* {
    box-sizing: border-box;
}

body {
    margin: 0;
    font-family: Arial, Helvetica, sans-serif;
    background: #f4f6f8;
    color: #222;
}

/* Kopfbereich */

header {
    background: #1f2937;
    color: white;
    text-align: center;
    padding: 60px 20px;
}

header h1 {
    margin: 0;
    font-size: 42px;
}

header p {
    margin-top: 12px;
    font-size: 18px;
    color: #d1d5db;
}


/* Hauptbereich */

main {
    max-width: 1100px;
    margin: 50px auto;
    padding: 0 20px;
}


/* Karten */

.cards {
    display: grid;
    grid-template-columns: repeat(3, 1fr);
    gap: 25px;
}

.card {
    background: white;
    border-radius: 12px;
    padding: 30px;
    box-shadow: 0 3px 12px rgba(0,0,0,0.08);
}

.icon {
    font-size: 45px;
}

.card h2 {
    margin-top: 20px;
}

.card p {
    line-height: 1.6;
    color: #555;
    min-height: 80px;
}

.card a {
    display: inline-block;
    margin-top: 15px;
    padding: 12px 18px;

    background: #2563eb;
    color: white;

    text-decoration: none;
    border-radius: 7px;

    font-weight: bold;
}

.card a:hover {
    background: #1d4ed8;
}


/* Fußbereich */

footer {
    text-align: center;
    padding: 30px;
    color: #777;
}


/* Smartphones */

@media (max-width: 800px) {

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

    header h1 {
        font-size: 34px;
    }
}

/* Unterseiten */

.back {
    color: #2563eb;
    text-decoration: none;
    font-weight: bold;
}

.projects {
    display: grid;
    gap: 20px;
    margin-top: 30px;
}

.project {
    display: flex;
    gap: 25px;
    align-items: center;

    background: white;
    padding: 25px;

    border-radius: 12px;
    box-shadow: 0 3px 12px rgba(0,0,0,0.08);
}

.number {
    display: flex;
    align-items: center;
    justify-content: center;

    min-width: 55px;
    height: 55px;

    border-radius: 50%;

    background: #2563eb;
    color: white;

    font-size: 24px;
    font-weight: bold;
}

.project h3 {
    margin: 0 0 8px 0;
    font-size: 21px;
}

.project p {
    margin: 0;
    color: #555;
    line-height: 1.5;
}

.project a {
    display: inline-block;
    margin-top: 12px;

    color: #2563eb;
    text-decoration: none;
    font-weight: bold;
}

.project a:hover,
.back:hover {
    text-decoration: underline;
}

/* Schritt-für-Schritt-Anleitungen */

.lesson-intro {
    background: white;
    padding: 25px;
    margin: 30px 0;
    border-radius: 12px;
    box-shadow: 0 3px 12px rgba(0,0,0,0.08);
}

.lesson-intro h2 {
    margin-top: 0;
}

.steps {
    display: grid;
    gap: 20px;
}

.step {
    display: flex;
    gap: 25px;

    background: white;
    padding: 25px;

    border-radius: 12px;
    box-shadow: 0 3px 12px rgba(0,0,0,0.08);
}

.step-number {
    display: flex;
    align-items: center;
    justify-content: center;

    min-width: 50px;
    height: 50px;

    background: #2563eb;
    color: white;

    border-radius: 50%;

    font-size: 20px;
    font-weight: bold;
}

.step h2 {
    margin-top: 8px;
}

.step p {
    line-height: 1.6;
}

.button {
    display: inline-block;

    margin-top: 10px;
    padding: 12px 18px;

    background: #2563eb;
    color: white;

    border-radius: 7px;

    text-decoration: none;
    font-weight: bold;
}

.button:hover {
    background: #1d4ed8;
}

.challenge {
    border: 2px solid #2563eb;
}