/* Engineering Knowledge Website - German */
/* Colors: Blue (#1e3a5f), Gray (#4a5568), Orange (#f6993f) */

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

:root {
    --primary-blue: #1e3a5f;
    --secondary-blue: #2d5a87;
    --light-blue: #4a7db3;
    --gray-900: #1a202c;
    --gray-700: #4a5568;
    --gray-500: #718096;
    --gray-300: #cbd5e0;
    --gray-100: #f7fafc;
    --orange: #f6993f;
    --orange-dark: #dd7631;
    --white: #ffffff;
    --shadow: 0 4px 6px rgba(0,0,0,0.1);
    --shadow-lg: 0 10px 15px rgba(0,0,0,0.1);
}

body {
    font-family: 'Segoe UI', Tahoma, Geneva, Verdana, sans-serif;
    line-height: 1.6;
    color: var(--gray-700);
    background-color: var(--gray-100);
}

header {
    background: linear-gradient(135deg, var(--primary-blue) 0%, var(--secondary-blue) 100%);
    color: var(--white);
    padding: 1rem 0;
    position: sticky;
    top: 0;
    z-index: 1000;
    box-shadow: var(--shadow);
}

nav {
    max-width: 1400px;
    margin: 0 auto;
    display: flex;
    justify-content: space-between;
    align-items: center;
    padding: 0 2rem;
}

.logo {
    font-size: 1.8rem;
    font-weight: 700;
    color: var(--white);
    text-decoration: none;
    display: flex;
    align-items: center;
    gap: 0.5rem;
}

.logo span {
    color: var(--orange);
}

.nav-links {
    display: flex;
    list-style: none;
    gap: 2rem;
}

.nav-links a {
    color: var(--white);
    text-decoration: none;
    font-weight: 500;
    transition: color 0.3s;
}

.nav-links a:hover {
    color: var(--orange);
}

.mobile-menu {
    display: none;
    cursor: pointer;
    font-size: 1.5rem;
}

.hero {
    background: linear-gradient(135deg, var(--primary-blue) 0%, var(--secondary-blue) 100%);
    color: var(--white);
    padding: 4rem 2rem;
    text-align: center;
}

.hero h1 {
    font-size: 3rem;
    margin-bottom: 1rem;
}

.hero p {
    font-size: 1.3rem;
    opacity: 0.9;
    max-width: 800px;
    margin: 0 auto 2rem;
}

.btn {
    display: inline-block;
    padding: 0.8rem 2rem;
    background: var(--orange);
    color: var(--white);
    text-decoration: none;
    border-radius: 5px;
    font-weight: 600;
    transition: background 0.3s;
    border: none;
    cursor: pointer;
}

.btn:hover {
    background: var(--orange-dark);
}

.btn-outline {
    background: transparent;
    border: 2px solid var(--white);
    margin-left: 1rem;
}

.btn-outline:hover {
    background: var(--white);
    color: var(--primary-blue);
}

.container {
    max-width: 1400px;
    margin: 0 auto;
    padding: 3rem 2rem;
}

.section-title {
    text-align: center;
    margin-bottom: 3rem;
}

.section-title h2 {
    font-size: 2.5rem;
    color: var(--primary-blue);
    margin-bottom: 0.5rem;
}

.section-title p {
    color: var(--gray-500);
    font-size: 1.1rem;
}

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

.card {
    background: var(--white);
    border-radius: 10px;
    padding: 2rem;
    box-shadow: var(--shadow);
    transition: transform 0.3s, box-shadow 0.3s;
}

.card:hover {
    transform: translateY(-5px);
    box-shadow: var(--shadow-lg);
}

.card-icon {
    width: 60px;
    height: 60px;
    background: linear-gradient(135deg, var(--primary-blue), var(--light-blue));
    border-radius: 10px;
    display: flex;
    align-items: center;
    justify-content: center;
    font-size: 1.8rem;
    margin-bottom: 1rem;
}

.card h3 {
    color: var(--primary-blue);
    margin-bottom: 0.5rem;
}

.card p {
    color: var(--gray-500);
    margin-bottom: 1rem;
}

.tools-grid {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(280px, 1fr));
    gap: 1.5rem;
}

.tool-card {
    background: var(--white);
    border-radius: 8px;
    padding: 1.5rem;
    box-shadow: var(--shadow);
    text-decoration: none;
    color: inherit;
    border-left: 4px solid var(--orange);
    transition: all 0.3s;
}

.tool-card:hover {
    transform: translateX(5px);
    box-shadow: var(--shadow-lg);
}

.tool-card h4 {
    color: var(--primary-blue);
    margin-bottom: 0.5rem;
}

.tool-card p {
    font-size: 0.9rem;
    color: var(--gray-500);
}

.category-section {
    margin-bottom: 3rem;
}

.category-title {
    color: var(--primary-blue);
    font-size: 1.5rem;
    margin-bottom: 1rem;
    padding-bottom: 0.5rem;
    border-bottom: 3px solid var(--orange);
}

.article-card {
    background: var(--white);
    border-radius: 10px;
    overflow: hidden;
    box-shadow: var(--shadow);
    transition: transform 0.3s;
}

.article-card:hover {
    transform: translateY(-5px);
}

.article-card img {
    width: 100%;
    height: 200px;
    object-fit: cover;
}

.article-content {
    padding: 1.5rem;
}

.article-content h3 {
    color: var(--primary-blue);
    margin-bottom: 0.5rem;
}

.article-content p {
    color: var(--gray-500);
    font-size: 0.95rem;
}

.article-meta {
    display: flex;
    gap: 1rem;
    margin-top: 1rem;
    font-size: 0.85rem;
    color: var(--gray-500);
}

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

.form-group label {
    display: block;
    margin-bottom: 0.5rem;
    font-weight: 600;
    color: var(--gray-700);
}

.form-group input,
.form-group select,
.form-group textarea {
    width: 100%;
    padding: 0.8rem;
    border: 1px solid var(--gray-300);
    border-radius: 5px;
    font-size: 1rem;
    font-family: inherit;
}

.form-group input:focus,
.form-group select:focus,
.form-group textarea:focus {
    outline: none;
    border-color: var(--light-blue);
    box-shadow: 0 0 0 3px rgba(74, 125, 179, 0.2);
}

.tool-page {
    background: var(--white);
    border-radius: 10px;
    padding: 2rem;
    box-shadow: var(--shadow);
}

.tool-page h1 {
    color: var(--primary-blue);
    margin-bottom: 1rem;
}

.tool-description {
    color: var(--gray-500);
    margin-bottom: 2rem;
    padding-bottom: 1rem;
    border-bottom: 1px solid var(--gray-300);
}

.calc-result {
    background: linear-gradient(135deg, var(--primary-blue), var(--secondary-blue));
    color: var(--white);
    padding: 1.5rem;
    border-radius: 8px;
    margin-top: 1.5rem;
}

.calc-result h3 {
    margin-bottom: 1rem;
}

.result-value {
    font-size: 2rem;
    font-weight: 700;
    color: var(--orange);
}

.result-unit {
    font-size: 1rem;
    opacity: 0.8;
}

footer {
    background: var(--gray-900);
    color: var(--white);
    padding: 3rem 2rem;
    margin-top: 4rem;
}

.footer-content {
    max-width: 1400px;
    margin: 0 auto;
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(250px, 1fr));
    gap: 2rem;
}

.footer-section h4 {
    color: var(--orange);
    margin-bottom: 1rem;
}

.footer-section a {
    color: var(--gray-300);
    text-decoration: none;
    display: block;
    margin-bottom: 0.5rem;
    transition: color 0.3s;
}

.footer-section a:hover {
    color: var(--orange);
}

.copyright {
    text-align: center;
    padding-top: 2rem;
    margin-top: 2rem;
    border-top: 1px solid var(--gray-700);
    color: var(--gray-500);
}

.breadcrumb {
    padding: 1rem 0;
    color: var(--gray-500);
}

.breadcrumb a {
    color: var(--primary-blue);
    text-decoration: none;
}

.breadcrumb span {
    margin: 0 0.5rem;
}

.error-page {
    text-align: center;
    padding: 4rem 2rem;
}

.error-page h1 {
    font-size: 6rem;
    color: var(--orange);
}

.error-page h2 {
    color: var(--primary-blue);
    margin-bottom: 1rem;
}

@media (max-width: 768px) {
    .nav-links {
        display: none;
        flex-direction: column;
        position: absolute;
        top: 100%;
        left: 0;
        right: 0;
        background: var(--primary-blue);
        padding: 1rem;
        gap: 1rem;
    }

    .nav-links.active {
        display: flex;
    }

    .mobile-menu {
        display: block;
    }

    .hero h1 {
        font-size: 2rem;
    }

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

    .section-title h2 {
        font-size: 1.8rem;
    }

    .btn-outline {
        margin-left: 0;
        margin-top: 1rem;
    }
}

/* Tool-specific styles */
.input-row {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(200px, 1fr));
    gap: 1rem;
}

.info-box {
    background: var(--gray-100);
    border-left: 4px solid var(--primary-blue);
    padding: 1rem;
    margin: 1rem 0;
    border-radius: 0 5px 5px 0;
}

.formula-box {
    background: var(--gray-100);
    padding: 1rem;
    border-radius: 5px;
    font-family: 'Times New Roman', serif;
    text-align: center;
    margin: 1rem 0;
    border: 1px solid var(--gray-300);
}

table {
    width: 100%;
    border-collapse: collapse;
    margin: 1rem 0;
}

th, td {
    padding: 0.75rem;
    text-align: left;
    border-bottom: 1px solid var(--gray-300);
}

th {
    background: var(--primary-blue);
    color: var(--white);
}

tr:nth-child(even) {
    background: var(--gray-100);
}

.article-full {
    max-width: 800px;
    margin: 0 auto;
}

.article-full img {
    width: 100%;
    border-radius: 10px;
    margin: 2rem 0;
}

.article-full h2 {
    color: var(--primary-blue);
    margin: 2rem 0 1rem;
}

.article-full p {
    margin-bottom: 1rem;
    line-height: 1.8;
}

.article-full ul, .article-full ol {
    margin: 1rem 0 1rem 2rem;
}

.article-full li {
    margin-bottom: 0.5rem;
}