/* Reset und Basis-Styles */
* {
    margin: 0;
    padding: 0;
    box-sizing: border-box;
}

body {
    font-family: -apple-system, BlinkMacSystemFont, 'Segoe UI', Roboto, 'Helvetica Neue', Arial, sans-serif;
    line-height: 1.6;
    color: #334155;
    background: linear-gradient(135deg, #f8fafc 0%, #e0f2fe 100%);
    min-height: 100vh;
}

.container {
    max-width: 1200px;
    margin: 0 auto;
    padding: 0 1rem;
}

/* Utility Classes */
.hidden {
    display: none !important;
}

/* Header */
.header {
    background: white;
    box-shadow: 0 1px 3px rgba(0, 0, 0, 0.1);
    border-bottom: 1px solid #e2e8f0;
    padding: 1.5rem 0;
}

.header-content {
    display: flex;
    justify-content: space-between;
    align-items: center;
}

.logo-section {
    display: flex;
    align-items: center;
    gap: 1rem;
}

.logo {
    height: 3rem;
    width: auto;
}

.logo-text h1 {
    font-size: 1.5rem;
    font-weight: 700;
    color: #1e293b;
    margin: 0;
}

.logo-text p {
    font-size: 0.875rem;
    color: #64748b;
    margin: 0;
}

.header-info {
    text-align: right;
}

.author {
    font-size: 0.875rem;
    color: #64748b;
    margin: 0;
}

.subtitle {
    font-size: 0.75rem;
    color: #94a3b8;
    margin: 0;
}

/* Main Content */
.main-content {
    padding: 3rem 0;
}

/* Hero Section */
.hero {
    text-align: center;
    margin-bottom: 3rem;
}

.hero h2 {
    font-size: 2.5rem;
    font-weight: 700;
    color: #1e293b;
    margin-bottom: 1rem;
}

.hero-description {
    font-size: 1.25rem;
    color: #64748b;
    max-width: 48rem;
    margin: 0 auto 2rem;
}

/* Course Selection */
.course-selection {
    max-width: 28rem;
    margin: 0 auto 2rem;
}

.select-wrapper {
    position: relative;
}

.course-dropdown {
    width: 100%;
    height: 3rem;
    padding: 0 3rem 0 1rem;
    border: 2px solid #e2e8f0;
    border-radius: 0.5rem;
    background: white;
    font-size: 1rem;
    color: #334155;
    cursor: pointer;
    appearance: none;
    transition: all 0.2s ease;
}

.course-dropdown:hover {
    border-color: #cbd5e1;
}

.course-dropdown:focus {
    outline: none;
    border-color: #3b82f6;
    box-shadow: 0 0 0 3px rgba(59, 130, 246, 0.1);
}

.select-arrow {
    position: absolute;
    right: 1rem;
    top: 50%;
    transform: translateY(-50%);
    color: #64748b;
    pointer-events: none;
}

/* Categories */
.categories {
    margin-bottom: 3rem;
}

.category-grid {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(300px, 1fr));
    gap: 2rem;
}

.category-card {
    background: white;
    border-radius: 0.75rem;
    padding: 1.5rem;
    box-shadow: 0 1px 3px rgba(0, 0, 0, 0.1);
    transition: all 0.3s ease;
    border: 1px solid #e2e8f0;
}

.category-card:hover {
    box-shadow: 0 10px 25px rgba(0, 0, 0, 0.1);
    transform: translateY(-2px);
}

.category-header {
    text-align: center;
    margin-bottom: 1.5rem;
}

.category-icon {
    width: 3rem;
    height: 3rem;
    border-radius: 50%;
    display: flex;
    align-items: center;
    justify-content: center;
    margin: 0 auto 1rem;
    font-size: 1.5rem;
}

.category-icon.medizin {
    background: #fef2f2;
    color: #dc2626;
}

.category-icon.it {
    background: #eff6ff;
    color: #2563eb;
}

.category-icon.management {
    background: #f0fdf4;
    color: #16a34a;
}

.category-card h3 {
    font-size: 1.25rem;
    font-weight: 600;
    margin-bottom: 0.5rem;
}

.category-card h3:first-of-type {
    color: #dc2626;
}

.category-card:nth-child(2) h3 {
    color: #2563eb;
}

.category-card:nth-child(3) h3 {
    color: #16a34a;
}

.category-header p {
    color: #64748b;
    font-size: 0.875rem;
}

.category-content {
    display: flex;
    flex-direction: column;
    gap: 0.5rem;
}

.course-item {
    display: flex;
    align-items: center;
    gap: 0.5rem;
    font-size: 0.875rem;
    color: #64748b;
}

.course-item i {
    width: 0.75rem;
    height: 0.75rem;
    font-size: 0.75rem;
}

/* Footer */
.footer {
    text-align: center;
    color: #94a3b8;
    font-size: 0.875rem;
    margin-top: 3rem;
}

.footer p {
    margin: 0.25rem 0;
}

/* Course Frame */
.course-frame {
    position: fixed;
    top: 0;
    left: 0;
    width: 100%;
    height: 100vh;
    background: white;
    z-index: 1000;
}

.frame-header {
    background: #1e293b;
    color: white;
    padding: 0.5rem 1rem;
    display: flex;
    justify-content: space-between;
    align-items: center;
    box-shadow: 0 2px 4px rgba(0, 0, 0, 0.1);
    height: 3rem;
}

.frame-header-left {
    display: flex;
    align-items: center;
    gap: 0.75rem;
}

.frame-logo {
    height: 1.5rem;
    width: auto;
}

.frame-title {
    font-size: 0.875rem;
    font-weight: 500;
}

.course-badge {
    background: #475569;
    color: white;
    padding: 0.125rem 0.5rem;
    border-radius: 0.25rem;
    font-size: 0.75rem;
}

.frame-header-right {
    display: flex;
    align-items: center;
    gap: 0.75rem;
}

.course-title-text {
    font-size: 0.75rem;
    color: #cbd5e1;
}

.back-button {
    background: transparent;
    border: none;
    color: white;
    padding: 0.25rem 0.5rem;
    border-radius: 0.25rem;
    cursor: pointer;
    font-size: 0.75rem;
    display: flex;
    align-items: center;
    gap: 0.25rem;
    transition: background-color 0.2s ease;
}

.back-button:hover {
    background: #475569;
}

.course-iframe {
    width: 100%;
    height: calc(100vh - 3rem);
    border: none;
}

/* Responsive Design */
@media (max-width: 768px) {
    .header-content {
        flex-direction: column;
        gap: 1rem;
        text-align: center;
    }

    .hero h2 {
        font-size: 2rem;
    }

    .hero-description {
        font-size: 1.125rem;
    }

    .category-grid {
        grid-template-columns: 1fr;
    }

    .frame-header {
        flex-direction: column;
        height: auto;
        padding: 0.75rem 1rem;
        gap: 0.5rem;
    }

    .frame-header-left,
    .frame-header-right {
        justify-content: center;
    }

    .course-iframe {
        height: calc(100vh - 4rem);
    }
}

@media (max-width: 480px) {
    .container {
        padding: 0 0.75rem;
    }

    .hero h2 {
        font-size: 1.75rem;
    }

    .hero-description {
        font-size: 1rem;
    }

    .course-selection {
        max-width: 100%;
    }
}

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

.landing-page {
    animation: fadeIn 0.6s ease-out;
}

.category-card {
    animation: fadeIn 0.6s ease-out;
}

.category-card:nth-child(1) {
    animation-delay: 0.1s;
}

.category-card:nth-child(2) {
    animation-delay: 0.2s;
}

.category-card:nth-child(3) {
    animation-delay: 0.3s;
}