/* Opšti stilovi */
* {
    margin: 0;
    padding: 0;
    box-sizing: border-box;
}

body {
    font-family: 'Segoe UI', Tahoma, Geneva, Verdana, sans-serif;
    background: linear-gradient(135deg, #f0f9ff 0%, #e0f7fa 50%, #b2ebf2 100%);
    min-height: 100vh;
    color: #333;
    display: flex;
    flex-direction: column;
}

/* Header */
header {
    background: linear-gradient(135deg, #26c6da 0%, #00acc1 50%, #0097a7 100%);
    padding: 2rem;
    text-align: center;
    box-shadow: 0 4px 6px rgba(0,0,0,0.1);
    border-bottom: 3px solid #00838f;
}

header h1 {
    color: #fff;
    font-size: 2.5rem;
    text-shadow: 2px 2px 4px rgba(0,0,0,0.2);
    margin-bottom: 0.5rem;
}

header p {
    color: #fff;
    font-size: 1.1rem;
    text-shadow: 1px 1px 2px rgba(0,0,0,0.2);
}

/* Navigacija */
nav {
    background: linear-gradient(135deg, #b2ebf2 0%, #80deea 50%, #4dd0e1 100%);
    padding: 1rem;
    text-align: center;
    box-shadow: 0 2px 4px rgba(0,0,0,0.1);
}

nav a {
    color: #fff;
    text-decoration: none;
    padding: 0.8rem 1.5rem;
    margin: 0 0.5rem;
    border-radius: 5px;
    background: #80deea;
    border: 2px solid #4dd0e1;
    transition: all 0.3s ease;
    display: inline-block;
    font-weight: 600;
    text-shadow: 1px 1px 2px rgba(0,0,0,0.3);
}

nav a:hover {
    background: #4dd0e1;
    border-color: #26c6da;
    transform: translateY(-2px);
    box-shadow: 0 4px 8px rgba(0,0,0,0.2);
}

nav a.active-page {
    background: #4dd0e1;
}

/* Dugme za povratak */
.back-btn {
    display: inline-block;
    margin: 2rem;
    padding: 0.8rem 1.5rem;
    background: #80deea;
    color: #fff;
    text-decoration: none;
    border-radius: 5px;
    border: 2px solid #4dd0e1;
    font-weight: 600;
    text-shadow: 1px 1px 2px rgba(0,0,0,0.3);
    transition: all 0.3s ease;
}

.back-btn:hover {
    background: #4dd0e1;
    border-color: #26c6da;
    transform: translateY(-2px);
    box-shadow: 0 4px 8px rgba(0,0,0,0.2);
}

.back-btn.hidden {
    display: none;
}

/* Container */
.container {
    max-width: 1200px;
    margin: 1rem auto;
    padding: 1rem;
    flex: 1;
}

/* Page sections */
.page {
    display: none;
    animation: fadeIn 0.5s ease;
}

.page.active {
    display: block;
}

@keyframes fadeIn {
    from { 
        opacity: 0; 
        transform: translateY(20px); 
    }
    to { 
        opacity: 1; 
        transform: translateY(0); 
    }
}

/* Welcome section */
.welcome-section {
    background: radial-gradient(circle, #ffffff 0%, #f0f9ff 40%, #e0f7fa 100%);
    padding: 2rem;
    border-radius: 5px;
    box-shadow: 0 8px 16px rgba(0,0,0,0.1);
    text-align: center;
    border: 2px solid #80deea;
}

.welcome-section h2 {
    color: #00838f;
    font-size: 2rem;
    margin-bottom: 1rem;
}

.welcome-section .subtitle {
    font-size: 1.2rem;
    color: #666;
    margin-top: 1rem;
}

/* Info box */
.info-box {
    background: linear-gradient(135deg, #e0f7fa 0%, #b2ebf2 50%, #80deea 100%);
    padding: 1.5rem;
    border-radius: 5px;
    margin: 1.5rem 0;
    box-shadow: 0 4px 8px rgba(0,0,0,0.1);
    border-left: 5px solid #4dd0e1;
}

.info-box h3 {
    color: #00838f;
    margin-bottom: 1rem;
}

.info-box p {
    margin: 0.5rem 0;
}

/* Info sekcija (tema.html) */
.info-section {
    background: radial-gradient(circle, #ffffff 0%, #f0f9ff 40%, #e0f7fa 100%);
    padding: 2rem;
    border-radius: 5px;
    box-shadow: 0 4px 8px rgba(0,0,0,0.1);
    margin-bottom: 2rem;
    border: 2px solid #80deea;
}

.info-section h2 {
    color: #00838f;
    margin-bottom: 1rem;
    font-size: 1.8rem;
}

.info-item {
    margin: 1rem 0;
    padding: 1rem;
    background: rgba(255,255,255,0.5);
    border-radius: 5px;
    border-left: 4px solid #4dd0e1;
}

.info-item strong {
    color: #00838f;
}

.info-item a {
    color: #00838f;
    text-decoration: underline;
}

/* Links sekcija */
.links-section {
    background: radial-gradient(circle, #f0f9ff 0%, #e0f7fa 50%, #b2ebf2 100%);
    padding: 2rem;
    border-radius: 5px;
    box-shadow: 0 4px 8px rgba(0,0,0,0.1);
    margin-bottom: 2rem;
    border: 2px solid #80deea;
}

.links-section h2 {
    color: #00838f;
    margin-bottom: 1.5rem;
    font-size: 1.8rem;
}

.link-card {
    display: block;
    padding: 1.2rem;
    margin: 1rem 0;
    background: rgba(255,255,255,0.7);
    border-radius: 5px;
    border: 2px solid #80deea;
    text-decoration: none;
    color: #00838f;
    font-weight: 600;
    transition: all 0.3s ease;
    box-shadow: 0 2px 4px rgba(0,0,0,0.1);
}

.link-card:hover {
    transform: translateY(-3px);
    box-shadow: 0 4px 8px rgba(0,0,0,0.2);
    background: rgba(255,255,255,0.9);
    border-color: #4dd0e1;
}

.link-card::before {
    content: "🔗 ";
    margin-right: 0.5rem;
}

/* About content */
.about-content {
    background: linear-gradient(135deg, #f0f9ff 0%, #e0f7fa 50%, #b2ebf2 100%);
    padding: 2rem;
    border-radius: 5px;
    box-shadow: 0 4px 8px rgba(0,0,0,0.1);
    line-height: 1.8;
    border: 2px solid #80deea;
}

.about-content h2 {
    color: #00838f;
    margin-bottom: 1rem;
}

.about-content p {
    margin-bottom: 1rem;
    color: #555;
}

.about-content .profile-image-container {
    text-align: center;
    margin-bottom: 2rem;
}

.about-content .profile-image {
    width: 200px;
    height: 200px;
    border-radius: 50%;
    border: 4px solid #80deea;
    box-shadow: 0 4px 8px rgba(0,0,0,0.2);
    object-fit: cover;
}

.about-content .grades-title {
    margin-top: 2rem;
    margin-bottom: 1rem;
}

/* Grades table */
.grades-table {
    width: 100%;
    border-collapse: collapse;
    background: white;
    border-radius: 5px;
    overflow: hidden;
    box-shadow: 0 2px 4px rgba(0,0,0,0.1);
}

.grades-table thead tr {
    background: linear-gradient(135deg, #b2ebf2 0%, #80deea 100%);
    color: #fff;
}

.grades-table th {
    padding: 1rem;
    text-align: left;
    border-bottom: 2px solid #4dd0e1;
}

.grades-table th.center {
    text-align: center;
}

.grades-table tbody tr {
    border-bottom: 1px solid #e0f7fa;
}

.grades-table td {
    padding: 0.8rem;
}

.grades-table td.center {
    text-align: center;
    font-weight: bold;
    color: #00838f;
}

/* Abstract sekcija */
.abstract-section {
    background: radial-gradient(circle, #ffffff 0%, #f0f9ff 40%, #e0f7fa 100%);
    padding: 2rem;
    border-radius: 5px;
    box-shadow: 0 4px 8px rgba(0,0,0,0.1);
    margin-bottom: 2rem;
    border: 2px solid #80deea;
}

.abstract-section h2 {
    color: #00838f;
    margin-bottom: 1rem;
    font-size: 1.8rem;
}

.abstract-section p {
    line-height: 1.8;
    color: #555;
    text-align: justify;
}

/* Images sekcija */
.images-section {
    background: radial-gradient(circle, #f0f9ff 0%, #e0f7fa 50%, #b2ebf2 100%);
    padding: 2rem;
    border-radius: 5px;
    box-shadow: 0 4px 8px rgba(0,0,0,0.1);
    margin-bottom: 2rem;
    border: 2px solid #80deea;
}

.images-section h2 {
    color: #00838f;
    margin-bottom: 1.5rem;
    font-size: 1.8rem;
}

.images-grid {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(300px, 1fr));
    gap: 1.5rem;
    margin-top: 1rem;
}

.image-card {
    background: rgba(255,255,255,0.7);
    padding: 1rem;
    border-radius: 5px;
    border: 2px solid #80deea;
    text-align: center;
    box-shadow: 0 2px 4px rgba(0,0,0,0.1);
}

.image-card img {
    width: 100%;
    height: auto;
    border-radius: 5px;
    margin-bottom: 0.5rem;
}

.image-card p {
    color: #00838f;
    font-weight: 600;
    font-size: 0.9rem;
}

/* Subjects grid */
.semester-title {
    color: #00838f;
    text-align: center;
    margin-bottom: 2rem;
}

.subjects-grid {
    display: grid;
    grid-template-columns: repeat(3, 1fr);
    gap: 1.5rem;
    margin-top: 2rem;
}

.subject-card {
    background: radial-gradient(circle, #f0f9ff 0%, #e0f7fa 50%, #b2ebf2 100%);
    padding: 2rem;
    border-radius: 5px;
    box-shadow: 0 4px 8px rgba(0,0,0,0.1);
    transition: all 0.3s ease;
    cursor: pointer;
    border: 2px solid #80deea;
    text-align: center;
}

.subject-card:hover {
    transform: translateY(-5px);
    box-shadow: 0 8px 16px rgba(0,0,0,0.2);
    background: radial-gradient(circle, #e0f7fa 0%, #b2ebf2 50%, #80deea 100%);
}

.subject-card h3 {
    color: #00838f;
    margin-bottom: 0.5rem;
    font-size: 1.3rem;
}

.subject-card .professor {
    color: #666;
}

.subject-links {
    display: none;
    margin-top: 1rem;
    padding-top: 1rem;
    border-top: 2px solid #80deea;
}

.subject-links.active {
    display: block;
}

.subject-links a {
    display: block;
    color: #00838f;
    text-decoration: none;
    padding: 0.5rem;
    margin: 0.5rem 0;
    background: rgba(255,255,255,0.5);
    border-radius: 5px;
    transition: all 0.3s ease;
}

.subject-links a:hover {
    background: rgba(255,255,255,0.8);
    padding-left: 1rem;
}

/* Contact page styles */
.contact-section {
    background: radial-gradient(circle, #ffffff 0%, #f0f9ff 40%, #e0f7fa 100%);
    padding: 2rem;
    border-radius: 5px;
    box-shadow: 0 4px 8px rgba(0,0,0,0.1);
    margin-bottom: 2rem;
    border: 2px solid #80deea;
}

.contact-section h2 {
    color: #00838f;
    margin-bottom: 1rem;
    font-size: 1.8rem;
}

.contact-intro {
    color: #555;
    margin-bottom: 2rem;
    line-height: 1.6;
}

.contact-form {
    max-width: 800px;
    margin: 0 auto;
}

.form-group {
    margin-bottom: 1.5rem;
}

.form-group label {
    display: block;
    color: #00838f;
    font-weight: 600;
    margin-bottom: 0.5rem;
    font-size: 1rem;
}

.form-group input,
.form-group textarea {
    width: 100%;
    padding: 0.8rem;
    border: 2px solid #80deea;
    border-radius: 5px;
    font-family: 'Segoe UI', Tahoma, Geneva, Verdana, sans-serif;
    font-size: 1rem;
    transition: all 0.3s ease;
    background: rgba(255, 255, 255, 0.9);
}

.form-group input:focus,
.form-group textarea:focus {
    outline: none;
    border-color: #4dd0e1;
    box-shadow: 0 0 0 3px rgba(77, 208, 225, 0.2);
}

.form-group textarea {
    resize: vertical;
    min-height: 150px;
}

.form-buttons {
    display: flex;
    gap: 1rem;
    justify-content: center;
    margin-top: 2rem;
}

.btn-submit,
.btn-reset {
    padding: 0.8rem 2rem;
    border: none;
    border-radius: 5px;
    font-size: 1rem;
    font-weight: 600;
    cursor: pointer;
    transition: all 0.3s ease;
    text-shadow: 1px 1px 2px rgba(0,0,0,0.2);
}

.btn-submit {
    background: linear-gradient(135deg, #26c6da 0%, #00acc1 100%);
    color: #fff;
    border: 2px solid #00acc1;
}

.btn-submit:hover {
    background: linear-gradient(135deg, #00acc1 0%, #0097a7 100%);
    transform: translateY(-2px);
    box-shadow: 0 4px 8px rgba(0,0,0,0.2);
}

.btn-reset {
    background: linear-gradient(135deg, #b2ebf2 0%, #80deea 100%);
    color: #fff;
    border: 2px solid #80deea;
}

.btn-reset:hover {
    background: linear-gradient(135deg, #80deea 0%, #4dd0e1 100%);
    transform: translateY(-2px);
    box-shadow: 0 4px 8px rgba(0,0,0,0.2);
}

.contact-info {
    background: radial-gradient(circle, #f0f9ff 0%, #e0f7fa 50%, #b2ebf2 100%);
    padding: 2rem;
    border-radius: 5px;
    box-shadow: 0 4px 8px rgba(0,0,0,0.1);
    border: 2px solid #80deea;
}

.contact-info h2 {
    color: #00838f;
    margin-bottom: 1.5rem;
    font-size: 1.8rem;
}

.contact-item {
    margin: 1rem 0;
    padding: 1rem;
    background: rgba(255,255,255,0.7);
    border-radius: 5px;
    border-left: 4px solid #4dd0e1;
}

.contact-item strong {
    color: #00838f;
    display: block;
    margin-bottom: 0.3rem;
}

.contact-item a {
    color: #00838f;
    text-decoration: none;
    transition: all 0.3s ease;
}

.contact-item a:hover {
    color: #0097a7;
    text-decoration: underline;
}

/* Footer */
footer {
    background: linear-gradient(135deg, #4dd0e1 0%, #26c6da 50%, #00acc1 100%);
    color: #fff;
    text-align: center;
    padding: 1.5rem;
    margin-top: 1.5rem;
    box-shadow: 0 -4px 6px rgba(0,0,0,0.1);
}

/* Responsive */
@media (max-width: 768px) {
    header h1 { 
        font-size: 1.8rem; 
    }
    
    nav a { 
        margin: 0.3rem; 
        padding: 0.6rem 1rem; 
    }
    
    .images-grid { 
        grid-template-columns: 1fr; 
    }
    
    .subjects-grid { 
        grid-template-columns: 1fr; 
    }
}