* { box-sizing: border-box; }
body {
    margin: 0;
    min-height: 100vh;
    min-height: 100dvh;
    font-family: 'IBM Plex Sans KR', 'Malgun Gothic', sans-serif;
    background: linear-gradient(145deg, #0c1929, #1e3a5f);
    display: flex;
    align-items: center;
    justify-content: center;
    padding: max(20px, env(safe-area-inset-top)) max(20px, env(safe-area-inset-right)) max(20px, env(safe-area-inset-bottom)) max(20px, env(safe-area-inset-left));
}
.auth-card {
    position: relative;
    width: 100%;
    max-width: 420px;
    background: #fff;
    border-radius: 16px;
    padding: 32px 28px;
    box-shadow: 0 20px 50px rgba(0,0,0,0.25);
}
.auth-build-tag {
    position: absolute;
    top: 14px;
    right: 16px;
    font-size: 11px;
    font-weight: 600;
    color: #94a3b8;
    letter-spacing: 0.02em;
    pointer-events: none;
    user-select: none;
}
.auth-card h1 { margin: 0 0 6px; font-size: 20px; color: #0f172a; }
.auth-card .sub { margin: 0 0 20px; font-size: 13px; color: #64748b; line-height: 1.5; }
label { display: block; font-size: 12px; font-weight: 600; color: #475569; margin-bottom: 6px; }
.pw-field { position: relative; margin-bottom: 14px; }
.pw-field input { width: 100%; border: 1px solid #e2e8f0; border-radius: 10px; padding: 12px 44px 12px 14px; font-size: 15px; margin-bottom: 0; font-family: inherit; }
input[type="text"]:not(.pw-field input) {
    width: 100%; border: 1px solid #e2e8f0; border-radius: 10px; padding: 12px 14px; font-size: 15px; margin-bottom: 14px; font-family: inherit;
}
textarea {
    width: 100%;
    border: 1px solid #e2e8f0;
    border-radius: 10px;
    padding: 12px 14px;
    font-size: 15px;
    margin-bottom: 14px;
    font-family: inherit;
    resize: vertical;
    min-height: 100px;
}
textarea:focus { outline: 2px solid #2563eb; border-color: #2563eb; }
.pw-toggle { position: absolute; right: 8px; top: 50%; transform: translateY(-50%); border: none; background: transparent; color: #64748b; cursor: pointer; padding: 6px; line-height: 0; border-radius: 6px; }
.pw-toggle:hover { color: #2563eb; background: #f1f5f9; }
.pw-toggle svg { width: 20px; height: 20px; display: block; }
.pw-field + .pw-hint { margin-top: -8px; }
.row-flex .pw-field { flex: 1; min-width: 120px; margin-bottom: 0; }
input:focus { outline: 2px solid #2563eb; border-color: #2563eb; }
.course-pick { margin-bottom: 18px; }
.course-pick-title { font-size: 12px; font-weight: 600; color: #475569; margin-bottom: 8px; }
.course-options { display: flex; gap: 10px; }
.course-opt {
    flex: 1;
    border: 2px solid #e2e8f0;
    border-radius: 12px;
    padding: 12px 10px;
    cursor: pointer;
    text-align: center;
    transition: border-color .15s, background .15s;
    user-select: none;
}
.course-opt input { display: none; }
.course-opt:has(input:checked) { border-color: #2563eb; background: #eff6ff; }
.course-opt .flag { font-size: 22px; line-height: 1; margin-bottom: 4px; }
.course-opt .lbl { font-size: 12px; font-weight: 600; color: #334155; }
.btn-primary {
    width: 100%;
    border: none;
    border-radius: 10px;
    padding: 14px;
    font-size: 15px;
    font-weight: 700;
    color: #fff;
    background: linear-gradient(145deg, #2563eb, #1d4ed8);
    cursor: pointer;
    font-family: inherit;
}
.btn-primary:active { transform: scale(0.98); }
.btn-ghost {
    display: block;
    width: 100%;
    margin-top: 12px;
    border: 1px solid #e2e8f0;
    border-radius: 10px;
    padding: 12px;
    font-size: 14px;
    font-weight: 600;
    color: #475569;
    background: #fff;
    cursor: pointer;
    font-family: inherit;
    text-align: center;
    text-decoration: none;
}
.notice { margin-top: 18px; padding-top: 16px; border-top: 1px solid #f1f5f9; }
.notice p { margin: 0 0 8px; font-size: 11px; color: #94a3b8; line-height: 1.5; }
.pw-hint { margin: -6px 0 14px; font-size: 11px; color: #64748b; line-height: 1.45; }
.err { color: #dc2626; font-size: 13px; min-height: 20px; margin-top: 8px; }
.ok-msg { color: #16a34a; font-size: 13px; min-height: 20px; margin-top: 8px; }