:root {
  --bg-color: #f5f7fa;
  --header-bg: #0f1f23;
  --header-text: #ffffff;
  --card-bg: rgba(255, 255, 255, 0.85);
  --card-border: rgba(209, 213, 219, 0.9);
  --text-main: #111827;
  --text-muted: #374151;
  --accent-color: #3ba4b5;
  --accent-hover: #2f8e9c;
  --success-color: #16a34a;
  --danger-color: #dc2626;
  --shadow: 0 10px 25px -5px rgba(15, 31, 35, 0.08);
  --glass-bg: rgba(255, 255, 255, 0.75);
  --glass-border: rgba(255, 255, 255, 0.4);
}

[data-theme="dark"] {
  --bg-color: #0b1214;
  --header-bg: #0f1f23;
  --header-text: #f8fafc;
  --card-bg: rgba(20, 32, 36, 0.85);
  --card-border: rgba(59, 164, 181, 0.15);
  --text-main: #f1f5f9;
  --text-muted: #94a3b8;
  --accent-color: #5ec0cf;
  --accent-hover: #7ed0db;
  --shadow: 0 20px 25px -5px rgba(0, 0, 0, 0.35);
  --glass-bg: rgba(15, 31, 35, 0.88);
  --glass-border: rgba(255, 255, 255, 0.08);
}

* {
  box-sizing: border-box;
  transition: background-color 0.25s ease, color 0.25s ease, border-color 0.25s ease, transform 0.2s ease;
}

body {
  font-family: "Inter", system-ui, -apple-system, sans-serif;
  margin: 0;
  padding: 0;
  background-color: var(--bg-color);
  color: var(--text-main);
  line-height: 1.5;
  background-image:
    radial-gradient(at 0% 0%, rgba(59, 164, 181, 0.08) 0, transparent 50%),
    radial-gradient(at 100% 100%, rgba(22, 163, 74, 0.06) 0, transparent 50%);
  background-attachment: fixed;
}

header {
  background-color: var(--header-bg);
  color: var(--header-text);
  padding: 40px 0;
  text-align: center;
  position: relative;
}

.theme-toggle {
  position: absolute;
  top: 20px;
  right: 20px;
  background: rgba(255, 255, 255, 0.1);
  border: 1px solid rgba(255, 255, 255, 0.2);
  color: white;
  width: 40px;
  height: 40px;
  border-radius: 10px;
  cursor: pointer;
  display: flex;
  align-items: center;
  justify-content: center;
  z-index: 2;
}

.header-container {
  max-width: 900px;
  margin: 0 auto;
  padding: 0 20px;
  position: relative;
  z-index: 1;
}

.header-brand {
  display: flex;
  align-items: center;
  justify-content: center;
  gap: 18px;
  margin-bottom: 8px;
}

#logo {
  width: 68px;
  height: 68px;
  object-fit: contain;
  border-radius: 16px;
}

header h1 {
  margin: 0;
  font-size: 2.4rem;
  font-weight: 800;
  letter-spacing: -0.03em;
}

header p {
  margin: 8px 0 0;
  color: #94a3b8;
}

main {
  max-width: 900px;
  margin: 0 auto;
  padding: 32px 20px 48px;
  display: grid;
  gap: 24px;
}

section {
  background: var(--glass-bg);
  backdrop-filter: blur(12px);
  -webkit-backdrop-filter: blur(12px);
  padding: 28px;
  border-radius: 20px;
  border: 1px solid var(--glass-border);
  box-shadow: var(--shadow);
}

h2 {
  margin: 0 0 18px;
  font-size: 1.35rem;
  display: flex;
  align-items: center;
  gap: 10px;
}

h2::before {
  content: "";
  width: 4px;
  height: 22px;
  background: var(--accent-color);
  border-radius: 2px;
}

.info-item {
  display: flex;
  justify-content: space-between;
  gap: 16px;
  padding: 12px 0;
  border-bottom: 1px solid var(--card-border);
}

.info-item:last-of-type {
  border-bottom: none;
}

.info-label {
  color: var(--text-muted);
  font-weight: 500;
}

.info-value {
  font-weight: 600;
  text-align: right;
}

.hint {
  color: var(--text-muted);
  margin: 0 0 16px;
}

.button-group {
  display: flex;
  flex-wrap: wrap;
  gap: 12px;
  margin-top: 18px;
}

.button {
  flex: 1;
  min-width: 200px;
  min-height: 48px;
  display: inline-flex;
  align-items: center;
  justify-content: center;
  gap: 8px;
  background: var(--accent-color);
  color: white;
  text-decoration: none;
  font-weight: 600;
  border-radius: 12px;
  border: none;
  cursor: pointer;
  box-shadow: 0 4px 12px rgba(59, 164, 181, 0.25);
}

.button:hover {
  background: var(--accent-hover);
  transform: translateY(-2px);
}

.button.secondary {
  background: transparent;
  color: var(--text-main);
  border: 1px solid var(--card-border);
  box-shadow: none;
}

.button.secondary:hover {
  border-color: var(--accent-color);
  color: var(--accent-color);
}

.button.disabled {
  opacity: 0.45;
  pointer-events: none;
}

.status-banner {
  margin-top: 16px;
  padding: 12px 14px;
  border-radius: 12px;
  background: rgba(59, 164, 181, 0.1);
  border: 1px solid rgba(59, 164, 181, 0.2);
  color: var(--text-main);
  font-size: 0.95rem;
}

.status-banner.error {
  background: rgba(220, 38, 38, 0.08);
  border-color: rgba(220, 38, 38, 0.2);
  color: var(--danger-color);
}

.feature-list {
  margin: 0;
  padding-left: 20px;
  color: var(--text-muted);
}

.feature-list li {
  margin-bottom: 8px;
}

footer {
  text-align: center;
  padding: 28px 20px 40px;
  color: var(--text-muted);
  font-size: 0.92rem;
}

footer a {
  color: inherit;
  text-decoration: none;
  font-weight: 600;
}

footer a:hover {
  color: var(--accent-color);
}

@media (max-width: 640px) {
  header h1 {
    font-size: 1.8rem;
  }

  .header-brand {
    flex-direction: column;
  }

  .button {
    width: 100%;
    min-width: unset;
  }
}