:root {
    --bg-dark: #0f172a;
    --bg-card: #1e293b;
    --bg-hover: #334155;
    --text-main: #f8fafc;
    --text-muted: #94a3b8;
    --accent: #3b82f6;
    --accent-hover: #2563eb;
    --border: #334155;
    --success: #10b981;
    --error: #ef4444;
}

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

body {
    font-family: 'Inter', sans-serif;
    background-color: var(--bg-dark);
    color: var(--text-main);
    line-height: 1.5;
}

.app-container {
    display: flex;
    height: 100vh;
    overflow: hidden;
}

/* Sidebar */
.sidebar {
    width: 260px;
    background-color: var(--bg-card);
    border-right: 1px solid var(--border);
    display: flex;
    flex-direction: column;
}

.logo {
    padding: 24px;
    border-bottom: 1px solid var(--border);
    display: flex;
    align-items: center;
    gap: 12px;
}

.logo h2 {
    font-size: 1.25rem;
    font-weight: 700;
    letter-spacing: -0.025em;
}

.badge {
    background-color: rgba(59, 130, 246, 0.2);
    color: var(--accent);
    padding: 4px 8px;
    border-radius: 9999px;
    font-size: 0.75rem;
    font-weight: 600;
}

.main-nav {
    padding: 16px;
    display: flex;
    flex-direction: column;
    gap: 8px;
}

.nav-btn {
    display: flex;
    align-items: center;
    gap: 12px;
    background: none;
    border: none;
    color: var(--text-muted);
    padding: 12px 16px;
    border-radius: 8px;
    font-size: 0.95rem;
    font-weight: 500;
    cursor: pointer;
    transition: all 0.2s;
    text-align: left;
    width: 100%;
}

.nav-btn svg {
    width: 20px;
    height: 20px;
}

.nav-btn:hover {
    background-color: var(--bg-hover);
    color: var(--text-main);
}

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

/* Content Area */
.content-area {
    flex: 1;
    overflow-y: auto;
    padding: 40px;
}

header {
    margin-bottom: 32px;
}

header h1 {
    font-size: 1.875rem;
    font-weight: 700;
    margin-bottom: 8px;
}

header p {
    color: var(--text-muted);
}

.view {
    animation: fadeIn 0.3s ease-in-out;
}

.hidden {
    display: none;
}

@keyframes fadeIn {
    from { opacity: 0; transform: translateY(5px); }
    to { opacity: 1; transform: translateY(0); }
}

/* Cards */
.card {
    background-color: var(--bg-card);
    border: 1px solid var(--border);
    border-radius: 12px;
    padding: 32px;
    box-shadow: 0 4px 6px -1px rgba(0, 0, 0, 0.1), 0 2px 4px -1px rgba(0, 0, 0, 0.06);
}

.section-title {
    font-size: 1.1rem;
    font-weight: 600;
    margin-bottom: 16px;
    color: var(--text-main);
    border-bottom: 1px solid var(--border);
    padding-bottom: 8px;
}

/* Forms */
.form-group-row {
    display: flex;
    gap: 24px;
    margin-bottom: 24px;
}

.form-group {
    flex: 1;
    display: flex;
    flex-direction: column;
    gap: 8px;
}

label {
    font-size: 0.875rem;
    font-weight: 500;
    color: var(--text-muted);
}

input, select {
    background-color: var(--bg-dark);
    border: 1px solid var(--border);
    border-radius: 6px;
    padding: 10px 12px;
    color: var(--text-main);
    font-family: inherit;
    font-size: 0.95rem;
    transition: border-color 0.2s;
}

input:focus, select:focus {
    outline: none;
    border-color: var(--accent);
}

small {
    color: var(--text-muted);
    font-size: 0.75rem;
}

.btn {
    padding: 12px 24px;
    border-radius: 6px;
    font-weight: 600;
    font-size: 0.95rem;
    cursor: pointer;
    transition: all 0.2s;
    border: none;
    display: inline-flex;
    align-items: center;
    justify-content: center;
    gap: 8px;
}

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

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

.btn-outline {
    background-color: transparent;
    border: 1px solid var(--border);
    color: var(--text-main);
}

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

/* Upload Area */
.upload-area {
    border: 2px dashed var(--border);
    border-radius: 12px;
    padding: 48px;
    text-align: center;
    transition: border-color 0.2s, background-color 0.2s;
}

.upload-area.dragover {
    border-color: var(--accent);
    background-color: rgba(59, 130, 246, 0.05);
}

.upload-area svg {
    width: 48px;
    height: 48px;
    color: var(--text-muted);
    margin-bottom: 16px;
}

.upload-area h3 {
    margin-bottom: 8px;
}

.upload-area p {
    color: var(--text-muted);
    margin-bottom: 24px;
}

.hidden-input {
    display: none;
}

.csv-format-hint {
    margin-top: 24px;
    padding: 16px;
    background-color: var(--bg-dark);
    border-radius: 8px;
    border: 1px solid var(--border);
    font-size: 0.875rem;
}

.status-msg {
    margin-top: 16px;
    padding: 12px;
    border-radius: 6px;
    text-align: center;
    font-weight: 500;
}

.status-msg.success { background-color: rgba(16, 185, 129, 0.1); color: var(--success); }
.status-msg.error { background-color: rgba(239, 68, 68, 0.1); color: var(--error); }

.calculated-preview {
    background-color: var(--bg-dark);
    border: 1px solid var(--border);
    border-radius: 8px;
    padding: 16px;
    margin-bottom: 24px;
    display: none;
}
.calculated-preview.show {
    display: block;
}
.preview-grid {
    display: grid;
    grid-template-columns: 1fr 1fr;
    gap: 16px;
}
.preview-item {
    display: flex;
    justify-content: space-between;
    font-size: 0.9rem;
}
.preview-item.total {
    font-weight: bold;
    border-top: 1px solid var(--border);
    padding-top: 8px;
    margin-top: 8px;
    color: var(--accent);
}