/* ── SHARED BACK BUTTON ───────────────────────────────────────────────── */
.back-btn {
    position: fixed;
    top: 18px;
    left: 20px;
    z-index: 9000;
    display: inline-flex;
    align-items: center;
    gap: 8px;
    font-family: 'JetBrains Mono', 'Share Tech Mono', monospace;
    font-size: 11px;
    font-weight: 700;
    letter-spacing: 3px;
    text-transform: uppercase;
    text-decoration: none;
    color: #aaa;
    background: rgba(0, 0, 0, 0.65);
    border: 1px solid rgba(255, 255, 255, 0.12);
    border-radius: 4px;
    padding: 9px 18px;
    backdrop-filter: blur(10px);
    -webkit-backdrop-filter: blur(10px);
    transition: color 0.2s ease, border-color 0.2s ease, background 0.2s ease, box-shadow 0.2s ease;
    white-space: nowrap;
}

.back-btn::before {
    content: '←';
    font-size: 14px;
    line-height: 1;
    transition: transform 0.2s ease;
}

.back-btn:hover {
    color: #fff;
    border-color: rgba(255, 255, 255, 0.35);
    background: rgba(255, 255, 255, 0.07);
    box-shadow: 0 0 16px rgba(255, 255, 255, 0.06);
}

.back-btn:hover::before {
    transform: translateX(-3px);
}

/* Theme colour overrides — add class alongside .back-btn */
.back-btn.red   { color: #ff3344; border-color: rgba(255,51,68,.25);  }
.back-btn.red:hover   { color: #ff6677; border-color: rgba(255,51,68,.6);  box-shadow: 0 0 16px rgba(255,51,68,.15); }

.back-btn.green { color: #00ff41; border-color: rgba(0,255,65,.25);   }
.back-btn.green:hover { color: #4dff77; border-color: rgba(0,255,65,.6);  box-shadow: 0 0 16px rgba(0,255,65,.12); }

.back-btn.cyan  { color: #00e5ff; border-color: rgba(0,229,255,.25);  }
.back-btn.cyan:hover  { color: #66f0ff; border-color: rgba(0,229,255,.6); box-shadow: 0 0 16px rgba(0,229,255,.12);}

.back-btn.gold  { color: #ffd700; border-color: rgba(255,215,0,.25);  }
.back-btn.gold:hover  { color: #ffe966; border-color: rgba(255,215,0,.6);  box-shadow: 0 0 16px rgba(255,215,0,.15); }

.back-btn.yellow{ color: #f1c40f; border-color: rgba(241,196,15,.25); }
.back-btn.yellow:hover{ color: #f5d553; border-color: rgba(241,196,15,.6); box-shadow: 0 0 16px rgba(241,196,15,.12); }

.back-btn.blue  { color: #3b82f6; border-color: rgba(59,130,246,.25); }
.back-btn.blue:hover  { color: #6ea8fb; border-color: rgba(59,130,246,.6); box-shadow: 0 0 16px rgba(59,130,246,.12); }