:root {
  --bg-color: #fcfdfe;
  --text-color: #0f172a;
  --text-muted: #64748b;
  --nav-bg: rgba(255, 255, 255, 0.7);
  --card-bg: #ffffff;
  --primary: #3b82f6;
  --gradient-1: #60a5fa;
  --gradient-2: #a855f7;
  --primary-gradient: linear-gradient(135deg, var(--gradient-1) 0%, var(--gradient-2) 100%);
  --card-shadow: 0 10px 15px -3px rgba(0, 0, 0, 0.05), 0 4px 6px -2px rgba(0, 0, 0, 0.03);
  --card-hover-shadow: 0 20px 25px -5px rgba(59, 130, 246, 0.1), 0 10px 10px -5px rgba(168, 85, 247, 0.04);
  --border-color: #e2e8f0;
  --glass-border: rgba(255, 255, 255, 0.4);
  --transition: all 0.3s cubic-bezier(0.4, 0, 0.2, 1);
}

[data-theme="dark"] {
  --bg-color: #0b1120;
  --text-color: #f8fafc;
  --text-muted: #94a3b8;
  --nav-bg: rgba(15, 23, 42, 0.7);
  --card-bg: #1e293b;
  --gradient-1: #38bdf8;
  --gradient-2: #c084fc;
  --primary-gradient: linear-gradient(135deg, var(--gradient-1) 0%, var(--gradient-2) 100%);
  --card-shadow: 0 10px 15px -3px rgba(0, 0, 0, 0.3);
  --card-hover-shadow: 0 20px 25px -5px rgba(0, 0, 0, 0.4), 0 0 15px rgba(96, 165, 250, 0.2);
  --border-color: #334155;
  --glass-border: rgba(255, 255, 255, 0.08);
}

* { margin: 0; padding: 0; box-sizing: border-box; }
body { background-color: var(--bg-color); color: var(--text-color); font-family: 'Inter', sans-serif; transition: background-color 0.4s ease; }
h1, h2, h3, .logo-text { font-family: 'Poppins', sans-serif; font-weight: 700; }
p { color: var(--text-muted); }
.text-gradient { background: var(--primary-gradient); -webkit-background-clip: text; -webkit-text-fill-color: transparent; }

@keyframes fadeIn { from { opacity: 0; } to { opacity: 1; } }
@keyframes slideUpFade { from { opacity: 0; transform: translateY(30px); } to { opacity: 1; transform: translateY(0); } }
.fade-in { animation: fadeIn 0.6s ease-out; }
.container-slide-up { animation: slideUpFade 0.5s ease-out; }

/* Nav */
.glass-nav { position: fixed; top: 0; width: 100%; height: 80px; display: flex; justify-content: space-between; align-items: center; padding: 0 8%; background-color: var(--nav-bg); backdrop-filter: blur(12px); border-bottom: 1px solid var(--glass-border); z-index: 1000; }
.logo-container { display: flex; align-items: center; gap: 10px; cursor: pointer; font-size: 1.4rem; }
.btn-theme-toggle { background: var(--card-bg); border: 1px solid var(--border-color); color: var(--text-color); padding: 8px 16px; border-radius: 50px; cursor: pointer; display: flex; align-items: center; gap: 8px; font-weight: 600; }
.theme-icon-dark, [data-theme="dark"] .theme-icon-light { display: none; }
[data-theme="dark"] .theme-icon-dark { display: inline; }

/* Layout */
.page { display: none; padding: 120px 5% 60px; max-width: 1200px; margin: 0 auto; }
.page.active { display: block; }
.hero { text-align: center; padding: 40px 0 60px; }
.hero-title { font-size: 3rem; margin-bottom: 15px; }

/* Grid & Cards */
.grid-container { display: grid; grid-template-columns: repeat(auto-fit, minmax(280px, 1fr)); gap: 30px; }
.premium-card { position: relative; background: var(--card-bg); border-radius: 24px; cursor: pointer; transition: var(--transition); border: 1px solid var(--border-color); box-shadow: var(--card-shadow); text-align: center; padding: 40px 20px; }
.premium-card:hover { transform: translateY(-8px); box-shadow: var(--card-hover-shadow); border-color: var(--gradient-1); }
.card-icon { font-size: 3.5rem; margin-bottom: 20px; }

/* Calculator UI */
.glass-calc-container { background: var(--card-bg); padding: 50px 30px; border-radius: 32px; border: 1px solid var(--border-color); box-shadow: var(--card-shadow); text-align: center; max-width: 500px; margin: 0 auto; }
.wider-container { max-width: 800px; }
.input-group { margin: 30px 0; display: flex; flex-direction: column; align-items: center; gap: 15px; }
.premium-input { width: 100%; max-width: 320px; padding: 14px 20px; border-radius: 12px; border: 2px solid var(--border-color); background: var(--bg-color); color: var(--text-color); font-size: 1.1rem; }
.premium-input:focus { outline: none; border-color: var(--gradient-1); }
.premium-btn { width: 100%; max-width: 320px; padding: 14px 24px; border-radius: 12px; border: none; background: var(--primary-gradient); color: white; font-size: 1.1rem; font-weight: 700; cursor: pointer; transition: var(--transition); }
.premium-btn:hover { transform: translateY(-3px); box-shadow: 0 8px 20px rgba(59, 130, 246, 0.3); }
.back-btn { background: transparent; color: var(--text-muted); border: none; font-weight: 600; margin-top: 30px; cursor: pointer; }

/* Results */
.premium-result-box { margin-top: 20px; padding: 25px; background: var(--bg-color); border-radius: 16px; border: 1px solid var(--border-color); text-align: left; }
.premium-result-box.hidden { display: none; }
.result-item { display: flex; justify-content: space-between; padding: 12px 0; border-bottom: 1px solid var(--border-color); font-size: 1.1rem; }
.result-value { font-weight: 700; color: var(--gradient-1); }
.result-huge { font-size: 3rem; text-align: center; font-weight: 800; color: var(--gradient-1); margin: 10px 0; }

/* Grid Results (Stats/Planets) */
.stats-grid { display: grid; grid-template-columns: repeat(auto-fit, minmax(130px, 1fr)); gap: 15px; margin-top: 15px; }
.stat-box { background: var(--card-bg); border: 1px solid var(--border-color); padding: 20px 10px; border-radius: 12px; text-align: center; }
.stat-value { font-size: 1.4rem; font-weight: 800; color: var(--gradient-1); display: block; }
.stat-label { font-size: 0.8rem; font-weight: 600; text-transform: uppercase; color: var(--text-muted); }