/* =========================================
   BASIS-STYLING (Wird auf jeder Seite geladen)
   ========================================= */

body { font-family: Arial, sans-serif; line-height: 1.6; margin: 0; padding: 20px; background-color: #f4f4f9; color: #333; }
main { max-width: 900px; margin: 20px auto; background: white; padding: 30px; border-radius: 8px; box-shadow: 0 0 10px rgba(0,0,0,0.1); }
h1 { color: white; margin: 0; }

/* Navigation */
.nav { text-align: center; margin: 20px 0; padding: 10px; background: #e9ecef; border-radius: 8px; }
.nav a { margin: 0 15px; text-decoration: none; font-weight: bold; transition: color 0.3s; }
.nav a:hover { text-decoration: underline; }
.sub-nav { text-align: center; margin-bottom: 30px; font-size: 0.9em; }
.sub-nav a { margin: 0 10px; color: #555; text-decoration: none; }

/* Aufklapp-Menüs (Details/Summary) */
summary { list-style: none; outline: none; cursor: pointer; font-weight: bold; font-size: 1.2em; }
summary::-webkit-details-marker { display: none; }
summary::after { content: "➕"; float: right; font-size: 1.2em; }
details[open] > summary::after { content: "➖"; }

/* Allgemeines */
.rechenschritt { color: #007bff; font-weight: bold; }
.bilder-reihe { display: flex; justify-content: center; gap: 20px; margin-bottom: 20px; flex-wrap: wrap; }
.bilder-reihe img { max-width: 45%; height: auto; border-radius: 5px; border: 1px solid #ddd; }
footer { text-align: center; margin-top: 50px; padding-top: 20px; border-top: 1px solid #ddd; color: #555; font-size: 0.9em; }