:root {
    /* Theme: Classic (Default) */
    --primary-color: #1a73e8;
    --primary-hover: #1557b0;
    --tg-color: #24A1DE;
    --danger-color: #d93025;
    --bg-color: #f0f2f5;
    --card-bg: #ffffff;
    --text-main: #202124;
    --text-sub: #5f6368;
    --border-color: #dadce0;
    --shadow: 0 8px 24px rgba(0,0,0,0.12);
    --transition: all 0.3s cubic-bezier(0.4, 0, 0.2, 1);
}

body {
    font-family: -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, Helvetica, Arial, sans-serif;
    display: flex;
    flex-direction: column;
    min-height: 100vh;
    margin: 0;
    background-color: var(--bg-color);
    color: var(--text-main);
    transition: background-color 0.5s ease;
}

@keyframes fadeIn { from { opacity: 0; transform: translateY(10px); } to { opacity: 1; transform: translateY(0); } }

.hidden { display: none !important; }

/* Skeleton Loader */
.skeleton {
    background: linear-gradient(90deg, var(--bg-color) 25%, var(--border-color) 50%, var(--bg-color) 75%);
    background-size: 200% 100%;
    animation: skeleton-loading 1.5s infinite;
}

@keyframes skeleton-loading {
    0% { background-position: 200% 0; }
    100% { background-position: -200% 0; }
}