:root {
  --bg: #f4f6f8;
  --card: #ffffff;
  --text: #1f2937;
  --accent: #0b5fff;
  --border: #d1d5db;
  --success: #0a7f2e;
  --error: #b91c1c;
}

* {
  box-sizing: border-box;
}

body {
  margin: 0;
  font-family: "Segoe UI", sans-serif;
  color: var(--text);
  background: linear-gradient(180deg, #eef3ff 0%, var(--bg) 40%);
  min-height: 100vh;
  display: flex;
  flex-direction: column;
}

header {
  background: #0f172a;
  color: #fff;
  padding: 1rem 1.25rem;
  display: flex;
  justify-content: space-between;
  align-items: center;
}

header a {
  color: #fff;
  text-decoration: none;
}

.link-button {
  border: 0;
  background: transparent;
  color: #fff;
  cursor: pointer;
  font: inherit;
  padding: 0;
  text-decoration: none;
}

main {
  max-width: 960px;
  margin: 1.5rem auto;
  padding: 0 1rem;
  width: 100%;
  flex: 1;
}

.card {
  background: var(--card);
  border: 1px solid var(--border);
  border-radius: 10px;
  padding: 1rem;
  margin-bottom: 1rem;
}

h1, h2 {
  margin-top: 0;
}

form p {
  margin: 0 0 0.8rem;
}

input[type="file"],
input[type="text"],
input[type="password"] {
  width: 100%;
  border: 1px solid var(--border);
  border-radius: 6px;
  padding: 0.55rem;
}

button,
.btn {
  display: inline-block;
  border: 0;
  background: var(--accent);
  color: #fff;
  border-radius: 6px;
  padding: 0.6rem 0.9rem;
  text-decoration: none;
  cursor: pointer;
}

table {
  width: 100%;
  border-collapse: collapse;
}

th, td {
  text-align: left;
  border-bottom: 1px solid var(--border);
  padding: 0.6rem;
}

.messages {
  list-style: none;
  margin: 0 0 1rem;
  padding: 0;
}

.messages li {
  border-radius: 8px;
  padding: 0.6rem 0.8rem;
  margin-bottom: 0.5rem;
}

.messages .success {
  background: #d9fbe5;
  color: var(--success);
}

.messages .error {
  background: #fee2e2;
  color: var(--error);
}

footer {
  border-top: 1px solid var(--border);
  background: #fff;
  color: #4b5563;
  font-size: 0.9rem;
  padding: 0.8rem 1.25rem;
}