:root {
    --bg-color: #ffffff;
    --text-color: #000000;
    --accent-color: #000000;
    --button-bg: #dddddd;
    --button-hover: #cccccc;
}

.theme-spring {
    --bg-color: #f0fff4;
    --text-color: #2e7d32;
    --accent-color: #ffb3c1;
    --button-bg: #e6ffe6;
    --button-hover: #ccffcc;
    background: url('images/spring.jpg') center/cover no-repeat;
    background-blend-mode: lighten;
    color: #2e5a3d;
}

.theme-summer {
    --bg-color: #fffdeb;
    --text-color: #00695c;
    --accent-color: #ffcc80;
    --button-bg: #fff176;
    --button-hover: #ffee58;
    background: url('images/summer.jpg') center/cover no-repeat;
    background-blend-mode: lighten;
}

.theme-autumn {
    --bg-color: #fff8e1;
    --text-color: #6d4c41;
    --accent-color: #ff8a65;
    --button-bg: #ffe0b2;
    --button-hover: #ffcc80;
    background: url('images/autumn.jpg') center/cover no-repeat;
    background-blend-mode: lighten;
}

.theme-winter {
    --bg-color: #e0f7fa;
    --text-color: #01579b;
    --accent-color: #b3e5fc;
    --button-bg: #ffffff;
    --button-hover: #b2ebf2;
    background: url('images/winter.jpg') center/cover no-repeat;
    background-blend-mode: lighten;
}

body {
    margin: 0;
    padding: 0;
    background-color: var(--bg-color);
    color: var(--text-color);
    transition: all 0.5s ease;
}

.cta-button {
    background-color: var(--button-bg);
    color: var(--text-color);
    border: none;
    padding: 0.8em 1.2em;
    margin-top: 1rem;
    cursor: pointer;
    border-radius: 8px;
    font-weight: 600;
    transition: background-color 0.3s ease;
}

.cta-button:hover {
    background-color: var(--button-hover);
}

.sunlight-glow {
    position: absolute;
    top: -50px;
    left: -50px;
    width: 200%;
    height: 200%;
    background: radial-gradient(circle at center, rgba(255, 241, 179, 0.15), transparent 70%);
    animation: glow 8s ease-in-out infinite;
    pointer-events: none;
    z-index: 0;
}

@keyframes glow {
    0%, 100% { transform: scale(1); opacity: 0.3; }
    50% { transform: scale(1.1); opacity: 0.6; }
}