/* VARIABEL DESAIN UTAMA (FUTURISTIC DARK THEME) */
:root {
    --bg-main: #0f172a;
    --bg-card: rgba(30, 41, 59, 0.7);
    --bg-card-border: rgba(255, 255, 255, 0.1);
    --primary-cyan: #06b6d4;
    --primary-blue: #3b82f6;
    --accent-violet: #8b5cf6;
    --text-light: #f8fafc;
    --text-muted: #94a3b8;
    --success-green: #10b981;
    --danger-red: #ef4444;
    --font-family: 'Segoe UI', system-ui, -apple-system, sans-serif;
}

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

body {
    background-color: var(--bg-main);
    background-image: 
        radial-gradient(at 0% 0%, rgba(6, 182, 212, 0.15) 0px, transparent 50%),
        radial-gradient(at 100% 100%, rgba(139, 92, 246, 0.15) 0px, transparent 50%);
    color: var(--text-light);
    font-family: var(--font-family);
    line-height: 1.6;
    min-height: 100vh;
}

.symbol-highlight {
    background: rgba(6, 182, 212, 0.2);
    color: var(--primary-cyan);
    padding: 0.15rem 0.5rem;
    border-radius: 6px;
    font-weight: 700;
    border: 1px solid rgba(6, 182, 212, 0.35);
    display: inline-block;
}

/* HEADER & NAVBAR */
.app-header {
    background: rgba(15, 23, 42, 0.85);
    backdrop-filter: blur(12px);
    border-bottom: 1px solid var(--bg-card-border);
    padding: 1rem 2rem;
    display: flex;
    justify-content: space-between;
    align-items: center;
    position: sticky;
    top: 0;
    z-index: 100;
}

.logo-container { display: flex; align-items: center; gap: 1rem; }
.logo-icon { font-size: 2.2rem; color: var(--primary-cyan); }
.logo-container h1 {
    font-size: 1.4rem;
    background: linear-gradient(90deg, var(--primary-cyan), var(--accent-violet));
    -webkit-background-clip: text;
    -webkit-text-fill-color: transparent;
}
.nav-links { display: flex; gap: 0.5rem; }
.nav-btn {
    background: transparent;
    border: 1px solid transparent;
    color: var(--text-muted);
    padding: 0.5rem 1rem;
    border-radius: 8px;
    cursor: pointer;
    font-weight: 600;
}
.nav-btn:hover, .nav-btn.active {
    background: rgba(6, 182, 212, 0.15);
    color: var(--primary-cyan);
    border-color: rgba(6, 182, 212, 0.3);
}
.btn-accent {
    background: linear-gradient(135deg, var(--primary-blue), var(--accent-violet));
    color: #fff;
    border: none;
}

/* CARDS & LAYOUT */
.main-content { max-width: 1200px; margin: 2rem auto; padding: 0 1.5rem; }
.tab-content { display: none; }
.tab-content.active { display: block; animation: fadeIn 0.4s ease-in-out; }
@keyframes fadeIn { from { opacity: 0; } to { opacity: 1; } }

.card {
    background: var(--bg-card);
    backdrop-filter: blur(12px);
    border: 1px solid var(--bg-card-border);
    border-radius: 16px;
    padding: 1.8rem;
    margin-bottom: 1.5rem;
}
.grid-2 { display: grid; grid-template-columns: repeat(auto-fit, minmax(300px, 1fr)); gap: 1.5rem; }
.grid-4 { display: grid; grid-template-columns: repeat(auto-fit, minmax(220px, 1fr)); gap: 1.5rem; }

/* HERO BANNER */
.hero-banner {
    display: flex;
    align-items: center;
    justify-content: space-between;
    background: linear-gradient(135deg, rgba(6, 182, 212, 0.1), rgba(139, 92, 246, 0.1));
    border: 1px solid var(--bg-card-border);
    border-radius: 20px;
    padding: 3rem;
    margin-bottom: 2rem;
}
.badge {
    background: rgba(6, 182, 212, 0.2);
    color: var(--primary-cyan);
    padding: 0.3rem 0.8rem;
    border-radius: 20px;
}
.btn-primary, .btn-secondary {
    padding: 0.75rem 1.5rem;
    border-radius: 10px;
    font-weight: 600;
    cursor: pointer;
    border: none;
}
.btn-primary { background: linear-gradient(135deg, var(--primary-cyan), var(--primary-blue)); color: #fff; }
.btn-secondary { background: rgba(255, 255, 255, 0.1); color: var(--text-light); }

.materi-tabs { display: flex; gap: 0.5rem; margin-bottom: 1.5rem; overflow-x: auto; }
.m-subnav {
    background: rgba(255, 255, 255, 0.05);
    border: 1px solid var(--bg-card-border);
    color: var(--text-muted);
    padding: 0.6rem 1.2rem;
    border-radius: 8px;
    cursor: pointer;
}
.m-subnav.active { background: var(--primary-cyan); color: #000; font-weight: bold; }
.materi-step { display: none; }
.materi-step.active { display: block; }

.formula-card {
    background: rgba(6, 182, 212, 0.1);
    border-left: 4px solid var(--primary-cyan);
    padding: 1.2rem;
    border-radius: 8px;
    margin: 1rem 0;
}

/* SIMULASI UI */
.sim-selector { display: flex; gap: 0.5rem; margin-bottom: 1.5rem; }
.sim-tab-btn { flex: 1; padding: 0.8rem; background: rgba(255, 255, 255, 0.05); border: 1px solid var(--bg-card-border); color: var(--text-light); border-radius: 10px; cursor: pointer; }
.sim-tab-btn.active { background: linear-gradient(135deg, var(--primary-blue), var(--accent-violet)); }
.sim-container { display: none; }
.sim-container.active { display: block; }
.matrix-grid { display: grid; grid-template-columns: repeat(6, 1fr); gap: 0.5rem; margin-top: 1rem; }
.matrix-cell { background: rgba(255, 255, 255, 0.05); border: 1px solid var(--bg-card-border); padding: 0.8rem; text-align: center; border-radius: 8px; }

/* VENN DIAGRAM */
.venn-board { display: flex; justify-content: center; gap: 1rem; margin: 1.5rem 0; background: rgba(0,0,0,0.2); padding: 1.5rem; border-radius: 16px; }
.venn-zone { border: 2px dashed var(--primary-cyan); border-radius: 12px; padding: 1rem; min-width: 130px; min-height: 120px; text-align: center; cursor: pointer; }
.item-pool { display: flex; gap: 0.5rem; flex-wrap: wrap; margin-top: 0.5rem; }
.ball-item { width: 36px; height: 36px; border-radius: 50%; background: var(--primary-cyan); color: #000; display: flex; align-items: center; justify-content: center; font-weight: bold; cursor: pointer; }

/* FORM & TABLE */
.form-group { margin-bottom: 1.2rem; }
.form-control { width: 100%; padding: 0.75rem; background: rgba(15, 23, 42, 0.8); border: 1px solid var(--bg-card-border); color: var(--text-light); border-radius: 8px; }
.data-table { width: 100%; border-collapse: collapse; margin-top: 1rem; }
.data-table th, .data-table td { padding: 0.8rem; border: 1px solid var(--bg-card-border); text-align: left; }
.data-table th { background: rgba(255, 255, 255, 0.05); color: var(--primary-cyan); }

/* FEEDBACK & MODAL */
.feedback-box { margin-top: 1rem; padding: 1rem; border-radius: 8px; }
.feedback-box.success { background: rgba(16, 185, 129, 0.2); border: 1px solid var(--success-green); color: #34d399; }
.feedback-box.danger { background: rgba(239, 68, 68, 0.2); border: 1px solid var(--danger-red); color: #f87171; }

.modal-overlay { position: fixed; top: 0; left: 0; width: 100%; height: 100%; background: rgba(0,0,0,0.8); backdrop-filter: blur(8px); display: flex; align-items: center; justify-content: center; z-index: 1000; }
.modal-overlay.hidden { display: none; }
.modal-card { background: var(--bg-main); border: 1px solid var(--bg-card-border); padding: 2rem; border-radius: 20px; width: 90%; max-width: 450px; position: relative; }
.modal-close { position: absolute; top: 1rem; right: 1rem; background: none; border: none; color: var(--text-muted); font-size: 1.5rem; cursor: pointer; }

.score-display { font-size: 2.5rem; font-weight: bold; color: var(--primary-cyan); margin: 1rem 0; }
.dash-toolbar { display: flex; gap: 1rem; margin-bottom: 1rem; }
.hidden { display: none !important; }
.text-accent { color: var(--primary-cyan); }
.text-center { text-align: center; }
.w-100 { width: 100%; }