:root {
    --bg-main: #f8fafc;
    --bg-sidebar: #000000;
    --bg-card: #ffffff;
    --text-primary: #121212;
    --text-secondary: #64748b;
    --accent: #000000;
    --border: #e2e8f0;
    --shadow-premium: 0 10px 25px -5px rgba(0, 0, 0, 0.05), 0 8px 10px -6px rgba(0, 0, 0, 0.05);
    --font-heading: 'Instrument Sans', sans-serif;
    --font-body: 'Inter', sans-serif;
}

* {
    margin: 0;
    padding: 0;
    box-sizing: border-box;
    -webkit-font-smoothing: antialiased;
}

body {
    font-family: var(--font-body);
    background: var(--bg-main);
}

.app-layout {
    display: flex;
    min-height: 100vh;
}

.sidebar {
    background: var(--bg-sidebar);
    width: 280px;
    min-width: 280px;
    height: 100vh;
    position: sticky;
    top: 0;
    padding: 40px 24px;
    display: flex;
    flex-direction: column;
    z-index: 1000;
    border-right: 1px solid #222;
}

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

.nav-link {
    display: flex;
    align-items: center;
    gap: 14px;
    padding: 14px 18px;
    border-radius: 14px;
    text-decoration: none;
    color: #888;
    font-size: 0.95rem;
    font-weight: 600;
    transition: all 0.25s cubic-bezier(0.4, 0, 0.2, 1);
}

.nav-link i {
    width: 20px;
    font-size: 1.1rem;
}

.nav-link:hover {
    background: #111;
    color: #fff;
    transform: translateX(4px);
}

.nav-link.active {
    background: #fff !important;
    color: #000 !important;
    box-shadow: 0 4px 12px rgba(255,255,255,0.15);
}

.main-wrapper {
    flex: 1;
    min-width: 0;
    background: var(--bg-main);
}

.main-content {
    padding: 64px 48px;
    max-width: 1200px;
    margin: 0 auto;
}

h1 {
    font-family: var(--font-heading);
    font-size: 2.75rem;
    font-weight: 700;
    letter-spacing: -0.05em;
    margin-bottom: 8px;
}

.subtitle {
    color: var(--text-secondary);
    font-size: 1.15rem;
    margin-bottom: 60px;
}

.tools-grid {
    display: grid;
    grid-template-columns: 1fr 1fr;
    gap: 24px;
}

.dropzone {
    background: var(--bg-card);
    border: 1px solid var(--border);
    border-radius: 24px;
    padding: 60px 32px;
    text-align: center;
    box-shadow: var(--shadow-premium);
    transition: all 0.25s cubic-bezier(0.4, 0, 0.2, 1);
    display: flex;
    flex-direction: column;
    align-items: center;
    justify-content: center;
}

.dropzone:hover {
    transform: translateY(-4px);
    border-color: #cbd5e1;
}

.dropzone-icon {
    width: 56px;
    height: 56px;
    background: #f8fafc;
    border-radius: 16px;
    display: flex;
    align-items: center;
    justify-content: center;
    margin-bottom: 24px;
}

.dropzone h3 { font-family: var(--font-heading); font-size: 1.25rem; font-weight: 700; margin-bottom: 6px; }
.dropzone p { color: var(--text-secondary); font-size: 0.9rem; margin-bottom: 24px; }

.btn {
    background: var(--accent);
    color: #fff;
    border: none;
    padding: 16px 32px;
    border-radius: 14px;
    font-weight: 700;
    font-size: 0.95rem;
    cursor: pointer;
    transition: opacity 0.2s;
}

.btn:hover { opacity: 0.9; }

.saving-card {
    background: var(--bg-card);
    border: 1px solid var(--border);
    border-radius: 24px;
}

@media (max-width: 768px) {
    .app-layout { flex-direction: column; }
    .sidebar { display: none; }
    .main-content { padding: 40px 20px; }
    .tools-grid { grid-template-columns: 1fr; }
}