/* CSS Custom Properties für Theme-Variablen */
:root {
    /* Light Theme (Standard) */
    --bg-primary: #f8f8f8;
    --bg-secondary: #fff;
    --bg-tertiary: #f9f9f9;
    --text-primary: #333;
    --text-secondary: #666;
    --text-tertiary: #777;
    --text-muted: #aaa;
    --accent-color: #0070f3;
    --accent-hover: #0051b3;
    --accent-secondary: #00a8ff;
    --border-color: #ddd;
    --border-light: #e0e0e0;
    --shadow-light: rgba(0, 0, 0, 0.1);
    --shadow-medium: rgba(0, 0, 0, 0.15);
    --footer-bg: #333;
    --footer-text: #fff;
}

/* Dark Theme */
@media (prefers-color-scheme: dark) {
    :root {
        --bg-primary: #0d1117;
        --bg-secondary: #161b22;
        --bg-tertiary: #21262d;
        --text-primary: #e6edf3;
        --text-secondary: #7d8590;
        --text-tertiary: #848d97;
        --text-muted: #6e7681;
        --accent-color: #58a6ff;
        --accent-hover: #1f6feb;
        --accent-secondary: #79c0ff;
        --border-color: #30363d;
        --border-light: #21262d;
        --shadow-light: rgba(0, 0, 0, 0.3);
        --shadow-medium: rgba(0, 0, 0, 0.4);
        --footer-bg: #0d1117;
        --footer-text: #e6edf3;
    }
}

* {
    margin: 0;
    padding: 0;
    box-sizing: border-box;
    font-family: 'Helvetica Neue', Arial, sans-serif;
}

body {
    background-color: var(--bg-primary);
    color: var(--text-primary);
    line-height: 1.6;
    transition: background-color 0.3s ease, color 0.3s ease;
}

.container {
    max-width: 1200px;
    margin: 0 auto;
    padding: 0 20px;
}

/* Header-Stil */
header {
    background-color: var(--bg-secondary);
    box-shadow: 0 2px 10px var(--shadow-light);
    position: sticky;
    top: 0;
    z-index: 100;
    transition: background-color 0.3s ease, box-shadow 0.3s ease;
}

.nav-container {
    display: flex;
    justify-content: space-between;
    align-items: center;
    padding: 20px 20px;
    min-height: 70px;
}

.logo {
    font-weight: bold;
    font-size: 24px;
    color: var(--text-primary);
    text-decoration: none;
    flex-shrink: 0;
    transition: color 0.3s ease;
}

nav ul {
    display: flex;
    list-style: none;
}

nav ul li {
    margin-left: 30px;
}

nav ul li a {
    text-decoration: none;
    color: var(--text-primary);
    font-weight: 500;
    transition: color 0.3s ease;
}

nav ul li a:hover,
nav ul li a.active {
    color: var(--accent-color);
}

.mobile-menu-btn {
    display: none;
    background: none;
    border: none;
    font-size: 24px;
    cursor: pointer;
    padding: 5px;
    color: var(--text-primary);
    transition: color 0.3s ease;
}

/* Hero Section */
.hero {
    min-height: 90vh;
    display: flex;
    align-items: center;
    background-color: var(--bg-secondary);
    margin-bottom: 60px;
    transition: background-color 0.3s ease;
}

.hero .container {
    display: flex;
    align-items: center;
}

.hero-content {
    width: 50%;
    padding-right: 40px;
}

.hero-image {
    width: 50%;
    overflow: hidden;
}

.hero-image img {
    width: 100%;
    height: auto;
    object-fit: cover;
    border-radius: 10px;
}

.hero h1 {
    font-size: 48px;
    margin-bottom: 20px;
    font-weight: 700;
    color: var(--text-primary);
    transition: color 0.3s ease;
}

.hero p {
    font-size: 18px;
    margin-bottom: 30px;
    color: var(--text-secondary);
    transition: color 0.3s ease;
}

.btn {
    display: inline-block;
    padding: 12px 30px;
    background-color: var(--accent-color);
    color: var(--bg-secondary);
    text-decoration: none;
    border-radius: 5px;
    font-weight: 500;
    transition: background-color 0.3s ease, color 0.3s ease;
    border: none;
    cursor: pointer;
}

.btn:hover {
    background-color: var(--accent-hover);
}

/* Über Mich Section */
.about {
    padding: 80px 0;
    background-color: var(--bg-secondary);
    margin-bottom: 60px;
    transition: background-color 0.3s ease;
}

.section-title {
    font-size: 36px;
    margin-bottom: 60px;
    text-align: center;
    color: var(--text-primary);
    font-weight: 700;
    transition: color 0.3s ease;
}

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

.about-text {
    width: 50%;
    padding-right: 40px;
}

.about-image {
    width: 40%;
}

.about-image img {
    width: 100%;
    border-radius: 10px;
    box-shadow: 0 10px 20px var(--shadow-light);
    transition: box-shadow 0.3s ease;
}

/* Timeline Sections - Erfahrung & Bildung */
.timeline-section {
    padding: 80px 0;
    background-color: var(--bg-secondary);
    margin-bottom: 60px;
    transition: background-color 0.3s ease;
}

.timeline {
    position: relative;
    max-width: 800px;
    margin: 0 auto;
}

.timeline::after {
    content: '';
    position: absolute;
    width: 2px;
    background-color: var(--accent-color);
    top: 0;
    bottom: 0;
    left: 50%;
    margin-left: -1px;
    transition: background-color 0.3s ease;
}

.timeline-item {
    position: relative;
    margin-bottom: 50px;
    opacity: 0;
    transform: translateY(50px);
    transition: all 0.6s ease;
}

.timeline-item.animate {
    opacity: 1;
    transform: translateY(0);
}

.timeline-item:nth-child(odd) {
    padding-right: 50%;
    text-align: right;
}

.timeline-item:nth-child(even) {
    padding-left: 50%;
    text-align: left;
}

.timeline-content {
    background-color: var(--bg-tertiary);
    padding: 30px;
    border-radius: 10px;
    box-shadow: 0 5px 15px var(--shadow-light);
    position: relative;
    transition: transform 0.3s ease, background-color 0.3s ease, box-shadow 0.3s ease;
    border: 1px solid var(--border-color);
}

.timeline-link {
    text-decoration: none;
    color: inherit;
    display: block;
}

.timeline-content:hover {
    transform: translateY(-5px);
    box-shadow: 0 8px 25px var(--shadow-medium);
}

.timeline-item:nth-child(odd) .timeline-content::after {
    content: '';
    position: absolute;
    top: 50%;
    right: -15px;
    margin-top: -15px;
    width: 0;
    height: 0;
    border: 15px solid transparent;
    border-left-color: var(--bg-tertiary);
    transition: border-left-color 0.3s ease;
}

.timeline-item:nth-child(even) .timeline-content::after {
    content: '';
    position: absolute;
    top: 50%;
    left: -15px;
    margin-top: -15px;
    width: 0;
    height: 0;
    border: 15px solid transparent;
    border-right-color: var(--bg-tertiary);
    transition: border-right-color 0.3s ease;
}

.timeline-date {
    font-size: 14px;
    color: var(--accent-color);
    font-weight: 600;
    margin-bottom: 10px;
    text-transform: uppercase;
    letter-spacing: 1px;
    transition: color 0.3s ease;
}

.timeline-title {
    font-size: 22px;
    font-weight: 700;
    margin-bottom: 8px;
    color: var(--text-primary);
    transition: color 0.3s ease;
}

.timeline-company {
    font-size: 16px;
    color: var(--text-secondary);
    font-weight: 500;
    margin-bottom: 15px;
    transition: color 0.3s ease;
}

.timeline-description {
    font-size: 14px;
    color: var(--text-tertiary);
    line-height: 1.6;
    transition: color 0.3s ease;
}

.timeline-dot {
    position: absolute;
    width: 16px;
    height: 16px;
    background-color: var(--accent-color);
    border: 4px solid var(--bg-secondary);
    border-radius: 50%;
    top: 50%;
    left: 50%;
    transform: translate(-50%, -50%);
    z-index: 10;
    box-shadow: 0 0 0 4px rgba(88, 166, 255, 0.2);
    transition: background-color 0.3s ease, border-color 0.3s ease;
}

@media (prefers-color-scheme: dark) {
    .timeline-dot {
        box-shadow: 0 0 0 4px rgba(88, 166, 255, 0.3);
    }
}

/* Skills Section */
.skills {
    padding: 80px 0;
    background-color: var(--bg-primary);
    margin-bottom: 60px;
    transition: background-color 0.3s ease;
}

.skills-filter {
    text-align: center;
    margin-bottom: 40px;
}

.filter-select {
    padding: 12px 20px;
    border: 2px solid var(--accent-color);
    border-radius: 5px;
    background-color: var(--bg-secondary);
    color: var(--text-primary);
    font-size: 16px;
    cursor: pointer;
    min-width: 200px;
    transition: background-color 0.3s ease, color 0.3s ease, border-color 0.3s ease;
}

.filter-select:focus {
    outline: none;
    box-shadow: 0 0 0 3px rgba(88, 166, 255, 0.2);
}

.skills-container {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(300px, 1fr));
    gap: 30px;
    max-width: 800px;
    margin: 0 auto;
}

.skill {
    background-color: var(--bg-secondary);
    padding: 20px;
    border-radius: 10px;
    box-shadow: 0 5px 15px var(--shadow-light);
    transition: all 0.3s ease;
    opacity: 1;
    transform: scale(1);
    border: 1px solid var(--border-color);
}

.skill.hidden {
    display: none;
}

.skill:hover {
    box-shadow: 0 8px 25px var(--shadow-medium);
    transform: translateY(-2px);
}

.skill h3 {
    margin-bottom: 10px;
    color: var(--text-primary);
    font-size: 18px;
    transition: color 0.3s ease;
}

.skill-category {
    font-size: 12px;
    color: var(--accent-color);
    text-transform: uppercase;
    letter-spacing: 1px;
    margin-bottom: 5px;
    transition: color 0.3s ease;
}

.progress-bar {
    width: 100%;
    height: 12px;
    background-color: var(--border-light);
    border-radius: 6px;
    overflow: hidden;
    position: relative;
    transition: background-color 0.3s ease;
}

.progress {
    height: 100%;
    background: linear-gradient(90deg, var(--accent-color), var(--accent-secondary));
    width: 0;
    transition: width 1.5s ease-in-out, background 0.3s ease;
    border-radius: 6px;
    position: relative;
}

.progress::after {
    content: '';
    position: absolute;
    top: 0;
    left: 0;
    bottom: 0;
    right: 0;
    background: linear-gradient(90deg, transparent, rgba(255, 255, 255, 0.4), transparent);
    animation: shimmer 2s infinite;
}

@media (prefers-color-scheme: dark) {
    .progress::after {
        background: linear-gradient(90deg, transparent, rgba(255, 255, 255, 0.2), transparent);
    }
}

@keyframes shimmer {
    0% {
        transform: translateX(-100%);
    }
    100% {
        transform: translateX(100%);
    }
}

.skill-percentage {
    text-align: right;
    margin-top: 5px;
    font-size: 14px;
    color: var(--text-secondary);
    font-weight: 600;
    transition: color 0.3s ease;
}

/* Kontakt-Formular */
.contact {
    padding: 80px 0;
    background-color: var(--bg-secondary);
    transition: background-color 0.3s ease;
}

.form-group {
    margin-bottom: 20px;
}

.form-control {
    width: 100%;
    padding: 12px;
    border: 1px solid var(--border-color);
    border-radius: 5px;
    font-size: 16px;
    background-color: var(--bg-secondary);
    color: var(--text-primary);
    transition: border-color 0.3s ease, background-color 0.3s ease, color 0.3s ease;
}

.form-control:focus {
    outline: none;
    border-color: var(--accent-color);
    box-shadow: 0 0 0 3px rgba(88, 166, 255, 0.2);
}

.form-control::placeholder {
    color: var(--text-secondary);
    transition: color 0.3s ease;
}

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

/* Footer */
footer {
    background-color: var(--footer-bg);
    color: var(--footer-text);
    padding: 40px 0;
    text-align: center;
    transition: background-color 0.3s ease, color 0.3s ease;
}

.social-icons {
    margin-bottom: 20px;
}

.social-icons a {
    color: var(--footer-text);
    font-size: 18px;
    margin: 0 15px;
    text-decoration: none;
    transition: color 0.3s ease;
}

.social-icons a:hover {
    color: var(--accent-color);
}

.copyright {
    color: var(--text-muted);
    transition: color 0.3s ease;
}

/* Responsive Design */
@media (max-width: 768px) {
    .container {
        padding: 0 15px;
    }

    .nav-container {
        padding: 15px 15px;
        position: relative;
    }

    .logo {
        font-size: 20px;
    }

    nav {
        display: none;
        position: absolute;
        top: 100%;
        left: 0;
        right: 0;
        background-color: var(--bg-secondary);
        box-shadow: 0 2px 10px var(--shadow-light);
        padding: 20px;
        z-index: 1000;
        border: 1px solid var(--border-color);
        border-top: none;
        transition: background-color 0.3s ease, box-shadow 0.3s ease;
    }

    nav.active {
        display: block;
    }

    nav ul {
        flex-direction: column;
        align-items: center;
    }

    nav ul li {
        margin: 10px 0;
        margin-left: 0;
    }

    .mobile-menu-btn {
        display: block;
    }

    .hero {
        min-height: auto;
        padding: 40px 0;
    }

    .hero .container {
        flex-direction: column;
        text-align: center;
    }

    .hero-content,
    .hero-image {
        width: 100%;
        padding-right: 0;
        margin-bottom: 30px;
    }

    .hero h1 {
        font-size: 32px;
    }

    .about-content {
        flex-direction: column-reverse;
        text-align: center;
    }

    .about-text,
    .about-image {
        width: 100%;
        padding-right: 0;
        margin-bottom: 30px;
    }

    .section-title {
        font-size: 28px;
        margin-bottom: 40px;
    }

    .skills-container {
        grid-template-columns: 1fr;
        gap: 20px;
    }

    /* Mobile Timeline */
    .timeline::after {
        left: 20px;
    }

    .timeline-item {
        padding-left: 50px;
        text-align: left;
    }

    .timeline-item:nth-child(odd) {
        padding-right: 0;
        text-align: left;
    }

    .timeline-item:nth-child(even) {
        padding-left: 50px;
    }

    .timeline-dot {
        left: 20px;
    }

    .timeline-item:nth-child(odd) .timeline-content::after,
    .timeline-item:nth-child(even) .timeline-content::after {
        left: -15px;
        border: 15px solid transparent;
        border-right-color: var(--bg-tertiary);
        border-left-color: transparent;
        transition: border-right-color 0.3s ease;
    }
}

@media (max-width: 480px) {
    .container {
        padding: 0 10px;
    }

    .nav-container {
        padding: 10px;
    }

    .hero {
        padding: 20px 0;
    }

    .hero h1 {
        font-size: 24px;
    }

    .hero p {
        font-size: 16px;
    }

    .section-title {
        font-size: 24px;
    }

    .timeline-content {
        padding: 20px;
    }
}

/* Smooth transitions for theme changes */
*,
*::before,
*::after {
    transition-property: background-color, color, border-color, box-shadow;
    transition-duration: 0.3s;
    transition-timing-function: ease;
}