/* NYU brand colors - https://www.nyu.edu/employees/.../nyu-colors.html */
:root {
  --nyu-violet: #57068c;
  --nyu-ultra-violet: #8900e1;
  --nyu-deep-violet: #330662;
  --nyu-medium-violet: #702b9d;
  --nyu-light-violet: #eee6f3;
  --nyu-teal: #009b8a;
  --nyu-magenta: #fb0f78;
  --nyu-blue: #59b2d1;
  --nyu-yellow: #f4ec51;
  --nyu-black: #000000;
  --nyu-white: #ffffff;

  --color-bg: #f8f6fa;
  --color-surface: var(--nyu-white);
  --color-primary: var(--nyu-violet);
  --color-primary-hover: var(--nyu-deep-violet);
  --color-accent: var(--nyu-teal);
  --color-text: #1a1a1a;
  --color-text-muted: #555;
  --color-border: #e0dce5;
  --shadow: 0 2px 8px rgba(87, 6, 140, 0.08);
  --shadow-lg: 0 8px 24px rgba(87, 6, 140, 0.12);
  --radius: 10px;
  --radius-sm: 6px;
  --font-sans: 'Inter', -apple-system, BlinkMacSystemFont, 'Segoe UI', Roboto, sans-serif;
}

* {
  box-sizing: border-box;
}

body {
  margin: 0;
  font-family: var(--font-sans);
  font-size: 16px;
  line-height: 1.5;
  color: var(--color-text);
  background: var(--color-bg);
  min-height: 100vh;
}

a {
  color: var(--color-primary);
  text-decoration: none;
}
a:hover {
  color: var(--color-primary-hover);
  text-decoration: underline;
}

/* Layout */
.app-header {
  background: var(--color-primary);
  color: var(--nyu-white);
  padding: 0.75rem 1.5rem;
  display: flex;
  align-items: center;
  justify-content: space-between;
  box-shadow: var(--shadow);
}
.app-header a {
  color: inherit;
  text-decoration: none;
}
.app-header a:hover {
  color: var(--nyu-light-violet);
  text-decoration: none;
}
.app-logo {
  display: inline-flex;
  align-items: center;
  gap: 0.6rem;
  font-weight: 700;
  font-size: 1.25rem;
  letter-spacing: -0.02em;
}

.app-logo-mark {
  width: 28px;
  height: 28px;
  display: block;
  filter: invert(1); /* make black SVG white on violet header */
}

.app-logo-text {
  white-space: nowrap;
}
.app-nav {
  display: flex;
  gap: 1.5rem;
  align-items: center;
}
.app-nav a.active {
  font-weight: 600;
  border-bottom: 2px solid var(--nyu-white);
  padding-bottom: 2px;
}

.main-content {
  max-width: 1200px;
  margin: 0 auto;
  padding: 1.5rem;
}

/* Cards */
.card {
  background: var(--color-surface);
  border-radius: var(--radius);
  box-shadow: var(--shadow);
  padding: 1.25rem 1.5rem;
  margin-bottom: 1rem;
  border: 1px solid var(--color-border);
}
.card h2, .card h3 {
  margin-top: 0;
  color: var(--color-primary);
}

/* Buttons */
.btn {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  gap: 0.5rem;
  padding: 0.6rem 1.2rem;
  font-size: 0.95rem;
  font-weight: 500;
  border-radius: var(--radius-sm);
  border: none;
  cursor: pointer;
  transition: background 0.2s, color 0.2s;
  font-family: inherit;
}
.btn-primary {
  background: var(--color-primary);
  color: var(--nyu-white);
}
.btn-primary:hover {
  background: var(--color-primary-hover);
  color: var(--nyu-white);
}
.btn-secondary {
  background: var(--nyu-light-violet);
  color: var(--color-primary);
}
.btn-secondary:hover {
  background: var(--nyu-medium-violet);
  color: var(--nyu-white);
}
.btn-accent {
  background: var(--color-accent);
  color: var(--nyu-white);
}
.btn-accent:hover {
  background: #007a6d;
  color: var(--nyu-white);
}

/* Forms */
input[type="text"],
input[type="email"],
input[type="password"],
textarea {
  width: 100%;
  padding: 0.6rem 0.75rem;
  font-size: 1rem;
  font-family: inherit;
  border: 1px solid var(--color-border);
  border-radius: var(--radius-sm);
  background: var(--color-surface);
}
input:focus, textarea:focus {
  outline: none;
  border-color: var(--color-primary);
  box-shadow: 0 0 0 3px rgba(87, 6, 140, 0.15);
}
label {
  display: block;
  margin-bottom: 0.35rem;
  font-weight: 500;
  color: var(--color-text);
}
.form-group {
  margin-bottom: 1rem;
}

/* Auth / Login */
.auth-page {
  min-height: 100vh;
  display: flex;
  align-items: center;
  justify-content: center;
  background: linear-gradient(135deg, var(--nyu-light-violet) 0%, var(--color-bg) 50%);
  padding: 1.5rem;
}
.auth-card {
  background: var(--color-surface);
  border-radius: var(--radius);
  box-shadow: var(--shadow-lg);
  padding: 2rem;
  max-width: 400px;
  width: 100%;
  text-align: center;
}
.auth-card h1 {
  margin-top: 0;
  color: var(--color-primary);
  font-size: 1.5rem;
}
.auth-card p {
  color: var(--color-text-muted);
  margin-bottom: 1.5rem;
}
.auth-card .btn {
  width: 100%;
  padding: 0.75rem;
  margin-bottom: 0.5rem;
}

/* Lists */
.list-unstyled { list-style: none; padding: 0; margin: 0; }
.list-item {
  display: flex;
  align-items: center;
  justify-content: space-between;
  padding: 0.75rem 0;
  border-bottom: 1px solid var(--color-border);
}
.list-item:last-child { border-bottom: none; }

/* Video */
.video-wrapper {
  position: relative;
  padding-bottom: 56.25%;
  height: 0;
  overflow: hidden;
  border-radius: var(--radius);
  background: var(--nyu-black);
}
.video-wrapper video {
  position: absolute;
  top: 0;
  left: 0;
  width: 100%;
  height: 100%;
}

/* Lesson content */
.lesson-content blockquote,
.lesson-content p {
  margin: 0.75rem 0;
}
.lesson-content img {
  max-width: 100%;
  height: auto;
  border-radius: var(--radius-sm);
}

/* Message board */
.thread-meta {
  font-size: 0.875rem;
  color: var(--color-text-muted);
  margin-top: 0.25rem;
}
.post {
  padding: 1rem;
  background: var(--color-bg);
  border-radius: var(--radius-sm);
  margin-top: 0.75rem;
  border-left: 3px solid var(--color-primary);
}

/* Utilities */
.text-muted { color: var(--color-text-muted); }
.mt-1 { margin-top: 0.5rem; }
.mt-2 { margin-top: 1rem; }
.mb-2 { margin-bottom: 1rem; }
.flex { display: flex; }
.gap-1 { gap: 0.5rem; }
.gap-2 { gap: 1rem; }