:root {
    --spotify-green: #1DB954;
    --dark: #0c0f11;
    --mid-dark: #12171c;
    --light: #f7fbff;
    --muted: #9fb3c8;
    --border: #1f252b;
    --card: rgba(18, 23, 28, 0.8);
    --shadow: 0 24px 60px rgba(0, 0, 0, 0.35);
    --radius: 16px;
}

* {
    box-sizing: border-box;
}

body {
    margin: 0;
    font-family: "Inter", system-ui, -apple-system, BlinkMacSystemFont, "Segoe UI", sans-serif;
    background: radial-gradient(circle at 10% 20%, rgba(29, 185, 84, 0.16), transparent 25%),
    radial-gradient(circle at 90% 10%, rgba(29, 185, 84, 0.12), transparent 25%),
    radial-gradient(circle at 70% 80%, rgba(29, 185, 84, 0.14), transparent 20%),
    linear-gradient(135deg, #0b1015 0%, #0f1620 35%, #0c1116 100%);
    color: var(--light);
    min-height: 100vh;
    display: flex;
    flex-direction: column;
}

.top-bar {
    display: flex;
    align-items: center;
    justify-content: space-between;
    padding: 20px 32px;
    position: sticky;
    top: 0;
    z-index: 10;
    backdrop-filter: blur(12px);
    background: rgba(11, 16, 21, 0.65);
    border-bottom: 1px solid var(--border);
}

.logo {
    display: inline-flex;
    align-items: center;
    gap: 10px;
    font-weight: 700;
    letter-spacing: 0.4px;
}

.logo-icon {
    font-size: 20px;
    display: grid;
    place-items: center;
    height: 40px;
    width: 40px;
    background: linear-gradient(135deg, var(--spotify-green), #1aa34a);
    border-radius: 50%;
    color: #0a0d0f;
}

.logo-text {
    font-size: 18px;
}

.layout {
    width: min(520px, 100% - 36px);
    margin: 72px auto 48px;
    display: flex;
    flex-direction: column;
    gap: 20px;
    align-items: center;
    text-align: center;
}

.auth-stack {
    display: grid;
    gap: 8px;
}

h1 {
    margin: 0;
    font-size: clamp(26px, 4vw, 34px);
    line-height: 1.15;
}

.lede {
    margin: 0;
    color: var(--muted);
    font-size: 15px;
}

.auth-card {
    background: var(--card);
    border: 1px solid var(--border);
    border-radius: var(--radius);
    padding: 24px;
    box-shadow: var(--shadow);
    backdrop-filter: blur(10px);
    width: 100%;
}

.tab-switcher {
    display: grid;
    grid-template-columns: repeat(2, 1fr);
    gap: 12px;
    margin-bottom: 12px;
    background: rgba(255, 255, 255, 0.02);
    padding: 6px;
    border-radius: 12px;
}

.tab-button {
    border: none;
    background: transparent;
    color: var(--muted);
    padding: 12px 14px;
    border-radius: 10px;
    font-weight: 700;
    cursor: pointer;
    transition: all 0.18s ease;
}

.tab-button.active {
    background: linear-gradient(135deg, rgba(29, 185, 84, 0.35), rgba(29, 185, 84, 0.24));
    color: var(--light);
}

.form {
    display: none;
    flex-direction: column;
    gap: 14px;
    margin-top: 12px;
}

.form.active {
    display: flex;
}

.form-group {
    display: flex;
    flex-direction: column;
    gap: 6px;
}

label {
    font-weight: 600;
    color: var(--light);
}

input {
    background: rgba(255, 255, 255, 0.04);
    border: 1px solid var(--border);
    border-radius: 12px;
    padding: 12px;
    color: var(--light);
    outline: none;
    transition: border-color 0.2s ease, box-shadow 0.2s ease;
}

input:focus {
    border-color: rgba(29, 185, 84, 0.6);
    box-shadow: 0 0 0 3px rgba(29, 185, 84, 0.12);
}

.primary-button {
    border: none;
    background: linear-gradient(135deg, var(--spotify-green), #1aa34a);
    color: #041006;
    font-weight: 800;
    padding: 14px;
    border-radius: 12px;
    cursor: pointer;
    transition: transform 0.2s ease, box-shadow 0.2s ease;
    box-shadow: 0 12px 30px rgba(29, 185, 84, 0.25);
}

.primary-button:hover {
    transform: translateY(-1px);
    box-shadow: 0 16px 40px rgba(29, 185, 84, 0.3);
}

.helper-text {
    margin: 0;
    color: var(--muted);
    font-size: 14px;
}

.link-button {
    background: none;
    border: none;
    padding: 0;
    color: var(--spotify-green);
    font-weight: 700;
    cursor: pointer;
}

.form-feedback {
    margin-top: 14px;
    padding: 12px;
    border-radius: 12px;
    background: rgba(29, 185, 84, 0.12);
    border: 1px solid rgba(29, 185, 84, 0.3);
    color: var(--light);
    display: none;
}

.form-feedback.show {
    display: block;
}

@media (max-width: 600px) {
    .top-bar {
        flex-wrap: wrap;
        gap: 12px;
    }
}