/* 
  ViperHarmonics: Expert Layout Engine
  Mobile-First Architecture
*/

#main-app {
    display: none;
    min-height: 100vh;
    min-height: 100dvh;
    padding: var(--gap-base);
    gap: var(--gap-base);
}

#main-app.visible {
    display: flex;
    flex-direction: column;
}

header {
    display: flex;
    justify-content: space-between;
    align-items: center;
    padding: 0.75rem 1.25rem;
    background: var(--panel-bg);
    border: 1px solid var(--panel-border);
    backdrop-filter: blur(12px);
    -webkit-backdrop-filter: blur(12px);
    border-radius: var(--border-radius);
    flex-shrink: 0;
}

.header-controls {
    display: flex;
    gap: 0.75rem;
}

/* Core Content Area */
.content-area {
    display: flex;
    flex-direction: column;
    flex: 1;
    gap: var(--gap-base);
    min-height: 0;
}

/* Sidebar / Controls Panel */
.controls-panel {
    background: var(--panel-bg);
    border: 1px solid var(--panel-border);
    backdrop-filter: blur(12px);
    -webkit-backdrop-filter: blur(12px);
    border-radius: var(--border-radius);
    padding: 1.25rem;
    display: flex;
    flex-direction: column;
    gap: 1.25rem;
    overflow-y: auto;
    flex-shrink: 0;
}

/* Main Workspace */
.main-stage {
    flex: 1;
    display: flex;
    flex-direction: column;
    gap: var(--gap-base);
    min-height: 0;
}

/* Dashboard: Visualizer & Notation */
.dashboard-row {
    display: flex;
    flex-direction: column;
    gap: var(--gap-base);
    flex-shrink: 0;
}

.visualizer-container,
.notation-container,
.keyboard-section {
    background: var(--panel-bg);
    border: 1px solid var(--panel-border);
    backdrop-filter: blur(12px);
    -webkit-backdrop-filter: blur(12px);
    border-radius: var(--border-radius);
    position: relative;
}

.visualizer-container {
    min-height: 8rem;
    flex: 1;
    overflow: hidden;
}

.notation-container {
    min-height: 12rem;
    display: flex;
    flex-direction: column;
    flex: 1;
}

.keyboard-section {
    flex: 1;
    padding: 1rem;
    display: flex;
    justify-content: center;
    align-items: center;
    min-height: 14rem;
}

#keyboard-container {
    width: 100%;
    max-width: 64rem; /* 1024px equivalent */
}

/* --- Breakpoint: Tablet (640px+) --- */
@media (min-width: 40rem) {
    .controls-panel {
        display: grid;
        grid-template-columns: repeat(2, 1fr);
        gap: 1.5rem;
    }
    
    .dashboard-row {
        flex-direction: row;
        min-height: 12rem;
    }
}

/* --- Breakpoint: Desktop (1024px+) --- */
@media (min-width: 64rem) {
    #main-app {
        padding: 1.5rem;
        gap: 1.5rem;
    }

    .content-area {
        flex-direction: row;
    }

    .controls-panel {
        display: flex;
        flex-direction: column;
        width: 20rem; /* 320px */
        padding: 1.5rem;
    }

    .main-stage {
        gap: 1.5rem;
    }

    .dashboard-row {
        gap: 1.5rem;
    }
    
    .keyboard-section {
        padding: 2.5rem;
    }
}