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

:root {
    --primary-color: #2563eb;
    --primary-hover: #1d4ed8;
    --danger-color: #dc2626;
    --danger-hover: #b91c1c;
    --success-color: #16a34a;
    --background: #f8fafc;
    --surface: #ffffff;
    --text-primary: #1e293b;
    --text-secondary: #64748b;
    --border-color: #e2e8f0;
    --shadow: 0 1px 3px 0 rgb(0 0 0 / 0.1), 0 1px 2px -1px rgb(0 0 0 / 0.1);
    --shadow-lg: 0 10px 15px -3px rgb(0 0 0 / 0.1), 0 4px 6px -4px rgb(0 0 0 / 0.1);
}

body {
    font-family: -apple-system, BlinkMacSystemFont, 'Segoe UI', Roboto, Oxygen, Ubuntu, Cantarell, sans-serif;
    background: var(--background);
    color: var(--text-primary);
    line-height: 1.6;
    min-height: 100vh;
}

.screen {
    min-height: 100vh;
}

.hidden {
    display: none !important;
}

/* Login Screen */
#loginScreen {
    display: flex;
    align-items: center;
    justify-content: center;
    background: linear-gradient(135deg, #667eea 0%, #764ba2 100%);
}

.login-container {
    background: var(--surface);
    padding: 3rem;
    border-radius: 1rem;
    box-shadow: var(--shadow-lg);
    width: 100%;
    max-width: 400px;
    margin: 1rem;
}

.login-container h1 {
    font-size: 2rem;
    margin-bottom: 0.5rem;
    color: var(--text-primary);
    text-align: center;
}

.subtitle {
    text-align: center;
    color: var(--text-secondary);
    margin-bottom: 2rem;
    font-size: 0.9rem;
}

#loginForm input {
    width: 100%;
    padding: 0.75rem;
    border: 2px solid var(--border-color);
    border-radius: 0.5rem;
    font-size: 1rem;
    margin-bottom: 1rem;
    transition: border-color 0.2s;
}

#loginForm input:focus {
    outline: none;
    border-color: var(--primary-color);
}

#loginForm button {
    width: 100%;
    padding: 0.75rem;
    background: var(--primary-color);
    color: white;
    border: none;
    border-radius: 0.5rem;
    font-size: 1rem;
    font-weight: 600;
    cursor: pointer;
    transition: background-color 0.2s;
}

#loginForm button:hover {
    background: var(--primary-hover);
}

.error-message {
    color: var(--danger-color);
    font-size: 0.875rem;
    margin-top: 0.5rem;
    text-align: center;
}

/* Header */
header {
    background: var(--surface);
    border-bottom: 1px solid var(--border-color);
    box-shadow: var(--shadow);
}

.header-content {
    max-width: 1200px;
    margin: 0 auto;
    padding: 1rem 1.5rem;
    display: flex;
    justify-content: space-between;
    align-items: center;
}

header h1 {
    font-size: 1.5rem;
    color: var(--text-primary);
}

.logout-btn {
    padding: 0.5rem 1rem;
    background: var(--danger-color);
    color: white;
    border: none;
    border-radius: 0.5rem;
    font-size: 0.875rem;
    font-weight: 600;
    cursor: pointer;
    transition: background-color 0.2s;
}

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

/* Main Content */
main {
    max-width: 1200px;
    margin: 0 auto;
    padding: 2rem 1.5rem;
}

section {
    background: var(--surface);
    border-radius: 0.75rem;
    padding: 2rem;
    margin-bottom: 2rem;
    box-shadow: var(--shadow);
}

h2 {
    font-size: 1.25rem;
    margin-bottom: 1.5rem;
    color: var(--text-primary);
}

/* Upload Section */
.upload-area {
    border: 2px dashed var(--border-color);
    border-radius: 0.75rem;
    padding: 3rem 2rem;
    text-align: center;
    transition: all 0.2s;
    cursor: pointer;
}

.upload-area:hover,
.upload-area.dragover {
    border-color: var(--primary-color);
    background: #eff6ff;
}

.upload-icon {
    width: 4rem;
    height: 4rem;
    color: var(--text-secondary);
    margin-bottom: 1rem;
}

.upload-text {
    color: var(--text-secondary);
    margin-bottom: 1rem;
}

.browse-btn {
    padding: 0.75rem 1.5rem;
    background: var(--primary-color);
    color: white;
    border: none;
    border-radius: 0.5rem;
    font-size: 0.875rem;
    font-weight: 600;
    cursor: pointer;
    transition: background-color 0.2s;
}

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

.status-message {
    margin-top: 1rem;
    padding: 0.75rem;
    border-radius: 0.5rem;
    font-size: 0.875rem;
    text-align: center;
}

.status-message.success {
    background: #dcfce7;
    color: #166534;
    border: 1px solid #bbf7d0;
}

.status-message.error {
    background: #fee2e2;
    color: #991b1b;
    border: 1px solid #fecaca;
}

.status-message.info {
    background: #dbeafe;
    color: #1e40af;
    border: 1px solid #bfdbfe;
}

/* Files Section */
.files-header {
    display: flex;
    justify-content: space-between;
    align-items: center;
    margin-bottom: 1.5rem;
}

.files-header h2 {
    margin-bottom: 0;
}

.refresh-btn {
    padding: 0.5rem 1rem;
    background: var(--primary-color);
    color: white;
    border: none;
    border-radius: 0.5rem;
    font-size: 0.875rem;
    font-weight: 600;
    cursor: pointer;
    transition: background-color 0.2s;
}

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

.files-list {
    display: grid;
    gap: 0.75rem;
}

.file-item {
    display: flex;
    justify-content: space-between;
    align-items: center;
    padding: 1rem;
    background: var(--background);
    border: 1px solid var(--border-color);
    border-radius: 0.5rem;
    transition: all 0.2s;
}

.file-item:hover {
    border-color: var(--primary-color);
    box-shadow: var(--shadow);
}

.file-info {
    flex: 1;
}

.file-name {
    font-weight: 600;
    color: var(--text-primary);
    margin-bottom: 0.25rem;
    word-break: break-all;
}

.file-meta {
    font-size: 0.875rem;
    color: var(--text-secondary);
}

.file-actions {
    display: flex;
    gap: 0.5rem;
}

.file-actions button {
    padding: 0.5rem 1rem;
    border: none;
    border-radius: 0.375rem;
    font-size: 0.875rem;
    font-weight: 600;
    cursor: pointer;
    transition: all 0.2s;
}

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

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

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

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

.loading,
.empty-state {
    text-align: center;
    padding: 2rem;
    color: var(--text-secondary);
}

/* Responsive */
@media (max-width: 768px) {
    .file-item {
        flex-direction: column;
        align-items: flex-start;
    }

    .file-actions {
        width: 100%;
        margin-top: 0.75rem;
    }

    .file-actions button {
        flex: 1;
    }

    .header-content {
        padding: 1rem;
    }

    main {
        padding: 1rem;
    }

    section {
        padding: 1.5rem;
    }

    .login-container {
        padding: 2rem;
    }
}