:root {
    /* Theme: Modern Deep Gray (Default) */
    --bg-color: #121212;
    --surface-color: #202026;
    --text-color: #E0E0E0;
    --accent-color: #5AA7DE;
    --shadow-color: rgba(0, 0, 0, 0.5);
}

[data-theme="luxury"] {
    --bg-color: #1A1A2E;
    --surface-color: #2A2A4A;
    --text-color: #E0E0E0;
    --accent-color: #00F2FE;
}

[data-theme="warm"] {
    --bg-color: #1C1C1C;
    --surface-color: #262626;
    --text-color: #E0E0E0;
    --accent-color: #F19E54;
}

[data-theme="scandinavian"] {
    --bg-color: #F9F9FA;
    --surface-color: #ECEEEF;
    --text-color: #374047;
    --accent-color: #5AA7DE;
    --shadow-color: rgba(0, 0, 0, 0.1);
}

* {
    margin: 0;
    padding: 0;
    box-sizing: border-box;
    font-family: 'Inter', -apple-system, BlinkMacSystemFont, 'Segoe UI', Roboto, sans-serif;
}

body {
    background-color: var(--bg-color);
    color: var(--text-color);
    height: 100vh;
    display: flex;
    flex-direction: column;
    overflow: hidden;
    transition: background-color 0.3s ease, color 0.3s ease;
}

/* Layout 1:9 (Top:Bottom) */
header {
    height: 10vh;
    min-height: 60px;
    background-color: var(--surface-color);
    display: grid;
    grid-template-columns: 1fr 8fr 1fr;
    align-items: center;
    padding: 0 20px;
    box-shadow: 0 2px 10px var(--shadow-color);
    z-index: 100;
}

main {
    height: 90vh;
    display: flex;
    overflow: hidden;
}

/* Flexible Panels with Fixed Sidebar Widths */
.left-panel { 
    flex: 0 0 260px; 
    border-right: 1px solid rgba(128, 128, 128, 0.1); 
    transition: flex 0.3s cubic-bezier(0.4, 0, 0.2, 1), transform 0.3s ease;
    position: relative;
    overflow: hidden;
}

.left-panel.collapsed {
    flex: 0 0 0px;
    border-right: none;
}

.center-panel { 
    flex: 1; 
    overflow-y: auto; 
    padding: 40px; 
}

.right-panel { 
    flex: 0 0 320px; 
    border-left: 1px solid rgba(128, 128, 128, 0.1); 
}

/* Sidebar Toggle Button */
.sidebar-toggle {
    position: absolute;
    top: 20px;
    right: -15px;
    width: 30px;
    height: 30px;
    background: var(--surface-color);
    border: 1px solid rgba(128, 128, 128, 0.2);
    border-radius: 50%;
    cursor: pointer;
    display: flex;
    align-items: center;
    justify-content: center;
    z-index: 10;
    box-shadow: 0 2px 5px var(--shadow-color);
    transition: all 0.2s ease;
}

.sidebar-toggle:hover {
    background: var(--accent-color);
    color: white;
}

.collapsed-toggle-btn {
    position: fixed;
    left: 10px;
    top: 50%;
    transform: translateY(-50%);
    z-index: 101;
    display: none;
}

/* 3D Button Style */
.btn-3d {
    background-color: var(--surface-color);
    color: var(--text-color);
    border: none;
    padding: 10px 20px;
    border-radius: 8px;
    cursor: pointer;
    font-weight: 600;
    box-shadow: 0 4px 0 var(--shadow-color);
    transition: all 0.1s active;
    position: relative;
    top: 0;
    display: inline-flex;
    align-items: center;
    justify-content: center;
    gap: 8px;
    outline: none;
}

.btn-3d:active {
    top: 2px;
    box-shadow: 0 2px 0 var(--shadow-color);
}

.btn-accent {
    background-color: var(--accent-color);
    color: white;
}

/* Specific UI Elements */
.logo { font-size: 1.5rem; font-weight: 800; letter-spacing: -1px; }
.ad-slot { 
    background: rgba(128, 128, 128, 0.05); 
    height: 80%; 
    display: flex; 
    align-items: center; 
    justify-content: center;
    border-radius: 4px;
    font-size: 0.8rem;
    color: gray;
}

.legal-notice {
    position: fixed;
    bottom: 10px;
    right: 10px;
    font-size: 0.7rem;
    opacity: 0.5;
}

/* Landing Page Specifics */
.landing-content {
    max-width: 800px;
    margin: 0 auto;
    text-align: center;
}

.hero-title { font-size: 3.5rem; margin-bottom: 20px; }
.hero-desc { font-size: 1.2rem; line-height: 1.6; margin-bottom: 40px; opacity: 0.8; }

.theme-selector {
    display: flex;
    gap: 10px;
    margin-bottom: 30px;
    justify-content: center;
}