:root {
    --primary: #0f172a;    /* Dark Blue */
    --accent: #2563eb;     /* Bright Blue */
    --bg: #f1f5f9;         /* Light Gray BG */
    --card: #ffffff;       /* White */
    --text: #334155;       /* Dark Gray Text */
    --text-light: #64748b; /* Light Gray Text */
    --border: #e2e8f0;
}

* { margin: 0; padding: 0; box-sizing: border-box; font-family: 'Segoe UI', sans-serif; }

body { background: var(--bg); color: var(--text); padding-bottom: 2rem; }

/* Header */
.app-header {
    background: var(--primary);
    color: white;
    padding: 1rem;
    display: flex;
    justify-content: space-between;
    align-items: center;
    position: sticky;
    top: 0;
    z-index: 50;
    box-shadow: 0 4px 10px rgba(0,0,0,0.1);
}

.header-left { display: flex; align-items: center; gap: 15px; }
.app-header h1 { font-size: 1.2rem; font-weight: 600; }
.icon-btn { font-size: 1.4rem; cursor: pointer; }

/* Utilities */
.hidden { display: none !important; }