/* Navigation commune aux quatre chapitres de 6e — Maths2Fly */
.m2f-chapter-header{position:sticky!important;top:0!important;z-index:90!important;width:100%;background:#081a57f5!important;border-bottom:2px solid #1ea7ff66!important;box-shadow:0 5px 20px #0002!important;color:#fff!important;font-family:system-ui,sans-serif!important}
.m2f-chapter-header *{box-sizing:border-box}
.m2f-chapter-header .m2f-header-inner{max-width:1220px;margin:auto;min-height:76px;padding:10px 18px;display:flex;align-items:center;gap:14px}
.m2f-chapter-header .m2f-brand{display:flex;align-items:center;gap:10px;min-width:0;flex:1 1 245px;text-decoration:none!important;color:#fff!important}
.m2f-chapter-header .m2f-brand img{width:58px!important;height:52px!important;object-fit:contain;flex:none}
.m2f-chapter-header .m2f-brand-title{font-weight:800;font-size:1rem;line-height:1.2;color:#fff!important}
.m2f-chapter-header .m2f-brand-title small{display:block;font-size:.78rem;font-weight:600;color:#b6e6ff!important;margin-top:4px}
.m2f-chapter-header .m2f-stations{display:flex;align-items:center;gap:5px;flex-wrap:nowrap;justify-content:center}
.m2f-chapter-header .m2f-stations a{display:grid;place-items:center;min-width:31px;height:33px;padding:0 6px;border:1px solid #7bbbe977;border-radius:9px;background:#ffffff12;color:#fff!important;font-weight:800;font-size:.9rem;text-decoration:none!important}
.m2f-chapter-header .m2f-stations a:hover,.m2f-chapter-header .m2f-stations a:focus-visible{background:#1ea7ff!important;border-color:#1ea7ff!important;color:#081a57!important}
.m2f-chapter-header .m2f-header-actions{display:flex;align-items:center;gap:7px;flex-wrap:nowrap}
.m2f-chapter-header .m2f-header-actions button{display:inline-flex;align-items:center;justify-content:center;white-space:nowrap;min-height:38px;padding:8px 11px;border-radius:10px;border:1px solid #76c9ff88;background:#1a579b!important;color:#fff!important;font-size:.88rem;font-weight:800;cursor:pointer;box-shadow:none!important;transform:none!important}
.m2f-chapter-header .m2f-header-actions button:hover{background:#2778c0!important}
@media(max-width:1050px){.m2f-chapter-header .m2f-header-inner{flex-wrap:wrap;gap:7px 12px}.m2f-chapter-header .m2f-brand{flex:1 1 250px}.m2f-chapter-header .m2f-stations{order:3;width:100%;justify-content:center;overflow-x:auto;padding:3px 0}.m2f-chapter-header .m2f-header-actions{margin-left:auto}}
@media(max-width:560px){.m2f-chapter-header .m2f-header-inner{padding:8px 10px}.m2f-chapter-header .m2f-brand{flex:1 1 140px}.m2f-chapter-header .m2f-brand img{width:42px!important;height:42px!important}.m2f-chapter-header .m2f-brand-title{font-size:.88rem}.m2f-chapter-header .m2f-brand-title small{font-size:.72rem}.m2f-chapter-header .m2f-header-actions button{padding:7px;font-size:.77rem;min-height:34px}.m2f-chapter-header .m2f-stations a{min-width:30px;height:32px}}