d87c86d55ab474fdcf74_dGVtcGxhdGVzL2luZGV4Lmh0bWw= 100644
--- a/templates/index.html
+++ b/templates/index.html
@@ -85,10 +85,10 @@
 {% endblock header %}
 
 {% block content %}
-<section class="section wow fadeIn">
+<div class="section wow fadeIn">
     <div class="container text-center">
         <h1 class="lead mb-4">
         <strong>TRYTON</strong> is business software, ideal for companies of any size, easy to use, complete and 100% Open Source.
         </h1>
         <a href="{{ url_for('download') }}" class="btn btn-primary btn-lg">Start with Tryton</a>
     </div>
@@ -89,10 +89,10 @@
     <div class="container text-center">
         <h1 class="lead mb-4">
         <strong>TRYTON</strong> is business software, ideal for companies of any size, easy to use, complete and 100% Open Source.
         </h1>
         <a href="{{ url_for('download') }}" class="btn btn-primary btn-lg">Start with Tryton</a>
     </div>
-</section>
+</div>
 
 <section class="section bg-light text-center" id="features">
     <div class="container">
diff --git a/templates/layout-toc.html b/templates/layout-toc.html
index c7f796f64d5761ff5aab3aa96ff7b8c00bd76054_dGVtcGxhdGVzL2xheW91dC10b2MuaHRtbA==..6b53e0a06b873497f6d8d87c86d55ab474fdcf74_dGVtcGxhdGVzL2xheW91dC10b2MuaHRtbA== 100644
--- a/templates/layout-toc.html
+++ b/templates/layout-toc.html
@@ -12,7 +12,7 @@
 </ul>
 {% endmacro %}
 {% block content %}
-<section class="section">
+<div class="section">
     <div class="container">
         <div class="row flex-md-nowrap">
             {{ super() }}
@@ -21,9 +21,9 @@
                 {{ nav(toc, "nav flex-column border-left") }}
             </div>
             {% endblock toc %}
-            <main class="col-sm-12 col-md-8 offset-md-2 order-1" role="main">
+            <main class="col-sm-12 col-md-8 offset-md-2 order-1">
             {% block main %}
             {% endblock main %}
             </main>
         </div>
     </div>
@@ -25,7 +25,7 @@
             {% block main %}
             {% endblock main %}
             </main>
         </div>
     </div>
-</section>
+</div>
 {% endblock content %}
diff --git a/templates/layout.html b/templates/layout.html
index c7f796f64d5761ff5aab3aa96ff7b8c00bd76054_dGVtcGxhdGVzL2xheW91dC5odG1s..6b53e0a06b873497f6d8d87c86d55ab474fdcf74_dGVtcGxhdGVzL2xheW91dC5odG1s 100644
--- a/templates/layout.html
+++ b/templates/layout.html
@@ -68,6 +68,6 @@
             {% endblock header %}
         </header>
 
-        <section id="content">
+        <div id="content">
             {% block content %}
             {% endblock content %}
@@ -72,6 +72,6 @@
             {% block content %}
             {% endblock content %}
-        </section>
+        </div>
 
         <footer id="footer">
             {% block footer %}
@@ -83,8 +83,8 @@
                             <div class="row">
                                 {% for title, items in menu.items() %}
                                 <div class="col-md-3">
-                                    <h2 id="nav-footer-{{ loop.index }}">{{ title }}</h2>
-                                    <nav aira-labelledby="nav-footer-{{ loop.index }}">
+                                    <h2>{{ title }}</h2>
+                                    <nav>
                                         <ul>
                                             {% for item, url in items %}
                                             <li>
@@ -118,7 +118,7 @@
                     </div>
                 </div>
             </section>
-            <section class="subfooter">
+            <div class="subfooter">
                 <div class="container">
                     <p>Contents © {{ copyright_dates }} Tryton <a href="https://creativecommons.org/licenses/by-sa/3.0/">CC BY-SA 3.0</a></p>
                 </div>
@@ -122,7 +122,7 @@
                 <div class="container">
                     <p>Contents © {{ copyright_dates }} Tryton <a href="https://creativecommons.org/licenses/by-sa/3.0/">CC BY-SA 3.0</a></p>
                 </div>
-            </section>
+            </div>
             {% endblock footer %}
         </footer>
 
diff --git a/templates/service_providers.html b/templates/service_providers.html
index c7f796f64d5761ff5aab3aa96ff7b8c00bd76054_dGVtcGxhdGVzL3NlcnZpY2VfcHJvdmlkZXJzLmh0bWw=..6b53e0a06b873497f6d8d87c86d55ab474fdcf74_dGVtcGxhdGVzL3NlcnZpY2VfcHJvdmlkZXJzLmh0bWw= 100644
--- a/templates/service_providers.html
+++ b/templates/service_providers.html
@@ -2,7 +2,7 @@
 {% extends "layout.html" %}
 {% block content %}
 {{ super() }}
-<section class="section bg-primary">
+<div class="section bg-primary">
     <div class="container">
         <section class="section-header text-center text-white bg-primary mb1 wow fadeInDown">
             <h1 class="pl-3 pr-3">{{ title }}</h1>
@@ -13,7 +13,7 @@
             </div>
         </div>
     </div>
-</section>
+</div>
 
 <section class="section">
     <div class="container">
@@ -26,7 +26,7 @@
     </div>
 </section>
 
-<section class="section">
+<div class="section">
     <div class="container">
         <div class="row">
             <div class="col-md-6 mx-auto text-center">
@@ -36,7 +36,7 @@
             </div>
         </div>
     </div>
-</section>
+</div>
 {% endblock content %}
 
 {% block script %}
@@ -40,7 +40,7 @@
 {% endblock content %}
 
 {% block script %}
-<script type="text/javascript">
+<script>
     function setupMap() {
         L.Icon.Default.imagePath = '/static/images/';
         var map = L.map('map').setView([0, 0], 1);
diff --git a/templates/service_providers/layout.html b/templates/service_providers/layout.html
index c7f796f64d5761ff5aab3aa96ff7b8c00bd76054_dGVtcGxhdGVzL3NlcnZpY2VfcHJvdmlkZXJzL2xheW91dC5odG1s..6b53e0a06b873497f6d8d87c86d55ab474fdcf74_dGVtcGxhdGVzL3NlcnZpY2VfcHJvdmlkZXJzL2xheW91dC5odG1s 100644
--- a/templates/service_providers/layout.html
+++ b/templates/service_providers/layout.html
@@ -1,2 +1,2 @@
-<div class="col mb-gutter" id="{{ name | lower }}">
+<div class="col mb-gutter" id="{{ name | lower | replace(' ', '-') }}">
     <div class="card mx-auto shadow" style="width: 24rem">
@@ -2,6 +2,8 @@
     <div class="card mx-auto shadow" style="width: 24rem">
-        <a href="{{ website }}">
-            <img class="card-img-top text-center d-block" src="{{ img }}" alt="{{ name }}" style="height: 240px"/>
+        <a href="{{ website }}" style="height: 240px">
+            {% if img %}
+            <img class="card-img-top text-center d-block" src="{{ img }}" alt="{{ name }}"/>
+            {% endif %}
         </a>
         <div class="card-body">
             <h2 class="h5 card-title">{{ name }}</h2>
diff --git a/templates/service_providers_start.html b/templates/service_providers_start.html
index c7f796f64d5761ff5aab3aa96ff7b8c00bd76054_dGVtcGxhdGVzL3NlcnZpY2VfcHJvdmlkZXJzX3N0YXJ0Lmh0bWw=..6b53e0a06b873497f6d8d87c86d55ab474fdcf74_dGVtcGxhdGVzL3NlcnZpY2VfcHJvdmlkZXJzX3N0YXJ0Lmh0bWw= 100644
--- a/templates/service_providers_start.html
+++ b/templates/service_providers_start.html
@@ -93,20 +93,20 @@
         </div>
         <div>
             <h2 class="h5 card-title" id="update">Keep up to date</h2>
-            <p class="card-text">
-            You must:
-            <ul>
-                <li>
-                    keep your company information and existing success stories up to date,
-                </li>
-                <li>
-                    stay active in the community and keep <a href="{{ url_for('contribute') }}">contributing</a>,
-                </li>
-                <li>
-                    submit new <a href="{{ url_for('success_stories') }}">success stories</a>.
-                </li>
-            </ul>
-            </p>
+            <div class="card-text">
+                <p>You must:</p>
+                <ul>
+                    <li>
+                        keep your company information and existing success stories up to date,
+                    </li>
+                    <li>
+                        stay active in the community and keep <a href="{{ url_for('contribute') }}">contributing</a>,
+                    </li>
+                    <li>
+                        submit new <a href="{{ url_for('success_stories') }}">success stories</a>.
+                    </li>
+                </ul>
+            </div>
         </div>
     </div>
 </div>
diff --git a/templates/success_stories.html b/templates/success_stories.html
index c7f796f64d5761ff5aab3aa96ff7b8c00bd76054_dGVtcGxhdGVzL3N1Y2Nlc3Nfc3Rvcmllcy5odG1s..6b53e0a06b873497f6d8d87c86d55ab474fdcf74_dGVtcGxhdGVzL3N1Y2Nlc3Nfc3Rvcmllcy5odG1s 100644
--- a/templates/success_stories.html
+++ b/templates/success_stories.html
@@ -7,7 +7,7 @@
 {% endblock %}
 {% block content %}
 {{ super() }}
-<section class="section section-banner background-banner-success-stories filter filter-primary text-center">
+<div class="section section-banner background-banner-success-stories filter filter-primary text-center">
     <div class="container">
         <h1 class="mb-0 text-white position-relative z-1">{{ title }}</h1>
     </div>
@@ -11,7 +11,7 @@
     <div class="container">
         <h1 class="mb-0 text-white position-relative z-1">{{ title }}</h1>
     </div>
-</section>
+</div>
 
 <section class="section">
     <div class="container">
@@ -25,7 +25,7 @@
                 <div class="card-body">
                     <h2 class="h5 card-title">{{ case.title }}</h2>
                     <p class="card-text">{{ case.description }}</p>
-                    <a href="{{ case.url }}" class="btn btn-primary {{ 'disabled' if not case.url else '' }}" aria-disabled="{{ not case.url }}">More<span class="sr-only">on {{ case.title }}</span></a>
+                    <a href="{{ case.url }}" class="btn btn-primary {{ 'disabled' if not case.url else '' }}" {% if not case.url %}aria-disabled="true"{% endif %}>More<span class="sr-only">on {{ case.title }}</span></a>
                 </div>
             </div>
         </div>
diff --git a/templates/success_stories/layout.html b/templates/success_stories/layout.html
index c7f796f64d5761ff5aab3aa96ff7b8c00bd76054_dGVtcGxhdGVzL3N1Y2Nlc3Nfc3Rvcmllcy9sYXlvdXQuaHRtbA==..6b53e0a06b873497f6d8d87c86d55ab474fdcf74_dGVtcGxhdGVzL3N1Y2Nlc3Nfc3Rvcmllcy9sYXlvdXQuaHRtbA== 100644
--- a/templates/success_stories/layout.html
+++ b/templates/success_stories/layout.html
@@ -1,7 +1,7 @@
 {% extends "layout.html" %}
 {% block content %}
 {{ super() }}
-<section class="section section-banner filter filter-primary text-center" style="background-image:url({{ url_for('static', filename='images/success-stories/%s' % banner) }});">
+<div class="section section-banner filter filter-primary text-center" style="background-image:url({{ url_for('static', filename='images/success-stories/%s' % banner) }});">
     <div class="container">
         <h1 class="mb-0 text-white position-relative z-1">{{ title }}</h1>
     </div>
@@ -5,8 +5,8 @@
     <div class="container">
         <h1 class="mb-0 text-white position-relative z-1">{{ title }}</h1>
     </div>
-</section>
-<section class="section">
+</div>
+<div class="section">
     <div class="container">
         <div class="row">
             <div class="col-sm-12 col-md-10 col-xl-6 mx-md-auto order-1" role="main">
@@ -43,5 +43,5 @@
             </div>
         </div>
     </div>
-</section>
+</div>
 {% endblock content %}
diff --git a/templates/supporters.html b/templates/supporters.html
index c7f796f64d5761ff5aab3aa96ff7b8c00bd76054_dGVtcGxhdGVzL3N1cHBvcnRlcnMuaHRtbA==..6b53e0a06b873497f6d8d87c86d55ab474fdcf74_dGVtcGxhdGVzL3N1cHBvcnRlcnMuaHRtbA== 100644
--- a/templates/supporters.html
+++ b/templates/supporters.html
@@ -2,9 +2,9 @@
 {% extends "layout.html" %}
 {% block content %}
 {{ super() }}
-<section class="section bg-primary">
+<div class="section bg-primary">
     <div class="container">
         <section class="section-header text-center text-white bg-primary mb1 wow fadeInDown">
             <h1 class="pl-3 pr-3">{{ title }}</h1>
         </section>
     </div>
@@ -6,9 +6,9 @@
     <div class="container">
         <section class="section-header text-center text-white bg-primary mb1 wow fadeInDown">
             <h1 class="pl-3 pr-3">{{ title }}</h1>
         </section>
     </div>
-</section>
+</div>
 
 <section class="section">
     <div class="container">
@@ -40,7 +40,6 @@
         <p class="mt-5 text-center">
         If you want to become a supporter, please send an email to <a href="mailto:foundation@tryton.org">foundation@tryton.org</a>.
         </p>
-        </div>
     </div>
 </section>
 {% endblock %}