:root {
    --brand-green: #01894d;
    --brand-green-dark: #016b3c;
    --brand-green-light: #e8f5ee;
    --brand-orange: #f39800;
    --brand-orange-light: #fff8ee;
    --bg-color: #f8fafb;
    --card-bg: #ffffff;
    --text-main: #333333;
    --text-sub: #666666;
    --border-color: #e5e7eb;
    --shadow: 0 4px 6px -1px rgba(0, 0, 0, 0.1), 0 2px 4px -1px rgba(0, 0, 0, 0.06);
    --radius: 12px;
}

/* Header */
.main-header {
    background-color: var(--brand-green);
    border-bottom: 2px solid var(--brand-orange);
    padding: 12px 0;
    color: #fff;
    position: sticky;
    top: 0;
    z-index: 100;
}

.main-header-inner {
    max-width: 1000px;
    margin: 0 auto;
    padding: 0 20px;
    display: flex;
    justify-content: space-between;
    align-items: center;
}

.logo-area {
    display: flex;
    align-items: center;
    gap: 12px;
}

.title-icon {
    width: 28px;
    height: 28px;
    color: #fff;
}

.brand-logo {
    font-size: 1.2rem;
    font-weight: 700;
    letter-spacing: -0.02em;
}

.btn-home {
    color: #fff;
    text-decoration: none;
    font-weight: 600;
    font-size: 0.9rem;
    padding: 6px 14px;
    border-radius: 6px;
    transition: background 0.2s;
}

.btn-home:hover {
    background-color: rgba(255, 255, 255, 0.2);
}

/* Cards */
.card {
    background: #fff;
    border-radius: var(--radius);
    border: 1px solid var(--border-color);
    box-shadow: var(--shadow);
}

.form-title {
    font-size: 1.1rem;
    font-weight: 700;
    color: var(--text-main);
    display: flex;
    align-items: center;
    gap: 10px;
}

.section-number {
    display: inline-flex;
    align-items: center;
    justify-content: center;
    width: 24px;
    height: 24px;
    background-color: var(--brand-green);
    color: #fff;
    border-radius: 50%;
    font-size: 0.85rem;
    font-weight: bold;
}

/* Info Section (Accordion) */
.info-section {
    background: #fff;
    border: 1px solid var(--border-color);
    border-radius: var(--radius);
    overflow: hidden;
}

.info-header {
    padding: 14px 20px;
    display: flex;
    justify-content: space-between;
    align-items: center;
    cursor: pointer;
    background: #fcfcfc;
    user-select: none;
}

.info-header h2 {
    font-size: 1rem;
    font-weight: 700;
    color: var(--brand-green);
    display: flex;
    align-items: center;
    gap: 8px;
}

.toggle-icon {
    width: 20px;
    height: 20px;
    color: var(--text-sub);
    transition: transform 0.3s ease;
}

.info-section.collapsed .toggle-icon {
    transform: rotate(-180deg);
}

.info-content {
    padding: 20px;
    border-top: 1px solid var(--border-color);
    display: block;
}

.info-section.collapsed .info-content {
    display: none;
}

/* Drop Zone */
.drop-zone {
    border: 2px dashed #cbd5e1;
    border-radius: 12px;
    padding: 32px 20px;
    text-align: center;
    background-color: #f8fafc;
    transition: all 0.2s ease;
    cursor: pointer;
}

.drop-zone:hover,
.drop-zone.drag-over {
    border-color: var(--brand-green);
    background-color: var(--brand-green-light);
}

.file-label {
    display: inline-block;
    background: var(--brand-green);
    color: #fff;
    padding: 9px 22px;
    border-radius: 8px;
    font-weight: 600;
    font-size: 0.9rem;
    cursor: pointer;
    transition: background 0.2s;
}

.file-label:hover {
    background: var(--brand-green-dark);
}

/* Buttons */
.calculate-btn {
    background: var(--brand-green);
    color: #fff;
    border: none;
    border-radius: 8px;
    cursor: pointer;
    transition: all 0.2s;
}

.calculate-btn:hover:not(:disabled) {
    background: var(--brand-green-dark);
    transform: translateY(-1px);
    box-shadow: 0 4px 12px rgba(1, 137, 77, 0.25);
}

.calculate-btn:disabled {
    background: #cbd5e1;
    cursor: not-allowed;
    transform: none;
    box-shadow: none;
}

.secondary-btn {
    background: #fff;
    color: #475569;
    border: 1px solid #cbd5e1;
    border-radius: 8px;
    font-weight: 600;
    cursor: pointer;
    transition: all 0.2s;
}

.secondary-btn:hover:not(:disabled) {
    background: #f1f5f9;
    border-color: #94a3b8;
    color: #1e293b;
}

.secondary-btn:disabled {
    background: #f8fafc;
    border-color: #e2e8f0;
    color: #94a3b8;
    cursor: not-allowed;
}

/* File List & Item Styling */
.file-item {
    background: #ffffff;
    border: 1px solid var(--border-color);
    border-radius: 10px;
    padding: 14px;
    transition: all 0.2s ease;
    cursor: grab;
}

.file-item:active {
    cursor: grabbing;
}

.file-item.dragging {
    opacity: 0.4;
    border-color: var(--brand-green);
    background: var(--brand-green-light);
}

.file-item.drag-over-top {
    border-top: 3px solid var(--brand-green);
}

.file-item.drag-over-bottom {
    border-bottom: 3px solid var(--brand-green);
}

.file-item:hover {
    border-color: #cbd5e1;
    box-shadow: 0 2px 8px rgba(0, 0, 0, 0.05);
}

.thumbnail-box {
    width: 60px;
    height: 80px;
    background: #f1f5f9;
    border: 1px solid #e2e8f0;
    border-radius: 4px;
    overflow: hidden;
    display: flex;
    align-items: center;
    justify-content: center;
    flex-shrink: 0;
}

.thumbnail-box canvas,
.thumbnail-box img {
    width: 100%;
    height: 100%;
    object-fit: cover;
}

/* Toast */
.toast {
    position: fixed;
    bottom: 24px;
    left: 50%;
    transform: translateX(-50%) translateY(100px);
    background: rgba(30, 41, 59, 0.95);
    color: #fff;
    padding: 10px 24px;
    border-radius: 30px;
    font-size: 0.875rem;
    font-weight: 500;
    box-shadow: 0 10px 15px -3px rgba(0, 0, 0, 0.2);
    opacity: 0;
    visibility: hidden;
    transition: all 0.3s cubic-bezier(0.16, 1, 0.3, 1);
    z-index: 9999;
}

.toast.show {
    transform: translateX(-50%) translateY(0);
    opacity: 1;
    visibility: visible;
}

/* Modals */
.modal {
    position: fixed;
    top: 0;
    left: 0;
    width: 100%;
    height: 100%;
    display: flex;
    align-items: center;
    justify-content: center;
    opacity: 0;
    visibility: hidden;
    transition: opacity 0.2s ease, visibility 0.2s ease;
    z-index: 1000;
    padding: 16px;
}

.modal.active {
    opacity: 1;
    visibility: visible;
}

.modal-overlay {
    position: absolute;
    top: 0;
    left: 0;
    width: 100%;
    height: 100%;
    background: rgba(15, 23, 42, 0.6);
    backdrop-filter: blur(2px);
}

.modal-content {
    position: relative;
    background: #fff;
    border-radius: 16px;
    padding: 20px 24px;
    width: 100%;
    box-shadow: 0 20px 25px -5px rgba(0, 0, 0, 0.2);
    z-index: 10;
}