:root {
    --primary-color: #4a90e2;
    --primary-hover: #357abd;
    --danger-color: #e74c3c;
    --danger-hover: #c0392b;
    --bg-color: #f5f7fa;
    --card-bg: #ffffff;
    --text-color: #333333;
    --text-secondary: #666666;
    --border-radius: 12px;
    --shadow: 0 4px 6px rgba(0, 0, 0, 0.1);
    --transition: all 0.3s ease;
}

* {
    box-sizing: border-box;
    margin: 0;
    padding: 0;
}

body {
    font-family: 'Segoe UI', Tahoma, Geneva, Verdana, sans-serif;
    background-color: var(--bg-color);
    color: var(--text-color);
    line-height: 1.6;
    min-height: 100vh;
    display: flex;
    flex-direction: column;
}

.container {
    max-width: 1200px;
    margin: 0 auto;
    padding: 20px;
    width: 100%;
    flex: 1;
}

/* Landing Page */
.landing-container {
    display: flex;
    justify-content: center;
    align-items: center;
    min-height: 80vh;
}

.card {
    background: var(--card-bg);
    padding: 40px;
    border-radius: var(--border-radius);
    box-shadow: var(--shadow);
    width: 100%;
    max-width: 400px;
    text-align: center;
}

.logo {
    font-size: 2.5rem;
    color: var(--primary-color);
    margin-bottom: 10px;
    font-weight: bold;
}

.subtitle {
    color: var(--text-secondary);
    margin-bottom: 30px;
}

.form-group {
    margin-bottom: 20px;
    text-align: left;
}

.form-group label {
    display: block;
    margin-bottom: 8px;
    font-weight: 500;
}

input[type="text"] {
    width: 100%;
    padding: 12px;
    border: 2px solid #e0e0e0;
    border-radius: 8px;
    font-size: 1rem;
    transition: var(--transition);
}

input[type="text"]:focus {
    border-color: var(--primary-color);
    outline: none;
}

.btn {
    display: inline-block;
    width: 100%;
    padding: 12px;
    border: none;
    border-radius: 8px;
    font-size: 1rem;
    font-weight: 600;
    cursor: pointer;
    transition: var(--transition);
    text-decoration: none;
    text-align: center;
}

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

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

.btn-outline {
    background-color: transparent;
    border: 2px solid var(--primary-color);
    color: var(--primary-color);
    margin-top: 10px;
}

.btn-outline:hover {
    background-color: rgba(74, 144, 226, 0.1);
}

.divider {
    margin: 20px 0;
    color: var(--text-secondary);
    font-size: 0.9rem;
    display: flex;
    align-items: center;
}

.divider::before, .divider::after {
    content: "";
    flex: 1;
    border-bottom: 1px solid #e0e0e0;
}

.divider::before {
    margin-right: 10px;
}

.divider::after {
    margin-left: 10px;
}

/* Room Page */
.room-header {
    background: var(--card-bg);
    padding: 20px;
    border-radius: var(--border-radius);
    box-shadow: var(--shadow);
    margin-bottom: 20px;
    display: flex;
    justify-content: space-between;
    align-items: center;
    flex-wrap: wrap;
    gap: 15px;
}

.room-info h1 {
    font-size: 1.5rem;
    margin-bottom: 5px;
}

.room-code {
    color: var(--primary-color);
    font-family: monospace;
    font-size: 1.8rem;
    font-weight: bold;
    letter-spacing: 2px;
}

.share-link {
    display: flex;
    align-items: center;
    gap: 10px;
    background: #f0f0f0;
    padding: 8px 15px;
    border-radius: 20px;
    font-size: 0.9rem;
    cursor: pointer;
}

.actions-bar {
    display: flex;
    gap: 15px;
    margin-bottom: 20px;
    flex-wrap: wrap;
}

.btn-action {
    padding: 10px 20px;
    border-radius: 8px;
    border: none;
    cursor: pointer;
    font-weight: 600;
    display: flex;
    align-items: center;
    gap: 8px;
    transition: var(--transition);
}

.btn-upload {
    background-color: var(--primary-color);
    color: white;
    flex: 1;
    justify-content: center;
}

.btn-danger {
    background-color: white;
    color: var(--danger-color);
    border: 1px solid var(--danger-color);
}

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

.file-grid {
    display: grid;
    grid-template-columns: repeat(auto-fill, minmax(200px, 1fr));
    gap: 20px;
}

.file-card {
    background: var(--card-bg);
    border-radius: var(--border-radius);
    box-shadow: var(--shadow);
    overflow: hidden;
    transition: var(--transition);
    position: relative;
    display: flex;
    flex-direction: column;
}

.file-card:hover {
    transform: translateY(-5px);
    box-shadow: 0 8px 15px rgba(0,0,0,0.1);
}

.file-preview {
    height: 150px;
    background: #f0f0f0;
    display: flex;
    justify-content: center;
    align-items: center;
    overflow: hidden;
}

.file-preview img {
    width: 100%;
    height: 100%;
    object-fit: cover;
}

.file-icon {
    font-size: 3rem;
    color: var(--text-secondary);
}

.file-info {
    padding: 15px;
    flex: 1;
}

.file-name {
    font-weight: 600;
    margin-bottom: 5px;
    white-space: nowrap;
    overflow: hidden;
    text-overflow: ellipsis;
    font-size: 0.95rem;
}

.file-meta {
    font-size: 0.8rem;
    color: var(--text-secondary);
    display: flex;
    justify-content: space-between;
}

.file-actions {
    padding: 10px 15px;
    border-top: 1px solid #f0f0f0;
    display: flex;
    justify-content: space-between;
}

.btn-icon {
    background: none;
    border: none;
    cursor: pointer;
    color: var(--text-secondary);
    transition: var(--transition);
    padding: 5px;
}

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

.btn-icon.delete:hover {
    color: var(--danger-color);
}

/* Upload Progress */
.progress-container {
    margin-top: 20px;
    display: none;
}

.progress-bar-bg {
    width: 100%;
    height: 8px;
    background: #e0e0e0;
    border-radius: 4px;
    overflow: hidden;
}

.progress-bar-fill {
    height: 100%;
    background: var(--primary-color);
    width: 0%;
    transition: width 0.3s ease;
}

/* Empty State */
.empty-state {
    text-align: center;
    padding: 50px;
    color: var(--text-secondary);
    grid-column: 1 / -1;
}

.empty-icon {
    font-size: 4rem;
    margin-bottom: 15px;
    opacity: 0.5;
}

/* Toast */
.toast {
    position: fixed;
    bottom: 20px;
    right: 20px;
    background: #333;
    color: white;
    padding: 12px 24px;
    border-radius: 8px;
    box-shadow: 0 4px 12px rgba(0,0,0,0.2);
    transform: translateY(100px);
    transition: transform 0.3s ease;
    z-index: 1000;
}

.toast.show {
    transform: translateY(0);
}

/* Responsive */
@media (max-width: 600px) {
    .room-header {
        flex-direction: column;
        align-items: stretch;
        text-align: center;
    }
    
    .share-link {
        justify-content: center;
    }
    
    .actions-bar {
        flex-direction: column;
    }
}

/* Footer */
footer {
    text-align: center;
    padding: 20px;
    background-color: var(--card-bg);
    margin-top: auto;
    box-shadow: 0 -2px 10px rgba(0,0,0,0.05);
}

footer p {
    font-size: 1.1rem;
    color: var(--text-secondary);
}

footer a {
    color: var(--primary-color);
    text-decoration: none;
    font-weight: bold;
    font-size: 1.2rem;
}

footer a:hover {
    text-decoration: underline;
}