@import url('https://fonts.googleapis.com/css2?family=DM+Sans:wght@400;500;600&display=swap');

:root {
  --font-brand: 'DM Sans', system-ui, -apple-system, sans-serif;
  --bg: #0d0d12;
  --bg-elevated: #16161f;
  --surface: #1e1e2a;
  --surface-hover: #282836;
  --border: #2e2e3d;
  --text: #eaeaf0;
  --text-muted: #8888a0;
  --accent: #6c8cff;
  --accent-glow: rgba(108, 140, 255, 0.25);
  --success: #4ecca3;
  --danger: #e94560;
  --warning: #f0b429;
  --radius: 1rem;
  --radius-lg: 1.25rem;
  --shadow: 0 8px 32px rgba(0, 0, 0, 0.4);
}

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

body {
  min-height: 100vh;
  font-family: system-ui, -apple-system, "Segoe UI", sans-serif;
  background: var(--bg);
  color: var(--text);
  line-height: 1.5;
}

/* Navigation */
.nav {
  display: flex;
  align-items: center;
  justify-content: space-between;
  padding: 1rem 1.5rem;
  background: var(--bg-elevated);
  border-bottom: 1px solid var(--border);
  position: sticky;
  top: 0;
  z-index: 100;
}

.nav-brand {
  font-family: var(--font-brand);
  font-size: 1.1rem;
  font-weight: 500;
  color: var(--text);
  text-decoration: none;
  letter-spacing: 0.03em;
}

.nav-brand span {
  color: var(--accent);
}

.nav-home {
  display: inline-flex;
  align-items: center;
  gap: 0.4rem;
  padding: 0.5rem 1rem;
  background: var(--surface);
  border: 1px solid var(--border);
  border-radius: 0.6rem;
  color: var(--text);
  text-decoration: none;
  font-size: 0.9rem;
  font-weight: 500;
  transition: background 0.15s, border-color 0.15s;
}

.nav-home:hover {
  background: var(--surface-hover);
  border-color: var(--accent);
}

.nav-actions {
  display: flex;
  align-items: center;
  gap: 0.5rem;
}

.nav-auth {
  display: inline-flex;
  align-items: center;
  max-width: 10rem;
  padding: 0.5rem 0.85rem;
  background: var(--surface);
  border: 1px solid var(--border);
  border-radius: 0.6rem;
  color: var(--text-muted);
  text-decoration: none;
  font-size: 0.82rem;
  font-weight: 500;
  overflow: hidden;
  text-overflow: ellipsis;
  white-space: nowrap;
  transition: background 0.15s, border-color 0.15s, color 0.15s;
}

.nav-auth:hover {
  background: var(--surface-hover);
  border-color: var(--accent);
  color: var(--text);
}

/* Homepage */
.home {
  max-width: 900px;
  margin: 0 auto;
  padding: 3rem 1.5rem 4rem;
}

.home-header {
  text-align: center;
  margin-bottom: 3rem;
}

.home-header h1 {
  font-family: var(--font-brand);
  font-size: 2.35rem;
  font-weight: 500;
  letter-spacing: 0.02em;
  margin-bottom: 0.5rem;
}

.home-header h1 span {
  color: var(--accent);
}

.home-header p {
  color: var(--text-muted);
  font-size: 1.1rem;
}

.home-account {
  display: inline-block;
  margin-top: 1rem;
  padding: 0.5rem 1rem;
  border: 1px solid var(--border);
  border-radius: 0.6rem;
  color: var(--text-muted);
  text-decoration: none;
  font-size: 0.9rem;
  transition: border-color 0.15s, color 0.15s;
}

.home-account:hover {
  border-color: var(--accent);
  color: var(--text);
}

.card-grid {
  display: grid;
  grid-template-columns: repeat(auto-fill, minmax(260px, 1fr));
  gap: 1.25rem;
}

.card {
  display: flex;
  flex-direction: column;
  gap: 0.75rem;
  padding: 1.75rem;
  background: var(--surface);
  border: 1px solid var(--border);
  border-radius: var(--radius-lg);
  text-decoration: none;
  color: inherit;
  transition: transform 0.15s, background 0.15s, border-color 0.15s, box-shadow 0.15s;
}

.card:hover {
  transform: translateY(-4px);
  background: var(--surface-hover);
  border-color: var(--card-accent, var(--accent));
  box-shadow: 0 12px 40px var(--card-glow, var(--accent-glow));
}

.card-icon {
  font-size: 2.25rem;
  line-height: 1;
}

.card h2 {
  font-size: 1.2rem;
  font-weight: 600;
}

.card p {
  color: var(--text-muted);
  font-size: 0.9rem;
}

.card--calc { --card-accent: #6c8cff; --card-glow: rgba(108, 140, 255, 0.2); }
.card--notes { --card-accent: #4ecca3; --card-glow: rgba(78, 204, 163, 0.2); }
.card--convert { --card-accent: #f0b429; --card-glow: rgba(240, 180, 41, 0.2); }
.card--timer { --card-accent: #e94560; --card-glow: rgba(233, 69, 96, 0.2); }
.card--colors { --card-accent: #c77dff; --card-glow: rgba(199, 125, 255, 0.2); }
.card--brain { --card-accent: #ff8c42; --card-glow: rgba(255, 140, 66, 0.2); }

/* Tool pages */
.page {
  max-width: 640px;
  margin: 0 auto;
  padding: 2rem 1.5rem 4rem;
}

.page-title {
  font-size: 1.75rem;
  font-weight: 700;
  margin-bottom: 0.25rem;
  letter-spacing: -0.02em;
}

.page-subtitle {
  color: var(--text-muted);
  margin-bottom: 2rem;
  font-size: 0.95rem;
}

.panel {
  background: var(--surface);
  border: 1px solid var(--border);
  border-radius: var(--radius-lg);
  padding: 1.5rem;
  box-shadow: var(--shadow);
}

/* Shared form elements */
input[type="text"],
input[type="number"],
textarea,
select {
  width: 100%;
  padding: 0.75rem 1rem;
  background: var(--bg);
  border: 1px solid var(--border);
  border-radius: 0.6rem;
  color: var(--text);
  font-size: 1rem;
  font-family: inherit;
  transition: border-color 0.15s;
}

input:focus,
textarea:focus,
select:focus {
  outline: none;
  border-color: var(--accent);
}

textarea {
  resize: vertical;
  min-height: 120px;
}

.btn {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  gap: 0.4rem;
  padding: 0.65rem 1.25rem;
  border: none;
  border-radius: 0.6rem;
  font-size: 0.95rem;
  font-weight: 500;
  font-family: inherit;
  cursor: pointer;
  transition: transform 0.1s, background 0.15s, opacity 0.15s;
}

.btn:active {
  transform: scale(0.97);
}

.btn-primary {
  background: var(--accent);
  color: #fff;
}

.btn-primary:hover {
  background: #5a7aee;
}

.btn-secondary {
  background: var(--surface-hover);
  color: var(--text);
  border: 1px solid var(--border);
}

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

.btn-danger {
  background: var(--danger);
  color: #fff;
}

.btn-danger:hover {
  background: #ff6b6b;
}

.btn-success {
  background: var(--success);
  color: var(--bg);
}

.btn-success:hover {
  background: #6ee7b7;
}

.tabs {
  display: flex;
  gap: 0.5rem;
  margin-bottom: 1.5rem;
}

.tab {
  flex: 1;
  padding: 0.75rem;
  background: var(--bg);
  border: 1px solid var(--border);
  border-radius: 0.6rem;
  color: var(--text-muted);
  font-size: 0.95rem;
  font-weight: 500;
  cursor: pointer;
  transition: background 0.15s, color 0.15s, border-color 0.15s;
}

.tab.active {
  background: var(--accent);
  border-color: var(--accent);
  color: #fff;
}

.tab-content {
  display: none;
}

.tab-content.active {
  display: block;
}