:root {
    --bg-color: #f0f2f5;
    --card-bg: #ffffff;
    --text-color: #1c1e21;
    --accent-color: #007bff;
    --input-border: #ddd;
}

@media (prefers-color-scheme: dark) {
    :root {
        --bg-color: #18191a;
        --card-bg: #242526;
        --text-color: #e4e6eb;
        --accent-color: #4599ff;
        --input-border: #3e4042;
    }
}

body {
    font-family: 'Segoe UI', Tahoma, Geneva, Verdana, sans-serif;
    background-color: var(--bg-color);
    color: var(--text-color);
    display: flex;
    justify-content: center;
    align-items: center;
    height: 100vh;
    margin: 0;
    transition: background-color 0.3s ease;
    user-select: none;
}

.container {
    background-color: var(--card-bg);
    padding: 2rem;
    border-radius: 12px;
    box-shadow: 0 4px 15px rgba(0, 0, 0, 0.1);
    width: 100%;
    max-width: 350px;
    text-align: center;
}

.container > div {
    display: flex; 
    gap: 5px;
}

.set-today-btn {
    width: auto;
    padding: 0 10px;
    margin-bottom: 15px;
}

h2 {
    margin-bottom: 1.5rem;
    font-size: 1.2rem;
}

label {
    display: block;
    text-align: left;
    margin-bottom: 5px;
    font-size: 0.9rem;
    opacity: 0.8;
}

input {
    width: 100%;
    padding: 10px;
    margin-bottom: 15px;
    border: 1px solid var(--input-border);
    border-radius: 6px;
    background-color: var(--card-bg);
    color: var(--text-color);
    box-sizing: border-box;
}

input[readonly] {
    background-color: rgba(0, 123, 255, 0.05);
    border-color: var(--accent-color);
    font-weight: bold;
    cursor: default;
}

button {
    width: 100%;
    padding: 12px;
    background-color: var(--accent-color);
    color: white;
    border: none;
    border-radius: 6px;
    cursor: pointer;
    font-size: 1rem;
    font-weight: 600;
    transition: opacity 0.2s;
}

button:hover {
    opacity: 0.9;
}

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