:root {
    --background-color: #ffffff;
    --text-color: #333333;
    --container-bg-color: #f0f0f0;
    --number-bg-color: #ffffff;
    --button-bg-color: #4CAF50;
    --button-text-color: #ffffff;
    --shadow-color: rgba(0, 0, 0, 0.1);
}

body.dark-mode {
    --background-color: #1a1a1a;
    --text-color: #ffffff;
    --container-bg-color: #2c2c2c;
    --number-bg-color: #3a3a3a;
    --button-bg-color: #5a8e6a;
    --shadow-color: rgba(255, 255, 255, 0.1);
}

body {
    background-color: var(--background-color);
    color: var(--text-color);
    font-family: 'Segoe UI', Tahoma, Geneva, Verdana, sans-serif;
    display: flex;
    justify-content: center;
    align-items: center;
    height: 100vh;
    margin: 0;
    transition: background-color 0.3s, color 0.3s;
}

.container {
    background-color: var(--container-bg-color);
    padding: 2em;
    border-radius: 15px;
    box-shadow: 0 10px 20px var(--shadow-color);
    text-align: center;
    width: 90%;
    max-width: 520px;
    position: relative;
}

.theme-switcher {
    position: absolute;
    top: 15px;
    right: 15px;
}

#theme-toggle {
    background: none;
    border: none;
    font-size: 1.5rem;
    cursor: pointer;
    color: var(--text-color);
}

h1 {
    margin-bottom: 1em;
    font-size: 2rem;
}

.numbers-container {
    display: flex;
    flex-direction: column;
    gap: 12px;
    margin-bottom: 1.5em;
}

.set-row {
    display: flex;
    align-items: center;
    gap: 12px;
}

.set-label {
    font-size: 0.9rem;
    font-weight: 600;
    min-width: 52px;
    text-align: left;
}

.number-set {
    display: flex;
    gap: 8px;
    flex-wrap: wrap;
}

.number {
    width: 46px;
    height: 46px;
    background-color: var(--number-bg-color);
    border-radius: 50%;
    display: flex;
    justify-content: center;
    align-items: center;
    font-size: 1.5rem;
    font-weight: bold;
    box-shadow: 0 4px 8px var(--shadow-color);
}

.actions {
    display: flex;
    justify-content: center;
    flex-wrap: wrap;
    gap: 10px;
    margin-bottom: 0.5em;
}

#generate-btn,
#copy-btn {
    background-color: var(--button-bg-color);
    color: var(--button-text-color);
    border: none;
    padding: 1em 2em;
    border-radius: 8px;
    font-size: 1rem;
    cursor: pointer;
    transition: background-color 0.3s;
}

#generate-btn:hover,
#copy-btn:hover {
    opacity: 0.9;
}

.copy-status {
    margin: 0;
    min-height: 1.2em;
    font-size: 0.9rem;
    opacity: 0.8;
}

@media (max-width: 480px) {
    .set-row {
        align-items: flex-start;
    }

    .set-label {
        min-width: auto;
    }

    .number {
        width: 42px;
        height: 42px;
        font-size: 1.3rem;
    }
}