body {
    background: linear-gradient(135deg, #1f213a, #2d3154);
    color: #f1f2f3;
    font-family: 'Segoe UI', Tahoma, Geneva, Verdana, sans-serif;
    display: flex;
    justify-content: center;
    align-items: center;
    min-height: 100vh;
    margin: 0;
}

.center {
    background-color: #252841;
    padding: 30px;
    border-radius: 16px;
    box-shadow: 0 10px 30px rgba(0, 0, 0, 0.3);
    max-width: 700px;
    width: 100%;
    box-sizing: border-box;
}

h2 {
    margin-top: 0;
    margin-bottom: 10px;
    font-weight: 600;
    text-align: center;
}

hr {
    border: none;
    height: 1px;
    background-color: #3b3f63;
    margin-bottom: 25px;
}

#vysledek {
    width: 100%;
    padding: 14px;
    background-color: #1a1c2e;
    border: 2px solid #3b3f63;
    border-radius: 8px;
    color: #fff;
    font-size: 1.1rem;
    letter-spacing: 1px;
    text-align: center;
    box-sizing: border-box;
    margin-bottom: 20px;
    outline: none;
    transition: border-color 0.3s;
}

#vysledek:focus {
    border-color: #6c5ce7;
}

.posuvnik-kontejner {
    margin-bottom: 25px;
}

.posuvnik-kontejner label {
    display: block;
    margin-bottom: 10px;
    font-size: 0.95rem;
    color: #b2bec3;
}

#zobrazenaDelka {
    color: #00cec9;
    font-weight: bold;
    font-size: 1.1rem;
}

input[type="range"] {
    width: 100%;
    height: 6px;
    background: #3b3f63;
    border-radius: 3px;
    outline: none;
}

input[type="range"]::-webkit-slider-thumb {
    -webkit-appearance: none;
    width: 18px;
    height: 18px;
    background: #00cec9;
    border-radius: 50%;
    cursor: pointer;
    transition: transform 0.1s;
}

input[type="range"]::-webkit-slider-thumb:hover {
    transform: scale(1.2);
}

.tlacitka-kontejner {
    display: flex;
    gap: 10px;
}

button {
    flex: 1;
    padding: 12px;
    border: none;
    border-radius: 8px;
    font-size: 0.95rem;
    font-weight: bold;
    cursor: pointer;
    transition: all 0.2s ease;
}

.btn-generovat {
    background-color: #6c5ce7;
    color: white;
}

.btn-generovat:hover {
    background-color: #5b4cdb;
    box-shadow: 0 4px 12px rgba(108, 92, 231, 0.3);
}

.btn-kopirovat {
    background-color: #484b6a;
    color: #f1f2f3;
}

.btn-kopirovat:hover {
    background-color: #575b80;
}

button:active {
    transform: scale(0.98);
}