Remove inline styling, add css classes (#10077)

diff --git a/erpnext/public/less/email.less b/erpnext/public/less/email.less
new file mode 100644
index 0000000..4077c49
--- /dev/null
+++ b/erpnext/public/less/email.less
@@ -0,0 +1,32 @@
+@import "../../../../frappe/frappe/public/less/variables.less";
+
+.panel-header {
+	background-color: @light-bg;
+	border: 1px solid @border-color;
+	border-radius: 3px 3px 0 0;
+}
+
+.panel-body {
+	background-color: #fff;
+	border: 1px solid @border-color;
+	border-top: none;
+	border-radius: 0 0 3px 3px;
+	overflow-wrap: break-word;
+}
+
+.sender-avatar {
+	width: 24px;
+	height: 24px;
+	border-radius: 3px;
+	vertical-align: middle;
+}
+
+.sender-avatar-placeholder {
+	.sender-avatar;
+
+	line-height: 24px;
+	text-align: center;
+	color: @border-color;
+	border: 1px solid @border-color;
+	background-color: #fff;
+}
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