:root {
  --bg-page: #F4F6F9;
  --bg-card: #FFFFFF;
  --card-radius: 12px;
  --card-shadow: 0 1px 4px rgba(0,0,0,0.08);
  --accent-primary: #1A56DB;
  --accent-primary-hover: #1347b8;
  --accent-secondary: #E8EFFD;
  --accent-light: #60A5FA;
  --text-primary: #111827;
  --text-secondary: #6B7280;
  --border: #E5E7EB;
  --border-input: #D1D5DB;
  --color-positive: #16A34A;
  --color-warning: #B45309;
  --color-warning-bg: #FEF3C7;
  --color-negative: #DC2626;
  --color-negative-bg: #FEE2E2;
  --font: 'Inter', sans-serif;
}

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

body {
  font-family: var(--font);
  background: var(--bg-page);
  color: var(--text-primary);
  line-height: 1.5;
}

[hidden] { display: none !important; }

/* Header */
.header {
  background: var(--bg-card);
  padding: 16px 40px;
  display: flex;
  justify-content: space-between;
  align-items: center;
  gap: 16px;
  border-bottom: 1px solid var(--border);
}
.header-left { display: flex; align-items: center; gap: 14px; }
.header-left img { height: 40px; }
.header-left h1 { font-size: 20px; font-weight: 700; }
.header-left p { font-size: 14px; color: var(--text-secondary); }
.header-right { display: flex; align-items: center; gap: 16px; font-size: 13px; color: var(--text-secondary); font-weight: 500; }

.link-btn {
  background: none; border: 1px solid var(--border-input); border-radius: 8px;
  padding: 7px 12px; font: 500 13px var(--font); color: var(--text-primary); cursor: pointer;
  text-decoration: none; white-space: nowrap;
}
.link-btn:hover { border-color: var(--accent-primary); color: var(--accent-primary); }

/* Container */
.container { max-width: 1200px; margin: 0 auto; padding: 32px 40px; }

.section-label {
  font-size: 13px; font-weight: 600; color: var(--text-secondary);
  text-transform: uppercase; letter-spacing: 0.5px; margin-bottom: 16px;
}

/* Global Stats Row */
.global-stats { display: grid; grid-template-columns: 1fr 1fr; gap: 20px; margin-bottom: 40px; }
.global-card {
  background: var(--accent-secondary);
  border-left: 4px solid var(--accent-primary);
  border-radius: var(--card-radius);
  padding: 24px 28px;
  box-shadow: var(--card-shadow);
}
.global-card .card-label { font-size: 13px; font-weight: 500; color: var(--text-secondary); margin-bottom: 6px; }
.global-card .card-value { font-size: 32px; font-weight: 700; font-variant-numeric: tabular-nums; }

/* Filter Bar */
.filter-bar { display: flex; flex-wrap: wrap; gap: 12px 16px; margin-bottom: 24px; align-items: center; }
.filter-bar label { font-size: 13px; font-weight: 500; color: var(--text-secondary); margin-right: -8px; }
.select {
  appearance: none; -webkit-appearance: none;
  background: var(--bg-card) url("data:image/svg+xml,%3Csvg xmlns='http://www.w3.org/2000/svg' width='12' height='12' viewBox='0 0 12 12'%3E%3Cpath fill='%236B7280' d='M2 4l4 4 4-4'/%3E%3C/svg%3E") no-repeat right 12px center;
  border: 1px solid var(--border-input);
  border-radius: 8px;
  padding: 10px 36px 10px 14px;
  font: 500 14px var(--font);
  color: var(--text-primary);
  cursor: pointer;
  min-width: 180px;
  transition: border-color 0.15s;
}
.select:hover { border-color: var(--accent-primary); }
.select:focus, .link-btn:focus-visible, .btn:focus-visible {
  outline: none; border-color: var(--accent-primary); box-shadow: 0 0 0 3px rgba(26,86,219,0.15);
}

/* Cards */
.card { background: var(--bg-card); border-radius: var(--card-radius); box-shadow: var(--card-shadow); padding: 24px 28px; }
.card .card-label { font-size: 13px; font-weight: 500; color: var(--text-secondary); margin-bottom: 4px; }
.card .card-value { font-size: 32px; font-weight: 700; font-variant-numeric: tabular-nums; }
.card .card-context { font-size: 12px; color: var(--text-secondary); margin-top: 4px; }
.card .card-title { font-size: 15px; font-weight: 600; margin-bottom: 16px; }

.stat-row { display: grid; grid-template-columns: repeat(auto-fit, minmax(200px, 1fr)); gap: 20px; margin-bottom: 24px; }

.chart-grid { display: grid; grid-template-columns: repeat(3, minmax(0, 1fr)); gap: 20px; margin-bottom: 24px; }
.chart-grid > *, .stat-row > *, .global-stats > * { min-width: 0; }
.chart-wrapper { height: 280px; position: relative; }

.no-data-overlay {
  display: none; position: absolute; inset: 0;
  justify-content: center; align-items: center; text-align: center;
  font-size: 15px; font-weight: 500; color: var(--text-secondary); background: var(--bg-card);
}

/* Knowledge ring */
.ring-wrap { height: 100%; display: flex; flex-direction: column; align-items: center; justify-content: center; gap: 12px; }
.ring { width: 100%; max-width: 200px; height: auto; max-height: 200px; }
.ring-track { stroke: var(--accent-secondary); }
.ring-value { stroke: var(--color-positive); transition: stroke-dashoffset 0.4s ease; }
.ring-text { font: 700 22px var(--font); fill: var(--text-primary); }
.ring-caption { font-size: 13px; color: var(--text-secondary); text-align: center; }

/* Buttons */
.btn {
  display: inline-flex; align-items: center; justify-content: center; gap: 6px;
  padding: 10px 16px; font: 600 14px var(--font); color: #fff; background: var(--accent-primary);
  border: 1px solid var(--accent-primary); border-radius: 8px; cursor: pointer; transition: background 0.15s;
}
.btn:hover { background: var(--accent-primary-hover); }
.btn:disabled { opacity: 0.5; cursor: not-allowed; }
.btn.secondary { background: var(--bg-card); color: var(--text-primary); border-color: var(--border-input); }
.btn.secondary:hover { border-color: var(--accent-primary); color: var(--accent-primary); }
.btn.small { padding: 6px 10px; font-size: 12px; font-weight: 500; }

/* Login Page */
.login-page { min-height: 100vh; display: flex; justify-content: center; align-items: center; padding: 16px; }
.login-card {
  background: var(--bg-card); border-radius: var(--card-radius); box-shadow: 0 4px 24px rgba(0,0,0,0.10);
  padding: 48px 40px 40px; width: 100%; max-width: 400px; text-align: center;
}
.login-card img { height: 72px; margin-bottom: 28px; }
.login-card h2 { font-size: 20px; font-weight: 700; margin-bottom: 4px; }
.login-card .login-subtitle { font-size: 14px; color: var(--text-secondary); margin-bottom: 28px; }
.login-card input {
  display: block; width: 100%; padding: 12px 14px; font: 14px var(--font);
  border: 1px solid var(--border-input); border-radius: 8px; margin-bottom: 14px; color: var(--text-primary);
}
.login-card input:focus { outline: none; border-color: var(--accent-primary); box-shadow: 0 0 0 3px rgba(26,86,219,0.15); }
.login-card .btn { width: 100%; margin-top: 6px; padding: 12px; font-size: 15px; }
.login-card .login-error { color: var(--color-negative); font-size: 13px; margin-top: 12px; min-height: 20px; }

.loading { padding: 80px 16px; text-align: center; color: var(--text-secondary); }

/* Toast */
.toast {
  position: fixed; bottom: 24px; left: 50%; transform: translateX(-50%);
  background: var(--text-primary); color: #fff; padding: 12px 18px; border-radius: 8px;
  font-size: 14px; box-shadow: 0 4px 16px rgba(0,0,0,0.2); z-index: 50; max-width: calc(100% - 32px);
}
.toast.error { background: var(--color-negative); }

@media (max-width: 900px) {
  .header { padding: 12px 16px; flex-wrap: wrap; }
  .container { padding: 20px 16px; }
  .global-stats, .chart-grid { grid-template-columns: minmax(0, 1fr); }
  .select { min-width: 0; flex: 1 1 160px; }
  .filter-bar label { flex-basis: 100%; margin: 0 0 -8px; }
}