:root {
    --bg-color: #ffffff;
    --text-color: #1a1a1a;
    --text-secondary: #666666;
    --accent-color: #2563eb;
    --accent-hover: #1d4ed8;
    --border-color: #e5e7eb;
    --shadow: 0 4px 6px -1px rgba(0, 0, 0, 0.1), 0 2px 4px -1px rgba(0, 0, 0, 0.06);
    --shadow-lg: 0 10px 15px -3px rgba(0, 0, 0, 0.1), 0 4px 6px -2px rgba(0, 0, 0, 0.05);
}

@media (prefers-color-scheme: dark) {
    :root {
        --bg-color: #0f172a;
        --text-color: #f1f5f9;
        --text-secondary: #94a3b8;
        --accent-color: #3b82f6;
        --accent-hover: #2563eb;
        --border-color: #334155;
        --shadow: 0 4px 6px -1px rgba(0, 0, 0, 0.3), 0 2px 4px -1px rgba(0, 0, 0, 0.2);
        --shadow-lg: 0 10px 15px -3px rgba(0, 0, 0, 0.4), 0 4px 6px -2px rgba(0, 0, 0, 0.3);
    }
}

* {
    margin: 0;
    padding: 0;
    box-sizing: border-box;
}

body {
    font-family: -apple-system, BlinkMacSystemFont, 'Segoe UI', Roboto, Oxygen, Ubuntu, Cantarell, sans-serif;
    background-color: var(--bg-color);
    color: var(--text-color);
    line-height: 1.6;
    min-height: 100vh;
    display: flex;
    align-items: center;
    justify-content: center;
    padding: 1rem;
    transition: background-color 0.3s ease, color 0.3s ease;
}

.container {
    max-width: 800px;
    width: 100%;
    padding: 2rem;
}

.header {
    text-align: center;
    margin-bottom: 3rem;
}

.title {
    font-size: clamp(1.75rem, 5vw, 3rem);
    font-weight: 700;
    margin-bottom: 0.75rem;
    letter-spacing: -0.02em;
}

.subtitle {
    font-size: clamp(0.95rem, 2.5vw, 1.125rem);
    color: var(--text-secondary);
    max-width: 600px;
    margin: 0 auto;
}

.countdown-section {
    margin-bottom: 3rem;
}

.countdown {
    display: grid;
    grid-template-columns: repeat(4, 1fr);
    gap: 1rem;
    margin-bottom: 2rem;
}

@media (max-width: 640px) {
    .countdown {
        grid-template-columns: repeat(2, 1fr);
        gap: 0.75rem;
    }
}

.countdown-item {
    background: var(--bg-color);
    border: 2px solid var(--border-color);
    border-radius: 12px;
    padding: 1.5rem 1rem;
    text-align: center;
    box-shadow: var(--shadow);
    transition: transform 0.2s ease, box-shadow 0.2s ease;
}

.countdown-item:hover {
    transform: translateY(-2px);
    box-shadow: var(--shadow-lg);
}

.countdown-value {
    display: block;
    font-size: clamp(2rem, 8vw, 3.5rem);
    font-weight: 700;
    font-variant-numeric: tabular-nums;
    line-height: 1;
    margin-bottom: 0.5rem;
    color: var(--accent-color);
}

.countdown-label {
    display: block;
    font-size: clamp(0.875rem, 2vw, 1rem);
    text-transform: uppercase;
    letter-spacing: 0.05em;
    color: var(--text-secondary);
    font-weight: 600;
}

.status-message {
    text-align: center;
    font-size: 1.25rem;
    font-weight: 600;
    color: var(--accent-color);
    min-height: 2rem;
    padding: 0.5rem;
}

.info-section {
    background: var(--bg-color);
    border: 2px solid var(--border-color);
    border-radius: 12px;
    padding: 2rem;
    box-shadow: var(--shadow);
}

.target-time {
    text-align: center;
    margin-bottom: 1.5rem;
    padding-bottom: 1.5rem;
    border-bottom: 1px solid var(--border-color);
}

.target-label {
    font-size: 0.875rem;
    text-transform: uppercase;
    letter-spacing: 0.05em;
    color: var(--text-secondary);
    margin-bottom: 0.5rem;
    font-weight: 600;
}

.target-value {
    font-size: 1.125rem;
    font-weight: 600;
    margin-bottom: 0.25rem;
}

.target-local {
    font-size: 1rem;
    color: var(--text-secondary);
}

.disclaimer {
    text-align: center;
    font-size: 0.875rem;
    color: var(--text-secondary);
    line-height: 1.5;
    margin-bottom: 1.5rem;
    padding: 0 1rem;
}

.copy-button {
    display: block;
    width: 100%;
    max-width: 200px;
    margin: 0 auto;
    padding: 0.75rem 1.5rem;
    font-size: 1rem;
    font-weight: 600;
    color: #ffffff;
    background-color: var(--accent-color);
    border: none;
    border-radius: 8px;
    cursor: pointer;
    transition: background-color 0.2s ease, transform 0.2s ease;
    box-shadow: var(--shadow);
}

.copy-button:hover {
    background-color: var(--accent-hover);
    transform: translateY(-1px);
    box-shadow: var(--shadow-lg);
}

.copy-button:active {
    transform: translateY(0);
}

.copy-button:focus {
    outline: 2px solid var(--accent-color);
    outline-offset: 2px;
}

@media (max-width: 640px) {
    .container {
        padding: 1.5rem;
    }

    .header {
        margin-bottom: 2rem;
    }

    .countdown-section {
        margin-bottom: 2rem;
    }

    .info-section {
        padding: 1.5rem;
    }

    .disclaimer {
        padding: 0;
    }
}