body {
    background: #f8f9fa;
}
.img_container {
    max-width: 360px;
    margin: 40px auto 0 auto;
    background: #fff;
    border-radius: 12px;
    box-shadow: 0 2px 16px rgba(0,0,0,0.08);
    padding: 1.5rem 1.2rem 2rem 1.2rem;
    display: block;
}
.drop-area {
    border: 3px dashed #0d6efd;
    border-radius: 16px;
    padding: 2.5rem 1rem;
    text-align: center;
    cursor: pointer;
    background: linear-gradient(135deg, #e3f2fd 0%, #f1f8ff 100%);
    transition: background 0.3s, border-color 0.3s, box-shadow 0.3s;
    box-shadow: 0 4px 24px rgba(13,110,253,0.07);
    position: relative;
    outline: none;
}
.drop-area.dragover {
    background: linear-gradient(135deg, #bbdefb 0%, #e3f2fd 100%);
    border-color: #0a58ca;
    box-shadow: 0 8px 32px rgba(13,110,253,0.15);
    animation: pulse 0.5s;
}
@keyframes pulse {
    0% { box-shadow: 0 0 0 0 rgba(13,110,253,0.2); }
    100% { box-shadow: 0 0 0 12px rgba(13,110,253,0); }
}
.drop-area i {
    font-size: 3.5rem;
    color: #0d6efd;
    margin-bottom: 0.5rem;
    transition: color 0.2s;
}
.drop-area.dragover i {
    color: #0a58ca;
}
.custom-file-input {
    display: none;
}
.kb-label {
    font-weight: 600;
    color: #0d6efd;
}
#result-message {
    margin-top: 1.5rem;
    font-size: 1.1rem;
    text-align: center;
    color: #198754;
    min-height: 1.5em;
}
@media (max-width: 600px) {
    .container {
        padding: 0.7rem 0.5rem 1.2rem 0.5rem;
        max-width: 98vw;
    }
    .drop-area {
        padding: 1.5rem 0.5rem;
    }
}
@media (max-width: 400px) {
    .container {
        padding: 0.3rem 0.2rem 0.7rem 0.2rem;
        max-width: 99vw;
    }
    .drop-area {
        padding: 1rem 0.2rem;
    }
}