/* CSS Variables for Sidebar */
:root {
    --primary-color: #21314D;
    --accent-light: #DCE7F5;
    --bg-light: #f5f5f5;
    --text-dark: #333;
    --white: #ffffff;
}

/* Sidebar Navigation */
.sidebar {
    position: fixed;
    left: 0;
    top: 70px;
    width: 300px;
    height: calc(100vh - 70px);
    background: var(--primary-color);
    color: var(--white);
    display: flex;
    flex-direction: column;
    overflow-y: auto;
    box-shadow: 2px 0 10px rgba(0, 0, 0, 0.1);
    z-index: 1000;
}

@media (max-width: 760px) {
  .sidebar {
    display: none;
  }
}

/* Profile Section */
.profile-section {
    padding: 16px 20px;
    text-align: center;
}

.profile-picture {
    width: 120px;
    height: 120px;
    border-radius: 50%;
    object-fit: cover;
    margin-bottom: 15px;
    box-shadow: 0 4px 8px rgba(0, 0, 0, 0.2);
}

.professor-name {
    font-size: 1.5rem;
    font-weight: bold;
    margin-bottom: 10px;
    color: var(--white);
}

.bio {
    font-size: 1rem;
    line-height: 1.1;
    color: rgba(255, 255, 255, 0.9);
}

/* Main Navigation Links */
.nav-links {
    list-style: none;
    padding: 12px 36px;
    flex-grow: 1;
}

.nav-links li {
    margin: 0;
    padding: 5px 15px;
}

.nav-link {
    display: inline-flex;
    align-items: center;
    padding: 10px 16px;
    color: var(--white);
    text-decoration: none;
    transition: all 0.3s ease;
    border-radius: 12px;
}

.nav-link:hover {
    background-color: rgba(220, 231, 245, 0.3);
    color: var(--accent-light);
}

.nav-link.active {
    background-color: var(--accent-light);
    color: var(--primary-color);
}

.nav-link i {
    width: 24px;
    font-size: 1.2rem;
    margin-right: 15px;
}

.nav-link span {
    font-size: 1rem;
    font-weight: 500;
}

hr {
    width: 90%;
    margin: 0 auto;
    border: 1px solid var(--white);
}

.hr-contacts {
    border: none;
    border-top: 2px solid var(--white);
    color: var(--white);
    overflow: visible;
    text-align: center;
    height: 6px;
    width: 90%;
    margin: 0 auto;
}

.hr-contacts::after {
    background: var(--primary-color);
    content: "Contact";
    padding: 0 8px;
    position: relative;
    top: -12px;
}

/* Contact Links */
.contact-links {
    display: flex;
    justify-content: space-around;
    align-items: center;
    padding: 12px;
}

.contact-link {
    color: var(--white);
    font-size: 1.3rem;
    transition: all 0.3s ease;
    padding: 10px;
}

.contact-link:hover {
    transform: scale(1.1);
}

@media (max-width: 770px) {
  .contact-links {
    position: fixed;
    bottom: 0;
    left: 0;
    width: 100%;
    height: 60px;

    display: flex;
    justify-content: space-around;
    align-items: center;

    background: var(--primary-color);
    border-top: 1px solid rgba(255, 255, 255, 0.2);
    z-index: 1000;
  }

  .contact-link {
    color: #fff;
    font-size: 20px;
  }

  .main-content {
    padding-bottom: 80px;
  }
}

/* Focus States for Accessibility */
.nav-link:focus,
.contact-link:focus {
    outline: 2px solid var(--accent-light);
    outline-offset: 2px;
}

/* Responsive Design */
@media (max-width: 768px) {
    .sidebar {
        width: 100%;
        height: auto;
        position: relative;
        top: 60px;
    }

    .profile-picture {
        width: 100px;
        height: 100px;
    }

    .professor-name {
        font-size: 1.3rem;
    }

    .bio {
        font-size: 0.85rem;
    }

    .nav-link {
        padding: 12px 20px;
    }

    .contact-links {
        flex-wrap: wrap;
        gap: 10px;
    }
}

@media (max-width: 480px) {
    .sidebar {
        width: 100%;
        top: 50px;
    }

    .profile-section {
        padding: 20px 15px;
    }

    .profile-picture {
        width: 80px;
        height: 80px;
    }

    .nav-link span {
        font-size: 0.9rem;
    }
}