diff --git a/frontend/src/index.css b/frontend/src/index.css
index 0e93a5a..75b6c4f 100644
--- a/frontend/src/index.css
+++ b/frontend/src/index.css
@@ -110,6 +110,224 @@ a:hover {
   outline-offset: 2px;
 }
 
+/* =====================================================
+   UTILITY CLASSES
+   ===================================================== */
+
+/* Spacing - Margin Bottom */
+.mb-xs {
+  margin-bottom: var(--space-xs);
+}
+
+.mb-sm {
+  margin-bottom: var(--space-sm);
+}
+
+.mb-md {
+  margin-bottom: var(--space-md);
+}
+
+.mb-lg {
+  margin-bottom: var(--space-lg);
+}
+
+.mb-xl {
+  margin-bottom: var(--space-xl);
+}
+
+/* Spacing - Margin Top */
+.mt-xs {
+  margin-top: var(--space-xs);
+}
+
+.mt-sm {
+  margin-top: var(--space-sm);
+}
+
+.mt-md {
+  margin-top: var(--space-md);
+}
+
+.mt-lg {
+  margin-top: var(--space-lg);
+}
+
+.mt-xl {
+  margin-top: var(--space-xl);
+}
+
+/* Spacing - Margin Left */
+.ml-xs {
+  margin-left: var(--space-xs);
+}
+
+.ml-sm {
+  margin-left: var(--space-sm);
+}
+
+.ml-md {
+  margin-left: var(--space-md);
+}
+
+/* Spacing - Padding */
+.p-sm {
+  padding: var(--space-sm);
+}
+
+.p-md {
+  padding: var(--space-md);
+}
+
+.p-lg {
+  padding: var(--space-lg);
+}
+
+.p-xl {
+  padding: var(--space-xl);
+}
+
+/* Flex Layouts */
+.flex {
+  display: flex;
+}
+
+.flex-col {
+  display: flex;
+  flex-direction: column;
+}
+
+.flex-center {
+  display: flex;
+  align-items: center;
+  justify-content: center;
+}
+
+.flex-between {
+  display: flex;
+  align-items: center;
+  justify-content: space-between;
+}
+
+.items-center {
+  align-items: center;
+}
+
+.justify-center {
+  justify-content: center;
+}
+
+/* Gaps */
+.gap-xs {
+  gap: var(--space-xs);
+}
+
+.gap-sm {
+  gap: var(--space-sm);
+}
+
+.gap-md {
+  gap: var(--space-md);
+}
+
+.gap-lg {
+  gap: var(--space-lg);
+}
+
+/* Text Utilities */
+.text-center {
+  text-align: center;
+}
+
+.text-xs {
+  font-size: 12px;
+}
+
+.text-sm {
+  font-size: 14px;
+}
+
+.font-medium {
+  font-weight: 500;
+}
+
+.font-semibold {
+  font-weight: 600;
+}
+
+.uppercase {
+  text-transform: uppercase;
+}
+
+.truncate {
+  overflow: hidden;
+  text-overflow: ellipsis;
+  white-space: nowrap;
+}
+
+/* Modal */
+.modal-overlay {
+  position: fixed;
+  inset: 0;
+  background-color: rgba(0, 0, 0, 0.5);
+  display: flex;
+  align-items: center;
+  justify-content: center;
+  z-index: 1000;
+}
+
+.modal-content {
+  max-width: 400px;
+  text-align: center;
+}
+
+/* Display */
+.hidden {
+  display: none;
+}
+
+.block {
+  display: block;
+}
+
+/* Width */
+.w-full {
+  width: 100%;
+}
+
+.max-w-sm {
+  max-width: 400px;
+}
+
+.max-w-md {
+  max-width: 600px;
+}
+
+.max-w-lg {
+  max-width: 800px;
+}
+
+.max-w-xl {
+  max-width: 1000px;
+}
+
+/* Min Width / Flex */
+.min-w-0 {
+  min-width: 0;
+}
+
+.flex-1 {
+  flex: 1;
+}
+
+/* Border */
+.border-t {
+  border-top: 1px solid var(--border);
+}
+
+/* =====================================================
+   END UTILITY CLASSES
+   ===================================================== */
+
 /* Button Base */
 .btn {
   display: inline-flex;
@@ -463,7 +681,7 @@ select.input {
 }
 
 .biomarker-info {
-  flex: 0 0 240px;
+  flex: 0 0 320px;
   min-width: 0;
   display: flex;
   flex-direction: row;
@@ -473,13 +691,11 @@ select.input {
 
 .biomarker-info .biomarker-name {
   font-size: 14px;
-  white-space: nowrap;
-  overflow: hidden;
-  text-overflow: ellipsis;
 }
 
 .biomarker-info .biomarker-unit {
   font-size: 11px;
+  flex-shrink: 0;
 }
 
 /* Biomarker Scale Bar */
@@ -785,4 +1001,97 @@ select.input {
 .page-loading {
   padding: var(--space-lg);
   color: var(--text-secondary);
+}
+
+/* =====================================================
+   SOURCES PAGE
+   ===================================================== */
+
+/* Upload Zone */
+.upload-zone {
+  border: 2px dashed var(--border);
+  border-radius: var(--radius-md);
+  padding: var(--space-xl);
+  text-align: center;
+  cursor: pointer;
+  transition: all 0.2s;
+}
+
+.upload-zone:hover {
+  border-color: var(--accent);
+  background-color: color-mix(in srgb, var(--accent) 5%, var(--bg-secondary));
+}
+
+.upload-zone.drag-over {
+  border-color: var(--accent);
+  background-color: color-mix(in srgb, var(--accent) 5%, var(--bg-secondary));
+}
+
+.upload-zone.uploading {
+  cursor: wait;
+}
+
+/* Upload Icon */
+.upload-icon {
+  width: 36px;
+  height: 36px;
+  display: block;
+  margin: 0 auto;
+}
+
+/* Source Item */
+.source-item {
+  padding: var(--space-sm) 0;
+  border-bottom: 1px solid var(--border);
+}
+
+/* Status Parsed */
+.status-parsed {
+  color: var(--indicator-normal);
+}
+
+/* Icon sizes */
+.icon-sm {
+  width: 14px;
+  height: 14px;
+}
+
+/* =====================================================
+   DASHBOARD PAGE
+   ===================================================== */
+
+/* Category Card */
+.category-card {
+  padding: 0;
+}
+
+/* Category Name */
+.category-name {
+  font-size: 16px;
+  font-weight: 600;
+  text-transform: uppercase;
+}
+
+/* Collapsible Header Button */
+.collapsible-header {
+  background: none;
+  border: none;
+  cursor: pointer;
+  text-align: left;
+  color: var(--text-primary);
+}
+
+/* Collapse Icon */
+.collapse-icon {
+  width: 18px;
+  height: 18px;
+  transition: transform 0.2s;
+}
+
+/* =====================================================
+   INSIGHTS PAGE
+   ===================================================== */
+
+.coming-soon-icon {
+  font-size: 48px;
 }
\ No newline at end of file
diff --git a/frontend/src/pages/Admin.tsx b/frontend/src/pages/Admin.tsx
index 966e8a8..e3a9eec 100644
--- a/frontend/src/pages/Admin.tsx
+++ b/frontend/src/pages/Admin.tsx
@@ -121,7 +121,7 @@ export function AdminPage() {
     const isConfigAdmin = (user: User) => user.username === CONFIG_ADMIN_USERNAME
 
     if (loading) {
-        return <div style={{ padding: 'var(--space-lg)' }}>Loading...</div>
+        return <div className="p-lg">Loading...</div>
     }
 
     if (!currentUser || currentUser.role !== 'admin') {
@@ -129,10 +129,10 @@ export function AdminPage() {
     }
 
     return (
-        <div style={{ padding: 'var(--space-lg)', maxWidth: '1000px', margin: '0 auto' }}>
-            <header style={{ marginBottom: 'var(--space-xl)' }}>
+        <div className="admin-page p-lg max-w-xl">
+            <header className="mb-xl">
                 <Link to="/" className="text-secondary text-sm">← Back to Dashboard</Link>
-                <div style={{ display: 'flex', justifyContent: 'space-between', alignItems: 'center', marginTop: 'var(--space-sm)' }}>
+                <div className="flex-between mt-sm">
                     <h1>User Management</h1>
                     <button className="btn btn-primary" onClick={() => setShowCreateModal(true)}>
                         + New User
@@ -172,7 +172,7 @@ export function AdminPage() {
                                 </td>
                                 <td className="text-secondary text-sm">{new Date(user.created_at).toLocaleDateString()}</td>
                                 <td>
-                                    <div style={{ display: 'flex', gap: 'var(--space-xs)' }}>
+                                    <div className="flex gap-xs">
                                         <button
                                             className="btn btn-secondary btn-sm"
                                             onClick={() => setEditingUser(user)}
@@ -243,7 +243,7 @@ export function AdminPage() {
                                     <option value="admin">Admin</option>
                                 </select>
                             </div>
-                            <div style={{ display: 'flex', gap: 'var(--space-sm)', marginTop: 'var(--space-lg)' }}>
+                            <div className="flex gap-sm mt-lg">
                                 <button type="submit" className="btn btn-primary">Create</button>
                                 <button type="button" className="btn btn-secondary" onClick={() => setShowCreateModal(false)}>Cancel</button>
                             </div>
@@ -327,7 +327,7 @@ function EditUserModal({ user, onClose, onSave, setMessage }: EditUserModalProps
                             placeholder="Full name"
                         />
                     </div>
-                    <div style={{ display: 'flex', gap: 'var(--space-sm)', marginTop: 'var(--space-lg)' }}>
+                    <div className="flex gap-sm mt-lg">
                         <button type="submit" className="btn btn-primary" disabled={saving}>
                             {saving ? 'Saving...' : 'Save'}
                         </button>
@@ -419,7 +419,7 @@ function ResetPasswordModal({ user, onClose, onSave, setMessage }: ResetPassword
                         />
                     </div>
                     {error && <div className="error-message">{error}</div>}
-                    <div style={{ display: 'flex', gap: 'var(--space-sm)', marginTop: 'var(--space-lg)' }}>
+                    <div className="flex gap-sm mt-lg">
                         <button type="submit" className="btn btn-primary" disabled={saving}>
                             {saving ? 'Resetting...' : 'Reset Password'}
                         </button>
diff --git a/frontend/src/pages/Dashboard.tsx b/frontend/src/pages/Dashboard.tsx
index 12c8d8e..b46e35c 100644
--- a/frontend/src/pages/Dashboard.tsx
+++ b/frontend/src/pages/Dashboard.tsx
@@ -60,53 +60,38 @@ export function DashboardPage() {
             </header>
 
             <section>
-                <h2 style={{ marginBottom: 'var(--space-md)' }}>Biomarker Categories</h2>
-                <div style={{ display: 'flex', flexDirection: 'column', gap: 'var(--space-sm)' }}>
+                <h2 className="mb-md">Biomarker Categories</h2>
+                <div className="flex-col gap-sm">
                     {categories.map(category => {
                         const categoryBiomarkers = getBiomarkersForCategory(category.id)
                         const isExpanded = expandedCategories.has(category.id)
 
                         return (
-                            <div key={category.id} className="card" style={{ padding: 0 }}>
+                            <div key={category.id} className="card category-card">
                                 <button
-                                    className="collapsible-header"
+                                    className="collapsible-header w-full p-md flex-between"
                                     onClick={() => toggleCategory(category.id)}
-                                    style={{
-                                        width: '100%',
-                                        padding: 'var(--space-md)',
-                                        display: 'flex',
-                                        justifyContent: 'space-between',
-                                        alignItems: 'center',
-                                        background: 'none',
-                                        border: 'none',
-                                        cursor: 'pointer',
-                                        textAlign: 'left',
-                                        color: 'var(--text-primary)',
-                                    }}
                                 >
                                     <div>
-                                        <span style={{ fontSize: '16px', fontWeight: 600, textTransform: 'uppercase' }}>{category.name}</span>
-                                        <span className="text-secondary text-sm" style={{ marginLeft: 'var(--space-sm)' }}>
+                                        <span className="category-name">{category.name}</span>
+                                        <span className="text-secondary text-sm ml-sm">
                                             ({categoryBiomarkers.length} biomarkers)
                                         </span>
                                     </div>
                                     <img
                                         src="/icons/general/icons8-collapse-arrow-50.png"
                                         alt="expand"
-                                        className="theme-icon"
+                                        className="theme-icon collapse-icon"
                                         style={{
-                                            width: 18,
-                                            height: 18,
-                                            transition: 'transform 0.2s',
                                             transform: isExpanded ? 'rotate(180deg)' : 'rotate(0)'
                                         }}
                                     />
                                 </button>
 
                                 {isExpanded && (
-                                    <div style={{ borderTop: '1px solid var(--border)', padding: 'var(--space-sm)' }}>
+                                    <div className="category-content border-t p-sm">
                                         {categoryBiomarkers.length === 0 ? (
-                                            <p className="text-secondary text-sm" style={{ padding: 'var(--space-sm)' }}>
+                                            <p className="text-secondary text-sm p-sm">
                                                 No biomarkers in this category
                                             </p>
                                         ) : (
diff --git a/frontend/src/pages/Insights.tsx b/frontend/src/pages/Insights.tsx
index c187bce..f89dbcc 100644
--- a/frontend/src/pages/Insights.tsx
+++ b/frontend/src/pages/Insights.tsx
@@ -6,8 +6,8 @@ export function InsightsPage() {
                 <p className="text-secondary">AI-powered analysis of your health data</p>
             </header>
 
-            <div className="card" style={{ textAlign: 'center', padding: 'var(--space-xl)' }}>
-                <div style={{ fontSize: '48px', marginBottom: 'var(--space-md)' }}>🚀</div>
+            <div className="card text-center p-xl">
+                <div className="coming-soon-icon mb-md">🚀</div>
                 <h3>Coming Soon</h3>
                 <p className="text-secondary">
                     AI-generated health insights and recommendations based on your biomarker data.
diff --git a/frontend/src/pages/Login.tsx b/frontend/src/pages/Login.tsx
index 9253ba2..d7e0ade 100644
--- a/frontend/src/pages/Login.tsx
+++ b/frontend/src/pages/Login.tsx
@@ -91,7 +91,7 @@ export function LoginPage() {
                     </button>
                 </form>
 
-                <p className="text-secondary text-sm" style={{ marginTop: 'var(--space-md)', textAlign: 'center' }}>
+                <p className="text-secondary text-sm mt-md text-center">
                     Don't have an account? <Link to="/signup">Sign up</Link>
                 </p>
             </div>
diff --git a/frontend/src/pages/Profile.tsx b/frontend/src/pages/Profile.tsx
index ff95192..f7c4363 100644
--- a/frontend/src/pages/Profile.tsx
+++ b/frontend/src/pages/Profile.tsx
@@ -123,7 +123,7 @@ export function ProfilePage() {
     }
 
     return (
-        <div className="page" style={{ maxWidth: '600px' }}>
+        <div className="page max-w-md">
             <header className="page-header">
                 <h1>Profile</h1>
                 <p className="text-secondary">Manage your account and health information</p>
@@ -131,8 +131,8 @@ export function ProfilePage() {
 
             <form onSubmit={handleSubmit}>
                 {/* Account Info */}
-                <div className="card" style={{ marginBottom: 'var(--space-lg)' }}>
-                    <h3 style={{ marginBottom: 'var(--space-md)' }}>Account</h3>
+                <div className="card mb-lg">
+                    <h3 className="mb-md">Account</h3>
                     <div className="form-group">
                         <label>Username</label>
                         <input type="text" className="input" value={username} disabled />
@@ -165,8 +165,8 @@ export function ProfilePage() {
                 </div>
 
                 {/* Physical Info */}
-                <div className="card" style={{ marginBottom: 'var(--space-lg)' }}>
-                    <h3 style={{ marginBottom: 'var(--space-md)' }}>Physical Info</h3>
+                <div className="card mb-lg">
+                    <h3 className="mb-md">Physical Info</h3>
 
                     <div className="form-group">
                         <label htmlFor="height">Height (cm)</label>
@@ -214,8 +214,8 @@ export function ProfilePage() {
                 </div>
 
                 {/* Lifestyle */}
-                <div className="card" style={{ marginBottom: 'var(--space-lg)' }}>
-                    <h3 style={{ marginBottom: 'var(--space-md)' }}>Lifestyle</h3>
+                <div className="card mb-lg">
+                    <h3 className="mb-md">Lifestyle</h3>
 
                     <div className="form-group">
                         <label htmlFor="diet">Diet</label>
diff --git a/frontend/src/pages/Signup.tsx b/frontend/src/pages/Signup.tsx
index f5da0bf..855184b 100644
--- a/frontend/src/pages/Signup.tsx
+++ b/frontend/src/pages/Signup.tsx
@@ -98,7 +98,7 @@ export function SignupPage() {
                     </button>
                 </form>
 
-                <p className="text-secondary text-sm" style={{ marginTop: 'var(--space-md)', textAlign: 'center' }}>
+                <p className="text-secondary text-sm mt-md text-center">
                     Already have an account? <Link to="/login">Sign in</Link>
                 </p>
             </div>
diff --git a/frontend/src/pages/Sources.tsx b/frontend/src/pages/Sources.tsx
index 5780083..30b3d04 100644
--- a/frontend/src/pages/Sources.tsx
+++ b/frontend/src/pages/Sources.tsx
@@ -117,13 +117,13 @@ export function SourcesPage() {
             </header>
 
             <div className="card">
-                <h3 style={{ marginBottom: 'var(--space-md)' }}>Upload Data</h3>
-                <p className="text-secondary text-sm" style={{ marginBottom: 'var(--space-lg)' }}>
+                <h3 className="mb-md">Upload Data</h3>
+                <p className="text-secondary text-sm mb-lg">
                     Upload lab reports in PDF, CSV, or Excel format to import your biomarker data.
                 </p>
 
                 {error && (
-                    <div className="alert alert-error" style={{ marginBottom: 'var(--space-md)' }}>
+                    <div className="alert alert-error mb-md">
                         {error}
                     </div>
                 )}
@@ -131,7 +131,7 @@ export function SourcesPage() {
                 <input
                     type="file"
                     ref={fileInputRef}
-                    style={{ display: 'none' }}
+                    className="hidden"
                     multiple
                     accept=".pdf,.csv,.xlsx,.xls,.jpg,.jpeg,.png"
                     onChange={(e) => handleUpload(e.target.files)}
@@ -139,15 +139,6 @@ export function SourcesPage() {
 
                 <div
                     className={`upload-zone ${dragOver ? 'drag-over' : ''}`}
-                    style={{
-                        border: `2px dashed ${dragOver ? 'var(--accent)' : 'var(--border)'}`,
-                        borderRadius: 'var(--radius-md)',
-                        padding: 'var(--space-xl)',
-                        textAlign: 'center',
-                        cursor: uploading ? 'wait' : 'pointer',
-                        backgroundColor: dragOver ? 'color-mix(in srgb, var(--accent) 5%, var(--bg-secondary))' : 'transparent',
-                        transition: 'all 0.2s',
-                    }}
                     onClick={() => !uploading && fileInputRef.current?.click()}
                     onDragOver={(e) => { e.preventDefault(); setDragOver(true) }}
                     onDragLeave={() => setDragOver(false)}
@@ -159,20 +150,20 @@ export function SourcesPage() {
                 >
                     {uploading ? (
                         <>
-                            <div style={{ marginBottom: 'var(--space-sm)', textAlign: 'center' }}>
-                                <img src="/icons/general/icons8-clock-50.png" alt="Uploading" className="theme-icon" style={{ width: 36, height: 36, display: 'block', margin: '0 auto' }} />
+                            <div className="mb-sm text-center">
+                                <img src="/icons/general/icons8-clock-50.png" alt="Uploading" className="upload-icon theme-icon" />
                             </div>
                             <p className="text-secondary">Uploading...</p>
                         </>
                     ) : (
                         <>
-                            <div style={{ marginBottom: 'var(--space-sm)', textAlign: 'center' }}>
-                                <img src="/icons/general/icons8-upload-to-the-cloud-50.png" alt="Upload" className="theme-icon" style={{ width: 36, height: 36, display: 'block', margin: '0 auto' }} />
+                            <div className="mb-sm text-center">
+                                <img src="/icons/general/icons8-upload-to-the-cloud-50.png" alt="Upload" className="upload-icon theme-icon" />
                             </div>
                             <p className="text-secondary">
                                 Drag & drop files here, or click to browse
                             </p>
-                            <p className="text-secondary text-xs" style={{ marginTop: 'var(--space-sm)' }}>
+                            <p className="text-secondary text-xs mt-sm">
                                 Supported: PDF, CSV, XLSX, Images
                             </p>
                         </>
@@ -180,8 +171,8 @@ export function SourcesPage() {
                 </div>
             </div>
 
-            <div className="card" style={{ marginTop: 'var(--space-lg)' }}>
-                <h3 style={{ marginBottom: 'var(--space-md)' }}>Recent Uploads</h3>
+            <div className="card mt-lg">
+                <h3 className="mb-md">Recent Uploads</h3>
 
                 {loading ? (
                     <p className="text-secondary text-sm">Loading...</p>
@@ -190,28 +181,22 @@ export function SourcesPage() {
                 ) : (
                     <div className="sources-list">
                         {sources.map(source => (
-                            <div key={source.id} className="source-item" style={{
-                                display: 'flex',
-                                alignItems: 'center',
-                                justifyContent: 'space-between',
-                                padding: 'var(--space-sm) 0',
-                                borderBottom: '1px solid var(--border)',
-                            }}>
-                                <div style={{ flex: 1, minWidth: 0 }}>
-                                    <div style={{ fontWeight: 500, overflow: 'hidden', textOverflow: 'ellipsis', whiteSpace: 'nowrap' }}>
+                            <div key={source.id} className="source-item flex-between">
+                                <div className="flex-1 min-w-0">
+                                    <div className="font-medium truncate">
                                         {source.name}
                                     </div>
                                     <div className="text-secondary text-xs">
                                         {source.file_type} • {formatFileSize(source.file_size)} • {formatDate(source.uploaded_at)}
                                     </div>
                                 </div>
-                                <div style={{ display: 'flex', gap: 'var(--space-sm)' }}>
+                                <div className="flex gap-sm items-center">
                                     {source.ocr_data ? (
-                                        <span style={{ color: 'var(--success)', fontSize: '12px', display: 'flex', alignItems: 'center', gap: '4px' }}>
-                                            <img src="/icons/general/icons8-checkmark-50.png" alt="Parsed" style={{ width: 14, height: 14 }} /> Parsed
+                                        <span className="status-parsed flex items-center gap-xs text-xs">
+                                            <img src="/icons/general/icons8-checkmark-50.png" alt="Parsed" className="icon-sm" /> Parsed
                                         </span>
                                     ) : (
-                                        <span style={{ color: 'var(--text-secondary)', fontSize: '12px' }}>Pending</span>
+                                        <span className="text-secondary text-xs">Pending</span>
                                     )}
                                     <button
                                         className="btn btn-danger btn-sm"
@@ -228,21 +213,13 @@ export function SourcesPage() {
 
             {/* Delete Confirmation Modal */}
             {deleteConfirmId !== null && (
-                <div style={{
-                    position: 'fixed',
-                    inset: 0,
-                    backgroundColor: 'rgba(0,0,0,0.5)',
-                    display: 'flex',
-                    alignItems: 'center',
-                    justifyContent: 'center',
-                    zIndex: 1000,
-                }}>
-                    <div className="card" style={{ maxWidth: 400, textAlign: 'center' }}>
-                        <h3 style={{ marginBottom: 'var(--space-md)' }}>Delete File?</h3>
-                        <p className="text-secondary" style={{ marginBottom: 'var(--space-lg)' }}>
+                <div className="modal-overlay">
+                    <div className="card modal-content">
+                        <h3 className="mb-md">Delete File?</h3>
+                        <p className="text-secondary mb-lg">
                             Are you sure you want to delete this file? This action cannot be undone.
                         </p>
-                        <div style={{ display: 'flex', gap: 'var(--space-sm)', justifyContent: 'center' }}>
+                        <div className="flex gap-sm justify-center">
                             <button className="btn" onClick={() => setDeleteConfirmId(null)}>
                                 Cancel
                             </button>