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

body {
    margin: 0;
    font-family: 'Arial', sans-serif;
    background-color: #121212;
    color: #fff;
    display: flex;
    flex-direction: column;
}

header {
    background-color: #1a1a1a;
    padding: 20px 40px;
    display: flex;
    justify-content: space-between;
    align-items: center;
}

header h1 {
    color: #e63946;
    margin: 0;
    font-size: 2rem;
}

.navbar-nav {
    list-style: none;
    display: flex;
    gap: 1.56rem;
    margin: 0;
    padding: 0;
}

.nav-link {
    color: #fff;
    text-decoration: none;
    font-weight: 600;
}

main h1 {
    text-align: center;
    margin-bottom: 0.625rem;
}

main > p {
    text-align: center;
    max-width: 43.75rem;
    margin: 0 auto 2.5rem auto;
    color: #555;
}

footer {
    background-color: #1a1a1a;
    padding: 2.5rem 1.25rem;
    color: #fff;
    font-weight: 600;

    display: flex;
    justify-content: space-between;
    align-items: center;
}

html, body {
    height: 100%;
    margin: 0;
}

.planner {
    padding: 1.25rem;
    max-width: 37.5rem;
    margin: auto;
    font-family: Arial, sans-serif;
}

.planner label{
    font-size: 1.3rem;
    font-weight: bold;
}

.planner h2 {
    text-align: center;
}

.planner input {
    display: block;
    width: 100%;
    padding: 0.5rem;
    margin: 0.5rem 0;
    border-radius: 0.375rem;
    border: 1px solid #1a1a1a;
}

.planner button {
    padding: 0.625rem;
    margin-top: 0.625rem;
    border: none;
    border-radius: 0.375rem;
    cursor: pointer;
}

.planner ul {
    list-style: none;
    padding: 0;
}

.planner li {
    background: #1e1e1e;
    margin-top: 0.625rem;
    padding: 0.625rem;
    border-radius: 0.375rem;

    display: flex;
    justify-content: space-between;
    align-items: center;
}

.planner li button {
    margin-left: 0.625rem;
    padding: 0.3125rem 0.5rem;
}

.error {
    color: #e63946;
    font-size: 0.9rem;
    margin-top: 0.3125rem;
}