/* Lines 1-16: Root Theme Variables & Dark Mode Toggle */
:root {
    --bg-color: #f1f5f9;
    --card-bg: #ffffff;
    --text-color: #0f172a;
    --border-color: #cbd5e1;
    --primary: #2563eb;
    --primary-hover: #1d4ed8;
    --accent: #f59e0b;
}

[data-theme="dark"] {
    --bg-color: #0f172a;
    --card-bg: #1e293b;
    --text-color: #f8fafc;
    --border-color: #334155;
    --primary: #3b82f6;
    --primary-hover: #2563eb;
}

/* Lines 18-67: Global Webpage Style & Layout Rules */
* {
    box-sizing: border-box;
    margin: 0;
    padding: 0;
    font-family: 'Segoe UI', Tahoma, Geneva, Verdana, sans-serif;
    transition: background-color 0.3s ease, color 0.3s ease, border-color 0.3s ease;
}

body {
    background-color: var(--bg-color);
    color: var(--text-color);
    line-height: 1.6;
    padding: 20px;
    display: flex;
    flex-direction: column;
    align-items: center;
    min-height: 100vh;
}

.container {
    width: 100%;
    max-width: 1100px;
    margin: 0 auto;
}

.card {
    background-color: var(--card-bg);
    border: 1px solid var(--border-color);
    border-radius: 12px;
    padding: 24px;
    margin-bottom: 24px;
    box-shadow: 0 4px 6px -1px rgba(0, 0, 0, 0.1);
}

.btn {
    background-color: var(--primary);
    color: #ffffff;
    border: none;
    padding: 10px 18px;
    border-radius: 6px;
    cursor: pointer;
    font-weight: 600;
    display: inline-flex;
    align-items: center;
    gap: 8px;
}

.btn:hover {
    background-color: var(--primary-hover);
}

.form-group {
    margin-bottom: 16px;
}

.form-group label {
    display: block;
    margin-bottom: 6px;
    font-weight: 500;
}

.form-control {
    width: 100%;
    padding: 10px 14px;
    border: 1px solid var(--border-color);
    border-radius: 6px;
    background-color: var(--card-bg);
    color: var(--text-color);
}

/* Lines 70-76: Responsive Grid Rules */
.room-grid {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(280px, 1fr));
    gap: 20px;
    margin-top: 20px;
}